Kinetics and mechanism of oxidation of (aqua-2-aminomethyl-pyridine) chromium(III) by N-bromosuccinimide

Abstract

The kinetics of oxidation of (aqua-2-aminomethyl-pyridine) CrIII by N-bromosuccinimide (NBS) in aqueous solution to yield chromium(VI) has been studied spectrophotometrically over the 25–40 °C range. The reaction rate is first order with respect to both [NBS] and [CrIII], and increases with increasing pH between 7.6 and 8.6. The thermodynamic activation parameters were calculated. The experimental rate law is consistent with a mechanism in which the deprotonated [Cr(L)2(OH)]2+ was considered to be the most reactive form compared to its conjugate acid. It is assumed that electron transfer takes place via an inner-sphere mechanism.