ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Determination of the Hammett constant σ_p for the thioamide group

J. Gabriel, I. Němec, N. Zimová, and K. Waisser

Department of Analytical Chemistry, Faculty of Natural Sciences, Charles University, CS-128 40 Prague

Abstract: The value of the Hammett substituent constant <σ_p = 0.40 has been obtained for the thioamide group from Potentiometrie determination of the dissociation constants for benzoic acid derivatives. Because of insolubility of 4-thiocarbamoylbenzoic acid in water, the series of pK_a measurements on seven derivatives of benzoic acid had to be carried out in diluted methanol and the ap value was obtained from the pK_a(50 % CH₃OH, 25 °C) vs. ap dependence.

Full paper in Portable Document Format: 433a389.pdf

Chemical Papers 43 (3) 389–393 (1989)