Electron spin resonance study of tert-butyl halides and carbon tetrachloride, neopentane and carbon tetrachloride binary mixtures irradiated at 77 °K

Abstract

Tert-butyl halides and carbon tetrachloride, neopentane and carbon tetrachloride binary mixtures were irradiated at 77 °K and electron spin resonance spectra were recorded at increasing temperatures until the radicals disappeared.Even at high concentrations of tert-butyl halides, the radicals obtained from CCl4 predominate, indicating that CCl4 has a high efficiency for electron capture. Maximum radical yields and the appearance of a narrow line spectrum with rising temperature were observed in (CH3)3C—X – CCl4 mixtures (X = Cl, Br, I) in concentration ranges where only a single phase exists. This spectrum consists of 17 lines which appear to belong to one odd-numbered spectrum (7 lines due to (CH3)2Ċ—X radical) and two even-numbered spectra (4 and 10 lines, the last being due to (CH3)3Ċ radical). The disappearance of the CCl4 broad band and the appearance of these radicals with increasing temperature can be interpreted as due to charge transfer from carbon tetrachloride cation to tert-butyl halide, facilitated by greater freedom of movement in the solid solutions. In contrast, neopentane and carbon tetrachloride mixtures do not display these features.