Butane-1,2,3,4-tetra-carboxylic acid dihydrate

The asymmetric unit of the title compound, C₈H₁₀O₈·2H₂O, contains one half-mol­ecule of butane-1,2,3,4-tetra­carboxylic acid and a water mol­ecule, with the complete tetra-acid generated by crystallographic inversion symmetry. Inter­molecular O—H⋯O hydrogen bonds form an extensive three-dimensional network, which consolidates the crystal packing.

Novel calcium carboxyphosphonate/polycarboxylate inorganic-organic hybrid materials from demineralization of calcitic biomineral surfaces

Dissolution of biologically important sparingly soluble salts, such as calcium carbonate and calcium oxalate, is possible by use of carboxyl- and carboxyl/phosphonate-bearing, anionic additives, citrate, malate, carboxyphosphonate, and butane tetracarboxylate. Calcium-containing dissolution products have been identified, characterized, and independently synthesized. These are polymeric materials composed of calcium and the additive as the ligand. Their full characterization was carried out by single-crystal X-ray crystallography and other techniques.