Oxidation of ,-Dimethylhydroxylamine by Hexachloroiridate(IV).

The oxidation of (CH)NOH (DMH, ,-dimethylhydroxylamine) is of interest because of the use of this reagent in actinide separations. Here, we report on the aqueous oxidation of DMH by [IrCl], a classic outer-sphere one-electron oxidant. The reaction is subject to adventitious catalysis by Fe and Cu, and this catalysis can be suppressed with 1 mM oxalate. The uncatalyzed reaction yields [IrCl] and nitrone (CH)N(O)CH. The rate law has two terms: one corresponding to oxidation of (CH)NOH and the other to oxidation of (CH)NO. A mechanism is inferred in which the rate-limiting steps are electron-transfer oxidations of these two DMH forms, leading to their corresponding radicals. The nitrone arises from the oxidation of the DMH radical, (CH)NO.