Photochemical reactions of triplet p-phenylbenzyl derivatives studied by using laser flash triplet-sensitization techniques

Abstract

Photochemical properties in the triplet states of p-phenylbenzyl derivatives (PBX; X = H, Cl, Br, OH or SH) were investigated by using laser photolysis techniques of triplet-acetone sensitization. Beta-bond dissociation of triplet phenylbenzyl mercaptan (X = SH) was shown for the first time while formation of triplet states were seen for phenyl toluene and phenylbenzyl alcohol by triplet energy transfer. Beta-bond cleavage was absent for halide compounds (X = Cl and Br) upon sensitization because of the short triplet lifetimes due to a heavy atom effect. The reactivity for beta-bond cleavage was interpreted in terms of difference in the bond enthalpy, D(C-X), relative to the triplet energies.