Short-Chain Kurrols Salts

Alkali metal and alkaline earth polyphosphates crystallize as short chains, two to six phosphate groups per chain or very long chains with hundreds to thousands of PO3 per chain. All polyphosphates in the alkali metal and alkaline earth systems are amorphous in the intermediate chain lengths. Control of the short chain length polyphosphates, both crystalline or amorphous, is a function of R, the M2O-P2O5 ratio. The control of the chain lengths of very long crystalline polyphosphates as Maddrell s salt, Kurrol s salt, and calcium phosphate fibers is not well understood. 

Attempts were made to grow short chain length Kurrol s salt from melts with M2O-P2O5 ratios between 1.04 (n = 50)... 

Maddrell s salt, which are interpreted as showing that kinetic effects are responsible for difficulties in converting the cyclic trimer into the linear polymeric forms. The potassium polyphosphate samples (Kurrol s salt) obtained from the fusion of potassium sulphate and phosphoric acid have chains terminated by OSOJ groups, according to i.r. spectra. Kinetic studies show a first-order dependence of polyphosphate concentration in the hydrolysis of Graham s salt to give trimetaphosphate and short-chain species. The vaporization of sodium metaphosphate from a Knudsen cell leads to predominantly monomeric, with some dimeric, species, according to mass-spectrometric data. ... 

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