Sodium ferrocyanide explained

Sodium ferrocyanide is the sodium salt of the coordination compound of formula [Fe(CN)<sub>6</sub>]4−. In its hydrous form, Na4Fe(CN)6 (sodium ferrocyanide decahydrate), it is sometimes known as yellow prussiate of soda. It is a yellow crystalline solid that is soluble in water and insoluble in alcohol. The yellow color is the color of ferrocyanide anion. Despite the presence of the cyanide ligands, sodium ferrocyanide has low toxicity (acceptable daily intake 0–0.025 mg/kg body weight[1]). The ferrocyanides are less toxic than many salts of cyanide, because they tend not to release free cyanide.[2] However, like all ferrocyanide salt solutions, addition of an acid or exposure to UV light can result in the production of hydrogen cyanide gas, which is extremely toxic. [3] [4]

Uses

When combined with an Fe(III) salt, it converts to a deep blue pigment called Prussian blue, Fe[Fe{{su|p=II}}([[Cyanide|CN]])].[5] It is used as a stabilizer for the coating on welding rods. In the petroleum industry, it is used for removal of mercaptans.

In the EU, ferrocyanides (E 535–538) were, as of 2018, solely authorized as additives in salt and salt substitutes, where they serve as anticaking agents. The kidneys are the organ susceptible to ferrocyanide toxicity, but according to the EFSA, ferrocyanides are of no safety concern at the levels at which they are used.[6]

Production

Sodium ferrocyanide is produced industrially from hydrogen cyanide, ferrous chloride, and calcium hydroxide, the combination of which affords Ca2[Fe(CN)<sub>6</sub>]. A solution of this salt is then treated with sodium salts to precipitate the mixed calcium-sodium salt CaNa2[Fe(CN)<sub>6</sub>]2, which in turn is treated with sodium carbonate to give the tetrasodium salt.

References

  1. Web site: 1974 . Toxicological evaluation of some food additives including anticaking agents, antimicrobials, antioxidants, emulsifiers and thickening agents . https://web.archive.org/web/20101201064627/https://inchem.org/documents/jecfa/jecmono/v05je02.htm . 1 December 2010 . 18 May 2009 . inchem.org . World Health Organization.
  2. Book: Holleman, A. F. . Wiberg, E. . Inorganic Chemistry . Academic Press . San Diego . 2001 . 0-12-352651-5 .
  3. Web site: PubChem Compound Summary for CID 26129, Sodium ferrocyanide . live . https://web.archive.org/web/20230213172049/https://pubchem.ncbi.nlm.nih.gov/compound/26129 . 2023-02-13 . 2023-01-17 . National Center for Biotechnology Information . PubChem . en.
  4. Web site: PubChem Compound Summary for CID 768, Hydrogen Cyanide . live . https://web.archive.org/web/20230303074319/https://pubchem.ncbi.nlm.nih.gov/compound/768 . 2023-03-03 . 2023-01-17 . National Center for Biotechnology Information . PubChem . en.
  5. Web site: Prussian blue . live . https://web.archive.org/web/20150905235045/https://www.britannica.com/technology/Prussian-blue . 5 September 2015 . 18 May 2009 . Encyclopædia Britannica.
  6. Peter Aggett, Fernando Aguilar, Riccardo Crebelli, Birgit Dusemund, Metka Filipič, Maria Jose Frutos, Pierre Galtier, David Gott, Ursula Gundert-Remy, Gunter Georg Kuhnle, Claude Lambré, Jean-Charles Leblanc, Inger Therese Lillegaard, Peter Moldeus, Alicja Mortensen, Agneta Oskarsson, Ivan Stankovic, Ine Waalkens-Berendsen, Rudolf Antonius Woutersen, Matthew Wright and Maged Younes. . Re-evaluation of sodium ferrocyanide (E 535), potassium ferrocyanide (E 536) and calcium ferrocyanide (E 538) as food additives . EFSA Journal . 2018 . 16 . 7 . 5374 . 10.2903/j.efsa.2018.5374 . 32626000 . 7009536 . free .

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sodium ferrocyanide".

Except where otherwise indicated, Everything.Explained.Today is © Copyright 2009-2024, A B Cryer, All Rights Reserved. Cookie policy.