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Kinetics and mechanism of the anilinolysis of S ‐aryl N ‐arylthiocarbamates in acetonitrile
Author(s) -
Sung Dae Dong,
Jang Hee Man,
Jung Dae Il,
Lee Ikchoon
Publication year - 2008
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.1418
Subject(s) - chemistry , aminolysis , tetrahedral carbonyl addition compound , nucleophile , acetonitrile , leaving group , aryl , amine gas treating , medicinal chemistry , concerted reaction , reaction rate constant , stereochemistry , kinetics , organic chemistry , catalysis , alkyl , physics , quantum mechanics
The aminolysis reactions of S ‐aryl N ‐arylthiocarbamates (YC 6 H 4 NHC(O)SC 6 H 4 Z, 1 ) with anilines in acetonitrile are studied. The reaction rates are more influenced by the nucleophilicity of the nucleophile than the nucleofugality of the leaving group, but the change in the effective charge from reactants to the TS for formation of the tetrahedral intermediate is slightly greater in the leaving group ( β Z from−0.07 to −0.14) than in the nucleophile ( β X = 0.04–0.12). The magnitude of the Brönsted coefficients are in the range of values that are consistent for a stepwise mechanism with rate‐limiting formation of the zwitterionic tetrahedral intermediate. Signs of cross‐interaction constants, ρ XY ( > 0), ρ XZ ( > 0) and ρ YZ (<0), are all consistent with a stepwise mechanism. It is concluded that the change of the amine from benzylamines to anilines causes a shift of the aminolysis mechanism from a concerted to a stepwise process. Copyright © 2008 John Wiley & Sons, Ltd.