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DICALCIUM PHOSPHATE

DICALCIUM PHOSPHATE

 

CAS Number: 7757-93-9
Molecular Mass: 172.088
IUPAC name: calcium hydrogen phosphate
EC Number: 231-826-1

Dicalcium phosphate is the calcium phosphate with the formula CaHPO4 and its dihydrate.
The "di" prefix in the common name arises because the formation of the HPO42– anion involves the removal of two protons from phosphoric acid, H3PO4.
Dicalcium phosphate is also known as dibasic calcium phosphate or calcium monohydrogen phosphate. Dicalcium phosphate is used as a food additive, it is found in some toothpastes as a polishing agent and is a biomaterial.

Preparation
Dibasic calcium phosphate is produced by the neutralization of calcium hydroxide with phosphoric acid, which precipitates the dihydrate as a solid.
At 60 °C the anhydrous form is precipitated: H3PO4 + Ca(OH)2 → CaHPO4 +2H2O

To prevent degradation that would form hydroxyapatite, sodium pyrophosphate or trimagnesium phosphate octahydrate are added when for example, dibasic calcium phosphate dihydrate is to be used as a polishing agent in toothpaste.

In a continuous process CaCl2 can be treated with (NH4)2HPO4 to form the dihydrate:
CaCl2 + (NH4)2HPO4 → CaHPO4•2H2O + 2NH4Cl

A slurry of the dihydrate is then heated to around 65–70 °C to form anhydrous CaHPO4 as a crystalline precipitate, typically as flat diamondoid crystals, which are suitable for further processing.

Dibasic calcium phosphate dihydrate is formed in "brushite" calcium phosphate cements (CPC's), which have medical applications. An example of the overall setting reaction in the formation of "β-TCP/MCPM" (β-tricalcium phosphate/monocalcium phosphate) calcium phosphate cements is: 
Ca3(PO4)2 + Ca(H2PO4)2•H2O + 7 H2O → 4 CaHPO4•2H2O

Structure
Three (3) forms of dicalcium phosphate are known:
dihydrate, CaHPO4•2H2O ('DPCD'), the mineral brushite
monohydrate, CaHPO4•H2O ('DCPM')
anhydrous CaHPO4, ('DCPA'), the mineral monetite. Below pH 4.8 the dihydrate and anhydrous forms of dicalcium phosphate are the most stable (insoluble) of the calcium phosphates.
The structure of the anhydrous and dihydrated forms have been determined by X-ray crystallography and the structure of the monohydrate was determined by electron crystallography. The dihydrate (shown in table above) as well as the monohydrate adopt layered structures.

Dibasic calcium phosphate is mainly used as a dietary supplement in prepared breakfast cereals, dog treats, enriched flour, and noodle products.
Dicalcium phosphate is also used as a tableting agent in some pharmaceutical preparations, including some products meant to eliminate body odor. Dibasic calcium phosphate is also found in some dietary calcium supplements (e.g. Bonexcin). It is used in poultry feed.
Dicalcium phosphate is also used in some toothpastes as a tartar control agent.

Heating dicalcium phosphate gives dicalcium diphosphate, a useful polishing agent:
2 CaHPO4 → Ca2P2O7 + H2O

In the dihydrate (brushite) form it is found in some kidney stones and in dental calculi.

Chemical formula: CaHPO4
Molar mass: 136.06 g/mol (anhydrous) 172.09 (dihydrate)
Appearance: white powder
Odor: odorless
Density: 2.929 g/cm3 (anhydrous) 2.31 g/cm3 (dihydrate)
Melting point: decomposes
Solubility in water: 0.02 g/100 mL (anhydrous) 0.02 g/100 mL (dihydrate)
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 4
Rotatable Bond Count: 0
Exact Mass: 174.8786022
Monoisotopic Mass: 174.8786022
Topological Polar Surface Area: 86.2 Ų
Heavy Atom Count: 7
Formal Charge: 1
Complexity: 36.8
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 3
Compound Is Canonicalized: Yes

Consumer Uses
Dicalcium phosphate is used in the following products: fertilisers, cosmetics and personal care products, inks and toners, adhesives and sealants, coating products and fillers, putties, plasters, modelling clay.
Other release to the environment of this substance is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials) and indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment).

Article service life
Release to the environment of this substance can occur from industrial use: formulation in materials.
Other release to the environment of this substance is likely to occur from: outdoor use, indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use in long-life materials with low release rate (e.g. metal, wooden and plastic construction and building materials), indoor use in long-life materials with low release rate (e.g. flooring, furniture, toys, construction materials, curtains, foot-wear, leather products, paper and cardboard products, electronic equipment), indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters) and outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids).
This substance can be found in complex articles, with no release intended: vehicles and machinery, mechanical appliances and electrical/electronic products (e.g. computers, cameras, lamps, refrigerators, washing machines).
This substance can be found in products with material based on: stone, plaster, cement, glass or ceramic (e.g. dishes, pots/pans, food storage containers, construction and isolation material), metal (e.g. cutlery, pots, toys, jewellery) and wood (e.g. floors, furniture, toys).

Widespread uses by professional workers
Dicalcium phosphate is used in the following products: pH regulators and water treatment products, coating products, fertilisers, fillers, putties, plasters, modelling clay, inks and toners, lubricants and greases, laboratory chemicals, polymers, pharmaceuticals and cosmetics and personal care products.
Dicalcium phosphate is used in the following areas: agriculture, forestry and fishing, formulation of mixtures and/or re-packaging, scientific research and development, building & construction work and health services.
Dicalcium phosphate is used for the manufacture of: plastic products, mineral products (e.g. plasters, cement) and food products.
Other release to the environment of dicalcium phosphate is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters) and outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids).

Formulation or re-packing
Dicalcium phosphate is used in the following products: pH regulators and water treatment products, fertilisers, coating products, fillers, putties, plasters, modelling clay, inks and toners, lubricants and greases, pharmaceuticals, adhesives and sealants and cosmetics and personal care products.
Dicalcium phosphate has an industrial use resulting in manufacture of another substance (use of intermediates).
Release to the environment of this substance can occur from industrial use: formulation of mixtures, formulation in materials and in the production of articles.
Other release to the environment of the dicalcium phosphate is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners) and outdoor use.

Uses at industrial sites
Dicalcium phosphate is used in the following products: pH regulators and water treatment products, coating products, adhesives and sealants, fertilisers, lubricants and greases, fillers, putties, plasters, modelling clay, inks and toners, polymers, pharmaceuticals and cosmetics and personal care products.
Dicalcium phosphate is used in the following areas: formulation of mixtures and/or re-packaging, health services, building & construction work, agriculture, forestry and fishing and scientific research and development.
Dicalcium phosphate is used for the manufacture of: chemicals, plastic products, food products and mineral products (e.g. plasters, cement).
Release to the environment of dicalcium phosphate can occur from industrial use: in the production of articles, formulation of mixtures and formulation in materials.
Other release to the environment of dicalcium phosphate is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners), outdoor use, indoor use in close systems with minimal release (e.g. cooling liquids in refrigerators, oil-based electric heaters) and outdoor use in close systems with minimal release (e.g. hydraulic liquids in automotive suspension, lubricants in motor oil and break fluids).

Manufacture
Release to the environment of dicalcium phosphate can occur from industrial use: manufacturing of the substance, formulation of mixtures, formulation in materials, in processing aids at industrial sites, as an intermediate step in further manufacturing of another substance (use of intermediates), as processing aid, for thermoplastic manufacture, as processing aid, of substances in closed systems with minimal release and in the production of articles.

 

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