Redox Potentials

Reduction of an electron acceptor (oxidant), or oxidation of an electron donor (reductant), is often achieved stepwise via one-electron processes in which the intermediate is a free radical. The reduction potentials of such one-electron couples are of value in predicting the direction or feasibility, and in some instances the rate constants, of many free-radical reactions. Electrochemical methods have limited applicability in measuring these properties of frequently unstable species, but fast, kinetic spectrophotometry (especially pulse radiolysis) has widespread application in this area. Tables of about 1,200 values of reduction potentials of about 700 one-electron couples in aqueous solution are presented. The majority of organic oxidants listed are quinones, nitroaryl and bipyridinium compounds. Reductants include phenols, aromatic amines, indoles and pyrimidines, thiols and phenothiazines. Inorganic couples largely involve compounds of oxygen, sulfur, nitrogen and the halogens. Proteins, enzymes, and metals and their complexes are excluded.

Published by:

P. Wardman,
J. Phys. Chem. Ref. Data, 18 1637-1755 (1989) __ Ordering info.

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Work jointly supported by:

Office of Basic Energy Sciences
United States Department of Energy

Standard Reference Data
National Institute of Standards and Technology