The formation and electron spin resonance spectra of some cyclic alkoxynitroxide radicals

Abstract

Strong signals attributed to substituted 3,4-dihydro-1H-2,1-benzoxazin-1-oxyl radicals are detected when aqueous solutions of titanium(III) ion, o-nitroarenediazonium ion, and an olefin are mixed in the flow cell of an e.s.r. spectrometer. Hyperfine splitting constants have been assigned for a number of such cyclic alkoxynitroxide radicals, and the factors which affect their magnitude, including conformational effects, have been noted. The mechanism of formation of the nitroxide radicals is thought to involve as consecutive steps, generation of o-nitroaryl radicals, addition to the olefin, and cyclization of the resultant 2-o-nitroarylalkyl radicals.