Reactions of vinyl and phenyl radicals with ethyne, ethene and benzene

Abstract

Rates of vinylation and phenylation of ethyne, ethene and benzene have been determined relative to vinyl recombination in a Knudsen cell flow reactor. Phenylvinylsulfone and divinylmercury were used as radical initiators and studies were done over the temperature range 1000–1330 K. Assuming a recombination rate constant of 1010.3 M−1s−1 for vinyl and 109.5 for phenyl, we obtain the following rate constants (M−1s−1) at 1100 K: k(R=vinyl) k(R=phenyl) R|+C2H2→R−C2H+H| 2.0±.4×108 2.6±.6×108 R|+C2H4→R−C2H3+H| 1.4±.2×108 1.5±.4×108 R|+C6H6→R−C6H5+H| 4.5±1.2×107 6.0±2.0×107 When combined with room temperature addition rates from the literature, we obtain (M−1s−1): k(vinyl+ethyne→vinylacetylene+H)=109.3 exp{−5.0 kcal/RT} k(phenyl+benzene→biphenyl+H)=108.6 exp{−4.0 kcal/RT}