Barium thiocyanate

Structural formula
General
Surname	Barium thiocyanate
other names	Barium rhodanide
Molecular formula	Ba (SCN) 2 Ba (SCN) 2 • 3H 2 O
Brief description	white, deliquescent, hygroscopic needle-shaped crystals
External identifiers / databases
CAS number 2092-17-3 (anhydrous) 5908-82-7 (dihydrate) 68016-36-4 (trihydrate) 336879-43-7 (unspecified hydrate) EC number 218-245-9 ECHA InfoCard 100.016.587 PubChem 164928 ChemSpider 144591 Wikidata Q4457900
properties
Molar mass	253.497 g mol −1 (anhydrous) 307.543 g mol −1 (trihydrate)
Physical state	firmly
density	2.286 g cm −3 (trihydrate)
solubility	readily soluble in water (167 g l −1 at 25 ° C) soluble in acetone, methanol and ethanol insoluble in trimethylamine
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary Caution H and P phrases H: 302 + 312 + 332-412 EUH: 032 P: 261-273-280-304 + 340-363-501
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Barium thiocyanate (Ba (SCN) ₂ , also: called barium rhodanide ) is a salt of thiocyanic acid (hydro thiocyanate ).

properties

At room temperature, barium thiocyanate trihydrate consists of white deliquescent and hygroscopic crystals , which deliquesce slowly in air . It dissolves very well in water, but has a very steep temperature-solubility gradient. Barium thiocyanate crystallizes in the monoclinic crystal system , space group C 2 / c (space group no. 15) with the lattice parameters a = 10.188, b = 6.872, c = 8.522 Å and β = 92.43 °. The anhydrate is very hygroscopic. The trihydrate always crystallizes out of aqueous solutions. It forms double salts with other alkali metal thiocyanates. The trihydrate gives off water of crystallization from around 70 ° C, whereby the dihydrate forms first and later (from 160 ° C) the anhydrate. This is stable up to 447 ° C and then decomposes to form barium sulfide, among other things .

Manufacturing

Barium thiocyanate can be produced from barium hydroxide and ammonium thiocyanate . Here the ammonia is driven out of the solution or out of equilibrium by boiling. Alternatively, it can also be made from barium hydroxide or barium carbonate and thiocyanic acid.

${\displaystyle \mathrm {Ba(OH)_{2}+2\ NH_{4}SCN\longrightarrow Ba(SCN)_{2}+2\ NH_{3}\uparrow +\ 2\ H_{2}O} }$

${\displaystyle \mathrm {Ba(OH)_{2}+2\ HSCN\longrightarrow Ba(SCN)_{2}+2\ H_{2}O} }$

${\displaystyle \mathrm {BaCO_{3}+2\ HSCN\longrightarrow Ba(SCN)_{2}+H_{2}O+CO_{2}\uparrow } }$

Single crystals can be represented by metathesis of sodium thiocyanate and barium chloride .

Barium thiocyanate was first synthesized by Berzelius , who roasted barium hexacyanoferrate (II) with sulfur.

use

Barium thiocyanate is used to conveniently prepare other thiocyanates, e.g. B. Cobalt (II) thiocyanate .

${\displaystyle \mathrm {CoSO_{4}+Ba(SCN)_{2}\longrightarrow BaSO_{4}\downarrow +\ Co(SCN)_{2}} }$

It was also used in the dye industry and photography.

Individual evidence

1. ↑ ^{a b c d e} David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Inorganic Compounds, pp. 4-51.
2. ↑ ^{a b c d e} Harold Simmons Booth: Volume 3 of Inorganic Syntheses . London, 1950, pp. 24 ( limited preview in Google Book search).
3. ↑ ^{a b} data sheet barium thiocyanate trihydrate from AlfaAesar, accessed on December 13, 2015 ( PDF )(JavaScript required) .
4. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the indicated labeling it falls under the group entries for barium salts, with the exception of barium sulphate, salts of 1-azo-2-hydroxynaphthalenyl aryl sulphonic acid , and of salts specified elsewhere in this Annex and alkali salts and alkali earth salts of thiocyanic acid, with the exception of those specified elsewhere in this Annex in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on March 18, 2017. Manufacturer or distributors can expand the harmonized classification and labeling .
5. ↑ ^{a b} C. Wickleder: M (SCN) ₂ (M = Eu, Sr, Ba): crystal structure, thermal behavior, vibrational spectroscopy . In: Journal for inorganic and general chemistry , 2001 , 627 , pp. 1693-1698 doi : 10.1002 / 1521-3749 (200107) 627: 7 <1693 :: AID-ZAAC1693> 3.0.CO; 2-U
6. ↑ R. Blachnik: Pocket book for chemists and physicists Volume 3: Elements, inorganic compounds and materials, minerals . Springer-Verlag, 2013, ISBN 978-3-642-58842-6 , pp. 330 ( limited preview in Google Book search).
7. ↑ K. Mereiter, A. Preisinger: Barium thiocyanate trihydrate. In: Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 38, p. 382, doi : 10.1107 / S0567740882003033 .
8. ↑ Georg Brauer: Handbook of Preparative Inorganic Chemistry . Elsevier, 2012, ISBN 978-0-323-16129-9 , pp. 1106 ( limited preview in Google Book search).
9. ↑ FH Cano, S. García-Blanco, AG Laverat: The crystal structure of cobalt (II) thiocyanate trihydrate. In: Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 32, p. 1526, doi : 10.1107 / S0567740876005694 .
10. ^ Christopher G. Morris, Academic Press: Academic Press Dictionary of Science and Technology . Gulf Professional Publishing, 1992, ISBN 0-12-200400-0 , pp. 218 ( limited preview in Google Book search).