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

Solubility, Stability, and Dissociation Constants of (2RS,4R)-2-Substituted Thiazolidine-4-carboxylic Acids in Aqueous Solutions

P. Butvin, J. Al-Ja'afreh, J. Světlík, and E. Havránek

Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University, SK-832 32 Bratislava

Abstract: (2RS)-2-Alkyl, 2,2-dialkyl, and 2-aryl derivatives of (4R)-thiazolidine-4-carboxylic acid were studied from the viewpoint of their solubility, stability, and dissociation constants in aqueous solutions using the potentiometric titration and HPLC method. Solubilities vary with the size of a molecule, position, and number of polar groups rather regularly. The stability decreases in the order: 2-carboxyl derivative, the acid (both stable), 2-alkyl, 2-aryl, and 2,2-dialkyl derivatives. It is likely that the more bulky and/or the electron-donating is a substituent, the deeper and faster is the decomposition. Their alkaline salts are more stable (intact up to 3 h). The dissociation constant of the imino nitrogen protolytic equilibrium is significantly influenced by the character of aryl substituents, while only a little by the alkyl ones.

Full paper in Portable Document Format: 535a315.pdf

Chemical Papers 53 (5) 315–322 (1999)