Effects of Nonionic Micelles on the rate of Alkaline Hydrolysis Of N-(2 '-Methoxyphenyl)Phthalimide (1): kinetic and Rheometric evidence for a transition from spherical to rodlike micelles under the typical reaction conditions

Ariffin, A. and Sim, Y.L. and Yusof, N.S.M. and Khan, M.N. (2011) Effects of Nonionic Micelles on the rate of Alkaline Hydrolysis Of N-(2 '-Methoxyphenyl)Phthalimide (1): kinetic and Rheometric evidence for a transition from spherical to rodlike micelles under the typical reaction conditions. Journal of Colloid and Interface Science, 360 (1). pp. 182-188. ISSN 0021-9797

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Abstract

Pseudo-first-order rate constants (k(obs)) for alkaline hydrolysis of N-(2'-methoxyphenyl)phthalimide (1) decrease nonlinearly with increasing total concentration of nonionic surfactant C(m)E(n) (i.e. [C(m)E(n)](T) where m and n represent the respective number of methyl/methylene units in the tail and polyoxyethylene units in the headgroup of a surfactant molecule and m/n = 16/20, 12/23 and 18/20) at constant 2% v/v CH(3)CN and 1.0 mM NaOH. The k(obs) vs. [C(m)E(n)](T) data follow the pseudophase micellar (PM) model at <= 50 mM C(16)E(20), <= 1.4 mM C(12)E(23) and <= 2.0 mM C(18)E(20) where rate of hydrolysis of 1 in micellar pseudophase could not be detected. The values of k(obs) fail to follow the PM model at > similar to 50 mM C(16)E(20), > similar to 1.4 mM C(12)E(23) and > similar to 2.0 mM C(18)E(20) which has been attributed to a micellar structural transition from spherical to rodlike which in turn increases C(m)E(n) micellar binding constant (K(s)) of 1 with increasing values of [C(m)E(n)](T). Rheological measurements show the presence of spherical micelles at <= 50 mM C(16)E(20), <= 1.4 mM C(12)E(23) and <= 3.0 mm C(18)E(20). The presence of rodlike micelles is evident from rheological measurements at > similar to 50 mM C(16)E(20), > 1.4 mM C(12)E(23) and > similar to 3.0 mM C(18)E(20). (C) 2011 Elsevier Inc. All rights reserved.

Item Type: Article
Additional Information: Department of Chemistry, Faculty of Science Building, University of Malaya, 50603 Kuala Lumpur, MALAYSIA
Uncontrolled Keywords: N-(2′-Methoxyphenyl)phthalimide; Nonionic surfactant; Pseudophase micellar model; Spherical micelles; Rodlike micelles
Subjects: Q Science > QD Chemistry
Divisions: Faculty of Science > Dept of Chemistry
Depositing User: Miss Malisa Diana
Date Deposited: 03 Jul 2013 04:15
Last Modified: 13 Mar 2015 06:14
URI: http://eprints.um.edu.my/id/eprint/8093

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