Sodium thiocyanate

Sodium thiocyanate
IUPAC name Sodium thiocyanate
Other names Sodium rhodanide Sodium sulfocyanate Sodium rhodanate Thiocyanic acid, sodium salt
Identifiers
CAS number	540-72-7 Y
PubChem	516871
ChemSpider	10443 Y
UNII	5W0K9HKA05 Y
EC number	208-754-4
ChEBI	CHEBI:30952 Y
RTECS number	XL2275000
Jmol-3D images	Image 1
SMILES [Na+].[S-]C#N
InChI InChI=1S/CHNS.Na/c2-1-3;/h3H;/q;+1/p-1 Y Key: VGTPCRGMBIAPIM-UHFFFAOYSA-M Y
Properties
Molecular formula	NaSCN
Molar mass	81.072 g/mol
Appearance	deliquescent colorless crystals
Density	1.735 g/cm3
Melting point	287 °C, 560 K, 549 °F
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	0 2 0
LD50	764 mg/kg (oral, rat)[1]
Related compounds
Other anions	Sodium cyanate Sodium cyanide
Other cations	Potassium thiocyanate Ammonium thiocyanate
Y thiocyanate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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

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 (pK_a = -1.28).^[5] This species is generated in situ from sodium thiocyanate; it adds to organic amines to afford derivatives of thiourea.^[6]

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", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv2p0366 ; 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., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3p0076 ; Coll. Vol. 3: 76