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Kinetics and mechanism of the pyridinolysis of benzenesulfonyl chlorides in methanol
Author(s) -
Hong Sung Wan,
Koh Han Joong,
Lee Ikchoon
Publication year - 1999
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/(sici)1099-1395(199906)12:6<425::aid-poc147>3.0.co;2-3
Subject(s) - chemistry , sn2 reaction , substituent , methanol , kinetics , hammett equation , medicinal chemistry , reaction rate constant , computational chemistry , substrate (aquarium) , stereochemistry , organic chemistry , physics , quantum mechanics , oceanography , geology
The kinetics of reactions between Y‐benzenesulfonyl chlorides and X‐pyridines in methanol at 35.0 °C were investigated. Strong para π‐acceptors, X = p ‐CN and p ‐COCH 3 , give good linear fits to Brønsted‐type plots with low β X (=0.32–0.45) but show positive deviations from linear Hammett plots (ρ X = −1.98 to −2.79). Excellent linear Hammett plots are obtained with substituent variations in the substrate with ρ Y = 0.6–1.0 which are similar to those for the anilinolysis. These results support an S N 2 mechanism for the pyridinolysis of benzenesulfonyl chlorides. The cross‐interaction constant ρ XY is a small negative value (−0.48). Much smaller magnitudes of β X , ρ X and ρ XY than the corresponding values for the anilinolysis suggest that the transition state is formed at a relatively earlier position along the reaction coordinate than for anilinolysis. Copyright © 1999 John Wiley & Sons, Ltd.