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

Sim, Y.L.; Yusof, N.S.; Ariffin, A.; Niyaz Khan, M. (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). ISSN 00219797

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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 > ∼50 mM C(16)E(20), > ∼1.4 mM C(12)E(23) and > ∼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 > ∼50 mM C(16)E(20), > ∼1.4 mM C(12)E(23) and > ∼3.0 mM C(18)E(20).

Item Type: Article
Creators:
  1. Sim, Y.L.(University of Malaya)
  2. Yusof, N.S.(University of Malaya)
  3. Ariffin, A.(University of Malaya)
  4. Niyaz Khan, M.(University of Malaya)
Journal or Publication Title: Journal of Colloid and Interface Science
Additional Information: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
Uncontrolled Keywords: Chemistry
Subjects: R Medicine
Divisions: Faculty of Science > Dept of Chemistry
Depositing User: Mr. Faizal Hamzah
Date Deposited: 04 Aug 2011 11:32
Last Modified: 11 Dec 2014 17:17
URI: http://eprints.um.edu.my/id/eprint/1931

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