Thermal Decomposition of the Benzyl Radical to Fulvenallene (C7H6) H

Abstract

We show that the benzyl radical decomposes to the C7H6 fragment fulvenallene (+H), by first principles/RRKM study. Calculations using G3X heats of formation and B3LYP/6-31G(2df,p) structural and vibrational parameters reveal that the reaction proceeds predominantly via a cyclopentenyl-allene radical intermediate, with an overall activation enthalpy of ca. 85 kcal mol(-1). Elementary rate constants are evaluated using Eckart tunneling corrections, with variational transition state theory for barrierless C-H bond dissociation in the cyclopentenyl-allene radical. Apparent rate constants are obtained as a function of temperature and pressure from a time-dependent RRKM study of the multichannel m..