Oxidation of <scp>D</scp>-gluconic acid by chromium(VI) in perchloric acid

Abstract

The oxidation of gluconic acid by chromium(VI) in perchloric acid has been found to follow the rate law: −d[Cr VI ]/dt = (k′ 1 + k′ 2 [GA])[H + ] 2 [Cr VI ], where k′ 1 = (7.1 ± 0.2) × 10 −4 M −2 s −1 and k′ 2 = (9.4 ± 0.2) × 10 −2 M −3 s −1 . This rate law corresponds to the reaction leading to the formation of 2-ketogluconic acid by C—H cleavage when a 20-fold or higher excess of acid over chromium(VI) is employed. Buildup and decay of chromium(V) intermediates accompany the decay of chromium(VI). Chromium(V) rates of decay are similar or slower than those of chromium(VI), as observed by electron paramagnetic resonance (epr) and visible spectrophotometry.