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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 5
BKCSDE 26(5)
May 20, 2005 

 
Title
Nucleophilic Substitution Reactions of α-Chloroacetanilides with Pyridines in Dimethyl Sulfoxide
Author
Shuchismita Dey, Keshab Kumar Adhikary, Chan Kyung Kim, Bon-Su Lee*, Hai Whang Lee*
Keywords
Pyridinolyses of α-chloroacetanilides, Cross-interaction constants, Stepwise mechanism
Abstract
The kinetic studies of the reactions of α-chloroacetanilides (YC6H4NRC(=O)CH2Cl; R=H (4) and CH3 (5)) with pyridines have been carried out in dimethyl sulfoxide at 95 oC. The pyridinolysis rates are faster with 4 than with 5 whereas the aminolysis rates with benzylamines are faster with 5 than with 4. The Brønsted βX values are in the range from 0.30 to 0.32 and the cross-interaction constants, ρXY, are small negative values; ρXY = ?0.06 and ?0.10 for 4 and 5, respectively. Based on these and other results, the pyridinolyses of α- chloroacetanilides are proposed to proceed via a stepwise mechanism with rate-limiting addition of the nucleophile to the carbonyl group to form zwitterionic tetrahedral intermediate (T±) followed by a bridged type transition state to expel the leaving group.
Page
776 - 780
Full Text
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