Preparation, properties, and crystal structure of the cyclic compound formed by the thermal dehydration of 1-hydroxyethylidenediphosphonic acid

Abstract

The thermal dehydration of 1-hydroxyethylidenediphosphonic acid at 170–180° produces a compound of formula C₄ H₁₂O₁₂P₄ which has a multi-acid function. The tetra-ammonium salt of this acid crystallises as the dihydrate in space group Pbca with cell dimension a= 8·745(15), b= 13·24(3), c= 16·41(3)Å and Z= 4. The structure has been solved by Patterson and Fourier techniques and refined by block-diagonal least-squares methods to R= 0·105 for 819 independent reflections. The anion has been shown to contain a [graphic omitted] heterocycle possessing a crystallographic centre of symmetry. The chemical and physical properties of the compound are described.