Kinetics and Mechanism of Oxidation of Gabapentin by N-bromosuccinimide in Aqueous Alkaline Medium. Comparing to the Kinetics of Oxidation by N-bromosuccinimide in Aqueous Acid Medium
Alaa Eldin Mokhtar Abdel-Hady *
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Sinai University, Arish City, Cairo, Egypt
*Author to whom correspondence should be addressed.
Abstract
The kinetics of oxidation of gabapentin (GBP) by N-bromosuccinimide (NBS) in an alkaline medium has been investigated. The oxidation reaction showed unique kinetics that greatly differed on going from acid to base medium. In an acid medium (pH=2.52), the reaction rate showed first order dependence on [NBS], fractional order dependence on both [GBP] and [H+] and increased with temperature over (303–321oK) range. In an alkaline medium, the rate showed first order dependence on [GBP], fractional order on [H+] over (1.99-39.80) x10-9 range and zero order dependence on [NBS]. It is noteworthy that the reaction rate decreased with temperature over the range studied. An inner-sphere mechanism for the oxidation pathway supported by free radicals intervention was proposed.
Keywords: Kinetics of oxidation, oxidation of gabapentin, oxidation with N-bromosuccinimide, reaction mechanism