Calcium phosphate dibasic
Calcium phosphate dibasic Chemical Properties
- Melting point:
- storage temp.
- Practically insoluble in water and in ethanol (96 per cent). It dissolves in dilute hydrochloric acid and in dilute nitric acid.
- gel (aged)
- 7 (10g/l, H2O, 20°C) suspension
- Water Solubility
- Sparingly soluble in water, practically insoluble in cold water.
- Solubility Product Constant (Ksp)
- pKsp: 7
- Stable. Incompatible with strong oxidizing agents.
- CAS DataBase Reference
- 7757-93-9(CAS DataBase Reference)
- EPA Substance Registry System
- Calcium hydrogen phosphate (7757-93-9)
Calcium phosphate dibasic Usage And Synthesis
Dibasic Calcium Phosphate is anhydrous or contains two molecules of water of hydration. It occurs as a white, odorless, tasteless powder that is stable in air. It is practically insoluble in water, but is readily soluble in dilute hydrochloric and nitric acids. It is insoluble in alcohol.
Dibasic calcium phosphate is produced by the reaction of phosphoric acid, calcium chloride, and sodium hydroxide. Calcium carbonate can be used in place of the calcium chloride and sodium hydroxide.
Dibasic calcium phosphate anhydrous is generally regarded as relatively nontoxic and nonirritant material. It is widely used in oral pharmaceutical products and food products.
Functional Use in Foods: Leavening agent; dough conditioner; nutrient; dietary supplement; yeast food.
Dibasic calcium phosphate is found in nature as the mineral monetite. It is used as a food supplement and source of calcium, both in human food and animal feed. It is used in dough conditioner; in several dental products and in medicine. Other applications are in fertilizers, plastics and in the manufacture of glass.
Dibasic calcium hydrogen phosphate may be prepared by several methods.
It is precipitated by mixing solutions of calcium chloride and disodium hydrogen phospate: CaCl2 + Na2HPO4 → CaHPO4 + 2NaCl
It also is prepared by treating phosphoric acid with lime water (suspension of calcium hydroxide in water). Also, it is obtained as a by-product in the preparation of hydroxypatite. The preparation involves the reaction of phosphoric acid with calcium phosphate.
H3PO4 + Ca3(PO4)2 → 3CaHPO4
Anhydrous dibasic calcium phosphate is a white, odorless, tasteless powder or crystalline solid. It occurs as triclinic crystals.
White triclinic crystal; density 2.92 g/cm3 (anhydrous) and 2.31 g/cm3 (dihy drate); hardness 3.5 Mohs; decomposes on heating; inosluble in water and alcohol; KSP 2.7x10-7; soluble in dilute mineral acid.
Replenisher (calcium); pharmaceutic aid (tablet base).
Calcium phosphates are usually prepared by reacting very pure phosphoric acid with calcium hydroxide, Ca(OH)2 obtained from limestone, in stoichiometric ratio in aqueous suspension followed by drying at a temperature that will allow the correct hydration state to be achieved. After drying, the coarse-grade material is obtained by means of a classification unit; the fine particle-size material is obtained by milling. Dibasic calcium phosphate, anhydrous, may also be prepared by spray-drying.
CalStar (FMC); D.C.P. (Parke-Davis).
Anhydrous dibasic calcium phosphate is used both as an excipient
and as a source of calcium in nutritional supplements. It is used
particularly in the nutritional/health food sectors. It is also used in
pharmaceutical products because of its compaction properties, and
the good flow properties of the coarse-grade material. The
predominant deformation mechanism of anhydrous dibasic calcium
phosphate coarse-grade is brittle fracture and this reduces the
strain-rate sensitivity of the material, thus allowing easier transition
from the laboratory to production scale. However, unlike the
dihydrate, anhydrous dibasic calcium phosphate when compacted
at higher pressures can exhibit lamination and capping. This
phenomenon can be observed when the material represents a
substantial proportion of the formulation, and is exacerbated by the
use of deep concave tooling. This phenomenon also appears to be
independent of rate of compaction.
Anhydrous dibasic calcium phosphate is abrasive and a lubricant is required for tableting, for example 1% w/w magnesium stearate or 1% w/w sodium stearyl fumarate.
Two particle-size grades of anhydrous dibasic calcium phosphate are used in the pharmaceutical industry. Milled material is typically used in wet-granulated or roller-compacted formulations. The ‘unmilled’ or coarse-grade material is typically used in directcompression formulations.
Anhydrous dibasic calcium phosphate is nonhygroscopic and stable at room temperature. It does not hydrate to form the dihydrate.
Anhydrous dibasic calcium phosphate is used in toothpaste and dentifrice formulations for its abrasive properties.
Dicalcium phosphate (CaHPO4) is made from calcium carbonate and phosphoric acid. It contains 34% citrate- soluble phosphorus pentoxide (P2O5). It is not commonly used as a fertilizer, but is used as a supplement to animal feed.
Skin and eye irritant. A nuisance dust.
Dibasic calcium phosphate anhydrous is widely used in oral pharmaceutical products, food products, and toothpastes, and is generally regarded as a relatively nontoxic and nonirritant material.
Dibasic calcium phosphate anhydrous is a nonhygroscopic,
relatively stable material. Under conditions of high humidity it
does not hydrate to form the dihydrate.
The bulk material should be stored in a well-closed container in a dry place.
Crystallise it from a near-saturated solution in 50% aqueous reagent grade phosphoric acid at 100o by filtering through fritted glass and cooling to room temperature. The crystals are filtered off, and this process is repeated three times using fresh acid. For the final crystallisation the solution is cooled slowly with constant stirring to give thin plate crystals that are filtered off on a fritted glass funnel, washed free of acid with anhydrous acetone and dry in a vacuum desiccator [Egan et al.J Am Chem Soc 78 1811 1956].
Dibasic calcium phosphate should not be used to formulate
The surface of milled anhydrous dibasic calcium phosphate is alkaline and consequently it should not be used with drugs that are sensitive to alkaline pH. However, reports suggest there are differences in the surface alkalinity/acidity between the milled and unmilled grades of anhydrous dibasic calcium phosphate; the unmilled form has an acidic surface environment. This difference has important implications for drug stability, particularly when reformulating from, e.g. roller compaction to direct compression, when the particle size of the anhydrous dibasic calcium phosphate might be expected to change.
Dibasic calcium phosphate dihydrate has been reported to be incompatible with a number of drugs and excipients, and many of these incompatibilities are expected to occur with dibasic calcium phosphate, anhydrous; see Calcium phosphate, dibasic dihydrate.
GRAS listed. Accepted as a food additive in Europe. Included in the FDA Inactive Ingredients Database (oral capsules and tablets). Included in nonparenteral medicines licensed in Europe. Included in the Canadian List of Acceptable Non-medicinal Ingredients.
Calcium phosphate dibasic Preparation Products And Raw materials
- MAGNESIUM PHOSPHATE
- Sodium phosphate dibasic dodecahydrate
- Calcium phosphate monobasic
- Ammonium phosphate dibasic
- octacalcium phosphate
- CALCIUM PHOSPHATE GEL (AGED)
- calcium sulfate
- ZINC PHOSPHATE, MONOBASIC
- CALCIUM GLYCEROPHOSPHATE
- FERROUS SULFATE
- calcium bicarbonate
- DICALCIUM PHOSPHATE DIHYDRATE
- Calcium phosphate tribasic
- Calcium phosphate
- calcium phosphate dibasic toothpaste
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