Superoxide, potassium, with alkyl halides

If the crown catalyzed reaction of potassium superoxide with alkyl halide is carried out in dimethylsulfoxide as solvent, the product is the corresponding alcohol [6—9]. The formation of alcohol rather than dialkyl peroxide has been shown to result from reaction of the alkyl hydroperoxide anion with dimethylsulfoxide to form alkoxide and dimethylsulfone (Eqs. 8.3-8.5) [9]. The alkyl hydroperoxide anion is presumably formed by reduction of the initial alkyl hydroperoxide radical by the superoxide anion [8, 9]. 

Tlie name superoxide was introduced in 1934 to signify an exceptional degree of reactivity of superoxide radical anion in KOj [187]. It was obtained by acting with dioxygen on metals such as potassium (and Rb, Cj). It is marked by nucleopliilicity. In aprotic media it reacts rapidly with primary and secondary alkyl halides to yield dialkyl peroxide and with acyl chlorides to yield diacyl peroxides. Superoxides are reduced to peroxides under some experimental conditions. Tlrey were recently reviewed by Sawyer and Valentine [188]. No explosive properties of metal superoxides or their mottures have been recorded. 

Crown-catalysed substitution by chromate ions provides a direct oxidation route from primary halides to aldehydes via chromate esters (39). Superoxide anion becomes a useful new type of oxygen nucleophile now that potassium superoxide can be solubilized with 18-crown-6 and derivatives. Alkyl halides or sulphonates (RX) may be converted to alcohols or dialkyl peroxides, depending on the exact conditions, through an initial nucleophilic substitution with inversion (Scheme 8). 

---