The thermal decomposition of the diazirines. Part IV. 3-Chloro-3-ethyldiazirine, 3-chloro-3-n-propyldiazirine, 3-chloro-3-isopropyldiazirine, and 3-chloro-3-t-butyldiazirine

Abstract

The thermal decomposition of a number of chlorodiazirines have been studied. The reactions are kinetically of the first order and probably unimolecular, and rate constants were determined in their high-pressure region. For the Arrhenius parameters k= A exp (–E/RT) sec.^–1 the following values were obtained: 3-chloro-3-ethyldiazirine, log₁₀A= 13·985 ± 0·047, E= 30,450 ± 85; 3-chloro-3-n-propyldiazirine, log₁₀A= 13·980 ± 0·034; E= 30,980 ± 0·034; 3-chloro-3-isopropyldiazirine, log,₁₀A= 14·011 ± 0·043, E= 30,590 ± 80; and 3-chloro-3-t-butyliazirine, log₁₀A= 13·36 ± 0·20, E=–29,500 ± 350 cal. mole^–1, R being taken as 1·987 cal. deg.^–1 mole^–1. The experimental evidence is consistent with the hypothesis that the gas-phase pyrolysis of these diazirines involves the intermediate formation of a carbene.