Andrew R. Miksztal

[7] Methods for the study of superoxide chemistry in nonaqueous solutions

Publisher Summary Current knowledge of the chemical properties of superoxide anion, O 2 - , is based on studies of superoxide reactions in aqueous and nonaqueous solution. The superoxide dismutases were postulated to play a protective role within the cell by reducing the steady-state levels of superoxide, a species that is inevitably produced in some unknown amount as a by-product of aerobic metabolism. In aqueous solution, studies of superoxide chemistry require specialized rapid reaction techniques because of the rapid, spontaneous disproportionation of superoxide in protic media. Interest in the reactivity of superoxide in nonaqueous media began with discoveries that electrochemical reduction of dioxygen in dimethyl sulfoxide yielded stable solutions of superoxide, and that crown ethers would solubilize KO 2 in aprotic solvents and could be used to prepare stable solutions of superoxide for various uses. This chapter reviews the methods for the preparation of solutions of superoxide in nonaqueous, aprotic solvents and the uses of these methods for the study of superoxide chemistry in such media.

Cytochrome P-450 Model Systems: Alkene Oxidation

Iron(III) porphyrins efficiently catalyze the epoxidation of alkenes and the hydroxylation of alkanes by iodosylbenzenes and peracids, most likely by the same mechanisms utilized by cytochrome P-450 enzymes. The synthetic catalysts mimic the enzymes in product stereospecificity, 1 the accompanying rearrangements, 2 and the suicide labelling which results in N-alkylhemin formation.3