Anhydrous (left) and hydrated (right) copper citrate.
| IUPAC name
| Other names
|Molar mass||568.85 g/mol|
|Appearance|| Blue solid (anhydrous)|
|Solubility||Insoluble in halocarbons, hydrocarbons|
|Vapor pressure||~0 mmHg|
|Safety data sheet||None|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Copper(II) citrate, also known as cuprocitrol, is an ionic compound of copper and citric acid with the formula Cu3(C6H5O7)2 or Cu3C12H10O14, with a molecular weight of 568.85 g/mol. It exists as a seafoam green hemipentahydrate and a sky-blue anhydrous solid.
Some resources incorrectly list its formula as Cu2C6H4O7 and a molecular weight of 360.2 g/mol, but this formulation would require the citric acid molecule to lose more protons than it has carboxylic groups.
Copper citrate is soluble in alkaline citrate solutions.
The hydrated salt will lose its water of crystallization at 100 °C, turning from green to blue.
When heated more strongly, the salt decomposes, leaving behind solid copper particles. When heated under vacuum, the resulting residue is claimed to be pyrophoric.
Copper citrate is a blueish solid, soluble in water.
- 3 CuO + 2 C6H8O7 → Cu3C12H10O14 + 3 H2O
Copper citrate has a low solubility in water, and can be prepared by precipitation from aqueous solution containing copper and citrate ions. A procedure is available from the Royal Society for Chemistry describing its preparation from citric acid or trisodium citrate and copper acetate or sulfate. However, when followed, the reaction proceeds only very slowly, and deposits the product as a crust. Heating the mixture will accelerate the reaction and give a finely-divided product.
Magnesium citrate, available in solution as a laxative, can also be used in place of trisodium citrate.
- Make pyrophoric copper
- Compound collecting
Copper citrate has low toxicity, though copper ions are harmful if consumed in large quantities.
Copper citrate should be kept in closed bottles, or air tight sealed ones if you want the anhydrous form.
Copper citrate should be disposed of just any other copper compound. Which is reduction to metallic copper followed by recycling. Although if the amount you hae is very small, you may flush it down the drain with lots of water.
- Gorrie, T., Kopf, P., & Toby, S. (1967) Kinetics of the reaction of some pyrophoric metals with oxygen. The Journal of Physical Chemistry, 1478(4), 3842–3845. Retrieved from http://pubs.acs.org/doi/pdf/10.1021/j100871a019
- Preparation of copper(II) citrate. RSC Student worksheet, http://www.rsc.org/learn-chemistry/resource/download/res00000903/cmp00001141/pdf