 | |
| Names | |
|---|---|
| IUPAC name Sodium [hexacyanoferrate(II)] | |
Other names
| |
| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ECHA InfoCard | 100.033.696 |
| EC Number |
|
| E number | E535(acidity regulators, ...) |
| UNII | |
| UN number | 3077 (SODIUM FERROCYANIDE) |
| |
| |
| Properties | |
| Na4[Fe(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) |
| 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 | |
| monoclinic | |
| Related compounds | |
Otheranions | Sodiumferricyanide (Red prussiate of soda) |
Othercations | Potassium ferrocyanide |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Sodium ferrocyanide is the sodiumsalt of thecoordination compound of formula[Fe(CN)6]4−. In itshydrous form,Na4Fe(CN)6·10H2O (sodiumferrocyanidedecahydrate), it is sometimes known asyellowprussiate of soda.[2] It is a yellowcrystalline solid that is soluble in water and insoluble inalcohol. The yellow color is the color of ferrocyanideanion. Despite the presence of thecyanideligands, sodium ferrocyanide has lowtoxicity (acceptable daily intake 0–0.025 mg/kg body weight[3]). Theferrocyanides are less toxic than many salts of cyanide, because they tend not to release free cyanide.[4] However, like all ferrocyanide salt solutions, addition of an acid or exposure to UV light can result in the production ofhydrogen cyanide gas, which is extremely toxic.[5][6]
When combined with a Fe(III) salt, it converts to a deep blue pigment calledPrussian blue,Fe3+4[Fe2+(CN)6]3.[7] It is used as a stabilizer for the coating onwelding rods. In thepetroleum industry, it is used for removal ofmercaptans.
In the EU, ferrocyanides (E 535–538) were, as of 2018, solely authorized as additives insalt andsalt substitutes, where they serve asanticaking agents. Thekidneys are the organ susceptible to ferrocyanidetoxicity, but according to theEFSA, ferrocyanides are of no safety concern at the levels at which they are used.[8]
Sodium ferrocyanide is produced industrially fromhydrogen cyanide,ferrous chloride, andcalcium hydroxide, the combination of which affordsCa2[Fe(CN)6]·11H2O. A solution of this salt is then treated with sodium salts to precipitate the mixed calcium-sodium saltCaNa2[Fe(CN)6]2, which in turn is treated withsodium carbonate to give the tetrasodium salt.[9]
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