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The isotoluenes in organic chemistry are the non-aromatic toluene isomers with an exocyclic double bond. They are of some academic interest in relation to aromaticity and isomerisation mechanisms.〔''Radical production from the interaction of closed-shell molecules. 10. Chemistry of methylenecyclohexadiene and the thermal polymerization of styrene'' W. David Graham, John Glass Green, and William A. Pryor J. Org. Chem.; 1979; 44(6) pp 907 - 914; .〕〔''Bimolecular reactions of 3-methylene-1,4-cyclohexadiene (p-isotoluene), 5-methylene-1,3-cyclohexadiene (o-isotoluene), 1-methylene-1,4-dihydronaphthalene (benzo-p-isotoluene), and 9-methylene-9,10-dihydroanthracene (dibenzo-p-isotoluene)'' Joseph J. Gajewski and Andrea M. Gortva J. Org. Chem.; 1989; 54(2) pp 373 - 378; 〕 The three basic isotoluenes are ''ortho''-isotoluene or ''5-methylene-1,3-cyclohexadiene'' (here labelled 1); ''para''-isotoluene (2); and ''meta''-isotoluene (3). Another structural isomer is the bicyclic compound ''5-methylenebicyclo() hexene'' (4). The ''o''- and ''p''-isotoluenes isomerise to toluene, a reaction driven by aromatic stabilisation. It is estimated that these compounds are 96 kJ mol−1 less stable. The isomerisation of ''p''-isotoluene to toluene takes place at 100 °C in benzene with bimolecular reaction kinetics by an intermolecular free radical reaction. The intramolecular isomerisation, a 1,3-sigmatropic reaction, is unfavorable because an antarafacial mode is enforced. Other dimer radical reaction products are formed as well. The ''ortho''-isomer is found to isomerise at 60 °C in benzene, also in a second order reaction. The proposed reaction mechanism is a concerted intermolecular ene reaction. The reaction product is either toluene or a mixture of dimerized ene reaction products, depending on the exact reaction conditions. ''Ortho''-isotoluene has been researched in connection with the mechanism of initiator-free polymerization of polystyrene. ==See also== * Pentacene 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Isotoluene」の詳細全文を読む スポンサード リンク
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