Electron spin resonance studies of elementary processes in radiation- and photo-chemistry. Part 9.—Carboxylic esters at cryogenic temperatures

Abstract

Some of the reactions occurring during the γ-radiolysis of a number of carboxylic esters at cryogenic temperatures have been identified by studying the e.s.r. spectra of trapped intermediate radicals. It appears that the capture of thermal electrons by the ester molecule is followed by dissociation of the radical-anion by one of two possible processes, each leading to the formation of alkyl radicals. Secondary radicals formed by abstraction of hydrogen from the ester appear during thermal annealing. Ultraviolet irradiation of these radicals leads to the regeneration of alkyl radicals. Hydrogen atoms produced by ultra-violet irradiation of mixtures of hydrogen sulphide and carboxylic esters react to give alkyl and acyl radicals, by a mechanism similar to that proposed for carboxylic acids.