Two‐Photon Chemistry in the Laser Jet: Photochemistry of the Diphenylhydroxymethyl Radical

Abstract

In the laser-jet mode (argon ion laser) the excited hydroxy-diphenylmethyl radical (3*) underwent H expulsion in inert solvents (benzene, acetonitrile) to produce benzophenone (two-photon product), besides dimerization of its ground state 3 to benzpinacol (one-photon product). In ethanol, the laser-jet photolysis of benzophenone afforded as new products (two-photon chemistry) benzhydrol, 4-(1-hydroxyethyl)benzophen-one (1), together with benzpinacol and 1,1-diphenyl-1,2-propandiol (4), which are also observed in low-intensity photolyses (one-photon chemistry). Benzhydrol is formed through H abstraction from the excited radical 3* and ketone 1 possibly by coupling of an excited radical 3* at its para position (highest spin density) with a transient 1-hydroxyethyl radical. Photolysis of α-phenylbenzoin (2) produced benzpinacol, benzophenone, pinacol 4, benzhydrol, ketone 1, and the benzoyl-derived products benzil and benzaldehyde. Also benzhydrol was observed as a two-photon product.