Abstract
Kinetics of oxidation of semicarbazide (SC) by iodamine-T (IAT), iodine monochloride and aqueous iodine has been studied in aqueous perchloric acid medium. The rate laws followed by the oxidation of SC were determined. The rates decreased slightly with increase in ionic strength of the medium in IAT and ICI oxidations, while the reverse trend was observed with I2. Decrease in dielectric constant of the medium increased the rates with IAT and ICI, while it decreased the rate in I2 oxidations. Addition of the reduced product,p-toluene-sulphonamide had no effect on the rate with IAT. Addition of I− had slight negative and positive effects on the rates of oxidations with IAT and ICI, respectively, but the negative effect was considerable in I2 oxidations. Mechanisms consistent with the observed rate laws have been proposed and discussed. Rate determining steps have been identified and their coefficients calculated. These constants were used to predict the rate constants from the deduced rate laws as [SC], [H+] and [I−] varied. Reasonable agreement between the calculated constants and experimental values provide support for the suggested mechanisms.
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References
Amis E S 1966Solvent effects on reaction rates and mechanisms (New York: Academic Press)
Benson S W 1960The foundations of chemical kinetics (New York: McGraw Hill)
Bishop E and Jennings V J 1958Talanta 1 197
Campbell M M and Johnson G 1978Chem. Rev. 78 65, and references therein
Entelis S G and Tiger R P 1976Reaction kinetics in the liquid phase (New York: Wiley)
Feigl F 1958Spot tests in inorganic analysis 5th edn. (Amsterdam: Elsevier)
Gowda B T and Bhat J I 1987aIndian J. Chem. A26 215
Gowda B T and Bhat J I 1987bTetrahedron 43 2119, and references therein
Gowda B T and Rao R V 1986Indian J. Chem. A25 908
Gowda B T and Rao R V 1987Oxid. Commun. 10 31
Gowda B T and Sherigara B S 1986aIndian J. Chem. A25 960
Gowda B T and Sherigara B S 1986bOxid. Commun. 9 165
Gowda B T and Mahadevappa D S 1983J. Chem. Soc., Perkin Trans. 2 323
Hardy F E and Johnston J P 1973J. Chem. Soc., Perkin Trans. 2 742
Laidler K J 1965Chemical kinetics (New York: McGraw Hill)
Latimer W M 1960Oxidation potentials (New York: Prentice Hall)
Pillai C P K and Indrasenan P 1980Talanta 27 751
Quinlan J E and Amis E S 1955J. Am. Chem. Soc. 77 4187
Van Nostrand 1976International encyclopedia of Chemical science (New York: Van Nostrand)
Zuman P and Patel R 1984Techniques in organic reaction kinetics (New York: Wiley)
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Gowda, B.T., Bhat, J.I. Mechanism of positive iodine reactions: Kinetics of oxidation of semicarbazide by iodamine-T, iodine monochloride and iodine. Proc. Indian Acad. Sci. (Chem. Sci.) 100, 275–286 (1988). https://doi.org/10.1007/BF02840536
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DOI: https://doi.org/10.1007/BF02840536