| Popis: |
Ammonia production from cyanate was measured as a function of pH. The kinetic description of the process included acid-catalyzed hydrolysis of isocyanic acid and spontaneous hydrolysis of isocyanic acid and cyanate. These reactions were predominant at pH values below 2, between 3 and 8, and above 9, respectively. The hydrolysis was strongly catalyzed by certain bivalent anions. The geometry of the anion appeared to be an important factor in the catalytic process, since carbonate, phosphate, succinate, maleate, citrate and phthalate were catalysts, whereas other bivalent anions, viz. sulfate, oxalate, fumarate and isophthalate, were without effect. Catalysis by bivalent anions was supposed to proceed via carbamoyl derivatives of the anions. The negatively charged group of the carbamoyl derivative was thought to cause an intramolecular general base-catalyzed reaction. The implications of this study for the mechanism of urease action were considered. |
