Spin trapping EPR investigation of the photolysis of aqua(alkyl)cobaloximes: 1,2-rearrangement reactions of photo-induced primary radicals and β-cyclodextrin's stabilizing effects

Abstract

The radicals formed from photolysis of aqua(alkyl)cobaloximes (R = sec-C₄H₉, n-C₄H₉, i-C₄H₉, c-C₅H₉ or c-C₆H₁₁) in the absence and presence of  β-cyclodextrin at room temperature have been characterized by the EPR spin trapping technique using 2-methyl-2-nitrosopropane. It has been found that only the primary alkyl radicals produced by Co–C bond cleavage of the cobaloximes during photolysis undergo 1,2-rearrangement reactions. The spin adducts formed can be included in the cavity of  β-cyclodextrin, which plays an important role in stabilizing the primary alkyl radicals.