Sodium thiocyanate

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Structural formula
Sodium ion Thiocyanate ion
General
Surname Sodium thiocyanate
other names
  • Sodium rhodanide
  • Sodium sulfocyanide
  • SODIUM THIOCYANATE ( INCI )
Molecular formula NaSCN
Brief description

colorless solid 

External identifiers / databases
CAS number 540-72-7
EC number 208-754-4
ECHA InfoCard 100.007.960
PubChem 516871
ChemSpider 10443
Wikidata Q425176
properties
Molar mass 81.07 g mol −1
Physical state

firmly

density

1.74 g cm −3 

Melting point

310 ° C 

Vapor pressure

<1 h Pa (20 ° C) 

solubility

very light in water (1250 g l −1 at 20 ° C)

safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
05 - Corrosive 07 - Warning

danger

H and P phrases H: 302 + 312 + 332-318-412
EUH: 032
P: 261-280-301 + 312 + 330-305 + 351 + 338 + 310
Toxicological data

764 mg kg −1 ( LD 50 ,  rat ,  oral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium thiocyanate is a chemical compound with the formula NaSCN, which is a white, hygroscopic solid at room temperature . It is used in many syntheses that require the thiocyanate ion (rhodanide) SCN - .

Extraction and presentation

The preparation of sodium thiocyanate is carried out with sodium cyanide and elemental sulfur :

properties

Crystals of NaSCN are orthorhombic , with each Na + surrounded by three sulfur and three nitrogen ligands. Isothiocyanic acid (S = C = NH, pK a = −1.28) is released from NaSCN by strong acids .

use

NaSCN is used in the conversion of haloalkanes into corresponding alkyl thiocyanates, it also being possible to use potassium thiocyanate and, more rarely, ammonium thiocyanate . Examples of such syntheses are the preparation of isopropyl thiocyanate from isopropyl bromide with NaSCN in hot ethanol. To produce thiourea , the unstable HSCN is generated in situ from NaSCN , which then forms thiourea compounds with organic amines. Like the other two thiocyanates mentioned (from K + and NH 4 + ), NaSCN is used in phototechnology (sensitization), electroplating (brightener for copper baths), metallurgy (extraction of zirconium , hafnium and lanthanides ), textile industry (dyeing agents, printing), chemical Industry and analytics (production of herbicides and fungicides , Fe 3+ detection) used.

Sodium thiocyanate is used in medicinal doses as a hair restorer and for skin care in atopic dermatitis.

Hazard warnings

Sodium thiocyanate is classified as less toxic, ie harmful if swallowed and if it comes into contact with the skin, but it develops very toxic gases if it comes into contact with acids. The carcinogenic and water-polluting potential of NaSCN is to be assessed as relatively low.

Individual evidence

  1. ↑ Entry on SODIUM THIOCYANATE in the CosIng database of the EU Commission, accessed on April 17, 2020.
  2. ↑ a b c d e Entry on sodium thiocyanate in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) }.
  3. ↑ a b c Data sheet sodium thiocyanate (PDF) from Merck , accessed on August 10, 2010.
  4. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry alkali metal salts and alkaline earth metal salts of thiocyanic acid, unless specifically listed in this appendix in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA ), accessed on January 7, 2017. Manufacturers or distributors can expand the harmonized classification and labeling .
  5. ^ PH van Rooyen, JCA Boeyens: Sodium thiocyanate. In: Acta Crystallographica . 1975, B31, pp. 2933-2934.
  6. ^ Y. Chiang, AJ Kresge: Determination of the Acidity Constant of Isothiocyanic Acid in Aqueous Solution. In: Canadian Journal of Chemistry . 78 (12), 2000, pp. 1627-1628, doi : 10.1139 / v00-152 .
  7. ↑ RL Shriner: Isopropyl Thiocyanate In: Organic Syntheses . 11, 1931, p. 92, doi : 10.15227 / orgsyn.011.0092 ; Coll. Vol. 2, 1943, p. 366 ( PDF ).
  8. ↑ CFH Allen, J. VanAllan: 2-Amino-6-Methylbenzothiazole In: Organic Syntheses . 22, 1942, p. 16, doi : 10.15227 / orgsyn.022.0016 ; Coll. Vol. 3, 1955, p. 76 ( PDF ).
  9. ↑ Miracle cure for hair loss? This is what the substance thiocyanate does. Focus Online, February 9, 2017, accessed March 29, 2017 .
  10. ↑ Use of thiocyanate. Thiocyn GmbH, accessed on March 29, 2017 .
  11. ↑ Patent EP0336236 : Means and method for the qualitative and quantitative promotion of hair growth in humans and farm animals. Published on October 11, 1989 , inventors: Theodor Hiepe, Stephan Koch, Axel Kramer, Hans Meffert, Siegfried Minnich, Bodo Thürkow, Marietta Völzke, Norbert Völzke, Wolfgang Weuffen, Hans Winetzka. ‌
  12. ↑ Patent DE4100975 : Cosmetic or pharmaceutical preparations for improving hair quality and promoting hair growth. Published on July 16, 1992 , inventors: Stefan Koch, Axel Kramer, Hans Meffert, Wolfgang Weuffen. ‌

literature