Kinetics and mechanism of oxidations of [N-(2-hydroxyethyl) ethylene-diamine-N,N',N'-triacetato] chromium (III) by N- bromosuccinimide

Abstract

The kinetics of oxidation of [N-(2-hydroxyethyl)ethylenediamine- N,N' -Nvtnacetato] chromium (III) complex [Cr^III (H₂O)(TOH) by N-bromosuccinimide(NBS) in aqueous solution to yield chromium (IV) has been studied spectrophotometrically at 20-40&deg;C range. The reaction is first order each in [NBS] and [Cr^III], and the rate increases with increase in <em>p</em>H between 6.30 and 7.33. The thermodynamic activation parameters have been calculated. The experimental rate law is consistent with a mechanism in which the deprotonated [Cr^III(OH)(TOH)^-&nbsp;] is considered to be the most reactive species compared to its conjugate acid. It is assumed that electron transfer takes place via an inner-sphere mechanism.