ABSTRACT
The diphosphonates and polyphosphonates are characterized in general by broad structural variations around the geminal grouping. The diphosphonates are synthesized by two major methods — the Arbuzov reaction and the condensation of phosphorus trichloride and an acid. The condensation reaction of an acid and phosphorus trichloride is one of the simplest methods of forming a hydroxydiphosphonate such as 1-hydroxyethlidene diphosphonate (HEDP). The diphosphonates such as CH3C(OH)(PO3H2)2, HEDP are polyprotic acids. The unique physical chemical properties of the diphosphonates with respect to the main inorganic constituent of mammalian skeleton, hydroxyapatite, suggested their potential use in metabolic aberrations of calcium phosphate metabolism. The net effect of crystal growth inhibition in the nascent calcium phosphate solid is to produce an apparent increase in solubility of hydroxapatite. The effectiveness of potential inhibitors of apatite crystal growth can also be followed titrimetically using a pH stat instrument.
