Kinetic Approach to the Mechanism of Oxidation of L-Ascorbic Acid by Periodate Ion in Acidic Medium

Babatunde O.A, Nwakama O.N
2013 Journal of Biology and Life Science  
The aim of this study is to investigate the mechanistic pathway of the oxidation of L-ascorbic acid by periodate ions in acidic medium reaction. The oxidation of L-ascorbic acid (H 2 A) by periodate ions in acidic medium has been investigated under pseudo-first order conditions at 27 ± 0 o C, [H + ] = 1.0 x 10 -3 mol dm -3 , I= 1.0 mol dm -3 (NaCl) and λ max 430nm. The stoichiometry of the reaction was observed to be 2:7 in terms of mole ratio of periodate ions and ascorbic acid consumed. The
more » ... action is first order in both reactants and shows dependence on acid concentration. The proposed rate law is d[IO -4 ]=(a + b [H + ])[H 2 A] [IO -4 ] With a = 7.15 x 10 -2 .dm 3 mol -1 s -1 (intercept) and b = 5.53 x 10 -1 mol dm 6 mol -2 s -1 (slope). The rate of reaction increased with increase in ionic strength. There is no evidence for the formation of an intermediate complex of significant stability and free radicals are probably not present in the reactions. This is supported by the result of the Michealis-Menten's plot. A plausible mechanism consistent with the outersphere mechanism is proposed.
doi:10.5296/jbls.v4i2.3349 fatcat:h6iotja435dlbfnn6aoy2dlfse