25593-53-7Relevant articles and documents
THE CATALYTIC EFFECT OF CATIONIC AMINO MICELLES ON THE HYDROLYSIS OF SUBSTITUTED PHENYL ESTERS
Rav-acha, Ch.,Ringel, I.,Sarel, S.,Katzhendler, J.
, p. 5879 - 5892 (2007/10/02)
The catalytic effects of two aminocationic micelles on the hydrolysis of substituted phenyldecanoate esters and a positively charced benzoate ester (CPNBA) were determined.The micellaric catalysts were of the general structure Br where n=2 (micelle 1); n=3 (micelle 2).The kinetics followed the expression: kobs=k0+kcat x Ka/(Ka+H+)+kcOH->.From the comparison of the kcOH rates with specific base catalysis rates deduced from reactions in non catalytic micelles, it was concluded that the kcOH term, is compatible mainly with an aminolysis reaction catalysed by hydroxide ion.The Hammett and Bronsted correlations (ρ=2.8; β=1.0), in addition to the very small deuterium isotope effect, suggested that kcat corresponded with a nukleophilic mechanism.The Bronsted plot of log kcat vs pKa of the phenolate leaving groups in micelles 1 and 2 showed a biphasic behaviour.The break in the curve occured at pK0=5.89 and pK0=6.78 respectively.The partition ratio k+/-/k-a of the zwiterionic tetrahedral intermediate was derived from the experimental data and produced the following correlation: log k+/-/k-a=-0.92pK0+0.43pKN+2.466.The ester CPNBA exhibited a deuterium isotope effect of 2.1.From product analysis it was concluded that the reaction proceeds via a general base catalysis of aminolysis.
