Sodium thiocyanate
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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 | [] |
| 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 disclaimer and 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]
[edit] 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. Treatment of isopropyl bromide with NaSCN in hot ethanolic solution affords isopropyl thiocyanate (b.p. 146–151 °C).[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]
[edit] References
- ^ Schwan, A. L. "Sodium Thiocyanate" in Encyclopedia of Reagents for Organic Synthesis, 2001, John Wiley & Sons, New York. DOI: 10.1002/047084289X.rs109.
- ^ van Rooyen, P. H.; Boeyens, J. C. A. "Sodium thiocyanate"Acta Crystallographica 1975, volume B31, pp 2933-2934. DOI:10.1107/S0567740875009326
- ^ Shriner, R. L. "Isopropyl Thiocyanate" Organic Syntheses, Collected Volume 2, p.366 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0366.pdf
- ^ Chiang, Y.; Kresge, A. J. “Determination of the Acidity Constant of Isothiocyanic Acid in Aqueous Solution” Canadian Journal of Chemistry 2000, volume 78, pages 1627-1628.
- ^ Allen, C. F. H.; VanAllan, J. "2-Amino-6-Methylbenzothiazole" Organic Syntheses, Collected Volume 3, p.76 (1955). http://www.orgsyn.org/orgsyn/pdfs/CV3P0076.pdf
[edit] External links
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