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Correlation of the rates of solvolysis of acetic p ‐toluenesulfonic anhydride (acetyl p ‐toluenesulfonate) and a comparison with acetyl halides
Author(s) -
Kevill Dennis N.,
Ryu Zoon Ha
Publication year - 2013
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.3146
Subject(s) - chemistry , solvolysis , nucleophile , bromide , acetonitrile , acetic anhydride , medicinal chemistry , solvent , kinetic isotope effect , methanol , solvation , halide , acetone , deuterium , inorganic chemistry , organic chemistry , hydrolysis , catalysis , physics , quantum mechanics
The specific rates of solvolysis of acetyl p ‐toluenesulfonate have been measured by a rapid‐response conductivity technique at temperatures in the temperature range of −10 to −55 °C. For 13 solvents at −39.6 °C, an extended Grunwald–Winstein equation correlation led to sensitivities to changes in solvent nucleophilicity of 0.56 and to changes in solvent ionizing power of 0.61. In 89.1% acetone at −20 °C, the comparison with acetyl bromide solvolysis led to a k OTs / k Br ratio of 1.4. In methanol and methanol‐ d at −39.6 °C, the solvent deuterium isotope effect k MeOH / k MeOD is 0.99. These results are consistent with an S N l reaction with appreciable nucleophilic solvation or an S N 2 reaction with a loose transition state. These two approaches lead to similar structures for the transition state. A solution of the acetyl p ‐toluenesulfonate was conveniently prepared by the rapid reaction of acetyl chloride with silver p ‐toluenesulfonate in acetonitrile. Copyright © 2013 John Wiley & Sons, Ltd.