Reactions of phenyl radicals with ethene, ethyne, and benzene

Abstract

In a low pressure flow reactor, rates for the displacement of H atoms from unsaturated molecules by phenyl radicals have been measured relative to phenyl radical recombination. Assuming a rate constant for the latter process of 109.5 M−1 s−1, the rate constants at 1030 K for displacement reaction from ethyne, ethene, and benzene are: Ph*+C2H4=PhC2H3+Hk=1.2×108M−1s−1Ph*+C2H2=PhC2H+Hk=1.6×108M−1s−1Ph*+PhH=Ph−Ph+Hk=3.0×107M−1s−1 The role of the reversibility of the formation of the initial radical-molecule complex is investigated by determining D-displacement rates for deuterated ethyne and benzene. Reversibility is important in the latter case, but not in the former.