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S N 2 reaction of a sulfonate ester in the presence of alkyltriphenylphosphonium bromides and mixed cationic‐cationic systems
Author(s) -
Mohareb Michael M.,
Ghosh Kallol K.,
Orlova Galina,
Palepu Rama M.
Publication year - 2006
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1082
Subject(s) - cationic polymerization , chemistry , sn2 reaction , counterion , reaction rate constant , bromide , kinetics , pulmonary surfactant , catalysis , medicinal chemistry , micelle , reaction rate , inorganic chemistry , polymer chemistry , organic chemistry , ion , aqueous solution , biochemistry , physics , quantum mechanics
The effects of alkyltriphenylphosphonium bromides (C n TPB, n = 10, 12, 14, 16) on the rates of S N 2 reactions of methyl 4‐nitrobenzenesulfonate and bromide ion have been studied. Observed first‐order rate constants are significantly higher than those found for other cationic surfactants for the same reaction. The results have been analyzed by the pseudophase model of micellar kinetics and show true micellar catalysis in the sense that second‐order micellar rate constants are higher than the second‐order rate constants in water. An attempt has also been made to investigate mixed cationic–cationic surfactant systems with respect to observed rates and pseudophase regression parameters. In addition, modeling of some cationic head groups has illustrated possible differences in head group charges and counterion interactions that may prove kinetically relevant. Copyright © 2006 John Wiley & Sons, Ltd.