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Kinetics and mechanism of alkaline hydrolysis of 4‐nitrophthalimide in the absence and presence of cationic micelles
Author(s) -
Niyaz Khan M.,
Abdullah Zunoliza
Publication year - 2001
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.1036
Subject(s) - chemistry , hydrolysis , alkaline hydrolysis , cationic polymerization , ammonium bromide , ionic strength , ammonium , micelle , aqueous solution , kinetics , bromide , reaction rate constant , inorganic chemistry , ion exchange , medicinal chemistry , ion , nuclear chemistry , polymer chemistry , organic chemistry , pulmonary surfactant , biochemistry , physics , quantum mechanics
Pseudo‐first‐order rate constants ( k obs ) for alkaline hydrolysis of 4‐nitrophthalimide (NPTH) decreased by nearly 8‐ and 6‐fold with the increase in the total concentration of cetyltrimethyl‐ammonium bromide ([CTABr] T ) from 0 to 0.02 M at 0.01 and 0.05 M NaOH, respectively. These observations are explained in terms of the pseudophase model and pseudophase ion‐exchange model of micelle. The increase in the contents of CH 3 CN from 1 to 70% v/v and CH 3 OH from 0 to 80% v/v in mixed aqueous solvents decreases k obs by nearly 12‐ and 11‐fold, respectively. The values of k obs increase by nearly 27% with the increase in the ionic strength from 0.03 to 3.0 M. The mechanism of alkaline hydrolysis of NPTH involves the reactions between HO − and nonionized NPTH as well as between HO − and ionized NPTH. The micellar inhibition of the rate of alkaline hydrolysis of NPTH is attributed to medium polarity effect. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 407–414, 2001