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| Sodium thiocyanate | |
|---|---|
| IUPAC name | Sodium thiocyanate |
| Other names | Sodium Rhodanide Sodium sulfocyanate Sodium rhodanate Thiocyanate Acid, Sodium Salt |
| Identifiers | |
| CAS number | 540-72-7 |
| Properties | |
| Molecular formula | NaSCN |
| Molar mass | 81.07 g/mole |
| Appearance | colourless crystals |
| Density | 1.735 g/cm3 |
| Melting point |
287 °C |
| Solubility | acetone, alcohols |
| Hazards | |
| NFPA 704 |
 0
3
1
|
| R-phrases | 20/21/22-32-52/53 |
| S-phrases | 13-61 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
|
Sodium thiocyanate is the chemical compound with the formula NaSCN. This colourless deliquescent salt is one of the main sources of the thiocyanate anion. As such, it is used as a precursor for the synthesis of pharmaceuticals and other specialty chemicals.1 Thiocyanate salts are typically prepared by the reaction of cyanide with elemental sulfur:
- NaCN + 1/8 S8 → NaSCN
NaSCN crystallises in an orthorhombic cell. Each Na+ center is surrounded by three sulfur and three nitrogen ligands provided by the triatomic thiocyanate anion.2 It is commonly used in the laboratory as a test for the presence of Fe3+ ions.
Applications in chemical synthesis
NaSCN is employed to convert alkyl halides into the corresponding alkylthiocyanates. Closely related reagents include ammonium thiocyanate and potassium thiocyanate, which has twice the solubility in water. Silver thiocyanate may be used as well; the precipitation of insoluble silver halides help simplify workup. Treatment of isopropyl bromide with NaSCN in hot ethanolic solution affords isopropyl thiocyanate.3 Protonation of NaSCN affords isothiocyanic acid, S=C=NH (pKa = -1.28).4 This species is generated in situ from NaSCN; it adds to organic amines to afford derivatives of thiourea.5
References
- ^ Schwan, A. L. (2001). Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rs109.
- ^ van Rooyen, P. H.; Boeyens, J. C. A. (1975). "Sodium thiocyanate". Acta Crystallographica B31: 2933–2934. doi:.
- ^ Shriner, R. L. (1943). "Isopropyl Thiocyanate". Org. Synth.; Coll. Vol. 2: 366.
- ^ Chiang, Y.; Kresge, A. J. (2000). "Determination of the Acidity Constant of Isothiocyanic Acid in Aqueous Solution". Canadian Journal of Chemistry 78: 1627–1628. doi:.
- ^ Allen, C. F. H.; VanAllan, J. (1955). "2-Amino-6-Methylbenzothiazole". Org. Synth.; Coll. Vol. 3: 76.
Wikipedia content modification information:
- This page was last modified on 24 October 2008, at 15:33.
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