Some Chemical Properties of Condensed Inorganic Polyphosphates

2 Some Chemical Properties of Condensed Inorganic Polyphosphates 

Condensed phosphates, other than branched phosphates, are stable in neutral aqueous solution at room temperature. The hydrolysis of the P-O-P bond in linear polyphosphates such as Graham s salt liberates energy equivalent to approximately 10 kcal/mol (Yoshida, 1955a,b Van Wazer, 1958), i.e. the same amount of energy as is liberated in the hydrolysis of the terminal phosphoric anhydride bonds in the adenosine 5 -triphosphate (ATP) molecule. Hydrolysis of the cyclotriphosphate also liberates this same amount of energy (Meyerhof etal, 1953). 

The linear polyphosphates and cyclophosphates are hydrolysed extremely slowly at neutral pH and room temperature in comparison with other polyacids such as polyarsenates and polyvanadates, and are unique in this respect. The half-hydrolysis time for the P-O-P bonds in linear polyphosphates at pH 7 and 25 °C is several years (Van Wazer, 1958). The rate of hydrolysis of these bonds is increased by raising the temperature, reducing the pH, and by the presence in the solution of colloidal gels and complex cations. The hydrolysis of these bonds is dependent on the ionic strength of the solutions (Van Wazer, 1958). 

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Some chemical properties of condensed inorganic polyphosphates... 

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