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The S N 3–S N 2 spectrum. Rate constants and product selectivities for solvolyses of benzenesulfonyl chlorides in aqueous alcohols
Author(s) -
Bentley T. William,
Jones Robert O.,
Kang Dae Ho,
Koo In Sun
Publication year - 2009
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.1522
Subject(s) - chemistry , aqueous solution , kinetic isotope effect , solvent , reaction rate constant , solvolysis , alcohol , chloride , methanol , medicinal chemistry , solvent effects , organic chemistry , computational chemistry , hydrolysis , kinetics , deuterium , physics , quantum mechanics
Abstract Rate constants for a wide range of binary aqueous mixtures and product selectivities ( S ) in ethanol–water (EW) and methanol–water (MW) mixtures, are reported at 25 °C for solvolyses of benzenesulfonyl chloride and the 4‐chloro‐derivative. S is defined as follows using molar concentrations: S = ([ester product]/[acid product]) × ([water solvent]/[alcohol solvent]). Additional selectivity data are reported for solvolyses of 4‐Z‐substituted sulfonyl chlorides (Z = OMe, Me, H, Cl and NO 2 ) in 2,2,2‐trifluoroethanol–water. To explain these results and previously published data on kinetic solvent isotope effects (KSIEs) and on other solvolyses of 4‐nitro and 4‐methoxybenzenesulfonyl chloride, a mechanistic spectrum involving a change from third order to second order is proposed. The molecularity of these reactions is discussed, along with new term ‘S N 3–S N 2 spectrum’ and its connection with the better established term ‘S N 2–S N 1 spectrum’. Copyright © 2009 John Wiley & Sons, Ltd.