Kinetics of the decomposition of diazirines

Abstract

Thermal decomposition of a series of meta-substituted 3-chloro-3-aryldiazirines in cyclohexene has been investigated over the temperature range 60–95 °C. In contrast to the kinetics of the para-substituted compounds in cyclohexene, the rates of decomposition of this series of compounds are linearly related to their respective σ values. The kinetics of decomposition of both series of compounds have been examined in acetic acid at 75 °C, and are similar to those observed in cyclohexene. Plausible mechanisms are proposed to account for the observed products. In addition, the thermal decompositions of 3-chloro-3-cyclopropyl- and 3-chloro-3-cycloheptyl-diazirine have been studied. The results are consistent with a polarized radical-like transition state for the decomposition of diazirines.