Synthesis and Reactivity of L-Cystine with Di-Oxo-Bridged Cobalt(III) Complex

Abstract

The kinetics of the oxidation of L-cystine by the di-oxo-bridged Co(III) complex have been studied at various temperatures, 298 K to 323 K, and pH, 3.30 to 4.45, using UV⁻vis spectroscopy in NaClO₄ medium. The product of the reaction has been characterized by UV-vis spectra, IR, and ¹H NMR spectroscopy. The activation parameters such as enthalpy, entropy, free energy, and activation energy have been evaluated. A new SN_i mechanism has been derived for this reaction. The oxidation product was found to be cystine disulfoxide, R-SO-SO-R at T ≤ 318 K and disulfone, R- (SO₂)₂-R at T = 323 K.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.

Keywords:

• kinetics
• L-cysteine
• product formation
• SNi mechanism

Acknowledgments

The author thanks the Department of Chemistry, Utkal University, for providing support on this research work.