Analysis of the kinetics of hydrolysis of p-nitrophenyl alkanoates in colloidal polymer dispersions by an ion-exchange model

Paul D. Miller, H. Olin Spivey, Stephanie L. Copeland, Rebecca Sanders, Andrea Woodruff, David Gearhart, Warren T. Ford

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Rates of hydrolyses of p-nitrophenyl acetate, hexanoate, and octanoate in borate buffer solutions at 30 °C are 2.3-16.5 times faster in the presence of 1.2 mg mL-1 quaternary ammonium ion exchange latex particles than those obtained in water alone. The latexes were constructed by emulsion copolymerization of styrene, butyl methacrylate, or 2-ethylhexyl methacrylate with 25 wt % vinylbenzyl chloride (VBC), 1% divinylbenzene, and 1% styrylmethyl(trimethylammonium chloride) followed by quaternization of the VBC units with either trimethylamine or tributylamine. Analysis of the kinetics as a function of particle concentration, pH, and buffer concentration using an ion-exchange model provided partition coefficients of the p-nitrophenyl esters, intraparticle second-order rate constants, and ion-exchange selectivity coefficients. The major contributors to the enhanced rates are the partition coefficient favoring absorption of the p-nitrophenyl ester into the latex by a factor as large as 90 000 and intraparticle hydroxide concentrations up to 10 times higher than those obtained in the external water. The intraparticle second-order rate constants differ little from those in water.

Original languageEnglish
Pages (from-to)108-114
Number of pages7
Issue number1
Publication statusPublished - 1 Jan 2000
Externally publishedYes


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