Gas-phase kinetics of pyrolysis of 1,2-dimethylcyclopropene

Abstract

The pyrolysis of 1,2-dimethylcyclopropene has been studied in the temperature range 260–300 °C. The sole product is isoprene and material recovery was complete to within ±3.5%. The reaction obeyed first-order kinetics and appeared to be homogeneous in a hexamethyldisilazane-conditioned Pyrex reactor, although surface catalysis could not be eliminated in a packed vessel. At 12 Torr (close to the high-pressure limit) rate constants fitted the Arrhenius equation (i). log(k/s^–1)=(13.63 ± 0.19)–(183.7 ± 2.0 kJ mol^–1)/RTln10 (i) This study provides further evidence for the deactivating effect of methyl substituents on cyclopropene isomerization.