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Kinetics of oxidation of some α‐amino acids L (−) arginine, L (−) histidine, L (+) ornithine, L (−) tryptophan, L (−) threonine by sodium N ‐chloro‐4 methyl benzene sulphonamide (chloramine‐ T ) in alkaline medium
Author(s) -
Gupta K. C.,
Gupta Kumkum
Publication year - 1985
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550170707
Subject(s) - chemistry , reaction rate constant , kinetics , histidine , tryptophan , ionic strength , amino acid , solvent , arginine , sodium , reaction rate , medicinal chemistry , inorganic chemistry , stereochemistry , organic chemistry , aqueous solution , biochemistry , catalysis , physics , quantum mechanics
Kinetic studies of oxidation of L (−) arginine, L (+) ornithine, L (−) histidine, L (−) tryptophan, L (−) threonine have been carried out in alkaline medium. The reaction showed an inverse fractional order in OH − and first‐order dependence on both amino acid and chloroamine‐ T concentration. The effect of varying ionic strength (KCl) on the rate of oxidation is negligible. A general mechanism for the oxidation has been suggested by considering interaction between anionic species of amino acid and p ‐toluene‐sulphochloramide. The effect of solvent and temperature have been also discussed. The fractional order obtained in OH − is due to the fact that a fraction of overall reaction proceeds via an alternative OH − independent path. The combined rate law in accordance to observed kinetics is derived as\documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm CAT}]}}{{dt}} = \frac{{2k_1 K_1 [{\rm AA}]_T [{\rm CAT}]_T }}{{[{\rm OH}^ - ]}} + 2k_3 K_1 K_3 [{\rm AA}]_T [{\rm CAT}]_T $$\end{document}The rate constants predicted by the derived rate law as the concentration of OH − ions change, are in excellent agreement with the observed rate constants, thus further justifying these rate laws and hence the proposed mechanistic schemes.