The pyrolysis of p‐xylene

Abstract A quantitative study of the pyrolysis of p ‐xylene at temperatures from 795° to 920° at low pressures has been made using a flow system at low contact times. A mechanism is postulated to account for the principal products. The primary rate controlling reactions are the dissociation of either a CH bond in the methyl side chain or a CC bond from the ring to the methyl group, the activation energies of which are 79 and 82 kcal., respectively. Evidence is presented for the existence of the intermediate p ‐xylylene molecule, and for its formation by disproportionation from the initially formed p ‐methylbenzyl radicals. The copolymerization of p ‐xylylene with maleic anhydride or chloroprene is described.