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:

Sodium thiocyanate
Sodium thiocyanate.png
The sodium cation
The thiocyanate anion (space-filling model)
Sodium thiocyanate.jpg
IUPAC name
Sodium thiocyanate
Other names
Sodium rhodanide
Sodium sulfocyanate
Sodium rhodanate
Thiocyanic acid, sodium salt
3D model (JSmol)
ECHA InfoCard 100.007.960 Edit this at Wikidata
EC Number
  • 208-754-4
RTECS number
  • XL2275000
  • InChI=1S/CHNS.Na/c2-1-3;/h3H;/q;+1/p-1 checkY
  • InChI=1S/CHNS.Na/c2-1-3;/h3H;/q;+1/p-1
  • [Na+].[S-]C#N
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
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation mark
H302, H312, H332, H412
P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P310, P312, P322, P330, P337+P313, P363, P501
NFPA 704 (fire diamond)
Lethal dose or concentration (LD, LC):
764 mg/kg (oral, rat)[1]
Safety data sheet (SDS) ICSC 0675
Related compounds
Other anions
Sodium cyanate
Sodium cyanide
Other cations
Lithium thiocyanate
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 checkY☒N ?)
8 NaCN + S8 → 8 NaSCN

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 synthesisEdit

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]


  1. ^ Sodium thiocyanate,
  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. ^ R. L. Shriner (1931). "Isopropyl Thiocyanate". Organic Syntheses. 11: 92. doi:10.15227/orgsyn.011.0092.
  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.{{cite journal}}: CS1 maint: multiple names: authors list (link); Collective Volume, vol. 3, p. 76