• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.776-780
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• 2005

The kinetic studies of the reactions of $\alpha$-chloroacetanilides $(YC_6H_4NRC(=O)CH_2Cl;\;R=H\;(4)\;and\;CH_3$ (5)) with pyridines have been carried out in dimethyl sulfoxide at 95 ${^{\circ}C}$. 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 ${\beta}_X$ values are in the range from 0.30 to 0.32 and the cross-interaction constants, $\rho_{XY}$, are small negative values; $\rho_{XY}$ = -0.06 and -0.10 for 4 and 5, respectively. Based on these and other results, the pyridinolyses of $\alpha$-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 ($T^{\pm}$) followed by a bridged type transition state to expel the leaving group.