SCHEDULED MAINTENANCE
The detection of a complex intermediate in the oxidation of ascorbic acid by ferric ion
Abstract
The oxidation of ascorbic acid by Fe3+ ion has been studied using the stopped-flow technique in an attempt to detect and study the formation of an intermediate. It has been shown that a transient species, believed to be a ferric ascorbate complex, and exhibiting a broad absorption band with λmax.= 560 nm is formed by a two-step mechanism. Values of 11 ± 6 l mol–1 cm–1 and 0·55 ± 0·4 for the extinction coefficient and formation constant respectively at 25 °C have been obtained for the overall complex formation. At 0 °C, the first step in the reaction is governed by the law, Rate =k[Fe3+][H2A], where k has the value of 30 ± 10 l mol–1 s–1. The probable mechanism of both the complex formation and overall redox reaction are discussed.
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