Spin-trapping in early and some recent nitroso chemistry

Abstract

The radical scavenging properties of nitroso compounds were discovered accidentally during investigations of photochemical nitrosation of hydrocarbons with alkyl nitrites. Depending on the nature of substrates and nitrosating agent, various nitroxides can be generated. Identification of these nitroxides by their esr spectra has triggered the development of the spin-trapping technique which has been useful in the elucidation of many organic radical reaction mechanisms. Recent studies have shown that the behavior of nitrosocyclopropanes and α-chloro-nitroso alkanes is unorthodox upon irradiation. Dark reactions of α-chloro-nitroso alkanes with Grignard reagents lead to nitrones by a polar mechanism and to oximes by electron transfer. In the latter case high yields of hydrocarbon dimers are sometimes obtained from the Grignard and other organometallic reagents, despite the presence of nitroso compounds. In the postulated reaction mechanism dimers and higher associates from the organometallic reagent play an essential role.