Sodium thiocyanate

Sodium thiocyanate (sometimes called sodium sulphocyanide) is the chemical compound with the formula NaSCN. This colorless 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.[2] Thiocyanate salts are typically prepared by the reaction of cyanide with elemental sulfur:

8 NaCN + S8 → 8 NaSCN
Sodium thiocyanate
The sodium cation
The thiocyanate anion (space-filling model)
Names
IUPAC name
Sodium thiocyanate
Other names
Sodium rhodanide
Sodium sulfocyanate
Sodium rhodanate
Thiocyanic acid, sodium salt
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.007.960
EC Number
  • 208-754-4
RTECS number
  • XL2275000
UNII
Properties
NaSCN
Molar mass 81.072 g/mol
Appearance deliquescent colorless crystals
Density 1.735 g/cm3
Melting point 287 °C (549 °F; 560 K)
Boiling point 307 °C (585 °F; 580 K) decomposes
139 g/100 mL (21 °C)
225 g/100 mL (100 °C)
Solubility soluble in acetone, alcohols, ammonia, SO2
Acidity (pKa) −1.28
1.545
Structure
orthorhombic
Hazards
Safety data sheet ICSC 0675
Harmful (Xn)
R-phrases (outdated) R20/21/22, R32, R36, R37, R38
S-phrases (outdated) S22, S26, S36
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
2
0
Lethal dose or concentration (LD, LC):
764 mg/kg (oral, rat)[1]
Related compounds
Other anions
 Sodium cyanate
Sodium cyanide
Other cations
 Potassium thiocyanate
Ammonium thiocyanate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Sodium thiocyanate crystallizes in an orthorhombic cell. Each Na+ center is surrounded by three sulfur and three nitrogen ligands provided by the triatomic thiocyanate anion.[3] It is commonly used in the laboratory as a test for the presence of Fe3+ ions.

Applications in chemical synthesis

Sodium thiocyanate 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 sodium thiocyanate in a hot ethanolic solution affords isopropyl thiocyanate.[4] Protonation of sodium thiocyanate affords isothiocyanic acid, S=C=NH (pKa = −1.28).[5] This species is generated in situ from sodium thiocyanate; it adds to organic amines to afford derivatives of thiourea.[6]

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References
  1. Sodium thiocyanate, chemicalland21.com
  2. Schwan, A. L. (2001). Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rs109.
  3. van Rooyen, P. H.; Boeyens, J. C. A. (1975). "Sodium thiocyanate". Acta Crystallographica. B31 (12): 2933–2934. doi:10.1107/S0567740875009326.
  4. Shriner, R. L. (1943). "Isopropyl Thiocyanate". Organic Syntheses.; Collective Volume, 2, p. 366
  5. Chiang, Y.; Kresge, A. J. (2000). "Determination of the Acidity Constant of Isothiocyanic Acid in Aqueous Solution". Canadian Journal of Chemistry. 78 (12): 1627–1628. doi:10.1139/cjc-78-12-1627.
  6. Allen, C. F. H.; VanAllan, J. (1955). "2-Amino-6-Methylbenzothiazole". Organic Syntheses.CS1 maint: multiple names: authors list (link); Collective Volume, 3, p. 76
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