Obtaining of novel pyrazolo pyrimidine disazo dyes derived from 4-position and a theoretical and experimental comparison of their characteristic properties

In the study, 5-(4-Arylazo-3-methyl-1H-pyrazole-5-ylazo)4-hydroxy-6-methyl-1H-pyrimidin-2-one dyes were synthesized and were reported. At the beginning of the study, first of all, aniline and aniline compounds derived from the 4 position were interacted with the 3-aminocrotononitrile which the active methylene compound. Then, these compounds were reacted with hydrazine monohydrate and 5-amino-4-arylazo-3-methyl-1H-pyrazole (2a-2e) mono azo dyes were synthesized as a result of ring closing reaction. In the next step, 2a-2e dyes were diazotized again and intermediate products were formed by coupling with ethyl acetoacetate. At the last stage, these intermediate compounds were heated with urea under appropriate laboratory conditions and were obtained 5-(4-Arylazo-3-methyl-1H-pyrazole-5-ylazo)4-hydroxy-6-methyl-1H-pyrimidin-2-one dyestuffs (3a-3e). In the continuation, the structure characteristics of compounds were characterized by methods such as elemental analysis, Fourier transform infrared spectroscopy-Attenuated total reflectance and 1 H-Nuclear magnetic resonance spectroscopy. The measurements of the dyes were taken in 6 different solvents in the UV Visible spectrophotometer. By comparing the results, the solvent, substituent and acid-base properties of the compounds were examined. In addition to the experimental characterization of the compounds discussed in the present article, their molecular structures, spectroscopic and electronic properties are analyzed theoretically using ab-initio calculation methods based on density functional theory (DFT) in the ground state to support experimental studies.