Formation of D and H atoms in the pyrolysis of benzene-d6 and chlorobenzene behind shock waves

From the measurements of H atoms during pyrolysis of chlorobenzene under similar conditions at 1570-1790K, the first-order rate constant for the dissociation of chlorobenzene to chlorine atoms and phenyl radicals was found to be about an order of magnitude greater than that for the pyrolysis of C6D6, and a rate constant still another order of magnitude greater was noted for the dissociation of phenyl radicals to H atoms and other products. From this information, a rate constant was derived for the dissociation of benzene-d6 to phenyl-d5 and D atoms. The rate constant for the H-D exchange reaction on benzene was determined over the temperature range of 300-1400K by combining results of this work with that of others at lower temperatures. A very simple kinetic model based on a reaction chain with H as carrier can relate the data presented from this work to other shock-tube work at higher benzene concentrations