Intermediate steps in autoxidation III. Reactions of MnIII acetate in acetic acid with benzene, chlorobenzene, and toluene

Product data on the reactions of manganic acetate in glacial acetic acid with benzene (100 °C), chlorobenzene, or toluene (110 °C) indicate that HOOCCH2· radicals are the primary intermediates. Presumably, these are formed from manganic acetate and acetic acid in a concerted step. In the absence of benzene derivatives, they react with manganic acetate to form acetoxyacetic acid or dimerize to succinic acid; acetoxyacetic acid is further degraded to methylene diacetate. Benzene, chlorobenzene, or toluene add on HOOCCH2· radicals, forming phenylacetic acid(s); these in turn are further degraded to benzyl acetate(s), benzal diacetate(s) and benzaldehyde(s) which are the main products, accounting for more than 60% of the oxidizing agent. In the presence of potassium bromide, toluene reacts at a much higher rate; products then are mainly benzyl acetate and benzyl bromide. Rates of reduction of MnIII acetate in the presence of manganous acetate are not affected by large proportions of benzene or chlorobenzene; toluene has a slight accelerating effect. Products and mechanisms are compared with those obtaining in oxidations by manganic acetate in which electron transfer is the primary step.