000276126 001__ 276126 000276126 005__ 20240712101003.0 000276126 0247_ $$2doi$$a10.1039/C5CP00253B 000276126 0247_ $$2ISSN$$a1463-9076 000276126 0247_ $$2ISSN$$a1463-9084 000276126 0247_ $$2WOS$$aWOS:000354195300070 000276126 0247_ $$2altmetric$$aaltmetric:4433633 000276126 0247_ $$2pmid$$apmid:25913267 000276126 037__ $$aFZJ-2015-06603 000276126 082__ $$a540 000276126 1001_ $$0P:(DE-HGF)0$$aAlarcón, P.$$b0 000276126 245__ $$aKinetic and mechanistic study of the reaction of OH radicals with methylated benzenes: 1,4-dimethyl-, 1,3,5-trimethyl-, 1,2,4,5-, 1,2,3,5- and 1,2,3,4-tetramethyl-, pentamethyl-, and hexamethylbenzene 000276126 260__ $$aCambridge$$bRSC Publ.$$c2015 000276126 3367_ $$0PUB:(DE-HGF)16$$2PUB:(DE-HGF)$$aJournal Article$$bjournal$$mjournal$$s1447754502_7446 000276126 3367_ $$2DataCite$$aOutput Types/Journal article 000276126 3367_ $$00$$2EndNote$$aJournal Article 000276126 3367_ $$2BibTeX$$aARTICLE 000276126 3367_ $$2ORCID$$aJOURNAL_ARTICLE 000276126 3367_ $$2DRIVER$$aarticle 000276126 520__ $$aThe reaction of OH radicals with a series of methylated benzenes was studied in a temperature range 300–350 K using a flash-photolysis resonance fluorescence technique. Reversible OH additions led to complex OH decays dependent on the number of distinguishable adducts. Except for hexamethylbenzene, triexponential OH decay curves were obtained, consistent with formation of at least two adduct species. For three compounds that can strictly form two adduct isomers for symmetry reasons (1,4-dimethyl-, 1,3,5-trimethyl-, and 1,2,4,5-tetramethylbenzene) with OH bound ortho or ipso with respect to the methyl groups, OH decay curves were analysed in terms of a reaction mechanism in which the two adducts can be formed directly by OH addition or indirectly by isomerization. In all cases one adduct (add1) is dominating the decomposition back to OH. The other (add2) is more elusive and only detectable at elevated temperatures, similar to the single OH adduct of hexamethylbenzene. Two limiting cases of the general reaction mechanism could be examined quantitatively: reversible formation of add2 exclusively in the OH reaction or by isomerization of add1. Total OH rate constants, adduct loss rate constants and products of forward and reverse rate constants of reversible reactions were determined. From these quantities, adduct yields, equilibrium constants, as well as reaction enthalpies and entropies were derived for the three aromatics. Adduct yields strongly depend on the selected reaction model but generally formation of add1 predominates. For both models equilibrium constants of OH reactions lie between those of OH + benzene from the literature and those obtained for OH + hexamethylbenzene. The corresponding reaction enthalpies of add1 and add2 formations are in a range −87 ± 20 kJ mol−1, less exothermic than for hexamethylbenzene (−101 kJ mol−1). Reaction enthalpies of possible add1 → add2 isomerizations are comparatively small. Because results for 1,3,5-trimethylbenzene are partly inconsistent with a direct formation of add2, we promote the existence of isomerization reactions. Moreover, based on available theoretical work in the literature, add1 and add2 are tentatively identified as ortho and ipso adducts, respectively. Total OH rate constants were obtained for all title compounds. They can be described by Arrhenius equations: kOH = A × exp(−B/T). The parameters ln(A/(cm3 s−1)) = −25.6 ± 0.3, −25.3 ± 0.6, −27.3 ± 0.3, −24.6 ± 0.3, −26.2 ± 0.4, −26.2 ± 0.4 and −24.5 ± 0.2, and B/K = −160 ± 90, −550 ± 180, −1120 ± 90, −330 ± 100, −820 ± 100, −980 ± 130, and −570 ± 40 were determined for 1,4-dimethyl-, 1,3,5-trimethyl-, 1,2,4,5-, 1,2,3,5- and 1,2,3,4-tetramethyl-, pentamethyl-, and hexamethylbenzene. 000276126 536__ $$0G:(DE-HGF)POF3-243$$a243 - Tropospheric trace substances and their transformation processes (POF3-243)$$cPOF3-243$$fPOF III$$x0 000276126 588__ $$aDataset connected to CrossRef 000276126 7001_ $$0P:(DE-Juel1)2693$$aBohn, B.$$b1$$eCorresponding author 000276126 7001_ $$0P:(DE-HGF)0$$aZetzsch, C.$$b2 000276126 773__ $$0PERI:(DE-600)1476244-4$$a10.1039/C5CP00253B$$gVol. 17, no. 19, p. 13053 - 13065$$n19$$p13053 - 13065$$tPhysical chemistry, chemical physics$$v17$$x1463-9084$$y2015 000276126 8564_ $$uhttps://juser.fz-juelich.de/record/276126/files/c5cp00253b.pdf$$yRestricted 000276126 8564_ $$uhttps://juser.fz-juelich.de/record/276126/files/c5cp00253b.gif?subformat=icon$$xicon$$yRestricted 000276126 8564_ $$uhttps://juser.fz-juelich.de/record/276126/files/c5cp00253b.jpg?subformat=icon-1440$$xicon-1440$$yRestricted 000276126 8564_ $$uhttps://juser.fz-juelich.de/record/276126/files/c5cp00253b.jpg?subformat=icon-180$$xicon-180$$yRestricted 000276126 8564_ $$uhttps://juser.fz-juelich.de/record/276126/files/c5cp00253b.jpg?subformat=icon-640$$xicon-640$$yRestricted 000276126 8564_ $$uhttps://juser.fz-juelich.de/record/276126/files/c5cp00253b.pdf?subformat=pdfa$$xpdfa$$yRestricted 000276126 909CO $$ooai:juser.fz-juelich.de:276126$$pVDB:Earth_Environment$$pVDB 000276126 915__ $$0StatID:(DE-HGF)0400$$2StatID$$aAllianz-Lizenz / DFG 000276126 915__ $$0StatID:(DE-HGF)0420$$2StatID$$aNationallizenz 000276126 915__ $$0StatID:(DE-HGF)0100$$2StatID$$aJCR$$bPHYS CHEM CHEM PHYS : 2014 000276126 915__ $$0StatID:(DE-HGF)0200$$2StatID$$aDBCoverage$$bSCOPUS 000276126 915__ $$0StatID:(DE-HGF)0300$$2StatID$$aDBCoverage$$bMedline 000276126 915__ $$0StatID:(DE-HGF)0310$$2StatID$$aDBCoverage$$bNCBI Molecular Biology Database 000276126 915__ $$0StatID:(DE-HGF)0199$$2StatID$$aDBCoverage$$bThomson Reuters Master Journal List 000276126 915__ $$0StatID:(DE-HGF)0110$$2StatID$$aWoS$$bScience Citation Index 000276126 915__ $$0StatID:(DE-HGF)0150$$2StatID$$aDBCoverage$$bWeb of Science Core Collection 000276126 915__ $$0StatID:(DE-HGF)0111$$2StatID$$aWoS$$bScience Citation Index Expanded 000276126 915__ $$0StatID:(DE-HGF)1150$$2StatID$$aDBCoverage$$bCurrent Contents - Physical, Chemical and Earth Sciences 000276126 915__ $$0StatID:(DE-HGF)9900$$2StatID$$aIF < 5 000276126 9141_ $$y2015 000276126 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)2693$$aForschungszentrum Jülich GmbH$$b1$$kFZJ 000276126 9131_ $$0G:(DE-HGF)POF3-243$$1G:(DE-HGF)POF3-240$$2G:(DE-HGF)POF3-200$$3G:(DE-HGF)POF3$$4G:(DE-HGF)POF$$aDE-HGF$$bErde und Umwelt$$lAtmosphäre und Klima$$vTropospheric trace substances and their transformation processes$$x0 000276126 920__ $$lyes 000276126 9201_ $$0I:(DE-Juel1)IEK-8-20101013$$kIEK-8$$lTroposphäre$$x0 000276126 980__ $$ajournal 000276126 980__ $$aVDB 000276126 980__ $$aI:(DE-Juel1)IEK-8-20101013 000276126 980__ $$aUNRESTRICTED 000276126 981__ $$aI:(DE-Juel1)ICE-3-20101013