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Kinetics and mechanism of oxidation of indigo carmine by hypohalites
Author(s) -
Mahadevappa D. S.,
Gowda N. M. Made
Publication year - 1991
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.550230104
Subject(s) - indigo carmine , chemistry , kinetics , ionic strength , reaction rate constant , halide , isatin , inorganic chemistry , ion , ionic bonding , nuclear chemistry , organic chemistry , aqueous solution , physics , quantum mechanics
Kinetics of oxidation of indigo carmine (IC) by sodium hypohalites, NaOX (X Cl or Br), in alkaline buffer of pH 9–11 has been studied spectrophotometrically at λ = 610 nm. The experimental rate law obtained is − d [IC]/ dt = k [OX − ][IC][OH − ] x where x <1. Variation of ionic strength or dielectric constant of the medium had no effect on the reaction rate while the addition of halide ions slightly retarded the rate. A most plausible mechanism proposed on the basis of experimental results involves the formation of isatin sulphonate which undergoes further oxidation to anthranilate. Activation parameters have been evaluated.