Abstract
Substituent effects on the rate constants for the triethylamine-catalyzed acyl exchange reactions of N- (substituted benzoyl) -O-acetyl-o-aminophenols were investigated by 1H-NMR spectroscopy. An analysis of the Hammett plots for the forward and backward exchange processes, in which the amide anion formation is very likely to become a rate-determining step, reveals that the reverse process has a larger reaction constant (ρ = 2.1 ± 0.1) as compared to that (ρ = 1.5 ± 0.1) for the forward process. This interesting observation was explained in terms of the idea that the greater negative charge is generated on the amide nitrogen in the transition state for the reverse process with an increase in the relative stability of acyl-exchanged isomers.
