Cyclo-polyphosphates

Polyphosphates occurring in water have either linear structures (catena-polyphosphates) or cyclic structures (cyclo-polyphosphates). 

The effect of cations on the rate of hydrolysis of cycio-tri- and cvc/o-tetra-phosphates has also been studied.260 Alkali metal cations retarded the hydrolysis of both cyclo-phosphates in acidic solution but accelerated the reaction in basic solution. The catalytic activity followed the sequence Li+ > Na+> K+. Mg11, Ca11 and Ni11 retarded the hydrolysis of the cyclo-phosphates in the pH range 1.0-2.0 or 1.0-2.7, but accelerated the reaction at pH>3. Catalysis by Cu11 is observed above pH 2, while Alni has a marked catalytic effect at pH 1 and 2. A variety of other papers have appeared dealing with metal ion-promoted hydrolysis of polyphosphates.261-264 However, the mechanistic details of these reactions remain unclear and the catalytically active complexes remain undefined. 

Commercial development of calcium polyphosphate fibres Discovery of new class of aluminophosphate molecular sieves Preparation of first carbophosphene - (bis methylene phosphorane) Discovery of Phospha-Cope rearrangement Synthesis of first compound with an As=P bond Cyclo-P, triple decker compound made First asymmetric hydrogenation catalyst discovered (a metallophosphine complex)... 

Kanaoka, Y., E. Sato, and O. Yonemitsu Amino Acids and Peptides. II. Cyclo-dehydration of Some Tryptophan-Dipeptides and their Derivatives with Polyphosphate Ester. Tetrahedron 24, 2591-2594 (1968). 

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