Electron Spin Resonance Studies of the Radiolysis of Aliphatic Amines at 77 °K

Several frozen aliphatic amines have been γ-irradiated at 77 °K and the electron spin resonance (e.s.r.) spectra of the trapped radicals obtained at 77 °K and on warming. Radiolysis of methyl, ethyl and isopropyl amines produces predominantly alkylamino [Formula: see text] radicals. The proton hyperfine (h.f.) couplings of [Formula: see text] radicals are 10–30% larger than those in the corresponding isoelectronic alkyl radicals and the parallel component of the 14 N coupling is about 35 G. Restricted rotation of alkyl groups occurs at 77 °K in some cases. On warming from 77 °K, the [Formula: see text] radicals generally abstract from the solvent or isomerize to produce radicals of the aminoalkyl type (e.g. RĊHNH 2 ). The alkyl proton h.f. splittings of these latter radicals are 20–40% lower than in the corresponding alkyl radicals, and the observed 14 N coupling was [Formula: see text] in ĊH 2 NR 2 and [Formula: see text] in (CH 3 ) 2 ĊNH 2 and CH 3 ĊHNH 2 . The amino proton couplings in the aminoalkyl radicals were not resolved. Irradiated dimethylamine produces both (CH 3 ) 2 N and CH 2 N(CH 3 ) radicals, but (CH 3 ) 2 N disappears on warming. Only ĊH 2 N(CH 3 ) 2 was observed after irradiation of (CH 3 ) 3 N at 77 °K. Solid methoxyamine (giving CH 3 ONH) and tert-butyl-amine were also studied.