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

摘要

The kinetics of oxidation of [N-(2-hydroxyethyl)ethylenediamine-N,N'.N'-triacetato] chromium (III) complex [Cr~III (H_2O) (TOH) by N-bromosuccinimide (NBS) in aqueous solution to yield chromium (IV) has been studied spectrophotometrtically at 20-40 deg C rante. The raction is first order each in [NBS] and [Cr~III], and the increases with increase in pH between 6.30 and 7.33. The thermodynamic activation parameters have been calculated. The experimental rate law is consistant with a mechanism in which the deportonated [Cr~III(OH)(TOH)~-] is considered to be the most reactive species compared to ist conjugate acid. It is assumed that electron transfer takes place via an inner-sphere mechanism.