Collect. Czech. Chem. Commun. 1998, 63, 793-802

Synthesis of Ring-Substituted Phenyl Hydrazinecarboxylates and Study of Their Protonation in Dimethyl Sulfoxide Solutions

Petr Vlasáka, Patrik Paříkb, Jiří Klicnarb and Jaromír Mindlb

a SYMPO, a.s., 532 10 Pardubice, Czech Republic
b Department of Organic Chemistry, University of Pardubice, 532 10 Pardubice, Czech Republic


The pKa values of nineteen phenyl hydrazinecarboxylate hydrochlorides R-C6H4OCONHNH2·HCl (R = H, 3- and 4-Cl, 3- and 4-O2N, 4-Me) and their 1-methyl or 2-methyl derivatives were determined by potentiometric titration with tetrabutylammonium hydroxide in DMSO. IR spectra of the hydrazinecarboxylates and their hydrochlorides revealed that the hydrazinecarboxylate protonation occurs at N2. The methods of synthesis of phenyl hydrazinecarboxylate and their N-methyl derivatives were optimized.

Keywords: Aryl hydrazinecarboxylates; Acidity constants.