Micellar‐accelerated hydrolysis of organophosphate and thiophosphates by pyridine oximate

Rate constants for the hydrolysis reaction of phosphate (paraoxon) and thiophosphate (parathion, fenitrothion) esters by oximate (pyridinealdoxime 2‐PyOx− and 4‐PyOx−) and its functionalized pyridinium surfactants 4‐(hydroxyimino) methyl)‐1‐alkylpyridinium bromide ions (alkyl = CnH2n+1, n = 10, 12,...

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Published inInternational journal of chemical kinetics Vol. 50; no. 11; pp. 827 - 835
Main Authors Kandpal, Neha, Dewangan, Hitesh K., Nagwanshi, Rekha, Ghosh, Kallol K., Satnami, Manmohan L.
Format Journal Article
LanguageEnglish
Published Hoboken Wiley Subscription Services, Inc 01.11.2018
Subjects
Catalysis
cationic micelles
Cations
Cetyltrimethylammonium bromide
Esters
functionalized surfactants
Hydrolysis
Micelles
Organophosphates
oximate
Oximes
phosphate esters
Rate constants
Spectrophotometry
Surfactants
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Summary:Rate constants for the hydrolysis reaction of phosphate (paraoxon) and thiophosphate (parathion, fenitrothion) esters by oximate (pyridinealdoxime 2‐PyOx− and 4‐PyOx−) and its functionalized pyridinium surfactants 4‐(hydroxyimino) methyl)‐1‐alkylpyridinium bromide ions (alkyl = CnH2n+1, n = 10, 12, 14, 16) have been measured kinetically at pH 9.5 and 27°C in micellar media of cationic surfactants cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB). Acid dissociation constant, pKa, of oximes has also been determined by spectrophotometric, kinetic, and potentiometric methods. The rate acceleration effects of cationic micelles have been explored. Cationic micelles of the pyridinium head group (CPB) showed a large catalytic effect than the ammonium head group (CTAB). The effects of pH, oximate concentration, and surfactants have been discussed.
ISSN:0538-8066
1097-4601
DOI:10.1002/kin.21217