Cobalt (II) chloride

Crystal structure
	__ Co 2+ __ Cl -
General
Surname	Cobalt (II) chloride
other names	Cobalt dichloride
Ratio formula	CoCl 2
Brief description	blue crystalline solid (anhydrous), as a hexahydrate red-violet solid
External identifiers / databases
EC number	231-589-4
ECHA InfoCard	100,028,718
PubChem	24288
ChemSpider	22708
Wikidata	Q407849
properties
Molar mass	129.84 g mol −1 (anhydrous) 237.93 g mol −1 (hexahydrate)
Physical state	firmly
density	3.356 g cm −3
Melting point	735 ° C
boiling point	1049 ° C
solubility	Easily soluble in water (529 g l −1 at 20 ° C) * soluble in methanol, ethanol, acetone, pyridine and diethyl ether;
safety instructions
H and P phrases	H: 350i-360F-302-317-334-341-410
	P: 201-273-280-302 + 352-304 + 340-342 + 311
Authorization procedure under REACH	particularly worrying : carcinogenic, toxic for reproduction ( CMR )
MAK	not specified because it is carcinogenic
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cobalt (II) chloride is a chemical compound of cobalt and chlorine . It is a blue salt in the anhydrous state and pink in color as hexahydrate .

Extraction and presentation

Cobalt (II) chloride can be obtained from the elements or by heating the hexahydrate in the presence of thionyl chloride or phosgene or in a stream of hydrogen chloride .

{\ displaystyle \ mathrm {CoCl_ {2} \ cdot 6 \ H_ {2} O + 6 \ SOCl_ {2} \ longrightarrow CoCl_ {2} +12 \ HCl + 6 \ SO_ {2}}}

The latter can in turn be obtained by reacting cobalt (II) hydroxide or cobalt (II) carbonate with hydrochloric acid .

{\ displaystyle \ mathrm {CoCO_ {3} +2 \ HCl \ longrightarrow CoCl_ {2} + H_ {2} O + CO_ {2}}}

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

{\ displaystyle \ mathrm {Co (CH_ {3} CO_ {2}) _ {2} \ cdot 4 \ H_ {2} O + 6 \ CH_ {3} COCl \ longrightarrow}}

{\ displaystyle \ mathrm {CoCl_ {2} +2 \ (CH_ {3} CO) _ {2} O + 4 \ CH_ {3} CO_ {2} H + 4 \ HCl}}

properties

Anhydrous cobalt (II) chloride is very hygroscopic and easily absorbs water. It changes its color very characteristically from blue to pink. The opposite color change from pink to blue is also possible by heating the hexahydrate to temperatures above 35 ° C. The color change depends on the form of the hydrate. The anhydrate has a blue color, the hexahydrate pink, the monohydrate blue-violet, the monohemihydrate dark blue-violet, the dihydrate pink-violet, the tetrahydrate peach blossom-red.

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

Cobalt (II) chloride (anhydrous)
Cobalt (II) chloride hexahydrate

It sublimes in a hydrogen chloride atmosphere at 500 ° C to form loose crystal flakes. Its crystal structure is trigonal and corresponds to that of cadmium (II) chloride with the space group R 3 m (No. 166) (a = 354.4 pm, c = 1743 pm). Template: room group / 166

use

Because of the typical color change, it was used as a moisture indicator in desiccants such as silica gel . With the help of cobalt (II) chloride, water can also be detected in other solutions.

It is also used as a so-called secret ink , since it is hardly visible as a hexahydrate in aqueous solution on the paper, but when it is heated (e.g. over a candle), deep blue writing emerges. It can also be used as an additive to the electrolyte (sulfuric acid) in lead-acid batteries to increase battery life and performance. The flash bulbs manufactured earlier contained a small blue dot of cobalt (II) chloride inside, which indicated that the bulb was OK. If the pear leaked, it drew in air and with it moisture and the point changed its color to pink as a sign that the pear was defective. The blue dot in lightning bulbs was first used in 1937 by an American company, which also received a patent for it.

Silica gel ( blue gel ) contains cobalt (II) chloride (dry = blue) as a color indicator.
Damp silica gel is pink - cobalt (II) chloride hexahydrate has formed.

Furthermore, cobalt (II) chloride is used in cell culture to simulate a lack of oxygen. This is important in cancer research because it is believed that a lack of oxygen promotes the development and spread of tumors. In breast cancer cells, there is an increased expression of the proteins HIF-1α, CXCR4 and VEGF.

safety instructions

Cobalt (II) chloride is considered to be carcinogenic and teratogenic and may be mutagenic. The substance was added to the candidate list of substances of very high concern on October 28, 2008 . On June 20, 2011, the entry was supplemented by the reproductive properties.

Cobalt (II) chloride is also (like all water-soluble compounds and the metal) a contact allergen .

Cobalt (II) chloride promotes the production of erythrocytes . There is therefore concern that cobalt (II) chloride is misused as a doping substance in sport.

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on cobalt (II) chloride in the GESTIS substance database of the IFA , accessed on December 7, 2019(JavaScript required) .
↑ ^a ^b ^c ^d Georg Brauer: Handbook of preparative inorganic chemistry . 3., reworked. Edition. tape III . Enke, Stuttgart 1981, ISBN 3-432-87823-0 , pp. 1660 .
↑ Entry on Cobalt dichloride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Entry in the SVHC list of the European Chemicals Agency , accessed on December 6, 2019.
^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1685.
↑ From powder flash to electronic flash
^ S. Li, J. Zhang, H. Yang, C. Wu, X. Dang, Y. Liu: Copper depletion inhibits CoCl2-induced aggressive phenotype of MCF-7 cells via downregulation of HIF-1 and inhibition of Snail / Twist -mediated epithelial-mesenchymal transition. In: Sci Rep. 5, 2015, p. 12410. doi: 10.1038 / srep12410
^ Q. Li, R. Ma, M. Zhang: CoCl2 increases the expression of hypoxic markers HIF-1α, VEGF and CXCR4 in breast cancer MCF-7 cells. In: Oncol Lett. 15 (1), 2018, pp. 1119–1124. doi: 10.3892 / ol.2017.7369
↑ cobalt dichloride. in the REACH-CLP Helpdesk of the federal authorities, accessed on November 16, 2019.
^ KA Zug, EM Warshaw, JF Fowler Jr, HI Maibach, DL Belsito, MD Pratt, D. Sasseville, FJ Storrs, JS Taylor, CG Mathias, VA Deleo, RL Rietschel, J. Marks: Patch-test results of the North American Contact Dermatitis Group 2005-2006. In: dermatitis . 20 (3), 2009, pp. 149-160.
↑ Wolfgang Jelkmann: The Disparate Roles of Cobalt in Erythropoiesis, and Doping Relevance . In: Open Journal of Hematology . tape 3 , 2012, ISSN 2075-907X , p. 3–6 , doi : 10.13055 / ojhmt_3_1_6.121211 .

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on cobalt (II) chloride in the GESTIS substance database of the IFA , accessed on December 7, 2019(JavaScript required) .

[brauer-2] Georg Brauer: Handbook of preparative inorganic chemistry . 3., reworked. Edition. tape III . Enke, Stuttgart 1981, ISBN 3-432-87823-0 , pp. 1660 .

[CLP_100.028.718-3] Entry on Cobalt dichloride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[SVHC-4] Entry in the SVHC list of the European Chemicals Agency , accessed on December 6, 2019.

[5] AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1685.

[6] From powder flash to electronic flash

[7] S. Li, J. Zhang, H. Yang, C. Wu, X. Dang, Y. Liu: Copper depletion inhibits CoCl2-induced aggressive phenotype of MCF-7 cells via downregulation of HIF-1 and inhibition of Snail / Twist -mediated epithelial-mesenchymal transition. In: Sci Rep. 5, 2015, p. 12410. doi: 10.1038 / srep12410

[8] Q. Li, R. Ma, M. Zhang: CoCl2 increases the expression of hypoxic markers HIF-1α, VEGF and CXCR4 in breast cancer MCF-7 cells. In: Oncol Lett. 15 (1), 2018, pp. 1119–1124. doi: 10.3892 / ol.2017.7369

[9] cobalt dichloride. in the REACH-CLP Helpdesk of the federal authorities, accessed on November 16, 2019.

[10] KA Zug, EM Warshaw, JF Fowler Jr, HI Maibach, DL Belsito, MD Pratt, D. Sasseville, FJ Storrs, JS Taylor, CG Mathias, VA Deleo, RL Rietschel, J. Marks: Patch-test results of the North American Contact Dermatitis Group 2005-2006. In: dermatitis . 20 (3), 2009, pp. 149-160.

[11] Wolfgang Jelkmann: The Disparate Roles of Cobalt in Erythropoiesis, and Doping Relevance . In: Open Journal of Hematology . tape 3 , 2012, ISSN 2075-907X , p. 3–6 , doi : 10.13055 / ojhmt_3_1_6.121211 .