Thermal isomerization of dewarbenzene derivatives

The rates of thermal conversion of seven simple dewarbenzene derivatives to their corresponding benzene isomers were measured. Relatively minor substituent changes were found to have profound effects; isomerization rates increased with the number and strength of electron-withdrawing moieties. Surprisingly, the rate of thermal isomerization for one derivative was the same in fluid solution as in a solid polymer matrix, suggesting that this reaction has a low volume of activation. Other preliminary experiments suggest that the putative intermediate has some polar character. These data may provide some insights into the reaction mechanism.