Kinetics and mechanism of the general base-catalyzed hydrolysis of N-hydroxyphthalimide

摘要

The kinetics and mechanism of hydrolysis of N-hydroxyphthalimide in the presence of various buffers (dichloroacetic acid, chloroacetic acid, glycine, sodium formate, sodium acetate, N-(2-morpholinoethane)sulfonic acid, and tris(hydroxymethyl)aminomethane) were studied at 50 °C and an ionic strength of 1.0 M. The second-order rate constants k_b for the buffer-catalyzed hydrolysis of N-hydroxyphthalimide were found to conform to the Br0nsted equation logfc_b = C + β pK_a. A plot of pK_a versus k_b, for the data obtained in the buffers and H2O (covering a pK_a range of —1.74 to 8.33) was constructed, and the data were fitted with a straight line that had a slope (β) of 0.29 ± 0.05 and an intercept (C) of -5.19 ± 0.20.