Communication: kinetics of the reaction of C6H5 with HBr

Article abstract of DOI:10.1002/kin.550251008

The rate constant for the reaction of phenyl radical with hydrogen bromide has been measured with the cavity-ring-down method at six temperatures between 297 and 523 K. The Arrhenius expression for the H abstraction reaction can be effectively given by: kφ = 10^-10.39±0.10 exp[-(551 ± 19)/T] cm³/s. The values of these parameters are similar to those for the H + HBr reaction, but are in sharp contrast to those for alkyl radical reactions. The gross difference between the alkyl radical reactions and the phenyl and H-atom reactions could be rationalized in terms of the inductive effects of these radicals as measured by Taft's σ (polar) constants.