Kinetics and Mechanism of Chromium(III) Catalysed Oxidation of Propan-1-ol and Butan-1-ol by Cerium(IV) in Aqueous Sulfuric acid Media

Abstract

The kinetics and mechanism of chromium(III) catalysed oxidation of propan-1-ol and butan-1-ol by cerium(IV) in aqueous sulfuric acid media have been studied at different temperatures (30-40° C) under the conditions, [substrate]T(0.025-0.70 mol dm-3) × [CeIV]T (2.5-4.5 × 10-3 mol dm-3) in the presence of [Cr]T = 0.0025-0.07 mol dm-3. At fixed [H+] and [HSO-4 ] the observed rate law conforms to: -d ln[CeIV]/df =kobs =A[S]T[Cr]T/{B + C[Cr]T(D + E[S]T)}, where, A, B, C, D and Ε are constants expressed in terms of different rate constants and equilibrium constants; [S]Tand [Cr]T denote the total substrate (i.e. propan-l-ol or butan-l-ol) and total chromium concentration respectively. The proposed mechanism involves the association of catalyst, substrate and oxidant at some pre-equilibrium steps before the electron transfer step. The overall process is found catalysed by H+ . From the [HSO-4] dependence, Ce(SO4)2 has been found kinetically active.