A method of making a phosphono-phosphate compound is disclosed. The method involves a first step of mixing a first component comprising a phosphonic acid, a phosphonate or mixtures thereof, with a second component comprising a source of phosphoric acid or phosphate. The mixture has a molar phosphorous ratio of the first component to the second component of from 1:1 to 1:10. The second step involves either physically or chemically dehydrating the mixture to produce a phosphono-phosphate compound.

Provided is a process for the preparation of certain bisphosphonate compounds and their ester derivatives. In this process certain bisphosphonate compounds such as medronic acid is prepared via the reaction of the corresponding isopropyl esters with (i) trimethylsilylbromide or trimethylsilyl iodide, or (ii) trimethylsilyl chloride and an alkali metal iodide or bromide; followed by treatment with a liquid comprising water. The process surprisingly provides the desired compounds, despite having relatively bulky ester groups such as isopropyl on the starting material bisphosphonate ester.

A method of making a phosphono-phosphate compound is disclosed. The method involves a first step of mixing a first component comprising a phosphonic acid, a phosphonate or mixtures thereof, with a second component comprising a source of phosphoric acid or phosphate. The mixture has a molar phosphorous ratio of the first component to the second component of from 1:1 to 1:10. The second step involves either physically or chemically dehydrating the mixture to produce a phosphono-phosphate compound.

The invention relates to novel silane compounds corresponding to the formula (I) below:
A-E-X (I)
in which: X represents a silyl group capable of creating a covalent bond after reaction with the hydroxyl or hydride functional groups of a support; E represents an organic spacer group; A represents a group chosen from the groups of formulae below: ##STR00001##
in which: Z.sub.1 to Z.sub.5 independently represent a hydrogen atom or a halogen atom; Z.sub.6 and Z.sub.7 represent a group for protecting the phosphonic acid functional group, a hydrogen atom or a monovalent cation; Z.sub.8 to Z.sub.12 independently represent a group for protecting the carboxylic acid functional group, a hydrogen atom or a monovalent cation; and Z.sub.13 represents an imidazole, N-hydroxysuccinimide, nitrophenyl, pentafluorophenyl or acid anhydride group. Use of these silane compounds for functionalizing solid supports and for immobilizing biological molecules on these supports.