 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.