Thermochemical kinetics of nitrogen compounds. Part III. The unimolecular thermal decomposition of N-allylcyclohexylamine in the gas phase

Abstract

The thermal, unimolecular gas-phase decomposition of N-allylcyclohexylamine to cyclohexylimine and propene has been studied in the temperature range 562–652 K. The rate constants for the homogeneous depletion of the starting material, using the internal standard technique fit the Arrhenius relationship log k/s^–1= 11·44 ± 0·21 –(42·18 ± 0·57 kcal mol^–1)/2·303RT and were independent of the initial pressure in the range 15–150 Torr. When toluene or ethylbenzene were added as diluent and potential radical traps, rate constants calculated on the basis of the products formed and the pressure changes observed were consistent with the internal standard results. The homogeneiety of the reaction was demonstrated by the concurring rate constants obtained in a packed reaction vessel with a 15-fold larger surface:volume ratio. The observed activation parameters are consistent with a concerted mechanism involving a cyclic six-centre-transition state and they are in good agreement with those reported for the analogous decompositions of allyl ethyl ether, but-3-en-1-ol, and but-3-enoic acid.