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Kinetics and mechanism of the oxidation of substituted benzaldehydes by hexamethylenetetramine‐bromine
Author(s) -
Gangwani H.,
Sharma P. K.,
Banerji K. K.
Publication year - 2000
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 - 10.1002/1097-4601(2000)32:10<615::aid-kin3>3.0.co;2-6
Subject(s) - chemistry , hexamethylenetetramine , acrylonitrile , bromine , benzaldehyde , benzoic acid , acetic acid , medicinal chemistry , kinetic isotope effect , kinetics , reaction rate , solvent , aldehyde , reaction rate constant , steric effects , aqueous solution , photochemistry , organic chemistry , catalysis , deuterium , polymer , physics , quantum mechanics , copolymer
The oxidation of thirty‐six monosubstituted benzaldehydes by hexa‐methylenetetramine‐bromine (HABR), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to HABR. Michaelis‐Menten–type kinetics were observed with respect to aldehyde. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of hexamethylenetetramine on the reaction rate. The oxidation of [ 2 H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta ‐ and para ‐substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho ‐substituted benzaldehydes correlated well with tetraparametric LDRS equation. The oxidation of para ‐substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho ‐ and meta ‐substituted compounds displayed a greater dependence on the field effect. The positive value of γ suggests the presence of an electron‐deficient reaction center in the rate‐determining step. The reaction is subjected to steric acceleration when ortho ‐substituents are present. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 615–622, 2000