Calcium citrate

Chemical properties

Calcium citrate is sparingly soluble in water. Needle-shaped crystals of tricalcium dicitrate tetrahydrate [Ca3(C6H5O7)2(H2O)2]·2H2O were obtained by hydrothermal synthesis. The crystal structure comprises a three-dimensional network in which eightfold coordinated Ca2+ cations are linked by citrate anions and hydrogen bonds between two non-coordinating crystal water molecules and two coordinating water molecules.

Production

Calcium citrate is an intermediate in the isolation of citric acid from the fungal fermentation process by which citric acid is produced industrially. The citric acid in the broth solution is neutralized by limewater, precipitating insoluble calcium citrate. This is then filtered off from the rest of the broth and washed to give clean calcium citrate. : 3 Ca(OH)2(s) + 2 C6H8O7(l) → Ca3(C6H5O7)2(s) + 6 H2O(l)

The calcium citrate thus produced may be sold as-is, or it may be converted to citric acid using dilute sulfuric acid.

Medical uses

It's primarily sold as a food supplement of calcium.

Bioavailability

In many individuals, bioavailability of calcium citrate is found to be equal to that of the cheaper calcium carbonate (CaCO3).

According to a 2009 research into calcium absorption after gastric bypass surgery,

References

References

1. "Use of Lime in the Chemical Industry". National Lime Association.
2. (9 June 2009). "What you need to know about calcium". Harvard Health Publications.