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
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Properties
NaSCN
Molar mass 81.07 g/mole
Appearance colourless crystals
Density 1.735 g/cm3
Melting point
Solubility acetone, alcohols
Hazards
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]

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]

References

  1. Schwan, A. L. (2001). Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rs109.
  2. van Rooyen, P. H.; Boeyens, J. C. A. (1975). "Sodium thiocyanate". Acta Crystallographica. B31: 2933–2934. doi:10.1107/S0567740875009326.
  3. Shriner, R. L. "Isopropyl Thiocyanate" Organic Syntheses, Collected Volume 2, p.366 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0366.pdf
  4. Chiang, Y.; Kresge, A. J. (2000). "Determination of the Acidity Constant of Isothiocyanic Acid in Aqueous Solution". Canadian Journal of Chemistry. 78: 1627–1628.
  5. 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

External links


ar:ثيوسيانات صوديوم de:Natriumthiocyanat it:Tiocianato di sodio



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