Potentiometric and thermodynamic studies of azosulfonamide drugs. X

Dissociation constants of azosulfonamide derivatives of rhodanine have been determined potentiometrically in 0.1 M-KCl and 30 vol. \% ethanol-water mixture. The data are discussed in terms of the electron nature of the substituents and of the change in temperature. The pK(1)(H) Values have been found to increase with increasing electron-donating nature of the substituents. The evaluated thermodynamic parameters (DeltaG, DeltaH, and DeltaS) indicated that the dissociation processes are not spontaneous, they are endothermic and entropically unfavourable.