Calcium pyrophosphate

Calcium pyrophosphate

Names
IUPAC name Calcium diphosphate
Other names Diphosphoric acid, calcium salt (1:2) Dicalcium diphosphate Dicalcium pyrophosphate
Identifiers
CAS Number	7790-76-3 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:32598 Y
ChemSpider	23034 Y
ECHA InfoCard	100.029.292
E number	E450(vi) (thickeners, ...)
MeSH	Calcium+pyrophosphate
PubChem CID	24632
UNII	X69NU20D19 Y
CompTox Dashboard (EPA)	DTXSID50872512
InChI InChI=1S/2Ca.H4O7P2/c;;1-8(2,3)7-9(4,5)6/h;;(H2,1,2,3)(H2,4,5,6)/q2*+2;/p-4 Y Key: JUNWLZAGQLJVLR-UHFFFAOYSA-J Y InChI=1/2Ca.H4O7P2/c;;1-8(2,3)7-9(4,5)6/h;;(H2,1,2,3)(H2,4,5,6)/q2*+2;/p-4 Key: JUNWLZAGQLJVLR-XBHQNQODAN
SMILES [Ca+2].[Ca+2].[O-]P([O-])(=O)OP([O-])([O-])=O
Properties
Chemical formula	Ca2O7P2
Molar mass	254.053 g/mol
Appearance	White powder
Density	3.09 g/cm3
Melting point	1,353 °C (2,467 °F; 1,626 K)
Solubility in water	insoluble
Solubility	soluble in HCl, nitric acids
Refractive index (nD)	1.585
Hazards
NFPA 704 (fire diamond)	2 0 0
Flash point	Non-flammable
Related compounds
Other anions	Calcium phosphate
Other cations	Magnesium pyrophosphate Sodium pyrophosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Calcium pyrophosphate refers to any member of a series of inorganic compound with the formula Ca₂P₂O₇(H₂O)_n. They are white solids that are insoluble in water. They contain the pyrophosphate anion, although sometimes they are referred to as phosphates. The inventory includes an anhydrous form, a dihydrate (Ca₂P₂O₇·2H₂O), and a tetrahydrate (Ca₂P₂O₇·4H₂O). Deposition of dihydrate crystals in cartilage are responsible for the severe joint pain in cases of calcium pyrophosphate deposition disease (pseudo gout) whose symptoms are similar to those of gout.^[1] Ca₂P₂O₇ is commonly used as a mild abrasive agent in toothpastes because of its insolubility and nonreactivity toward fluoride.^[2]