Oxidation of Carbamazepine by Lipopathic Mn(VII), Cetyltrimethylammonium Permanganate: A Mechanistic Study |
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| Authors: | Sarita Garnayak Sabita Patel |
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| Affiliation: | Department of Chemistry, National Institute of Technology‐Rourkela, Rourkela, India |
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| Abstract: | In this contribution, we report the oxidation of an established anticonvulsant and antiepileptic drug, carbamazepine, by a lipopathic oxidant, cetyltrimethylammonium permanganate (CTAP), in a nonpolar medium. 1H‐Dibenzo[b,f]azepine‐4,5‐dione is found to be the major product of the oxidation reaction. The kinetics of the reaction is studied in organic media spectrophotometrically by monitoring the disappearance of Mn(VII) at 530 nm. The reaction is found to be fractional order with respect to carbamazepine and first order with respect to CTAP. Based on the experimental findings, a suitable ionic mechanism is proposed where carbamazepine reacts with CTAP in a slow rate‐determining step to form a hypomanganate ester intermediate through a nonpolar cyclic transition state. Subsequently, the intermediate decomposes and hydrolyzes in fast steps to the dicarbonyl product. The proposed reaction mechanism is also supported by the effect of solvent and temperature on the rate of the reaction. The addition of ionic surfactants increases the rate of reaction, and the catalyzing effect is explained through the possible formation of mixed reverse micellar aggregates where carbamazepine is partitioned more to the interfacial region in the vicinity of the permanganate anion. |
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