MAGDI M. MOSSOBA, IONEL ROSENTHAL, and PETER RIESZ. Can. J. Chem. 60, 1493 (1982). The reactions of hydroxyl radicals with methylamine, dimethylamine, trimethylamine, diethylamine, see-butylamine, ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, 1,7-diaminoheptane, ornithine, spermidine, spermine, agmatine, and arcaine in aqueous solutions have been investigated by spin-trapping and esr. Hydroxyl radicals were generated by the uv photolysis of H,O, and 2-methyl-2-nitrosopropane (MNP) was used as the spin-trap. The effects of ionizing radiation on the same polyamines in the polycrystalline state were also investigated. The free radicals produced by y-radiolysis of these solids at ro0.m temperature in the absence of air were identified by dissolution in aqueous solutions of MNP. The predominant reaction of OH with amines and polyamines below pH 7 was the abstraction of hydrogen atoms from a carbon that is not adjacent to the protonated amino group. For agmatine and arcaine which contain guanidinium groups abstraction occurred from the a-CH. Dimethylamine was oxidized to the dimethylnitroxyl radical by H,O, in the dark. y-Radiolysis of polyamines in the polycrystalline state generated radicals due to H-abstraction from either the a-CH or from a carbon atom in the middle of the alkyl chain. The deamination radical was obtained from ornithine. Faisant appel B la rpe et B I'utilisation de piegeurs de spin, on a itudiC la reaction des radicaux hydroxyles avec des solutions aqueuses des amines suivantes: methylamine, dimethylamine, trimethylamine, diethylamine, see-butylamine, Cthylknediamine, I diamino-1,3 propane, putrescine, cadavtrine, diamino-1,7 heptane, ornithine, spermidine, spermine, agmatine et arcaine. Les