Autoxidation phosphorus compounds

The autoxidation of triphenylphosphine and phosphorus esters has been studied kinetically. After a short induction period the reaction gave the corresponding quinquecovalent phosphorus compounds. The intermediate (55) is probably formed by the addition of oxygen to perfluoroacyl-diarylphosphines. Subsequent decomposition afforded diarylphosphinates (56). The oxadiazine (57) has been prepared from the reaction of carbon dioxide and allyl isocyanate in the presence of tributylphosphine. ... 

By Oxidation of Phosphines.—The kinetics of the AIBN-catalysed autoxidation of various tervalent phosphorus compounds have been... 

The function of an antioxidant is often to divert the peroxy radicals and thus prevent a chain process. Other antioxidants function by reacting with potential initiators, and thus retard oxidative degradation by preventing initiation of chains. Many sulfiu and phosphorus compounds are believed to function in the latter way. In particular, hydroperoxides that are potential chain initiators are also products of autoxidation. This fact gives autoxidations the potential of being autocatalytic, since the more oxidation products formed, the higher the initiator concentration. Divalent sulfur compounds and trivalent phosphorus compounds can reduce hydroperoxides, yielding stable products ... 

If in the chain initiated reaction when v,- = const the induction period is independent of the efficiency of retardation action of the inhibitor but is determined by its concentration, then during autoxidation the inhibitor is more slowly consumed when it more efficiently terminate chains because ROOM is more slowly accumulated and the retardation period increases. Then the initiated oxidation of hydrocarbons is retarded only by compounds terminating chains. Autoxidation is retarded by compounds decomposing hydroperoxides. This decomposition, if it is not accompanied by the formation of free radicals, decreases the concentration of the accumulated hydroperoxide and, hence, the autoxidation rate. Hydroperoxide decomposition is induced by compounds of sulfur, phosphorus and various metal complexes, for example, thiophosphate, thiocarbamates of zinc, nickel, and other metals. 

Methylbenzimidazole (492 R = Me) yields the benzimidazoline (506) in the Vilsmeier-Haack reaction with DMF-phosphorus oxychloride. Treatment of 2-amino-l-benzhydryl-benzimidazole with sodium in liquid ammonia affords a mixture of 2-nitrobenzimidazole and the azo-compound (507) by an autoxidation process. " The benzimidazole derivative (508), prepared by the action of diphenylamine-2,2 -dicarbonyl chloride on benzimidazole, is dearomatized on heating to give the condensed heterocycle (509). ... 

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