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

MeSH | Calcium+pyrophosphate

PubChem CID

* 24632

UNII |

* X69NU20D19 Y

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)  |

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 (Ca2P2O7) is a chemical compound, an insoluble calcium salt containing the pyrophosphate anion. There are a number of forms reported: 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,[citation needed] because of its insolubility and nonreactivity toward fluoride.[2]

## Contents

* 1 Preparation
* 2 Structure of anhydrous and hydrated forms
* 3 References

## Preparation

Crystals of the tetrahydrate can be prepared by reacting sodium pyrophosphate, Na4P2O7 with calcium nitrate, Ca(NO3)2, at carefully controlled pH and temperature:[3]

Na4P2O7(aq)+2 Ca(NO3)2(aq)→ Ca2P2O7·4 H2O + 4 NaNO3

The dihydrate, sometimes termed CPPD, can be formed by the reaction of pyrophosphoric acid with calcium chloride:[citation needed]

CaCl2 \+ H4P2O7(aq) → Ca2P2O7·2 H2O + HCl.

The anhydrous forms can be prepared by heating dicalcium phosphate:[citation needed]

2 CaHPO4 → Ca2P2O7 \+ H2O

At 240-500 °C an amorphous phase is formed, heating to 750 °C forms β-Ca2P2O7, heating to 1140 - 1350 °C forms the α-Ca2P2O7.

## Structure of anhydrous and hydrated forms

The stable tetrahydrate was originally reported to be rhombohedral but is now believed to be monoclinic. Additionally there is an unstable monoclinic form.[3]

The dihydrate is triclinic, with hydrogen bonding between the two water molecules and hydrogen bonds to the O atoms on the anion.[citation needed] An hexagonal dihydrate has also been reported.[4]

The anhydrous form has 3 polymorphs, α-, β-, and metastable γ[5] (Tα/β=1140ºС[6]). The high temperature form α- is monoclinic (P21/n, a=12.66(1)Å, b=8.542(8)Å, c=5.315(5)Å, Z=4, ρα=2.95 g/cm3), with 8 coordinate calcium, the lower temperature form β- is tetragonal (P41, a=b=6.684Å, c=24.144Å, V=915.40Å3, Z=8, ρβ=3.128 g/cm3), with calcium in four different coordination environments, 2 that are 7 coordinate, one eight and one 9. In both the pyrophosphates are essentially eclipsed.[7][8][9]

## References

1. ↑ Calcium Pyrophosphate Deposition Disease at eMedicine
2. ↑ Klaus Schrödter; Gerhard Bettermann; Thomas Staffel; Friedrich Wahl; Thomas Klein; Thomas Hofmann (2012). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
3. ↑ 3.0 3.1 Christoffersen, Margaret R.; Balic-Zunic, Tonci; Pehrson, Søren; Christoffersen, Jørgen (2000). "Growth and precipitation of a monoclinic calcium pyrophosphate tetrahydrate indicating auto-inhibition at pH7". Journal of Crystal Growth 212 (3–4): 500–506. doi:10.1016/S0022-0248(00)00231-1. Bibcode: 2000JCrGr.212..500C.
4. ↑ Mandel, Gretchen S.; Renne, Kathleen M.; Kolbach, Ann M.; Kaplan, Wayne D.; Miller, Jay D.; Mandel, Neil S. (1988). "Calcium pyrophosphate crystal deposition disease: Preparation and characterization of crystals". Journal of Crystal Growth 87 (4): 453–462. doi:10.1016/0022-0248(88)90093-0. Bibcode: 1988JCrGr..87..453M.
5. ↑ Parodi, J. A.; Hickok, R. L.; Segelken, W. G.; Cooper, J. R. (1965). "Electronic Paramagnetic Resonance Study of the Thermal Decomposition of Dibasic Calcium Orthophosphate" (in en). Journal of the Electrochemical Society 112 (7): 688. doi:10.1149/1.2423665. Bibcode: 1965JElS..112..688P. https://iopscience.iop.org/article/10.1149/1.2423665.
6. ↑ Hill, W L; Reynolds, D S; Hendbicks, S B; Jacob, K D (1945-02-01). "Nutritive Evaluation of Defluorinated Phosphates and Other Phosphorus Supplements. I. Preparation and Properties of the Samples". Journal of AOAC International 28 (1): 105–118. doi:10.1093/jaoac/28.1.105. ISSN 0095-9111. https://doi.org/10.1093/jaoac/28.1.105.
7. ↑ Calvo, C. (1968-07-01). "Crystal structure of .alpha.-calcium pyrophosphate". Inorganic Chemistry 7 (7): 1345–1351. doi:10.1021/ic50065a019. ISSN 0020-1669. https://doi.org/10.1021/ic50065a019.
8. ↑ Parodi, J. A.; Hickok, R. L.; Segelken, W. G.; Cooper, J. R. (1965). "Electronic Paramagnetic Resonance Study of the Thermal Decomposition of Dibasic Calcium Orthophosphate". Journal of the Electrochemical Society 112 (7): 688. doi:10.1149/1.2423665. Bibcode: 1965JElS..112..688P.
9. ↑ Webb, N. C. (1966). "The crystal structure of β-Ca2P2O". Acta Crystallographica 21 (6): 942–948. doi:10.1107/S0365110X66004225.

* v
* t
* e

Calcium compounds

* CaAl2O4
* CaB6
* CaBr2
* Ca(BrO3)2
* CaC2
* CaCN2
* Ca(CN)2
* CaCO3
* CaC2O4
* CaCl2
* Ca(ClO)2
* Ca(ClO3)2
* CaCrO4
* CaF2
* CaH2
* Ca(HCO3)2
* CaH2S2O6
* CaI2
* Ca(IO3)2
* Ca(MnO4)2
* CaN6
* Ca(NO3)2
* CaO
* CaO2
* Ca(OH)2
* CaP
* CaS
* CaSO3
* CaSO4
* CaSe
* CaSi
* CaSi2
* CaTiO3
* Ca2P2O7
* Ca2SiO4
* Ca3Al2O6
* Ca3(AsO4)2
* Ca3(BO3)2
* Ca3(C6H5O7)2
* Ca3N2
* Ca3P2
* Ca4(PO4)2O
* Ca3(PO4)2
* Ca(H2PO4)2
* CaHPO4
* C36H70CaO4

ja:ピロリン酸カルシウム

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Calcium pyrophosphate. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Chemistry:Calcium_pyrophosphate&oldid=3338516"
*[CID]: Compound ID
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template