Calcium citrate
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| Calcium citrate | |
|---|---|
| Calcium citrate | |
| Chemical name | Tricalcium citrate |
| Chemical formula | Ca3(C6H5O7)2 |
| Molecular mass | 498.46 g/mol |
| CAS number | [5785-44-4] |
| Density | 1.63 g/cm3 |
| Melting point | 120 °C |
| Boiling point | decomposition |
| SMILES |
C(C(=O)[O-])C(CC(=O)[O-])(C(=O)[O-])O. |
| Disclaimer and references | |
Calcium citrate is the calcium salt of citric acid. It is commonly used as a food additive (E333), usually as a preservative, but sometimes for flavor. In this sense, it is similar to sodium citrate. Calcium citrate is also used as a water softener. Calcium citrate is also found in some dietary calcium supplements.
Chemical properties
Like citric acid, calcium citrate has a sour taste. Like other salts, however, it also has a salty taste. For this reason, citrates such as sodium and calcium citrate are commonly known as sour salt.
Solubility in water 25 °C is 0.095 g/100 ml
Melt Point:120 °C (loses water)
Boiling Point: Decomposes
Production of calcium citrate and it's use in the isolation of citric acid
Calcium citrate is an intermediate stage in the isolation of citric acid from the firmentation broth solution, in which citric acid is firmented on an industrial scale. The citric acid in the broth solution is nutralised by calcium hydroxide, precipitating insoluable calcium citrate. This is then filterd off from the rest of the broth and washed before, either being sold as calcium citrate. Or otherwise treated with dilute sulfuric acid, which displaces the citrate ions in calcium citrate producing calcium sulfate and re forming citric acid in a more concentrated and . This is because citrate ions are strong conjugate baces whereas sulphate ions are very week conjugate baces but sulfuric acid is a very strong proton doner. Therefore the sulfuric acid looses H+ ions to the citrate ions, which form aquious citric acid. The resulting calcium sulfate salt is insoluable in water and forms a precipitate which is filterd off.
==Biological role==
Calcium citrate supplements may increase aluminium toxicity. Patients with renal disease are at an increased risk of toxicity.
Bioavailability is 2.5 times higher than calcium carbonate. For this reason, patients who have undergone the Roux-en-Y variety of weight-loss surgery (also known as gastric bypass) are usually instructed to take calcium citrate as a dietary supplement.
Organometallic importance
Calcium citrate is used as a water softener because the citrate chelates unwanted metal ions.