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Kinetic evidence for the copper peroxide intermediate with two copper ions in proximity
Author(s) -
Selvarani S.,
Medona B.,
Ramachandran M. S.
Publication year - 2006
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.20168
Subject(s) - chemistry , copper , peroxide , aqueous solution , inorganic chemistry , decomposition , ion , hydroxide , catalysis , reaction rate constant , hydrogen peroxide , metal ions in aqueous solution , metal , chemical decomposition , kinetics , organic chemistry , physics , quantum mechanics
The decomposition of caroate (peroxomonosulfate, PMS) is catalyzed by Cu(II) ions even at 5 × 10 −5 M in aqueous alkaline solution. The rate is second order in copper(II) ions concentrations and first order in [PMS]. The rate constant values are found to decrease with increase in hydroxide ion concentrations. The turnover number for the reaction is estimated as >1000. The experimental results suggest that the formation of peroxide type intermediate with two copper(II) ions is the rate‐determining step. This peroxide intermediate reacts with another molecule of PMS to give the products oxygen, SO 2− 4and copper ions. The overall entropy of activation is positive with a value of ∼20 cals/mol/K. The very high turnover number suggests that Cu(II) ion is one of the best catalysts for the decomposition of caroate ions in alkaline medium. The reaction also represents a system in which metal ion catalyzed decomposition of caroate does not involve radical intermediates. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 439–443, 2006