Synthesis and electron spin resonance of 3-oxy-1,3-diazacyclohexene 1-oxide (1,3-nitrone–nitroxide) radicals

Abstract

Six-membered ring 1,3-nitrone–nitroxide radicals (3) possessing a potentially labile hydrogen atom have been obtained by oxidation of NN′-dihydroxy precursors (2), prepared in turn from an open-chain bishydroxylamine (1) and formaldehyde or acetaldehyde. Reaction between the bishydroxylamine and benzaldehyde produced a dinitrone (4). The nitrone–nitroxides have longer lifetimes than comparable simple α-unsubstituted nitroxides; the radical (3a) decomposes with first-order kinetics: k_e.s.r. 6 × 10^–4 s^–1 in benzene at 25 °C.