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.
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[2.2.0] 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.