Kinetic Oxidation Studies of Pentoxifylline by N-Chlorosuccinimide in Acidic Medium Using Iridium(III) Chloride as Inhibitor

Abstract

In present study, the kinetics and mechanism of oxidation of pentoxifylline (PTX) by N-chlorosuccinimide (NCS) in acidic conditions at 40 ± 0.1 ºC is reported. The reaction depicts first-order kinetics in regard to [NCS], [PTX] and [HClO4]. The reaction rate goes on decreasing as the concentration of iridium(III) chloride is increased. This shows that iridium(III) chloride plays the role of an inhibitor in the reaction under investigation. Nil impact of [Hg(OAc)2], [NHS] and dielectric constant (D) of the medium on the rate of oxidation of pentoxifylline have been observed. This reaction has been investigated from 308-323 K and the monitored rate of reaction suggests a direct relationship between temperature and the rate of reaction. From the graph between log k and 1/T, value of activation energy (Ea) was numerated and more activation parameters like enthalpy of activation (ΔH#), entropy of activation (ΔS#) and free energy of activation (ΔG#) were calculated with the help of activation energy (Ea). On account of experimentally determined the kinetic orders and activation parameters, a most plausible reaction path has been suggested for the oxidation of pentoxifylline in presence of Ir(III) as an inhibitor.