Zirconium-hydroxide-mediated alkaline hydrolysis of phosphate esters
Under mildly alkaline conditions (pH 7–9) the hydrolysis of phosphate monoesters such as 4-nitrophenyl phosphate, glucose 1-phosphate, and glycerol 1-phosphate proceeds slowly, if at all. However, in the presence of gelatinous zirconium hydroxide the rate of hydrolysis of 4-nitrophenyl phosphate is increased by a factor of ca. 30, although the rates of hydrolysis of a range of phosphate esters and related compounds such as adenosine mono- and tri-phosphates, nitrophenyl glycosides, and nitrophenyl sulphates and acetates are not altered. The effects of pH, zirconium hydroxide concentration, phosphate ion, and zirconium phosphate upon this catalysis are described. Titanium(IV) hydroxide exhibited only a slight catalytic effect. A mechanism for the selective catalytic reaction of the zirconium hydroxide is suggested.