FTIR AND MASS-SPECTROMETRIC MEASUREMENTS OF THE RATE-CONSTANT FOR THEC6H5-2 REACTION(H)

The rate constant for the C6H5 + H-2 --> C6H6 + H reaction has been me asured by pyrolysis/Fourier transform infrared spectrometry (P/FTIRS) in the temperature range of 548-607 K and by pulsed-laser photolysis/ mass spectrometry (PLP/MS) in the temperature range of 701-1017 K. By P/FTIRS, the reaction was studied by measuring time-resolved concentra tion profiles of the reactant (C6H5NO) and the product (C6H6) using hi ghly diluted mixtures of C6H5NO in H-2 (with or without Ar dilution). In PLP/MS experiments, the C6H5 radical was generated by the photolysi s of C6H5COCH3 at 193 nm in the presence of several Torr of H-2. The C 6H5 + H-2 rate constant was determined by the absolute yields of C6H6 and C6H5CH3 products. The results of these two spectrometric measureme nts agree closely with our theoretically predicted expression, k = 5.7 2 x 10(4)T(2.43) exp (-3159/T) cm(3)/(mol.s) and with that of a shock- tube study by Tree and co-workers (ref 20) in the temperature range of 1050-1450 K. Preliminary kinetic data on the CH3 + C6H5 association r eaction are also presented.