E.S.R. of nitroxide radicals. I. Photolysis of indoles, phenols, disulphides, and thiols

Abstract

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-1-thiol consists of a simple triplet hyperfine splitting with a_N 18.5 G and g 2.0071, attributed to the trapping of butane-1-thiyl radicals. Phenol and indole give similar triplet spectra with a_N 15.55 G, g 2.0061, and a_N 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.