1 research outputs found
Physicochemical Properties and Supernucleophilicity of Oxime-Functionalized Surfactants: Hydrolytic Catalysts toward Dephosphorylation of Di- and Triphosphate Esters
Aggregation and kinetic studies have
been performed to understand
the hydrolytic potencies of the series of oxime-functionalized surfactants,
viz., 3- hydroxyiminomethyl-1-alkylpyridinium bromide (alkyl = C<sub><i>n</i></sub>H<sub>2<i>n</i>+1</sub>, <i>n</i> = 10, 12, 14, 16, 18) in the cleavage of phosphate esters, <i>p</i>-nitrophenyl diphenyl phosphate (PNPDPP) and bisÂ(2,4-dinitrophenyl)
phosphate (BNDPP), in mixed micelles with cetylpyridinium bromide
(CPB). Micellization and surface properties of mixed micelles functional
surfactants with CPB were studied by conductivity and surface tension
measurements. Acid dissociation constants (p<i>K</i><sub>a</sub>) were determined, the effect of functional surfactant alkyl
chain length and pH on the observed rate constant (<i>k</i><sub>obs</sub>) for phosphate ester cleavage has been discussed,
and the effect of substrate on the supernucleophilicities of the studied
oximes was monitored. Functionalized oxime-based surfactants were
proved to be supernucleophiles to attack on the Pî—»O center of tri- and diphosphate
esters. Oximes with hexadecyl alkyl chain length (3-C<sub>16</sub>) showed maximum micellar effect on the rate constants toward PNPDPP.
Micellar effects were analyzed in terms of the pseudophase model