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Influence of some steric and electronic effects on the mechanism of S N Ar reactions in dimethyl sulphoxide
Author(s) -
Onyido Ikenna,
Hirst Jack
Publication year - 1991
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.610040608
Subject(s) - chemistry , steric effects , aniline , base (topology) , nucleophile , nucleophilic aromatic substitution , medicinal chemistry , electronic effect , nucleophilic substitution , photochemistry , catalysis , organic chemistry , mathematical analysis , mathematics
The reactions of 1‐chloro‐ and 1‐fluoro‐2,4‐dinitrobenzenes with aniline and 4‐methylaniline in dimethyl sulphoxide are not base catalysed. When the nucleophile is 2‐methylaniline, the reaction of the fluoro compound is base catalysed whereas that of the chloro compound is not. The reactions of 1‐bromo‐2‐fluoro‐ and 1‐bromo‐2‐chloro‐3,5‐dinitrobenzenes with both aniline and 2‐methylaniline are not base catalysed. These results indicate that, in certain cases, the incidence or absence of base catalysis in aromatic nucleophilic substitution ( S N Ar) reactions in dipolar aprotic solvents results from an interplay of steric and electronic factors as they affect the magnitude of the ( k 2 + k 3 [ B ])/ k −1 ratio.