A theoretical study on mechanism and kinetics of the reaction between para-aminotoluene and OH radical

doi:10.21203/rs.3.rs-4176914/v1

A theoretical study on mechanism and kinetics of the reaction between para-aminotoluene and OH radical

2024 · doi:10.21203/rs.3.rs-4176914/v1

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The paper uses ab initio quantum chemistry to model the potential energy landscape and kinetics for the gas-phase reaction of para-aminotoluene with the OH radical, computing thermal rate constants and product branching ratios from 300–2000 K using CCSD(T) single-point energies with M06-2X-optimized structures, and statistical TST and RRKM master-equation calculations. It finds that the product channel para-aminotoluene + OH → NH-C6H4-CH3 + H2O dominates across the temperature range, with a 41–72% branching ratio at P = 760 Torr. The overall second-order rate constant at 760 Torr (N2) is fit by a modified Arrhenius expression, giving an ambient-condition total rate constant of 2.16×10−11 cm3 molecule−1 s−1, and the authors compare it to measured/calculated rates for toluene and aniline + OH. The main limitation is that the study is purely theoretical/kinetic modeling based on the chosen electronic-structure and statistical assumptions rather than experimental validation. The paper does not explicitly discuss endometriosis or adenomyosis; it was included in the corpus via a keyword match in the upstream search index.

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Abstract

Abstract We conducted an ab initio exploration of the potential energy landscape for the para-aminotoluene reaction with OH, employing the CCSD(T)//M06-2X/6-311 + + G(3df,2p) level of theory. Additionally, thermal rate constants and branching ratios spanning the 300–2000 K temperature range were calculated. These calculations relied on the CCSD(T) energies and the M06-2X structures of the involved species, utilizing statistical theoretical TST and RRKM master equation computations. The calculated results reveal that the reaction channel para-aminotoluene + OH → NH-C6H4-CH3 + H2O prevails under the 300–2000 K temperature range, with the branching ratio in the range of 41%- 72% at P = 760 Torr. The overall second-order rate constants of the titled reaction obtained at the pressure 760 Torr (N2) can be illustrated by the modified Arrhenius expression of k_total(T) = 2.04×10− 18 T2.07 exp[(11.2 kJ.mol− 1)/RT]. The total rate constant at the ambient conditions in this work, 2.16×10− 11 cm3 molecule− 1 s− 1, is about one order of magnitude larger than those for the toluene reaction with OH at the same conditions measured by Davis et al. (6.11 ± 0.4×10− 12 cm3 molecule− 1 s− 1), Doyle et al. (4.15 ± 1.49×10− 12 cm3 molecule− 1 s− 1), Hansen et al. (5.78 ± 0.58×10− 12 cm3 molecule− 1 s− 1), Tully et al. (6.36 ± 0.69×10− 12 cm3 molecule− 1 s− 1), Knispel et al. (7.0 ± 0.41×10− 12 cm3 molecule− 1 s− 1) or calculated by Zhang et al. (5.69×10− 12 cm3 molecule− 1 s− 1). However, the value 2.16×10− 11 cm3 molecule− 1 s− 1 is smaller than those of the aniline + OH reaction measured by Atkinson and co-workers (1.18 ± 0.11×10− 10 cm3 molecule− 1 s− 1), Rinke et al. (1.20 ± 0.24×10− 10 cm3 molecule− 1 s− 1), and Witte et al. (1.23×10− 10 cm3 molecule− 1 s− 1) or calculated by Abdel-Rahman et al. (4.4×10− 10 cm3 molecule− 1 s− 1) and Mai et al. (1.3×10− 10 cm3 molecule− 1 s− 1). This study provides a thorough comprehension of the mechanisms and kinetics associated with the interaction between para-aminotoluene and OH radical.

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A theoretical study on mechanism and kinetics of the reaction between para-aminotoluene and OH radical | 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 Research Article A theoretical study on mechanism and kinetics of the reaction between para-aminotoluene and OH radical Tien V. Pham This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4176914/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 We conducted an ab initio exploration of the potential energy landscape for the para-aminotoluene reaction with OH, employing the CCSD(T)//M06-2X/6-311 + + G(3df,2p) level of theory. Additionally, thermal rate constants and branching ratios spanning the 300–2000 K temperature range were calculated. These calculations relied on the CCSD(T) energies and the M06-2X structures of the involved species, utilizing statistical theoretical TST and RRKM master equation computations. The calculated results reveal that the reaction channel para-aminotoluene + OH → NH-C 6 H 4 -CH 3 + H 2 O prevails under the 300–2000 K temperature range, with the branching ratio in the range of 41%- 72% at P = 760 Torr. The overall second-order rate constants of the titled reaction obtained at the pressure 760 Torr (N 2 ) can be illustrated by the modified Arrhenius expression of k_ total (T) = 2.04×10 − 18 T 2.07 exp[(11.2 kJ.mol − 1 )/RT]. The total rate constant at the ambient conditions in this work, 2.16×10 − 11 cm 3 molecule − 1 s − 1 , is about one order of magnitude larger than those for the toluene reaction with OH at the same conditions measured by Davis et al. (6.11 ± 0.4×10 − 12 cm 3 molecule − 1 s − 1 ), Doyle et al. (4.15 ± 1.49×10 − 12 cm 3 molecule − 1 s − 1 ), Hansen et al. (5.78 ± 0.58×10 − 12 cm 3 molecule − 1 s − 1 ), Tully et al. (6.36 ± 0.69×10 − 12 cm 3 molecule − 1 s − 1 ), Knispel et al. (7.0 ± 0.41×10 − 12 cm 3 molecule − 1 s − 1 ) or calculated by Zhang et al. (5.69×10 − 12 cm 3 molecule − 1 s − 1 ). However, the value 2.16×10 − 11 cm 3 molecule − 1 s − 1 is smaller than those of the aniline + OH reaction measured by Atkinson and co-workers (1.18 ± 0.11×10 − 10 cm 3 molecule − 1 s − 1 ), Rinke et al. (1.20 ± 0.24×10 − 10 cm 3 molecule − 1 s − 1 ), and Witte et al. (1.23×10 − 10 cm 3 molecule − 1 s − 1 ) or calculated by Abdel-Rahman et al. (4.4×10 − 10 cm 3 molecule − 1 s − 1 ) and Mai et al. (1.3×10 − 10 cm 3 molecule − 1 s − 1 ). This study provides a thorough comprehension of the mechanisms and kinetics associated with the interaction between para-aminotoluene and OH radical. para-aminotoluene hydroxyl radical TST RRKM NH2C6H4CH3 Full Text Additional Declarations No competing interests reported. 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-4176914","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":286247793,"identity":"7c6b8943-76a8-4186-9e9f-9427b1a8b16d","order_by":0,"name":"Tien V. Pham","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAt0lEQVRIiWNgGAWjYDACZjBpA8SMjQeI0sED0ZIG0tJApBYIdRhMEqfFnp352GPeHeft1rYfBtpSYxNNhMPY0g1nnrmdvO1MIlDLsbTcBsJaeMwkPrbdTjY7ANTC2HCYGC383yQS284lm51/SLQWHjagLQfszG4QbcthNjPJmWeSE8xuAG1JIMYv7P2Hn0nz7rCzNzuf/vDBhxobwlrAgLGBIRGsMoEo5VAt9kQrHgWjYBSMgpEHAPSdQkTe1qa3AAAAAElFTkSuQmCC","orcid":"","institution":"Hanoi University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Tien","middleName":"V.","lastName":"Pham","suffix":""}],"badges":[],"createdAt":"2024-03-27 14:45:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4176914/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4176914/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":55486588,"identity":"1d778871-d1bf-47d3-a488-e6dc388c1626","added_by":"auto","created_at":"2024-04-29 06:12:32","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":736903,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4176914/v1_covered_4b510982-802d-4477-9ede-94389d9e7e0a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A theoretical study on mechanism and kinetics of the reaction between para-aminotoluene and OH radical","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"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":"para-aminotoluene, hydroxyl radical, TST, RRKM, NH2C6H4CH3","lastPublishedDoi":"10.21203/rs.3.rs-4176914/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4176914/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWe conducted an ab initio exploration of the potential energy landscape for the para-aminotoluene reaction with OH, employing the CCSD(T)//M06-2X/6-311\u0026thinsp;+\u0026thinsp;+\u0026thinsp;G(3df,2p) level of theory. Additionally, thermal rate constants and branching ratios spanning the 300\u0026ndash;2000 K temperature range were calculated. These calculations relied on the CCSD(T) energies and the M06-2X structures of the involved species, utilizing statistical theoretical TST and RRKM master equation computations. The calculated results reveal that the reaction channel para-aminotoluene\u0026thinsp;+\u0026thinsp;OH \u0026rarr; NH-C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e4\u003c/sub\u003e-CH\u003csub\u003e3\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO prevails under the 300\u0026ndash;2000 K temperature range, with the branching ratio in the range of 41%- 72% at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;760 Torr. The overall second-order rate constants of the titled reaction obtained at the pressure 760 Torr (N\u003csub\u003e2\u003c/sub\u003e) can be illustrated by the modified Arrhenius expression of k_\u003csub\u003etotal\u003c/sub\u003e(T)\u0026thinsp;=\u0026thinsp;2.04\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;18\u003c/sup\u003e T\u003csup\u003e2.07\u003c/sup\u003e exp[(11.2 kJ.mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)/RT]. The total rate constant at the ambient conditions in this work, 2.16\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;11\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, is about one order of magnitude larger than those for the toluene reaction with OH at the same conditions measured by Davis et al. (6.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;12\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Doyle et al. (4.15\u0026thinsp;\u0026plusmn;\u0026thinsp;1.49\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;12\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Hansen et al. (5.78\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;12\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Tully et al. (6.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.69\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;12\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Knispel et al. (7.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;12\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) or calculated by Zhang et al. (5.69\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;12\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). However, the value 2.16\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;11\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is smaller than those of the aniline\u0026thinsp;+\u0026thinsp;OH reaction measured by Atkinson and co-workers (1.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.11\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;10\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Rinke et al. (1.20\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;10\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and Witte et al. (1.23\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;10\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) or calculated by Abdel-Rahman et al. (4.4\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;10\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and Mai et al. (1.3\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;10\u003c/sup\u003e cm\u003csup\u003e3\u003c/sup\u003e molecule\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). This study provides a thorough comprehension of the mechanisms and kinetics associated with the interaction between para-aminotoluene and OH radical.\u003c/p\u003e","manuscriptTitle":"A theoretical study on mechanism and kinetics of the reaction between para-aminotoluene and OH radical","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-02 17:35:52","doi":"10.21203/rs.3.rs-4176914/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":"fc93a698-a166-48c2-9119-428dd7f9fa53","owner":[],"postedDate":"April 2nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-29T06:10:14+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-02 17:35:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4176914","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4176914","identity":"rs-4176914","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}

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