[Physiochemical properties of 7-aminoacetoxycephalosporanic acid].

Potentiometric titration of the zwitter-ion of 7-aminoacetoxycephalosporanic acid (7-ACA) was performed and the constants of its ionization were estimated. The minimum solubility of the 7-ACA zwitter-ion (20 degrees C, 0.1 M NaCl) was determined and the solubility curve of 7-ACA at wide pH ranges was calculated. Equilibrium of the cationic, zwitter-ionic and anionic forms of 7-ACA was estimated as dependent on pH.