M. Kabir, A. Awwal, D. Hossain
Aug 1, 2004
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Journal
Indian Journal of Chemistry Section B-organic Chemistry Including Medicinal Chemistry
Abstract
The kinetics and mechanism of nucleophilic substitution reactions of 2-chloro-1-methylpyridinium iodide (PI) with different phenols have been studied spectrophotometrically. The reactions are first-order with respect to PI and phenols and the overall reaction order is second. The Bronsted coefficient β for the series is 0.09 ′ 0.02, which is in agreement for the nucleophilic substitution reactions. From the Hammett correlation, p is found to be -0.29 ′ 0.07. Activation parameters for the substitution reactions have been reported. The isokinetic temperature is calculated (321 K) and it is observed that the substitution reactions are enthalpy controlled. A two-step reaction mechanism is consistent with the observed results in which the formation of an intermediate is rate determining.