Reaction of 1,2-Diphenylethane with D2

Article abstract of DOI:10.1021/jo00103a040

The reaction of 1,2-diphenylethane (DPE) with D2 (2000 psi) was studied at 450 deg C.The results of GC/MS and NMR analysis of reaction products and of products from reactions of 1,2-diphenylethane-1,1-d2, 1,2-di(phenyl-d5)ethane, and 1,2,3,4-tetraphenylbutane confirm a mechanistic scheme in which the main process for introduction of D is the reaction of 1,2-diphenylethyl radical with D2.This reaction, though energetically uphill, competes with termination processes because of the high concentration of D2 relative to that of radical species.The reaction generates D atoms which attack aromatic ring positions to give substitution for both H and alkyl substituents.Evidence is provided for D and H atom transfer between aliphatic positions in DPE in the presence of either N2 or H2 and between aromatic positions only when provoked by H2 or D2.Only a small amount of exchange between aromatic and aliphatic positions is observed under any conditions.The attack of D atoms at H-carrying aromatic positions makes H atoms available for transfer to other aromatic positions.The process results in a D2-provoked generation of benzene-d0.Mechanistic alternatives for these and other processes are discussed.