Sodium thiocyanate

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Sodium thiocyanate
Sodium thiocyanate.png
The sodium cation The thiocyanate anion (space-filling model)
Identifiers
CAS number 540-72-7 YesY
PubChem 516871
ChemSpider 10443 YesY
UNII 5W0K9HKA05 YesY
EC number 208-754-4
ChEBI CHEBI:30952 YesY
ChEMBL CHEMBL1644028 N, CHEMBL84336, CHEMBL1078613
RTECS number XL2275000
Jmol-3D images Image 1
Properties
Molecular formula NaSCN
Molar mass 81.072 g/mol
Appearance deliquescent colorless crystals
Density 1.735 g/cm3
Melting point 287 °C (549 °F; 560 K)
Solubility in water 139 g/100 mL (21 °C)
Solubility soluble in acetone, alcohols
Refractive index (nD) 1.545
Hazards
MSDS ICSC 0675
EU Index 615-004-00-3
EU classification Harmful (Xn)
R-phrases R20/21/22, R32, R36, R37, R38
S-phrases S22, S26, S36
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
LD50 764 mg/kg (oral, rat)[1]
Related compounds
Other anions Sodium cyanate
Sodium cyanide
Other cations Potassium thiocyanate
Ammonium thiocyanate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

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 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[edit]

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]

References[edit]

  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", Org. Synth. ; Coll. Vol. 2: 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", Org. Synth. ; Coll. Vol. 3: 76