Sodium ferrocyanide

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Sodium ferrocyanide[1]
Sodium ferrocyanide.png
Identifiers
CAS number 13601-19-9 YesY
PubChem 26129
EC number 237-081-9
Jmol-3D images Image 1
Properties
Molecular formula Na4Fe(CN)6
Molar mass 303.91 g/mol
Appearance pale yellow crystals
Odor odorless
Density 1.458 g/cm3
Melting point 435 °C (815 °F; 708 K) (anhydrous)
81.5 °C (178.7 °F; 354.6 K) (decahydrate) (decomposes)
Solubility in water 10.2 g/100 mL (10 °C)
17.6 g/100 mL (20 °C)
39.7 g/100 mL (96.6 °C)
Refractive index (nD) 1.530
Structure
Crystal structure monoclinic
Hazards
S-phrases S22 S24 S25
Related compounds
Other anions Sodium ferricyanide (Red prussiate of soda)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Sodium ferrocyanide is the sodium salt of the coordination compound of formula [Fe(CN)6]4-. It is a yellow crystalline solid that is soluble in water and insoluble in alcohol. Despite the presence of the cyanide ligands, sodium ferrocyanide is not especially toxic (acceptable daily intake 0–0.025 mg/kg body weight[2]) because the cyanides are tightly bound to the metal. However, like all ferrocyanide salt solutions, addition of an acid (a hydrogen donor) can result in the production of cyanide gas (HCN), which is toxic. In its hydrous form, Na4Fe(CN)6·10H2O (sodium ferrocyanide decahydrate), it is sometimes known as yellow prussiate of soda. The yellow color is the color of ferrocyanide anion.

Uses[edit]

Sodium ferrocyanide is a chemical additive known as E 535 in the EU. It is added to road and food grade salt as an anticaking agent.[2] When combined with iron, it converts to a deep blue pigment called Prussian blue.[3] In photography, it is used for bleaching, toning, and fixing. It is used as a stabilizer for the coating on welding rods. In the petroleum industry, it is used for removal of mercaptans.

Production[edit]

Sodium ferrocyanide is produced industrially from hydrogen cyanide, ferrous chloride, and calcium hydroxide, the combination of which affords Ca2[Fe(CN)6].11H2O. A solution of this salt is then treated with sodium salts to precipitate the mixed calcium-sodium salt CaNa2[Fe(CN)6], which in turn is treated with sodium carbonate to give the tetrasodium salt.[4]

References[edit]

  1. ^ Sodium ferrocyanide MSDS
  2. ^ a b "Toxicological evaluation of some food additives including anticaking agents, antimicrobials, antioxidants, emulsifiers and thickening agents". World Health Organization, Geneva. 1974. Retrieved 18 May 2009. 
  3. ^ "Prussian blue". Encyclopædia Britannica. Retrieved 18 May 2009. 
  4. ^ Gail, E.; Gos, S.; Kulzer, R.; Lorösch, J.; Rubo, A.; Sauer, M.; Kellens, R.; Reddy, J.; Steier, N.; Hasenpusch, W. (2011). "Cyano Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_159.pub3.