Cobalt (II) bromide

Crystal structure
__ Co 2+      __ Br -
General
Surname	Cobalt (II) bromide
other names	Cobalt dibromide
Ratio formula	CoBr 2
Brief description	green solid (anhydrous) red-purple solid (hexahydrate)
External identifiers / databases
CAS number 7789-43-7 85017-77-2 (hydrate) PubChem 24610 Wikidata Q420300
properties
Molar mass	218.74 g mol −1
Physical state	firmly
density	4.909 g cm −3 (25 ° C) 2.46 g cm −3 (hexahydrate)
Melting point	678 ° C 47-48 ° C (hexahydrate)
solubility	soluble in acetone, ethanol and methanol
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 302-317-334-341-350-410 P: 201-261-280-284-304 + 340-308 + 313
Toxicological data	406 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 .

Cobalt (II) bromide is a chemical compound of cobalt and is one of the bromides .

Extraction and presentation

Cobalt (II) bromide can be obtained by reacting cobalt with bromine .

${\displaystyle \mathrm {Co+Br_{2}\longrightarrow CoBr_{2}} }$

It can also be obtained by thermal decomposition of the hexahydrate at 130–150 ° C.

${\displaystyle \mathrm {CoBr_{2}\cdot 6H_{2}O\longrightarrow CoBr_{2}+6\ H_{2}O} }$

The preparation from cobalt (II) acetate tetrahydrate and acetyl bromide is also possible .

${\displaystyle \mathrm {Co(CH_{3}CO_{2})_{2}\cdot 4H_{2}O+6\ CH_{3}COBr\longrightarrow } }$ ${\displaystyle \mathrm {CoBr_{2}+2\ (CH_{3}CO)_{2}O+4\ CH_{3}CO_{2}H+4\ HBr} }$

properties

Cobalt (II) bromide is a green, hygroscopic solid that changes to the red hexahydrate in air. It is easily soluble in water with a red color. Cobalt (II) bromide has a cadmium iodide crystal structure. The red hexahydrate dissolves in air . With concentrated sulfuric acid or when heated to 130–140 ° C, it gives off all water of crystallization. At 100 ° C, the hexahydrate gives off water of crystallization and changes into the purple-colored dihydrate. The dihydrate has a crystal structure with the space group C 2 / m (space group no. 12) and the lattice parameters a = 7.630, b = 8.770, c = 3.765  Å and β = 97.54 °.

use

Cobalt (II) bromide can be used as a catalyst in the oxidation of organic compounds.

Individual evidence

1. ↑ ^{a b c} Erwin Riedel: Inorganic Chemistry. 6th edition, Walter de Gruyter, 2004, ISBN 3-11-018168-1 , p. 834.
2. ↑ ^{a b c d} Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1661.
3. ↑ ^{a b c d e f g} data sheet Cobalt (II) bromide, 99% from Sigma-Aldrich , accessed on June 21, 2017 ( PDF ).
4. ^ ^{A b c} Dale L. Perry: Handbook of Inorganic Compounds, Second Edition . Taylor & Francis US, 2011, ISBN 1-4398-1462-7 , pp. 483 ( limited preview in Google Book search).
5. ↑ Cobalt dibromide. In: webelements.com. Retrieved June 21, 2017 (English). 
6. ↑ B. Morosin: Crystal Structure of Manganese (II) and Cobalt (II) Bromide Dihydrate. In: The Journal of Chemical Physics. 47, 1967, p. 417, doi: 10.1063 / 1.1711911 .
7. ↑ Data sheet Cobalt (II) bromide hydrate from Sigma-Aldrich , accessed on January 30, 2012 ( PDF ).