Melaminium Tris Dihydrogen Phosphate (MTDP): A New Green and Sustainable Tricationic Ionic Liquid Catalyst for the Knoevenagel Synthesis of 5-Arylidene(thio)barbituric Acids in Water

Melaminium Tris Dihydrogen Phosphate (MTDP): A New Green and Sustainable Tricationic Ionic Liquid Catalyst for the Knoevenagel Synthesis of 5-Arylidene(thio)barbituric Acids in Water | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Melaminium Tris Dihydrogen Phosphate (MTDP): A New Green and Sustainable Tricationic Ionic Liquid Catalyst for the Knoevenagel Synthesis of 5-Arylidene(thio)barbituric Acids in Water Hossein Khorramabadi, Nader Daneshvar, Farhad Shirini, Hassan Tajik This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8718605/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study focuses on the preparation and characterization of melaminium tris dihydrogen phosphate (MTDP), a tricationic Brønsted acidic ionic liquid, through various advanced analytical techniques, including FT-IR, ¹H, ¹³C NMR and ³¹P NMR spectroscopies within a full comparative study between the TGA/DTG diagrams of melamine and MTDP. Following its comprehensive identification, MTDP was employed as an efficient and recyclable catalytic agent in the synthesis of 5-arylidene (thio)barbituric acid derivatives. The proposed methodology offers several notable advantages, such as high product yields (84–95%), rapid reaction rates (5–13 minutes), mild reaction conditions, and the utilization of low amounts of environmentally benign, non-toxic reagents (2 mol%). Physical sciences/Chemistry Earth and environmental sciences/Environmental sciences Tricationic liquid Melaminium Dihydrogen Phosphate 5-arylidene (thio)barbituric acid Knoevenagel reaction Mild reaction condition Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Ionic liquids (ILs) have garnered significant interest over the past two decades due to their unique physicochemical properties, including negligible vapor pressure, high thermal stability, non-flammability, and the capacity for tunable solubility and polarity through structural modification of their cationic and anionic components [ 1 , 2 ]. These features have propelled ILs into a wide array of applications, ranging from catalysis and electrochemistry to separation processes and material science [ 3 , 4 ]. Melamine (1,3,5-triazine-2,4,6-triamine) is a nitrogen-rich heterocyclic compound widely recognized for its affordability, rigidity, and high thermal stability. Owing to its symmetrical triazine ring and multiple exocyclic amine groups, melamine serves as an ideal scaffold for the development of functionalized ILs, particularly those with polycationic architectures [ 5 ]. The preparation of melamine was first reported by Justus Von Liebig, a German chemist in 1834 via heating the potassium thiocyanate and ammonium chloride [ 5 ]. The term “Melamine” is a combination of two terms, “Melam” (a residue of heating ammonium thiocyanate) and “Amine” [ 6 ] (Scheme 1 ). Melamine is a compound that demonstrates limited solubility in water under ambient conditions, with a measured solubility of 3.1 g/L at 25°C. However, its solubility significantly increases in water at elevated temperatures, reaching a notable 51 g/L at 99°C. This pronounced enhancement in solubility as a function of temperature is primarily attributed to the thermal disruption of hydrogen bonds within water molecules, which facilitates the dissolution process. Such a property proves particularly beneficial in industrial settings, where melamine is frequently processed under high-temperature conditions. This is especially pertinent in the production of melamine-formaldehyde resins, where the improved solubility at elevated temperatures is utilized to optimize the efficiency and effectiveness of material synthesis, thereby aligning with key manufacturing objectives [ 7 – 9 ]. This compound is typically not classified as acutely toxic, largely owing to its relatively high lethal dose (LD50) values. In rats, melamine exhibits LD 50 levels ranging between 3.1 g/kg and over 6.4 g/kg, while in mice, these values extend from 3.2 g/kg to 7.0 g/kg. Nevertheless, it can be harmful in higher concentrations and prolonged exposure, according to studies [ 10 ]. In the recent decade, the preparation and application of melamine-based ionic liquids and catalysts such as tribromomelamine [ 11 ], melamine trisulfonic acid [ 12 ], and melaminium hydrogen sulfide / melaminium nitrate [ 13 ] in various organic transformations have been attended due to their high efficiency, low toxicity, and affordability. The Knoevenagel condensation is a landmark reaction in organic chemistry, renowned for its ability to form carbon–carbon bonds by enabling the condensation of aldehydes or ketones with active methylene-containing compounds under mild conditions. Typically carried out in the presence of a weak base, such as a secondary amine or an ammonium salt, this reaction was first introduced by Emil Knoevenagel in 1896. Over time, it has gained significant importance for synthesizing α,β-unsaturated compounds and various heterocyclic structures. Its broad applicability stems from advantages like gentle reaction requirements, high atom efficiency, and the remarkable versatility of the substrates involved [ 14 , 15 ]. Barbituric acid, commonly referred to as malonylurea or 6-hydroxyuracil, is a pivotal organic compound characterized by its pyrimidine-based heterocyclic structure. Presented as an odorless, crystalline powder, it exhibits solubility in water, facilitating its utility in various chemical and pharmaceutical contexts. Although barbituric acid itself lacks inherent pharmacological activity, it serves as the foundational precursor for the synthesis of barbiturates, a pharmacological class renowned for their sedative and hypnotic effects. The chemical framework of barbituric acid permits modification through the substitution of specific carbon atoms within its structure, enabling the production of a diverse array of barbiturate derivatives [16]. While the parent compound (barbituric acid) lacks intrinsic pharmacological activity, its derivatives display marked bioactivity across various domains. Notably, those modifications involving alkyl substitutions at the carbon-5 position have demonstrated significant therapeutic potential, including hypnotic, anesthetic, and antiepileptic effects, such as Phenobarbital. Barbiturate derivatives exhibit acute toxicity that can lead to central nervous system dysfunction, significant respiratory distress, and unstable hemodynamics. Additionally, their use may trigger allergic responses, including potentially life-threatening anaphylactic shock [17–19] (Scheme 2 ). 5-Arylidene (thio)barbituric acids are enduringly useful Knoevenagel adducts that combine a strongly electron-withdrawing barbiturate core with a tunable arylidene π-fragment. This push–pull architecture underpins their broad utility as chromophores, ligands, corrosion inhibitors, and bioactive scaffolds [20,21]. Due to the importance of the 5-arylidene (thio) barbituric acid in organic chemistry, various types of catalysts have been reported for the promotion of their synthesis. Some of them are [Bmim][BF 4 ] [ 22 ], H 2 NSO 3 H [ 23 ], Diammonium hydrogen phosphate [ 24 ], PVP-Ni [ 25 ], CeO 2 :MgO:ZrO 2 (1:0.6:0.4) [26], [Nmm-PDO][OAc] [ 27 ], Taurine [ 28 ], [H 2 -Pip][H 2 PO 4 ] 2 [ 29 ], [H 2 -Bisim][HSO 4 ] and [H 2 -Bisim][ClO 4 ] [ 30 ], [TPPHSP]Br [ 31 ], [2,2′-H 2 -Bipy][H 2 PO 4 ] 2 [ 32 ], Fe 3 O 4 – NPs [ 33 ], [H-Succinimide][ClO 4 ] [ 34 ], Graphite electrode / NaBr (0.1 M) [ 35 ] and [PEI-Mim][Cl] [36]. In this research, in continuation of our previous works on the introduction of various types of catalysts for the Knoevenagel reaction between barbituric acid derivatives and aldehyde to achieve 5-arylidene (thio)barbituric acid derivatives, and in order to solve some of the restrictions which are accompanied with the use of above-mentioned catalysts, we have introduced an green and affordable melamine tris dihydrogen phosphate, [H 3 -Melamaine][H 2 PO 4 ] 3 , as a tri-cationic organic salt from the combination of melamine and phosphoric acid in a mild and safe condition. Experimental Materials All chemical reagents used in this study, including solvents, aldehydes, barbituric acid, malononitrile, and dimedone, were procured from Merck Chemical Company, Munich, and were used as received without undergoing further purification processes. The progression of the reactions was systematically monitored using Thin Layer Chromatography (TLC) as the analytical technique. Characterization techniques The substrate's purity analysis and reaction monitoring were performed using thin-layer chromatography (TLC) on silica-gel Polygram SILG/UV 254 plates. Melting points were determined with an electrothermal IA9100 melting point apparatus, employing open capillaries. Fourier-transform infrared (FT-IR) spectra of samples prepared in KBr disks were captured using a Perkin-Elmer Spectrum BX series instrument. Thermogravimetric Analysis (TGA) was performed using a THERMO-NIKOLET STA 1500. Nuclear magnetic resonance (NMR) spectra, including 1 H, 13 C, and 31 P, were acquired on a Bruker 400 MHz spectrometer with deuterated DMSO- d 6 as the solvent. Chemical shifts were reported in δ (ppm) units, utilizing tetramethylsilane (TMS) as the internal standard. The mass diagram was gained using an Agilent Technologies device model G708, 1B MSD with Tripe-Axis Detector (EI, 20–70 eV). Preparation of melaminium tris dihydrogen phosphate [H-Melamine][HPO] In a 50 mL round-bottom flask kept in an ice bath, 10 mmol (1.26 g) of melamine was mixed with 20.0 mL of freshly distilled dichloromethane and stirred. Over the course of 10 minutes, excess phosphoric acid (2.4 mL, roughly 35 mmol) was added gradually dropwise into the solution carefully. After completing the addition process, the reaction mixture was left to stir at room temperature for a duration of 24 hours. Following this, the solvent was carefully decanted, and the resulting white solid was systematically washed several times, first using diethyl ether (three washes of 25 mL each), then ethanol (two washes of 20 mL each). These washes effectively removed any non-ionic residues. The product was subsequently dried using a rotary evaporator, yielding highly pure melaminium tris dihydrogen phosphate (MTDP) with an impressive 94% yield (3.95 g) as shown in Scheme 3 . Characterization data for melamine White powder; M.P. = 343 ℃ Dec; FT-IR (KBr, cm − 1 ) υ max : 3469, 3418, 3331, 3127, 2195, 1651, 1547, 1434, 1023, 812,; 1 H NMR (400 MHz, DMSO- d 6 ) (ppm): 6.10 (brs, 6H, 3x NH 2 ); 13 C NMR (100 MHz, DMSO- d 6 ) (ppm): 168.0; ( 1 H NMR and 13 C NMR spectra and data of melamine are obtained from different reliable sorces [ 37 – 39 ]). Characterization data of melaminium tris dihydrogen phosphate [H 3 -Melamine][H 2 PO 4 ] 3 White powder; M.p. = 240 ℃ Dec; FT-IR (KBr, cm − 1 ) υ max : 3397, 3152, 2960, 2930,1729,1670,1513, 1239, 1181, 1066, 963, 897, 705, 503; 1 H NMR (400 MHz, DMSO- d 6 ) (ppm): 6.76 (s, 9H, 3x NH 3 + ), 8.57 (brs, 6H, 3 x H 2 PO 4 ); 13 C NMR (100 MHz, DMSO- d 6 ) (ppm): 164.8; 31 P NMR (162 MHz, DMSO- d 6 ) (ppm): 0.31 (H 2 PO 4 − ). General procedure for the synthesis of 5-Arylidene (thio)barbituric acid derivatives In a 10 mL round-bottom flask, an aromatic aldehyde (1 mmol), (1,3-dimethyl) barbituric acid or thioarbituric acid (1 mmol) and catalyst [H 3 -Melamine][H 2 PO 4 ] 3 (0.010 g, 2 mol%) were combined in 4 mL of water. The mixture was stirred at 80°C while reaction progress was monitored by TLC using a n -hexane/ethyl acetate/Ethanol (7:3:1 ratio) solvent system. After completion, the mixture was cooled to room temperature, followed by the addition of 5 mL of water and 2 minutes of stirring to isolate the catalyst. The residue was filtered, oven-dried at 60°C, and obtained with no further purification required. Physical and spectral data of 5-(3-bromobenzylidene)-2-thioxodihydropyrimidine-4,6(1 H , 5 H )-dione (New compound) Yellow solid; Melting point: 282–283 ℃; FT-IR (KBr, cm − 1 ) υ max : 3447, 3066, 2908, 2603, 1654, 1538,1198, 671(C-Br); 1 H NMR (400 MHz, DMSO- d 6 ) (ppm): 5.98 (d, J = 0.8Hz, 1H, C = C-H), 7.02 (dq, J 1 = 4.0 Hz, J 2 = 1.2 Hz, 1H, Ar-H), 7.10 (q, J = 1.2 Hz, 1H, Ar-H), 7.17 (t, J = 8.0 Hz, 1H, Ar-H), 7.28 (dquin, J 1 = 8.0 Hz, J 2 = 1.2 Hz, 1H, Ar-H), 11.63 (s, 1H, -NH) 11.80 (brs, 1H, -NH). MS (70 eV, EI) Molecular ion m/z: 311.9 (M + 2), 309.9 (M). Results and discussion In recent decades, significant progress has been achieved in the development of innovative catalytic systems aimed at enhancing organic transformations, which has become a central focus of ongoing research initiatives. Over the past three decades, our efforts have been concentrated on improving the efficiency and performance of both heterogeneous and homogeneous catalysts while addressing inherent limitations. Within this research framework, particular emphasis has been placed on the design, synthesis, characterization, and functional applications of Brønsted acidic ionic liquids. As an extension of these endeavors, this study details the synthesis and comprehensive characterization of [H 3 -Melamine][H 2 PO 4 ] 3 through advanced analytical methodologies, including FT-IR, 1 H NMR, 13 C NMR, and 31 P NMR spectroscopies within TGA/DTG thermal analysis. Experimental results underscore the efficacy of this compound as a catalytic agent, particularly in facilitating reactions that benefit from acidic conditions to accelerate chemical processes. Additionally, its catalytic performance was systematically evaluated in the synthesis of a wide array of 5-arylidene (thio)barbituric acid compounds, yielding promising outcomes that highlight its practical applicability in organic synthesis. Characterization of the catalyst FT-IR analysis of [H 3 -Melamine][H 2 PO 4 ] 3 The FT-IR analysis reveals significant spectral changes upon the transformation of melamine to MTDP. Notably, the disappearance of two characteristic peaks at 3469 cm − ¹ and 3418 cm − ¹, corresponding to the symmetric and asymmetric stretching of NH 2 groups in melamine, which indicates their conversion into NH 3 + in the MTDP spectrum. A broad absorption band spanning 3500 − 3000 cm − ¹ is attributed to acidic hydrogen bonding within the compound. Additionally, a broader peak in the region of 3150 − 3030 cm − ¹ is associated with aromatic C–H stretching vibrations. The O-H bending vibration is clearly manifested as a distinct peak at 1670 cm − ¹. The P = O asymmetric vibrations are represented by the peak at 1239 cm − ¹, while peaks at 1181 cm − ¹ and 1066 cm − ¹ correspond to the P-O asymmetric and symmetric stretching vibrations, respectively. Furthermore, a pronounced peak at 503 cm − ¹ indicates the stretching vibrations of P-O-H (Fig. 1 ). NMR spectroscopy 1 H NMR spectroscopy [H 3 -Melamine][H 2 PO 4 ] 3 In the 1 H NMR spectrum of [H 3 -Melamine][H 2 PO 4 ] 3 , a distinct peak appearing at 6.76 ppm with an integral value of nine corresponds to the three NH 3 + groups within the melaminium moiety. Additionally, a broad singlet observed at 8.57 ppm with an integral value of six is associated with the three H 2 PO 4 counter-anions (Fig. 2 ). Comparison between 1 H NMR spectra of melamine and [H 3 -Melamine][H 2 PO 4 ] 3 Investigation on the 1 H NMR of melamine in DMSO obtained from some other reliable sources indicates that the chemical shift for NH 2 groups of melamine has always been between 5.95–6.10 ppm [ 37 – 39 ]. This range of fluctuation may be due to calibration, temperature, purity of solvent, etc, but it never reaches 6.20 ppm (Fig. 1 ). In this research, after the reaction of melamine with phosphoric acid and the conversion of NH 2 to NH 3 + , a noticeable chemical shift to lower fields is observed (6.76 ppm). Among all reactions and catalyst introduction using melamine, this is the first time that this observation is reported with the precise assignment of the chemical shift of H 2 PO 4 hydrogens (Fig. 2 ). 13 C NMR spectroscopy [H 3 -Melamine][H 2 PO 4 ] 3 The 13 C NMR spectrum of [H 3 -Melamine][H 2 PO 4 ] 3 reveals a single peak at 164.8 ppm, which is indicative of the presence of a single chemically distinct carbon environment within its molecular framework (Fig. 3 ). Based on the above-mentioned references, the chemical shift of the melamine carbon in DMSO is 168.0 ppm, showing a little upfield shift in MTDP. 31 P NMR spectroscopy [H 3 -Melamine][H 2 PO 4 ] 3 The 31 P NMR spectrum of [H 3 -Mel][H 2 PO 4 ] 3 exhibits a single peak at 0.31 ppm, corresponding to the phosphorus atom in the H 2 PO 4 − counter-anions. This observation confirms the presence of dihydrogen phosphate anions within the composition of the solid organic salt (Fig. 4 ). Thermogravimetric Analysis TGA/DTG of melamine Analysis of the TGA/DTG graph for melamine highlights a distinct thermal decomposition process characterized by a single phase, which occurs over a narrow temperature interval spanning from 320℃ to 350℃. This swift and definitive one-step degradation underscores the transformation of melamine into ammonia, along with a mixture of other volatile compounds. The outcome of this process is noteworthy as it completely prevents the formation of any residual material, emphasizing the efficiency and completeness of the thermal breakdown. The TGA/DTG analysis of MTDP exhibits a small peak at 50°C, indicative of the removal of organic solvent from the compound's framework. Upon protonation of melamine by phosphoric acid, its decomposition pathway is distinctly modified. The dihydrogen phosphate anion acts as a catalyst, accelerating both condensation and dehydration reactions, while phosphorus promotes robust char formation. This degradation process unfolds through multiple stages, starting with an acid-catalyzed reaction occurring between 220°C and 240°C. This is followed by intensified condensation and structural breakdown within the range of 310°C to 350°C. Finally, pyrolysis ensues at approximately 400°C, accompanied by a complete structural collapse and significant char production, driven by phosphorus as an efficient charring agent. The comparative analysis of the thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) diagrams for melamine and MTDP reveals several significant distinctions. Firstly, while the degradation process of the melamine structure occurs in a single step, MTDP undergoes a multi-stage degradation mechanism. Secondly, melamine remains thermally stable and does not exhibit any measurable degradation below approximately 340°C. In contrast, MTDP demonstrates its initial degradation phase at a considerably lower temperature, around 240°C, which was also confirmed by the observation of turbidity during melting point assessment. Furthermore, MTDP undergoes successive stages of thermal breakdown spanning temperatures up to 400°C. Lastly, post-degradation analysis indicates that melamine leaves approximately no residue at 340°C, whereas MTDP retains approximately 35% of its original mass as char, persisting up to 600°C. In the end, the differences between the catalyst and the starting material are clearly noticeable based on the aspects discussed above. Furthermore, given the catalyst's full thermal stability up to 240 degrees and the annealing temperature referenced in this study, which is 80 degrees, it can be concluded that the catalyst maintains complete physical stability throughout the reaction process, with no structural alterations caused by the reaction temperature. Catalytic activity of [H 3 -Melamine][H 2 PO 4 ] 3 Optimization of the reaction After successfully synthesizing and characterizing MTDP, the molecular structure revealed polar sites that demonstrated significant promise for serving as an efficient catalytic agent in chemical reactions requiring a moderately acidic environment to enhance reaction rates. So, the potential applications of MTDP as a catalyst were further investigated, specifically through its utilization in the preparation of various 5-arylidene (thio)barbituric acid derivatives. In pursuit of ideal reaction conditions, critical parameters such as the quantity of the catalyst, the choice of solvent, and the appropriate reaction temperature were systematically evaluated. To refine these factors, the synthesis of a barbituric acid derivative using 4-chlorobenzaldehyde was conducted under diverse experimental settings. The optimization process led to the identification of conditions that delivered superior results. The data clearly highlight the most effective combination of parameters for achieving high efficiency and product yield, which is the use of 10 mg of the catalyst, in water at 80 ℃ for 1 mmol of the reactants (Table 1 ). Table 1 Optimizing the reaction conditions in the synthesis 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione Entry Catalyst (mg) Solvent Temp. ( o C) Time (min.) Conversion yield (%) 1 --- --- 100 120 Trace 2 10 --- 100 120 Trace 3 20 --- 110 120 Trace 4 10 CH 3 CN Reflux 120 40 a 5 10 CH 3 Cl Reflux 120 Trace 6 10 C 2 H 5 OH r.t. 120 25 a 7 10 C 2 H 5 OH Reflux 120 55 a 8 10 H 2 O r.t. 90 45 a 9 10 H 2 O 50 40 78 b 10 5 H 2 O 80 14 90 b 11 10 H 2 O 60 9 90 b 12 10 H 2 O 80 5 94 b 13 10 H 2 O Reflux 4 86 b 14 15 H 2 O 80 13 88 b 15 10 H 2 O/EtOH (1:1) 80 25 81 b a Not completed, b Isolated yields. Derivation step To evaluate the broad applicability of this approach, a range of aromatic aldehydes incorporating both electron-withdrawing and electron-donating functional groups was employed in the reaction. Furthermore, thiobarbituric acid and 1,3-dimethyl barbituric acid were utilized as substitutes for barbituric acid to expand the scope of the study (Scheme 4 ). Aldehydes containing halogen substituents exhibit a significantly higher reaction rate compared to other aldehydes when utilizing MTDP as the catalyst. Although the changes are not very distinguished but it can be concluded that aldehydes containing electron-withdrawing groups on aromatic ring demonstrate a little higher reactivity to those containing electron-donating groups, highlighting the influence of the substituent effects on the catalytic efficiency (Table 2 ). Also, comparison of the reactivity between barbituric acid, thiobarbituric acid shows that the reactivity of barbituric and thiobarbituric acid is approximately close and a little higher than dimethyl barbituric acid. These observations may be related to the stability of the related activated aldehydes, intermediates, and also the acidic strength of the barbituric derivatives and stability of their enolates. Table 2 Synthesis of 5-arylidene barbituric acid derivatives in the presence of MTDP in water. Entry Ar R X Time (Min.) Yield (%) a Melting point ( o C) Ref. Observed Reported 1 Ph H O 8 90 256–258 259–261 [ 28 ] 2 2-Cl-Ph H O 7 91 252–254 249–251 [ 30 ] 3 3-Cl-Ph H O 7 90 268–269 271–273 [ 33 ] 4 4-Cl-Ph H O 5 94 296–298 298–300 [ 31 ] 5 3-Br-Ph H O 6 89 281–283 278–280 [ 40 ] 6 4-Br-Ph H O 8 92 291–292 292–294 [ 30 ] 7 4-F-Ph H O 7 86 255–258 254–255 [ 31 ] 8 2-NO 2 -Ph H O 5 91 274–276 274–276 [ 30 ] 9 3-NO 2 -Ph H O 7 95 235–236 234–236 [ 30 ] 10 4-NO 2 -Ph H O 7 93 269–270 268–270 [ 31 ] 11 2-OMe-Ph H O 9 88 264–267 269–271 [ 29 ] 12 3-MeO-Ph H O 12 84 227–230 230–232 [ 30 ] 13 4-MeO-Ph H O 12 90 228–230 229–230 [ 28 ] 15 4-Me-Ph H O 11 87 273–275 274–276 [ 28 ] 16 2-Furanyl H O 7 90 262–263 260–262 [ 30 ] 17 2-Thiophenyl H O 8 86 270–272 273 [ 41 ] 18 2-NMe-pyrrol H O 6 92 280 Dec 280 Dec [ 30 ] 19 Ph Me O 13 88 162–164 160 [ 42 ] 20 4-Cl-Ph Me O 8 91 170–172 170–172 [ 43 ] 21 3-Br-Ph Me O 9 88 154–156 151–153 [ 44 ] 22 3-NO 2 -Ph Me O 9 93 147–149 146–149 [ 45 ] 23 4-NO 2 -Ph Me O 10 95 192–194 193–195 [ 45 ] 24 4-MeO-Ph Me O 16 87 142–144 143–145 [ 45 ] 25 Ph H S 7 86 269–271 271–272 [ 34 ] 26 4-Cl-Ph H S 6 91 288–290 286–289 [ 28 ] 27 3-Br-Ph H S 5 85 282–283 new new 28 3-NO 2 -Ph H S 7 92 265–266 266 − 258 [46] 29 4-NO 2 -Ph H S 7 92 243–245 240–242 [ 34 ] 30 4-MeO-Ph H S 10 87 295–297 296–298 [46] a Isolated yields Comparison of the catalyst performance The findings from our study were carefully compared with the previously documented data in existing scientific literature concerning the synthesis of 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione derivatives. Particular emphasis was placed on examining the impact of variables such as the amount of the catalyst used, the duration required for the reaction to complete, and the yield of the resultant product. Through this comparative analysis, it became evident that some alternative approaches described in the literature tend to demand either significantly higher quantities of catalysts, prolonged reaction times, or a combination of both. Additionally, some of these methods demand complex multi-step synthesis processes and rely on non-ecofriendly materials or conditions during catalyst preparation or separation steps (Table 3 ). Table 3 Evaluation of the outcomes from synthesizing 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione derivatives using [H 3 -Melamine][H 2 PO 4 ] 3 in comparison with some previously documented results in the scientific literature. Entry Catalyst Solvent Amount Temp (℃) Time (Min.) Yield (%) TON TOF Ref. 1 [Bmim][BF 4 ] - 48 mol% r.t. 125 78 1.62 0.78 [ 22 ] 2 H 2 NSO 3 H - 50 mol% r.t. 180 93 1.86 0.62 [ 23 ] 3 Diammonium hydrogen phosphate EtOH/H 2 O (1:1) 10 mol% r.t. 120 81 a 8.10 4.05 [ 24 ] 4 PVP-Ni Ethylene glycol 1.5 mol% 50 10–15 93 62 298 [ 25 ] 5 CeO 2 :MgO:ZrO 2 (1:0.6:0.4) EtOH 0.2 g 60–70 60 85 - - [26] 6 [Nmm-PDO][OAc] b H 2 O 20 mol% r.t. 1200 94 4.7 0.24 [ 27 ] 7 Taurine H 2 O 20 mol% 80 9 96 4.8 32 [ 28 ] 8 [H 2 -Pip][H 2 PO 4 ] 2 EtOH/H 2 O (1:1) 5 mol% 80 20 96 19.2 57.6 [ 29 ] 9 [TPPHSP]Br c EtOH/H 2 O (3:1) 2 mol% Reflux 10 93 46.5 279 [ 30 ] 10 [2,2′‑H 2 -Bipy][H 2 PO 4 ] 2 H 2 O 3 mol% 70 10 95 31.7 190 [ 31 ] 11 Fe 3 O 4 -NPs EtOH 20 mole% Reflux 30 93 4.65 9.3 [ 32 ] 12 [H-Succinimide][ClO 4 ] H 2 O 2.5 mol% 80 5 98 39.2 470 [ 33 ] 13 Graphite electrode / NaBr (0.1 M) H 2 O 20 mA 70 6 80 - - [ 34 ] 14 [PEI-Mim][Cl] d H 2 O 20 mol% r.t. 240 90 4.5 1.13 [ 35 ] 15 [H 3 -Melamine][H 2 PO 4 ] 3 (this work) H 2 O 2 mol% 80 5 94 47 564 - (a) 4-Bromo benzaldehyde derivative (b) N -methyl morpholine (Nmm) based ionic liquid (c) Triphenyl(propyl-3-hydrogen sulfate)phosphonium bromide (d) Polyethyleneimine supported in methylimidazolium chloride Mechanism study The proposed method for synthesizing 5-arylidene (thio)barbituric acid derivatives demonstrates that the carbonyl group of the aldehyde is initially activated by the acidic hydrogen atoms from the catalyst (MTDP). This activation enhances its susceptibility to nucleophilic attack by the active methylene group in (thio)barbituric acid. As a result, the intermediate (I) is formed which subsequently, facilitated by MTDP, a water molecule is eliminated from this intermediate, ultimately yielding the final product containing a carbon-carbon double bond (Scheme 5 ). Reusability of the catalyst The reusability of the catalyst was assessed through the synthesis of 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1 H ,3 H ,5 H )-trione. To show its compatibility with green chemistry rules, after the reaction concluded, the resulting mixture was filtered. The process was then repeated using the filtered solution without adding fresh catalyst. This method confirmed that the catalyst could be reused for up to five successive cycles with negligible changes in reaction time and yield throughout all trials (Fig. 5 ). The FT-IR spectrum of the recovered catalyst after five cycles shows a high level of structural stability during the reaction conditions. The observed broad absorption in the 3300–3500 cm -1 region, which covered the NH 3 + , is related to the absorbed water in the structure of the ionic liquid catalyst, which is predictable for this ionic structure. The existence of the stretching C = N vibrations at 1673 cm -1 and bending N-H vibrations of the melamine between 1570–1615 cm -1 and also, distinguished bunch of vibrations related to H 2 PO 4 - in the area of 800–1250 cm -1 is evidence of maintaining the catalyst structure as the starting form. Conclusion This study presents a methodical and uncomplicated approach to synthesizing melamine tris dihydrogen phosphate, formulated as [H 3 -Melamine][H 2 PO 4 ] 3 and commonly referred to as MTDP. The compound is prepared through the reaction of melamine with phosphoric acid under exceptionally mild and controlled conditions. Comprehensive characterization of the synthesized MTDP was conducted using FT-IR, 1 H, 13 C, and 31 P NMR spectroscopies, and thermogravimetric analysis to confirm its structural and thermal properties. After successful synthesis and characterization, MTDP was utilized as a novel and highly efficient three-cationic ionic liquid catalyst in the production of 5-arylidene (thio)barbituric derivatives. These derivatives were synthesized from easily available and inexpensive starting materials, showcasing the versatility and applicability of the method. The proposed synthetic procedure offers numerous advantages, such as a straightforward and rapid product separation process, significantly short reaction times (5–13 minutes), exceptional yields (84–95%), in the presence of very low amounts of the catalyst (2 mol%), and environmentally friendly catalytic properties. Moreover, it ensures economical operation and adheres to mild reaction conditions, making it a highly appealing and sustainable approach for such chemical transformations. Also, this development paves the way for innovative, unexplored catalyst design and characterization methods based on melamine, and also for new material research, such as flame-retardant materials. Declarations Acknowledgments We appreciate the help of the Research Council of the University of Guilan in doing this study. Statement of author contributions based on CRediT Hossein Khorramabadi: Writing-original draft, Methodology, Investigation. Nader Daneshvar: Conceptualization, Validation, Formal analysis . Farhad Shirini: Conceptualization, Validation, Formal analysis, Data curation, Writing the final version of the article. Hassan Tajik de: Formal analysis, Writing- original draft. Data availability The data that support the findings of this study are available from the corresponding author upon reasonable request. Funding The authors received no financial support for the research publication of this article. Conflict of Interest The authors declare no conflict of interest. References Y. Hu, Y. Xing, H. Yue, T. Chen, Y. Diao, W. Wei, S. Zhang, Ionic liquids revolutionizing biomedicine: recent advances and emerging opportunities, Chem. Soc. Rev. 52 (2023) 7262-7293, https://doi.org/10.1039/D3CS00510K H. Guo, J. Pang, P. Iglesias, Recent Advances and Challenges of Ionic Liquids in Tribology. In: Ionic Liquids-Recent Advances. IntechOpen, (2024), https://doi.org/10.5772/intechopen.1005538 N. Matmat, A. Abdelaziz, D. Trache, A. Sabrina, A.F. Tarchoun, A comprehensive investigation of 1,3-dibutylimidazolium nitrate ionic liquid as a green energetic oxidizer: From design to thermal stability assessment, J. Mol. 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Chem. 50 (2012) 266-270, https://doi.org/10.1002/mrc.2858 N. Seyyedi, F. Shirini, M.S.N. Langarudi, DABCO-based ionic liquids: green and recyclable catalysts for the synthesis of barbituric and thiobarbituric acid derivatives in aqueous media, RSC Adv. 6 (2016) 44630-44640. http://dx.doi.org/10.13005/ojc/380323 Schemes Schemes are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Supplementaryfile.docx Schemes.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8718605","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":607959416,"identity":"003710ec-7d32-4cb4-9b8b-cbdb4aa5edab","order_by":0,"name":"Hossein Khorramabadi","email":"","orcid":"","institution":"University of Guilan","correspondingAuthor":false,"prefix":"","firstName":"Hossein","middleName":"","lastName":"Khorramabadi","suffix":""},{"id":607959417,"identity":"3ebebc80-d078-4fda-aca1-9069c3e8d471","order_by":1,"name":"Nader Daneshvar","email":"","orcid":"","institution":"University of 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16:12:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":23751,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic comparison of the \u003csup\u003e1\u003c/sup\u003eH NMR chemical shift peaks between NH\u003csub\u003e2\u003c/sub\u003e in melamine and NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e in MTDP in DMSO.\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/eb8fb40ee6cc0274f7380099.png"},{"id":104916051,"identity":"62b1b6ef-f9a6-4f71-a99f-18fc7ba9d9fc","added_by":"auto","created_at":"2026-03-18 16:12:46","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":287638,"visible":true,"origin":"","legend":"\u003cp\u003e\u003csup\u003e13\u003c/sup\u003eC NMR spectrum (100 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/94d672f60307e5c6fbf2424d.png"},{"id":105034294,"identity":"f5607dbf-bdc0-4f07-b2d0-26b8d98c2799","added_by":"auto","created_at":"2026-03-20 07:23:02","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":273692,"visible":true,"origin":"","legend":"\u003cp\u003e\u003csup\u003e31\u003c/sup\u003eP NMR (162 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e.\u003c/p\u003e","description":"","filename":"floatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/f14d4ae8dd82831994dbfa22.png"},{"id":105034524,"identity":"f67c431d-66b4-411f-a87e-85615477bf41","added_by":"auto","created_at":"2026-03-20 07:23:29","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":410037,"visible":true,"origin":"","legend":"\u003cp\u003eTGA/DTG diagrams of melamine (a) and MTDP (b)\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/fc86b7bc9186541491d97f87.png"},{"id":105034043,"identity":"b586f08b-2895-429a-80ac-f3f2946a55c5","added_by":"auto","created_at":"2026-03-20 07:22:30","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":53349,"visible":true,"origin":"","legend":"\u003cp\u003eReusability of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e in the synthesis of 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1\u003cem\u003eH\u003c/em\u003e,3\u003cem\u003eH\u003c/em\u003e,5\u003cem\u003eH\u003c/em\u003e)-trione\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/fcc4eb9443485c17fd0662e8.png"},{"id":104916049,"identity":"696cf410-15f7-49ad-a3e3-40e41915a88a","added_by":"auto","created_at":"2026-03-18 16:12:46","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":213913,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR spectra of the recovered MTDP catalyst after 3 recycles.\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/dc8cd05c91d277318d55f43f.png"},{"id":106959420,"identity":"3d49c8ec-3baf-4003-b45d-1cd5c1bf2e3d","added_by":"auto","created_at":"2026-04-15 09:08:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3183730,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/fa85392e-586d-4e6c-86d3-5fba18d747ba.pdf"},{"id":105034590,"identity":"a4b4d7b8-4169-423d-bdd5-2aa2f66b5ca9","added_by":"auto","created_at":"2026-03-20 07:23:40","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1359956,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryfile.docx","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/67a662413d2dfede7cf4ec4c.docx"},{"id":105034342,"identity":"dcfceec1-e648-4a4c-ba58-151126c922fd","added_by":"auto","created_at":"2026-03-20 07:23:09","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":93897,"visible":true,"origin":"","legend":"","description":"","filename":"Schemes.docx","url":"https://assets-eu.researchsquare.com/files/rs-8718605/v1/07a50711ae33585b45cb4c63.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Melaminium Tris Dihydrogen Phosphate (MTDP): A New Green and Sustainable Tricationic Ionic Liquid Catalyst for the Knoevenagel Synthesis of 5-Arylidene(thio)barbituric Acids in Water","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIonic liquids (ILs) have garnered significant interest over the past two decades due to their unique physicochemical properties, including negligible vapor pressure, high thermal stability, non-flammability, and the capacity for tunable solubility and polarity through structural modification of their cationic and anionic components [\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e]. These features have propelled ILs into a wide array of applications, ranging from catalysis and electrochemistry to separation processes and material science [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMelamine (1,3,5-triazine-2,4,6-triamine) is a nitrogen-rich heterocyclic compound widely recognized for its affordability, rigidity, and high thermal stability. Owing to its symmetrical triazine ring and multiple exocyclic amine groups, melamine serves as an ideal scaffold for the development of functionalized ILs, particularly those with polycationic architectures [\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe preparation of melamine was first reported by Justus Von Liebig, a German chemist in 1834 \u003cem\u003evia\u003c/em\u003e heating the potassium thiocyanate and ammonium chloride [\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e]. The term “Melamine” is a combination of two terms, “Melam” (a residue of heating ammonium thiocyanate) and “Amine” [\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e] (Scheme \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003e\u003c/h3\u003e\n\u003cp\u003eMelamine is a compound that demonstrates limited solubility in water under ambient conditions, with a measured solubility of 3.1 g/L at 25°C. However, its solubility significantly increases in water at elevated temperatures, reaching a notable 51 g/L at 99°C. This pronounced enhancement in solubility as a function of temperature is primarily attributed to the thermal disruption of hydrogen bonds within water molecules, which facilitates the dissolution process. Such a property proves particularly beneficial in industrial settings, where melamine is frequently processed under high-temperature conditions. This is especially pertinent in the production of melamine-formaldehyde resins, where the improved solubility at elevated temperatures is utilized to optimize the efficiency and effectiveness of material synthesis, thereby aligning with key manufacturing objectives [\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e–\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e]. This compound is typically not classified as acutely toxic, largely owing to its relatively high lethal dose (LD50) values. In rats, melamine exhibits LD\u003csub\u003e50\u003c/sub\u003e levels ranging between 3.1 g/kg and over 6.4 g/kg, while in mice, these values extend from 3.2 g/kg to 7.0 g/kg. Nevertheless, it can be harmful in higher concentrations and prolonged exposure, according to studies [\u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the recent decade, the preparation and application of melamine-based ionic liquids and catalysts such as tribromomelamine [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e], melamine trisulfonic acid [\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e], and melaminium hydrogen sulfide / melaminium nitrate [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e] in various organic transformations have been attended due to their high efficiency, low toxicity, and affordability.\u003c/p\u003e \u003cp\u003eThe Knoevenagel condensation is a landmark reaction in organic chemistry, renowned for its ability to form carbon–carbon bonds by enabling the condensation of aldehydes or ketones with active methylene-containing compounds under mild conditions. Typically carried out in the presence of a weak base, such as a secondary amine or an ammonium salt, this reaction was first introduced by Emil Knoevenagel in 1896. Over time, it has gained significant importance for synthesizing α,β-unsaturated compounds and various heterocyclic structures. Its broad applicability stems from advantages like gentle reaction requirements, high atom efficiency, and the remarkable versatility of the substrates involved [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBarbituric acid, commonly referred to as malonylurea or 6-hydroxyuracil, is a pivotal organic compound characterized by its pyrimidine-based heterocyclic structure. Presented as an odorless, crystalline powder, it exhibits solubility in water, facilitating its utility in various chemical and pharmaceutical contexts. Although barbituric acid itself lacks inherent pharmacological activity, it serves as the foundational precursor for the synthesis of barbiturates, a pharmacological class renowned for their sedative and hypnotic effects. The chemical framework of barbituric acid permits modification through the substitution of specific carbon atoms within its structure, enabling the production of a diverse array of barbiturate derivatives [16]. While the parent compound (barbituric acid) lacks intrinsic pharmacological activity, its derivatives display marked bioactivity across various domains. Notably, those modifications involving alkyl substitutions at the carbon-5 position have demonstrated significant therapeutic potential, including hypnotic, anesthetic, and antiepileptic effects, such as Phenobarbital. Barbiturate derivatives exhibit acute toxicity that can lead to central nervous system dysfunction, significant respiratory distress, and unstable hemodynamics. Additionally, their use may trigger allergic responses, including potentially life-threatening anaphylactic shock [17–19] (Scheme \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eScheme \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003cp\u003e5-Arylidene (thio)barbituric acids are enduringly useful Knoevenagel adducts that combine a strongly electron-withdrawing barbiturate core with a tunable arylidene π-fragment. This push–pull architecture underpins their broad utility as chromophores, ligands, corrosion inhibitors, and bioactive scaffolds [20,21].\u003c/p\u003e \u003cp\u003eDue to the importance of the 5-arylidene (thio) barbituric acid in organic chemistry, various types of catalysts have been reported for the promotion of their synthesis. Some of them are [Bmim][BF\u003csub\u003e4\u003c/sub\u003e] [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e], H\u003csub\u003e2\u003c/sub\u003eNSO\u003csub\u003e3\u003c/sub\u003eH [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e], Diammonium hydrogen phosphate [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e], PVP-Ni [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e], CeO\u003csub\u003e2\u003c/sub\u003e:MgO:ZrO\u003csub\u003e2\u003c/sub\u003e (1:0.6:0.4) [26], [Nmm-PDO][OAc] [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e], Taurine [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e], [H\u003csub\u003e2\u003c/sub\u003e-Pip][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e], [H\u003csub\u003e2\u003c/sub\u003e-Bisim][HSO\u003csub\u003e4\u003c/sub\u003e] and [H\u003csub\u003e2\u003c/sub\u003e-Bisim][ClO\u003csub\u003e4\u003c/sub\u003e] [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e], [TPPHSP]Br [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e], [2,2′-H\u003csub\u003e2\u003c/sub\u003e-Bipy][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e], Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e – NPs [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e], [H-Succinimide][ClO\u003csub\u003e4\u003c/sub\u003e] [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e], Graphite electrode / NaBr (0.1 M) [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e] and [PEI-Mim][Cl] [36].\u003c/p\u003e \u003cp\u003eIn this research, in continuation of our previous works on the introduction of various types of catalysts for the Knoevenagel reaction between barbituric acid derivatives and aldehyde to achieve 5-arylidene (thio)barbituric acid derivatives, and in order to solve some of the restrictions which are accompanied with the use of above-mentioned catalysts, we have introduced an green and affordable melamine tris dihydrogen phosphate, [H\u003csub\u003e3\u003c/sub\u003e-Melamaine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e, as a tri-cationic organic salt from the combination of melamine and phosphoric acid in a mild and safe condition.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003cdiv id=\"Sec4\" class=\"Section3\"\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Experimental","content":"\u003ch2\u003eMaterials\u003c/h2\u003e\u003cp\u003eAll chemical reagents used in this study, including solvents, aldehydes, barbituric acid, malononitrile, and dimedone, were procured from Merck Chemical Company, Munich, and were used as received without undergoing further purification processes. The progression of the reactions was systematically monitored using Thin Layer Chromatography (TLC) as the analytical technique.\u003c/p\u003e\n\u003ch3\u003eCharacterization techniques\u003c/h3\u003e\n\u003cp\u003eThe substrate's purity analysis and reaction monitoring were performed using thin-layer chromatography (TLC) on silica-gel Polygram SILG/UV 254 plates. Melting points were determined with an electrothermal IA9100 melting point apparatus, employing open capillaries. Fourier-transform infrared (FT-IR) spectra of samples prepared in KBr disks were captured using a Perkin-Elmer Spectrum BX series instrument. Thermogravimetric Analysis (TGA) was performed using a THERMO-NIKOLET STA 1500. Nuclear magnetic resonance (NMR) spectra, including \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC, and \u003csup\u003e31\u003c/sup\u003eP, were acquired on a Bruker 400 MHz spectrometer with deuterated DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e as the solvent. Chemical shifts were reported in δ (ppm) units, utilizing tetramethylsilane (TMS) as the internal standard. The mass diagram was gained using an Agilent Technologies device model G708, 1B MSD with Tripe-Axis Detector (EI, 20\u0026ndash;70 eV).\u003c/p\u003e\n\u003ch3\u003ePreparation of melaminium tris dihydrogen phosphate [H-Melamine][HPO]\u003c/h3\u003e\n\u003cp\u003eIn a 50 mL round-bottom flask kept in an ice bath, 10 mmol (1.26 g) of melamine was mixed with 20.0 mL of freshly distilled dichloromethane and stirred. Over the course of 10 minutes, excess phosphoric acid (2.4 mL, roughly 35 mmol) was added gradually dropwise into the solution carefully. After completing the addition process, the reaction mixture was left to stir at room temperature for a duration of 24 hours. Following this, the solvent was carefully decanted, and the resulting white solid was systematically washed several times, first using diethyl ether (three washes of 25 mL each), then ethanol (two washes of 20 mL each). These washes effectively removed any non-ionic residues. The product was subsequently dried using a rotary evaporator, yielding highly pure melaminium tris dihydrogen phosphate (MTDP) with an impressive 94% yield (3.95 g) as shown in Scheme \u003cspan refid=\"Sch3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eCharacterization data for melamine\u003c/h3\u003e\n\u003cp\u003eWhite powder; M.P. = 343 ℃ Dec; FT-IR (KBr, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) υ\u003csub\u003emax\u003c/sub\u003e: 3469, 3418, 3331, 3127, 2195, 1651, 1547, 1434, 1023, 812,; \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) (ppm): 6.10 (brs, 6H, 3x NH\u003csub\u003e2\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (100 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) (ppm): 168.0; (\u003csup\u003e1\u003c/sup\u003eH NMR and \u003csup\u003e13\u003c/sup\u003eC NMR spectra and data of melamine are obtained from different reliable sorces [\u003cspan additionalcitationids=\"CR38\" citationid=\"CR36\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e39\u003c/span\u003e]).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization data of melaminium tris dihydrogen phosphate [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e\u003c/h2\u003e \u003cp\u003eWhite powder; M.p. = 240 ℃ Dec; FT-IR (KBr, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) υ\u003csub\u003emax\u003c/sub\u003e: 3397, 3152, 2960, 2930,1729,1670,1513, 1239, 1181, 1066, 963, 897, 705, 503; \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) (ppm): 6.76 (s, 9H, 3x NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e), 8.57 (brs, 6H, 3 x H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (100 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) (ppm): 164.8; \u003csup\u003e31\u003c/sup\u003eP NMR (162 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) (ppm): 0.31 (H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003e \u0026lt;Scheme 3\u0026gt;\u003c/strong\u003e\u003c/p\u003e\n\n\u003ch3\u003e\u003cScheme \u003e\u003c/h3\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eGeneral procedure for the synthesis of 5-Arylidene (thio)barbituric acid derivatives\u003c/h2\u003e \u003cp\u003eIn a 10 mL round-bottom flask, an aromatic aldehyde (1 mmol), (1,3-dimethyl) barbituric acid or thioarbituric acid (1 mmol) and catalyst [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e (0.010 g, 2 mol%) were combined in 4 mL of water. The mixture was stirred at 80\u0026deg;C while reaction progress was monitored by TLC using a \u003cem\u003en\u003c/em\u003e-hexane/ethyl acetate/Ethanol (7:3:1 ratio) solvent system. After completion, the mixture was cooled to room temperature, followed by the addition of 5 mL of water and 2 minutes of stirring to isolate the catalyst. The residue was filtered, oven-dried at 60\u0026deg;C, and obtained with no further purification required.\u003c/p\u003e \u003cp\u003e \u003cb\u003ePhysical and spectral data of 5-(3-bromobenzylidene)-2-thioxodihydropyrimidine-4,6(1\u003c/b\u003e \u003cb\u003eH\u003c/b\u003e,\u003cb\u003e5\u003c/b\u003e\u003cb\u003eH\u003c/b\u003e\u003cb\u003e)-dione (New compound)\u003c/b\u003e\u003c/p\u003e \u003cp\u003eYellow solid; Melting point: 282\u0026ndash;283 ℃; FT-IR (KBr, cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) υ\u003csub\u003emax\u003c/sub\u003e: 3447, 3066, 2908, 2603, 1654, 1538,1198, 671(C-Br); \u003csup\u003e1\u003c/sup\u003eH NMR (400 MHz, DMSO-\u003cem\u003ed\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) (ppm): 5.98 (d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.8Hz, 1H, C\u0026thinsp;=\u0026thinsp;C-H), 7.02 (dq, \u003cem\u003eJ\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e= 4.0 Hz, \u003cem\u003eJ\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.2 Hz, 1H, Ar-H), 7.10 (q, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.2 Hz, 1H, Ar-H), 7.17 (t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, 1H, Ar-H), 7.28 (dquin, \u003cem\u003eJ\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e= 8.0 Hz, \u003cem\u003eJ\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.2 Hz, 1H, Ar-H), 11.63 (s, 1H, -NH) 11.80 (brs, 1H, -NH). MS (70 eV, EI) Molecular ion m/z: 311.9 (M\u0026thinsp;+\u0026thinsp;2), 309.9 (M).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eIn recent decades, significant progress has been achieved in the development of innovative catalytic systems aimed at enhancing organic transformations, which has become a central focus of ongoing research initiatives. Over the past three decades, our efforts have been concentrated on improving the efficiency and performance of both heterogeneous and homogeneous catalysts while addressing inherent limitations. Within this research framework, particular emphasis has been placed on the design, synthesis, characterization, and functional applications of Br\u0026oslash;nsted acidic ionic liquids. As an extension of these endeavors, this study details the synthesis and comprehensive characterization of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e through advanced analytical methodologies, including FT-IR, \u003csup\u003e1\u003c/sup\u003eH NMR, \u003csup\u003e13\u003c/sup\u003eC NMR, and \u003csup\u003e31\u003c/sup\u003eP NMR spectroscopies within TGA/DTG thermal analysis. Experimental results underscore the efficacy of this compound as a catalytic agent, particularly in facilitating reactions that benefit from acidic conditions to accelerate chemical processes. Additionally, its catalytic performance was systematically evaluated in the synthesis of a wide array of 5-arylidene (thio)barbituric acid compounds, yielding promising outcomes that highlight its practical applicability in organic synthesis.\u003c/p\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization of the catalyst\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003eFT-IR analysis of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e\u003c/h2\u003e \u003cp\u003eThe FT-IR analysis reveals significant spectral changes upon the transformation of melamine to MTDP. Notably, the disappearance of two characteristic peaks at 3469 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1; and 3418 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1;, corresponding to the symmetric and asymmetric stretching of NH\u003csub\u003e2\u003c/sub\u003e groups in melamine, which indicates their conversion into NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e in the MTDP spectrum. A broad absorption band spanning 3500\u0026thinsp;\u0026minus;\u0026thinsp;3000 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1; is attributed to acidic hydrogen bonding within the compound. Additionally, a broader peak in the region of 3150\u0026thinsp;\u0026minus;\u0026thinsp;3030 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1; is associated with aromatic C\u0026ndash;H stretching vibrations. The O-H bending vibration is clearly manifested as a distinct peak at 1670 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1;. The P\u0026thinsp;=\u0026thinsp;O asymmetric vibrations are represented by the peak at 1239 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1;, while peaks at 1181 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1; and 1066 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1; correspond to the P-O asymmetric and symmetric stretching vibrations, respectively. Furthermore, a pronounced peak at 503 cm\u003csup\u003e\u0026minus;\u003c/sup\u003e\u0026sup1; indicates the stretching vibrations of P-O-H (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e\u0026lt;Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026gt;\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003eNMR spectroscopy\u003c/h2\u003e \u003cp\u003e \u003csup\u003e \u003cb\u003e1\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eH NMR spectroscopy [H\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-Melamine][H\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003ePO\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e]\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003c/p\u003e \u003cp\u003eIn the \u003csup\u003e1\u003c/sup\u003eH NMR spectrum of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e, a distinct peak appearing at 6.76 ppm with an integral value of nine corresponds to the three NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e groups within the melaminium moiety. Additionally, a broad singlet observed at 8.57 ppm with an integral value of six is associated with the three H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e counter-anions (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eComparison between \u003csup\u003e1\u003c/sup\u003eH NMR spectra of melamine and [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e\u003c/h2\u003e \u003cp\u003eInvestigation on the \u003csup\u003e1\u003c/sup\u003eH NMR of melamine in DMSO obtained from some other reliable sources indicates that the chemical shift for NH\u003csub\u003e2\u003c/sub\u003e groups of melamine has always been between 5.95\u0026ndash;6.10 ppm [\u003cspan additionalcitationids=\"CR38\" citationid=\"CR36\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. This range of fluctuation may be due to calibration, temperature, purity of solvent, etc, but it never reaches 6.20 ppm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In this research, after the reaction of melamine with phosphoric acid and the conversion of NH\u003csub\u003e2\u003c/sub\u003e to NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e, a noticeable chemical shift to lower fields is observed (6.76 ppm). Among all reactions and catalyst introduction using melamine, this is the first time that this observation is reported with the precise assignment of the chemical shift of H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e hydrogens (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e\u0026lt;Figure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026gt;\u003c/h2\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003e \u003cb\u003e13\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eC NMR spectroscopy [H\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-Melamine][H\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003ePO\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e]\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003c/p\u003e \u003cp\u003eThe \u003csup\u003e13\u003c/sup\u003eC NMR spectrum of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e reveals a single peak at 164.8 ppm, which is indicative of the presence of a single chemically distinct carbon environment within its molecular framework (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Based on the above-mentioned references, the chemical shift of the melamine carbon in DMSO is 168.0 ppm, showing a little upfield shift in MTDP.\u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003e \u003cb\u003e31\u003c/b\u003e \u003c/sup\u003e \u003cb\u003eP NMR spectroscopy [H\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e-Melamine][H\u003c/b\u003e \u003csub\u003e \u003cb\u003e2\u003c/b\u003e \u003c/sub\u003e \u003cb\u003ePO\u003c/b\u003e \u003csub\u003e \u003cb\u003e4\u003c/b\u003e \u003c/sub\u003e \u003cb\u003e]\u003c/b\u003e \u003csub\u003e \u003cb\u003e3\u003c/b\u003e \u003c/sub\u003e \u003c/p\u003e \u003cp\u003eThe \u003csup\u003e31\u003c/sup\u003eP NMR spectrum of [H\u003csub\u003e3\u003c/sub\u003e-Mel][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e exhibits a single peak at 0.31 ppm, corresponding to the phosphorus atom in the H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e counter-anions. This observation confirms the presence of dihydrogen phosphate anions within the composition of the solid organic salt (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eThermogravimetric Analysis\u003c/h2\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003eTGA/DTG of melamine\u003c/h2\u003e \u003cp\u003eAnalysis of the TGA/DTG graph for melamine highlights a distinct thermal decomposition process characterized by a single phase, which occurs over a narrow temperature interval spanning from 320℃ to 350℃. This swift and definitive one-step degradation underscores the transformation of melamine into ammonia, along with a mixture of other volatile compounds. The outcome of this process is noteworthy as it completely prevents the formation of any residual material, emphasizing the efficiency and completeness of the thermal breakdown.\u003c/p\u003e \u003cp\u003eThe TGA/DTG analysis of MTDP exhibits a small peak at 50\u0026deg;C, indicative of the removal of organic solvent from the compound's framework. Upon protonation of melamine by phosphoric acid, its decomposition pathway is distinctly modified. The dihydrogen phosphate anion acts as a catalyst, accelerating both condensation and dehydration reactions, while phosphorus promotes robust char formation. This degradation process unfolds through multiple stages, starting with an acid-catalyzed reaction occurring between 220\u0026deg;C and 240\u0026deg;C. This is followed by intensified condensation and structural breakdown within the range of 310\u0026deg;C to 350\u0026deg;C. Finally, pyrolysis ensues at approximately 400\u0026deg;C, accompanied by a complete structural collapse and significant char production, driven by phosphorus as an efficient charring agent.\u003c/p\u003e \u003cp\u003eThe comparative analysis of the thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) diagrams for melamine and MTDP reveals several significant distinctions. Firstly, while the degradation process of the melamine structure occurs in a single step, MTDP undergoes a multi-stage degradation mechanism. Secondly, melamine remains thermally stable and does not exhibit any measurable degradation below approximately 340\u0026deg;C. In contrast, MTDP demonstrates its initial degradation phase at a considerably lower temperature, around 240\u0026deg;C, which was also confirmed by the observation of turbidity during melting point assessment. Furthermore, MTDP undergoes successive stages of thermal breakdown spanning temperatures up to 400\u0026deg;C. Lastly, post-degradation analysis indicates that melamine leaves approximately no residue at 340\u0026deg;C, whereas MTDP retains approximately 35% of its original mass as char, persisting up to 600\u0026deg;C.\u003c/p\u003e \u003cp\u003eIn the end, the differences between the catalyst and the starting material are clearly noticeable based on the aspects discussed above. Furthermore, given the catalyst's full thermal stability up to 240 degrees and the annealing temperature referenced in this study, which is 80 degrees, it can be concluded that the catalyst maintains complete physical stability throughout the reaction process, with no structural alterations caused by the reaction temperature.\u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eCatalytic activity of [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e\u003c/h2\u003e \u003cdiv id=\"Sec21\" class=\"Section3\"\u003e \u003ch2\u003eOptimization of the reaction\u003c/h2\u003e \u003cp\u003eAfter successfully synthesizing and characterizing MTDP, the molecular structure revealed polar sites that demonstrated significant promise for serving as an efficient catalytic agent in chemical reactions requiring a moderately acidic environment to enhance reaction rates. So, the potential applications of MTDP as a catalyst were further investigated, specifically through its utilization in the preparation of various 5-arylidene (thio)barbituric acid derivatives. In pursuit of ideal reaction conditions, critical parameters such as the quantity of the catalyst, the choice of solvent, and the appropriate reaction temperature were systematically evaluated. To refine these factors, the synthesis of a barbituric acid derivative using 4-chlorobenzaldehyde was conducted under diverse experimental settings. The optimization process led to the identification of conditions that delivered superior results. The data clearly highlight the most effective combination of parameters for achieving high efficiency and product yield, which is the use of 10 mg of the catalyst, in water at 80 ℃ for 1 mmol of the reactants (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOptimizing the reaction conditions in the synthesis 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1\u003cem\u003eH\u003c/em\u003e,3\u003cem\u003eH\u003c/em\u003e,5\u003cem\u003eH\u003c/em\u003e)-trione\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEntry\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCatalyst (mg)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSolvent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTemp. (\u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTime (min.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eConversion yield (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e---\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e---\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTrace\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e---\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTrace\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e---\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e110\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTrace\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCH\u003csub\u003e3\u003c/sub\u003eCN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReflux\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e40 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCH\u003csub\u003e3\u003c/sub\u003eCl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReflux\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTrace\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003eOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e25 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003eOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReflux\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e55 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e45 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e78 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e90 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e90 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e12\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eO\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e80\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e94\u003c/b\u003e \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReflux\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e86 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e88 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO/EtOH (1:1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e81 \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003e Not completed, \u003csup\u003eb\u003c/sup\u003e Isolated yields.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003e\u0026lt;Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026gt;\u003c/h2\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003eDerivation step\u003c/h2\u003e \u003cp\u003eTo evaluate the broad applicability of this approach, a range of aromatic aldehydes incorporating both electron-withdrawing and electron-donating functional groups was employed in the reaction. Furthermore, thiobarbituric acid and 1,3-dimethyl barbituric acid were utilized as substitutes for barbituric acid to expand the scope of the study (Scheme \u003cspan refid=\"Sch4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003e\u0026lt;Scheme \u003cspan refid=\"Sch4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u0026gt;\u003c/h2\u003e \u003cp\u003eAldehydes containing halogen substituents exhibit a significantly higher reaction rate compared to other aldehydes when utilizing MTDP as the catalyst. Although the changes are not very distinguished but it can be concluded that aldehydes containing electron-withdrawing groups on aromatic ring demonstrate a little higher reactivity to those containing electron-donating groups, highlighting the influence of the substituent effects on the catalytic efficiency (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Also, comparison of the reactivity between barbituric acid, thiobarbituric acid shows that the reactivity of barbituric and thiobarbituric acid is approximately close and a little higher than dimethyl barbituric acid. These observations may be related to the stability of the related activated aldehydes, intermediates, and also the acidic strength of the barbituric derivatives and stability of their enolates.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSynthesis of 5-arylidene barbituric acid derivatives in the presence of MTDP in water.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEntry\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAr\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eX\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTime\u003c/p\u003e \u003cp\u003e(Min.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eYield (%)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eMelting point (\u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eObserved\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eReported\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e256\u0026ndash;258\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e259\u0026ndash;261\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2-Cl-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e252\u0026ndash;254\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e249\u0026ndash;251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3-Cl-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e268\u0026ndash;269\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e271\u0026ndash;273\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e 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colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3-NO\u003csub\u003e2\u003c/sub\u003e-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e235\u0026ndash;236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e234\u0026ndash;236\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-NO\u003csub\u003e2\u003c/sub\u003e-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e269\u0026ndash;270\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e268\u0026ndash;270\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e 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align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-MeO-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e228\u0026ndash;230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e229\u0026ndash;230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-Me-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e273\u0026ndash;275\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e274\u0026ndash;276\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2-Furanyl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e262\u0026ndash;263\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e260\u0026ndash;262\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2-Thiophenyl\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e270\u0026ndash;272\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e273\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2-NMe-pyrrol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e280 Dec\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e280 Dec\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e162\u0026ndash;164\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-Cl-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e170\u0026ndash;172\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e170\u0026ndash;172\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3-Br-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e154\u0026ndash;156\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e151\u0026ndash;153\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3-NO\u003csub\u003e2\u003c/sub\u003e-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e147\u0026ndash;149\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e146\u0026ndash;149\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-NO\u003csub\u003e2\u003c/sub\u003e-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e192\u0026ndash;194\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e193\u0026ndash;195\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-MeO-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e142\u0026ndash;144\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e143\u0026ndash;145\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e269\u0026ndash;271\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e271\u0026ndash;272\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-Cl-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e288\u0026ndash;290\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e286\u0026ndash;289\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3-Br-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e282\u0026ndash;283\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003enew\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003enew\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3-NO\u003csub\u003e2\u003c/sub\u003e-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e265\u0026ndash;266\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e266\u0026thinsp;\u0026minus;\u0026thinsp;258\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[46]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-NO\u003csub\u003e2\u003c/sub\u003e-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e243\u0026ndash;245\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e240\u0026ndash;242\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4-MeO-Ph\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e295\u0026ndash;297\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e296\u0026ndash;298\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e[46]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"9\"\u003e\u003csup\u003ea\u003c/sup\u003e Isolated yields\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003e\u0026lt;Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u0026gt;\u003c/h2\u003e \u003cdiv id=\"Sec26\" class=\"Section4\"\u003e \u003ch2\u003eComparison of the catalyst performance\u003c/h2\u003e \u003cp\u003eThe findings from our study were carefully compared with the previously documented data in existing scientific literature concerning the synthesis of 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1\u003cem\u003eH\u003c/em\u003e,3\u003cem\u003eH\u003c/em\u003e,5\u003cem\u003eH\u003c/em\u003e)-trione derivatives. Particular emphasis was placed on examining the impact of variables such as the amount of the catalyst used, the duration required for the reaction to complete, and the yield of the resultant product. Through this comparative analysis, it became evident that some alternative approaches described in the literature tend to demand either significantly higher quantities of catalysts, prolonged reaction times, or a combination of both. Additionally, some of these methods demand complex multi-step synthesis processes and rely on non-ecofriendly materials or conditions during catalyst preparation or separation steps (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEvaluation of the outcomes from synthesizing 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1\u003cem\u003eH\u003c/em\u003e,3\u003cem\u003eH\u003c/em\u003e,5\u003cem\u003eH\u003c/em\u003e)-trione derivatives using [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e in comparison with some previously documented results in the scientific literature.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEntry\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCatalyst\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSolvent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAmount\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eTemp (℃)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTime (Min.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eYield (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTON\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eTOF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[Bmim][BF\u003csub\u003e4\u003c/sub\u003e]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e48 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eNSO\u003csub\u003e3\u003c/sub\u003eH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e50 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e180\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDiammonium hydrogen phosphate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEtOH/H\u003csub\u003e2\u003c/sub\u003eO (1:1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e81 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e8.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e4.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePVP-Ni\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEthylene glycol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.5 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u0026ndash;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e298\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCeO\u003csub\u003e2\u003c/sub\u003e:MgO:ZrO\u003csub\u003e2\u003c/sub\u003e (1:0.6:0.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEtOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.2 g\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60\u0026ndash;70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[26]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[Nmm-PDO][OAc] \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTaurine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[H\u003csub\u003e2\u003c/sub\u003e-Pip][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEtOH/H\u003csub\u003e2\u003c/sub\u003eO (1:1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e19.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e57.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[TPPHSP]Br \u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEtOH/H\u003csub\u003e2\u003c/sub\u003eO (3:1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eReflux\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e46.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e279\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[2,2\u0026prime;‑H\u003csub\u003e2\u003c/sub\u003e-Bipy][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e31.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e190\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-NPs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEtOH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 mole%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eReflux\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e9.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[H-Succinimide][ClO\u003csub\u003e4\u003c/sub\u003e]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.5 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e39.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e470\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGraphite electrode / NaBr (0.1 M)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 mA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[PEI-Mim][Cl] \u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003er.t.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e240\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e[H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(this work)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 mol%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e564\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"10\"\u003e(a) 4-Bromo benzaldehyde derivative (b) \u003cem\u003eN\u003c/em\u003e-methyl morpholine (Nmm) based ionic liquid (c) Triphenyl(propyl-3-hydrogen sulfate)phosphonium bromide (d) Polyethyleneimine supported in methylimidazolium chloride\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section3\"\u003e \u003ch2\u003e\u0026lt;Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u0026gt;\u003c/h2\u003e \u003cdiv id=\"Sec28\" class=\"Section4\"\u003e \u003ch2\u003eMechanism study\u003c/h2\u003e \u003cp\u003eThe proposed method for synthesizing 5-arylidene (thio)barbituric acid derivatives demonstrates that the carbonyl group of the aldehyde is initially activated by the acidic hydrogen atoms from the catalyst (MTDP). This activation enhances its susceptibility to nucleophilic attack by the active methylene group in (thio)barbituric acid. As a result, the intermediate (I) is formed which subsequently, facilitated by MTDP, a water molecule is eliminated from this intermediate, ultimately yielding the final product containing a carbon-carbon double bond (Scheme \u003cspan refid=\"Sch5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eScheme \u003cspan refid=\"Sch5\" class=\"InternalRef\"\u003e5\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec29\" class=\"Section2\"\u003e \u003ch2\u003eReusability of the catalyst\u003c/h2\u003e \u003cp\u003eThe reusability of the catalyst was assessed through the synthesis of 5-(4-chlorobenzylidene)pyrimidine-2,4,6(1\u003cem\u003eH\u003c/em\u003e,3\u003cem\u003eH\u003c/em\u003e,5\u003cem\u003eH\u003c/em\u003e)-trione. To show its compatibility with green chemistry rules, after the reaction concluded, the resulting mixture was filtered. The process was then repeated using the filtered solution without adding fresh catalyst. This method confirmed that the catalyst could be reused for up to five successive cycles with negligible changes in reaction time and yield throughout all trials (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe FT-IR spectrum of the recovered catalyst after five cycles shows a high level of structural stability during the reaction conditions. The observed broad absorption in the 3300\u0026ndash;3500 cm\u003csup\u003e-1\u003c/sup\u003e region, which covered the NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e, is related to the absorbed water in the structure of the ionic liquid catalyst, which is predictable for this ionic structure. The existence of the stretching C\u0026thinsp;=\u0026thinsp;N vibrations at 1673 cm\u003csup\u003e-1\u003c/sup\u003e and bending N-H vibrations of the melamine between 1570\u0026ndash;1615 cm\u003csup\u003e-1\u003c/sup\u003eand also, distinguished bunch of vibrations related to H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e in the area of 800\u0026ndash;1250 cm\u003csup\u003e-1\u003c/sup\u003e is evidence of maintaining the catalyst structure as the starting form.\u003c/p\u003e \u003cp\u003e \u003cb\u003e\u0026lt;\u003c/b\u003eFigure \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e\u0026gt;\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study presents a methodical and uncomplicated approach to synthesizing melamine tris dihydrogen phosphate, formulated as [H\u003csub\u003e3\u003c/sub\u003e-Melamine][H\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e]\u003csub\u003e3\u003c/sub\u003e and commonly referred to as MTDP. The compound is prepared through the reaction of melamine with phosphoric acid under exceptionally mild and controlled conditions. Comprehensive characterization of the synthesized MTDP was conducted using FT-IR, \u003csup\u003e1\u003c/sup\u003eH, \u003csup\u003e13\u003c/sup\u003eC, and \u003csup\u003e31\u003c/sup\u003eP NMR spectroscopies, and thermogravimetric analysis to confirm its structural and thermal properties. After successful synthesis and characterization, MTDP was utilized as a novel and highly efficient three-cationic ionic liquid catalyst in the production of 5-arylidene (thio)barbituric derivatives. These derivatives were synthesized from easily available and inexpensive starting materials, showcasing the versatility and applicability of the method. The proposed synthetic procedure offers numerous advantages, such as a straightforward and rapid product separation process, significantly short reaction times (5\u0026ndash;13 minutes), exceptional yields (84\u0026ndash;95%), in the presence of very low amounts of the catalyst (2 mol%), and environmentally friendly catalytic properties. Moreover, it ensures economical operation and adheres to mild reaction conditions, making it a highly appealing and sustainable approach for such chemical transformations. Also, this development paves the way for innovative, unexplored catalyst design and characterization methods based on melamine, and also for new material research, such as flame-retardant materials.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe appreciate the help of the Research Council of the University of Guilan in doing this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatement of author contributions based on CRediT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e Hossein Khorramabadi:\u003c/strong\u003e Writing-original draft, Methodology, Investigation. \u003cstrong\u003eNader Daneshvar:\u003c/strong\u003e Conceptualization, Validation, Formal analysis\u003cstrong\u003e. Farhad Shirini:\u003c/strong\u003e Conceptualization, Validation, Formal analysis, Data curation, Writing the final version of the article. \u003cstrong\u003eHassan Tajik \u003c/strong\u003e\u003cstrong\u003ede: \u003c/strong\u003eFormal analysis, Writing- original draft.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors received no financial support for the research publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eY. Hu, Y. Xing, H. Yue, T. Chen, Y. Diao, W. Wei, S. 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Langarudi, DABCO-based ionic liquids: green and recyclable catalysts for the synthesis of barbituric and thiobarbituric acid derivatives in aqueous media, RSC Adv. 6 (2016) 44630-44640. http://dx.doi.org/10.13005/ojc/380323\u003c/li\u003e\n\u003c/ol\u003e\n\n"},{"header":"Schemes ","content":"\u003cp\u003eSchemes are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Tricationic liquid, Melaminium Dihydrogen Phosphate, 5-arylidene (thio)barbituric acid, Knoevenagel reaction, Mild reaction condition","lastPublishedDoi":"10.21203/rs.3.rs-8718605/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8718605/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study focuses on the preparation and characterization of melaminium tris dihydrogen phosphate (MTDP), a tricationic Brønsted acidic ionic liquid, through various advanced analytical techniques, including FT-IR, ¹H, ¹³C NMR and ³¹P NMR spectroscopies within a full comparative study between the TGA/DTG diagrams of melamine and MTDP. Following its comprehensive identification, MTDP was employed as an efficient and recyclable catalytic agent in the synthesis of 5-arylidene (thio)barbituric acid derivatives. The proposed methodology offers several notable advantages, such as high product yields (84–95%), rapid reaction rates (5–13 minutes), mild reaction conditions, and the utilization of low amounts of environmentally benign, non-toxic reagents (2 mol%).\u003c/p\u003e","manuscriptTitle":"Melaminium Tris Dihydrogen Phosphate (MTDP): A New Green and Sustainable Tricationic Ionic Liquid Catalyst for the Knoevenagel Synthesis of 5-Arylidene(thio)barbituric Acids in Water","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-18 16:12:41","doi":"10.21203/rs.3.rs-8718605/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bbfe16b5-e875-4cd9-8b5d-8d32b9ee648b","owner":[],"postedDate":"March 18th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":64690487,"name":"Physical sciences/Chemistry"},{"id":64690488,"name":"Earth and environmental sciences/Environmental sciences"}],"tags":[],"updatedAt":"2026-04-08T10:45:41+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-18 16:12:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8718605","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8718605","identity":"rs-8718605","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}