Tricalcium phosphate

Tricalcium phosphate

Names
IUPAC name Tricalcium bis(phosphate)
Other names Tribasic calcium phosphate
Identifiers
CAS Number	7758-87-4 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:9679 Y
ChemSpider	22864 Y
ECHA InfoCard	100.028.946
PubChem	516943
UNII	K4C08XP666 Y
InChI InChI=1S/3Ca.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6 Y Key: QORWJWZARLRLPR-UHFFFAOYSA-H Y InChI=1S/3Ca.2H3O4P/c;;;2*1-5(2,3)4/h;;;2*(H3,1,2,3,4)/q3*+2;;/p-6 Key: QORWJWZARLRLPR-CYFPFDDLAC Key: QORWJWZARLRLPR-UHFFFAOYSA-H
SMILES [O-]P(=O)([O-])[O-].[O-]P(=O)([O-])[O-].[Ca+2].[Ca+2].[Ca+2]
Properties
Chemical formula	Ca3(PO4)2
Appearance	White amorphous powder
Density	3.14 g/cm3
Melting point	Liquifies under high pressure at 1670 K (1391 °C)
Solubility in water	0.002 g/100 g
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-4126 kcal/mol (α-form)
Pharmacology
ATC code	A12AA01 (WHO)
Hazards
NFPA 704	0 1 0
Flash point	Non-flammable
Related compounds
Other anions	Calcium pyrophosphate
Other cations	Trimagnesium phosphate Trisodium phosphate Tripotassium phosphate
Related compounds	Monocalcium phosphate Dicalcium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Tricalcium phosphate (sometimes abbreviated TCP) is a calcium salt of phosphoric acid with the chemical formula Ca₃(PO₄)₂. It is also known as tribasic calcium phosphate and bone phosphate of lime (BPL). Calcium phosphate is one of the main combustion products of bone (see bone ash). Calcium phosphate is also commonly derived from inorganic sources such as mineral rock.

It has three crystalline polymorphs α, α' and β. The α and α' states are formed at high temperatures. As rock, it is found in Whitlockite.

Calcium phosphate refers to minerals containing calcium ions (Ca²⁺) together with orthophosphates (PO₄³⁻), metaphosphates or pyrophosphates (P₂O₇⁴⁻) and occasionally hydrogen or hydroxide ions. Especially, the common mineral apatite has formula Ca₅(PO₄)₃X, where X is F, Cl, OH, or a mixture; it is hydroxyapatite if the extra ion is mainly hydroxide. Much of the "tricalcium phosphate" on the market is actually powdered hydroxyapatite.

It is generally believed that tricalcium phosphate cannot be precipitated directly from aqueous solution. Typically a double decomposition reaction involving a soluble phosphate and calcium salts (e.g. (NH₄)₂HPO₄ + Ca(NO₃)₂) is performed under carefully controlled pH conditions. The precipitate will either be "amorphous tricalcium phosphate", ATCP, or calcium deficient hydroxyapatite, CDHA, Ca₉(HPO₄)(PO₄)₅(OH), (note CDHA is sometimes termed apatitic calcium triphosphate). Crystalline tricalcium phosphate can be obtained by calcining the precipitate. β-Ca₃(PO₄)₂ is generally formed, higher temperatures are required to produce α-Ca₃(PO₄)₂.