ESR OF NITROXIDE RADICALS .1. PHOTOLYSIS OF INDOLES, PHENOLS, DISULPHIDES, AND THIOLS

The formation of stable nitroxide radicals during the photochemical decomposition of a number of indoles, phenols, disulphides, and thiols in the presence of a nitrosoalkane radical scavenger has been demonstrated. The predominant e.s.r. spectrum obtained with dibutyl disulphide or butane-l-thiol consists of a simple triplet hyperfine splitting with αN 18·5 G and g 2·0071, attributed to the trapping of butane-l-thiyl radicals. Phenol and indole give similar triplet spectra with αN 15·55 G, g 2·0061, and αN 16·26 G, g 2·0060, respectively. The formation of trichloromethyl radicals during the photolysis of indole in carbon tetrachloride has been confirmed by analysis of the e.s.r. spectrum of the trichloromethyl nitroxide radical using a least- squares curve-fitting procedure. Isotropic hyperfine splitting constants for 14N, 35Cl, and 37Cl have been obtained. © 1969, CSIRO. All rights reserved.