Cu(II)‐catalyzed oxidation of thiols by superoxide ligated to CoIII2 |
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Authors: | Ritu Mishra Rupendranath Banerjee Subrata Mukhopadhyay |
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Institution: | 1. Department of Chemistry and Environment, Heritage Institute of Technology, , Kolkata, 700 107 India;2. Department of Chemistry, Jadavpur University, , Kolkata, 700 032 India |
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Abstract: | Copper(II) dramatically catalyzes the oxidation of thiols by a superoxide bridging two CoIII ions. The catalyzed path overwhelmingly dominates over the uncatalysed path and is first order in the superoxo complex concentration. The first‐order rate constants show a first‐order dependence in Cu2+], a second‐order dependence in thiol] and linearly varies with H+]?3. On the basis of observed kinetics reported here, it is proposed that Cu(II) reacts with two thiol molecules to form a CuII(thiol)2 complex, an electron is transferred from one ligated thiol to the CuII center to form CuI(thiol) and a thiyl radical. The copper(I)‐thiol complex is oxidized by the conjugate base of the title complex to regenerate CuII(thiol). A CuII/I catalytic cycle is thus believed to be responsible for the observed catalysis. Copyright © 2012 John Wiley & Sons, Ltd. |
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Keywords: | superoxide 2‐mercaptoethanol thioglycolic acid L‐cysteine cobalt(III) kinetics |
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