Alkoxy radical intermediates in the thermal and photochemical oxidation of alcohols

Abstract

Radical scavenging by nitrone and nitroso compounds, used in conjunction with e. s. r. spectroscopy, has demonstrated that alkoxy radicals are important intermediates during the thermal and photochemical oxidation of primary and secondary aliphatic alcohols: R 1 R 2 CHOH+X(ox) → R 1 R 2 CHȮH + + X(red) R 1 R 2 CHȮH + +R 1 R 2 CHOH → R 1 R 2 CHO. + R 1 R 2 CHOH + 2 R 1 R 2 CHO. + PhCH ═ NBu t → R 1 R 2 CHO─CHPh─.O─NBu t ─R 1 R 2 CHoH→R 1 R 2 C─OH + Bu t N ═ O → R 1 R 2 C─N─Bu t ─OH─O. Oxidants include the herbicidal paraquat ion, peroxydisulphate ion, the peroxydisulphatesilver (ɪ) couple, lead tetraacetate and uranyl nitrate. Independet generation of alkoxy radicals (photolysis of the corresponding alkyl nitrites R 1 R 2 CHONO) and their hydroxyalkyl isomers (H abstraction from the parent alcohol) confirms the e. s. r. assignments: mechanistic consequences of the results are discussed.