Mechanistic and Catalytic Behavior of Os(VIII) for the Chlorpheniramine Maleate and Bromamine-B Redox System: A Kinetics Based Approach

Abstract

Chlorpheniramine maleate (CPM) is an important antihistamine agent. To the best of our knowledge there is no report in the literature about the oxidation of CPM with halogen + 1 oxidant from the stand point of its kinetics and mechanistic chemistry. Hence, a systematic kinetics and mechanistic study on the oxidation of CPM with bromamine-B (BAB) in the presence of NaOH and Os(VIII) catalyst has been carried out at 303 K. The reaction exhibits a first-order dependence of rate on [BAB]o and [Os(VIII)]. The order with respect to [CPM]o is zero, whereas it is fractional on [NaOH]. Activation parameters were evaluated. The stoichiometry of the reaction is 1:1 and the oxidation products were identified as (4-chlorophenyl)(pyridine-2-yl)methanol and 2-(dimethylamino)acetaldehyde from GC-MS analysis. The Os(VIII) catalyzed reaction is about four-fold faster than the uncatalyzed reaction. Based on the experimental results, possible reaction mechanism and kinetic model have been proposed.

Keywords: Chlorpheniramine maleate, Bromamine-B, Oxidation-kinetics, Os(VIII)
catalysis, mechanism