Synergistic catalytic activity of RuCl3 and OsO4 on the selective oxidation of pregabalin drug molecule: Exploration of scope, reaction mechanism and kinetic modeling

Abstract

a b s t r a c tThe kinetics and mechanism of (RuCl 3 + OsO 4 ) in combination and, RuCl 3 and OsO 4 alone catalyzed oxidation of pregabalin (PGB) drug with chloramine-T have been investigated at 313 K in aqueous alkaline medium. The kinetic characteristics were found to be varied for each catalyzed reactions. In all the three catalyzed reactions, the reaction rate shows a first-order dependence of rate on [CAT] 0 and a negativefractional-order on [NaOH]. The order of [PGB] 0 is found to be unity incase of [OsO 4 ], but it is fractional in both RuCl 3 and [RuCl3 + OsO4] catalyzed reactions. The orders with respect to [RuCl 3 ] and [OsO 4 ] are less than one whereas it is unity in case of [RuCl 3 + OsO 4 ]. Activation parameters have been evaluated. 2-isobutylsuccinic acid was identified as the oxidation product of PGB. Under identical set of experimental conditions, the reaction rates revealed that all the three catalyzed reactions are about 25 to 71-fold faster than the uncatalyzed reactions. The catalytic efficiency of these catalysts follows the order (RuCl 3 + OsO 4 ) > OsO 4 > RuCl 3 . The observed reactivity sequence may be attributed to the different d-electronic configuration of the catalysts. Most noteworthy is the significant catalytic activity of 71-fold in case of (RuCl 3 + OsO 4 ) catalyst. It justifies the synergistic effect of (RuCl 3 + OsO 4 ) catalyst on the oxidation of PGB drug. An isokinetic relationship is observed with ˇ = 366 K, indicating that enthalpy factors are controlling the rate. The reaction mechanisms put forward and rigorous kinetic models deduced, give the best fit to the experimental results for each catalyzed reactions.

Dynamic Impact of RuCl3 Catalyst on the Oxidation of Cyclamate with Acidified Bromamine-T: Elucidation of Mechanistic Pathways and Kinetic Modeling

“…The catalysis by platinum metal ions in the redox reactions is of great interest due to strong catalytic influence of these ions in many reactions [16][17][18][19][20][21][22]. This catalysis plays an important role in understanding the mechanism of redox reactions.…”

“…This catalysis plays an important role in understanding the mechanism of redox reactions. Among the platinum group metal ions, RuCl 3 has widely been used as a homogeneous catalyst in various redox systems [16][17][18][19][20][21][22]. This catalysis involves different degrees of complexity, due to the formation of different intermediate complexes, free radicals and different oxidation states of ruthenium [23,24].…”