Thermal unimolecular reactions of bicyclo[3,2,0]hept-2-ene

Abstract

The thermal reactions of bicyclo[3,2,0]hept-2-ene have been investigated in the gas phase over the temperature range 307–353 °C. The primary decomposition proceeds by three pathways to yield bicyclo[2,2,1]hept-2-ene, cyclopentadiene and ethylene, and cis-hepta-1,3,6-triene. At the temperature of this study, bicyclo[2,2,1]hept-2-ene and cis-hepta-1,3,6-triene undergo rapid further reactions. Rate constants for the overall loss of reactant were independent of pressure above 2 Torr and fitted the Arrhenius equation: log k/s^–1= 14·76 ± 0·09 – 48,640 ± 240 cal mol^–1/2·303RT. Because of the complexity of the system, rate constants for individual processes are subject to large errors as are the parameters in the derived Arrhenius equations. Direct comparison between experimental Arrhenius parameters and those estimated based on a biradical mechanism is difficult, but experimental and estimated rates are compared.