Cobalt chloride (CoCl2 (structure, nomenclature, properties

The Cobalt chloride or cobalt (II) chloride is an inorganic solid formed by the union of cobalt metal in its oxidation state +2 with the chloride ion. Its chemical formula is CoCl_two.

The CoCl_two It is a crystalline solid that when in its hydrated form is red-violet in color. Gently heating it and removing the water of hydration turns it blue. These color changes are due to your coordinating number changing.

It has been used in the past to treat certain types of anemia, but has been found to cause heart problems, deafness, gastrointestinal problems, poor thyroid function, and atherosclerosis. For these reasons, it stopped being used and is still under study..

The CoCl_two it is used to speed up various chemical reactions. Its hexahydrate form in solution is used as a reference for certain chemical analyzes..

It is used to mimic hypoxia or low oxygen concentration in certain biological or medical-scientific research experiences. It has also been used to improve some mechanical properties of polymers.

Article index

• 1 Structure
• 2 Nomenclature
• 3 Properties
  • 3.1 Physical state
  • 3.2 Molecular weight
  • 3.3 Melting point
  • 3.4 Boiling point
  • 3.5 Density
  • 3.6 Solubility
  • 3.7 Other properties
• 4 Uses
  • 4.1 Treatment of special cases of anemia
  • 4.2 In catalysis of chemical reactions
  • 4.3 As a standard in chemical analysis
  • 4.4 In ischemia research
  • 4.5 As a model to mimic hypoxia in biological and medical research
  • 4.6 In research on the use of water as a source of hydrogen
  • 4.7 To improve the mechanical properties of polymers
  • 4.8 Administration harmful or lethal to horses
• 5 References

Structure

Cobalt (II) chloride is formed by a cobalt atom in its oxidation state +2 and two chloride anions Cl^-.

The electron configuration of the cation Co^two+ it is:

1s^two, 2s^two 2 P⁶, 3s^two 3p⁶ 3d⁷, 4s⁰,

because it has lost the 2 electrons from the 4s shell.

The electronic structure of the anion Cl^- it is:

1s^two, 2s^two 2 P⁶, 3s^two 3p⁶,

because it has gained an electron in the 3p shell.

Nomenclature

-Cobalt (II) chloride

-Cobaltous chloride

-Cobalt dichloride

-Dichlorocobalt

-Cobalt muriate

-CoCl_two: anhydrous cobalt chloride (without water of hydration)

-CoCl_two•2H_twoO: cobalt chloride dihydrate

-CoCl_two•6H_twoO: cobalt chloride hexahydrate

Properties

Physical state

Crystalline solid whose color depends on the degree of hydration.

CoCl_two anhydrous: pale blue

CoCl_two•2H_twoO: violet

CoCl_two•6H_twoO: red-purple or pink

Molecular weight

CoCl_two: 129.84 g / mol

CoCl_two•2H_twoO: 165.87 g / mol

CoCl_two•6H_twoO: 237.93 g / mol

Melting point

CoCl_two: 735 ºC

CoCl_two•6H_twoO: 86 ºC

Boiling point

CoCl_two: 1053 ºC

Density

CoCl_two: 3.356 g / cm³

CoCl_two•2H_twoO: 2.477 g / cm³

CoCl_two•6H_twoO: 1,924 g / cm³

Solubility

CoCl_two: 45 g / 100 mL of water

CoCl_two•2H_twoOr: 76 g / 100mL of water

CoCl_two•6H_twoOr: 93 g / 100mL of water

Other properties

Cobalt (II) chloride hexahydrate is pinkish, but when slightly heated it turns blue as it loses water. If the CoCl_two anhydrous is left in a humid atmosphere, it turns pink.

The color of the cobalt ion depends on the coordination number, that is, on the groups attached to the Co ion.^two+. A coordination number of 6 corresponds to pink compounds and a coordination number of 4 results in blue compounds..

When the CoCl_two is found in aqueous solution, the following equilibrium occurs:

Co (H_twoOR)₆⁺⁺ + 4 Cl^- ⇔ CoCl₄^- + 6 h_twoOR

When equilibrium shifts towards Co (H_twoOR)₆⁺⁺ the solution is red, while when it moves towards the CoCl₄^- the solution is blue.

Applications

Treatment of special cases of anemia

Cobalt chloride was widely used since the 1930s for the treatment of certain types of anemia, both in Europe and in the United States..

Its oral administration favors an increase in hemoglobin, erythrocyte count and hematocrit. The response is proportional to the dose used. This is because it exerts a stimulating action on the bone marrow..

However, its use was discontinued due to side effects such as gastrointestinal upset, cardiomyopathy, nerve deafness, and abnormal thyroid function..

Despite such drawbacks, in 1975 it was successfully tested in kidney failure patients whose anemia is caused by repeated blood loss due to dialysis..

Hematocrit and red cell volume were found to increase in these patients indicating stimulation of erythropoiesis or red blood cell formation..

For this reason, cobalt chloride was thought to be of value in hemodialysis patients in whom other ways of alleviating anemia have failed..

However, it was later observed that high levels of Co^two+ in blood were related to atherosclerosis, so more studies are currently being carried out to determine its potential benefits or harm for this type of patients.

In catalysis of chemical reactions

Cobalt chloride has application in the acceleration of certain chemical reactions.

For example, in the esterification of high molecular weight unsaturated compounds, the use of CoCl_two As a catalyst it leads to obtaining the desired product without the formation of collateral derivatives.

Increasing the CoCl concentration_two and the temperature increases the rate of the reaction.

As a standard in chemical analysis

The CoCl_two•6H_twoOr it is used as a standard or color reference in some analysis methods of the American Public Health Association, or APHA. American Public Health Association).

In ischemia research

Ischemia is the decrease in blood flow in a part of the body and remedies are continually being investigated to avoid it or prevent its consequences.

CoCl has been found_two can induce apoptosis or cell death of cancer model cells.

The CoCl_two it triggers the production of reactive oxygen species in such cancer model cells, which leads to their death via apoptosis. Said to induce a hypoxia-mimicking response.

This result indicates that the CoCl_two can help to investigate the molecular mechanism in hypoxia-associated cell death and to find remedies against ischemia.

As a model to mimic hypoxia in biological and medical research

Hypoxia is the decrease in available oxygen necessary for the function of the cell. The CoCl_two is one of the compounds used in medical-scientific and biological research to induce chemical hypoxia.

The mechanism of action of CoCl_two in cells gives the researcher a longer time to manipulate and analyze their samples under hypoxic conditions.

Its use is considered a reliable method, since it allows experiments under low oxygen conditions without the use of special cameras..

However, the interpretation of the results obtained must be carefully reviewed, as the researcher must ensure that cobalt does not have other effects on the function of the cells under study apart from mimicking hypoxia..

In research on the use of water as a source of hydrogen

Cobalt chloride has been studied as a catalyst in the investigation of obtaining hydrogen from water using solar energy.

The Co ion^two+ can act as a homogeneous catalyst during the photochemical oxidation of water under acidic conditions (presence of acid HCl and pH 3) to avoid precipitation.

This type of study sheds light and helps in the search for clean energy and sustainable solar energy..

To improve the mechanical properties of polymers

Some researchers incorporated CoCl_two to acrylonitrile-butadiene-styrene polymer blends, or ABS. Acrylonitrile-Butadiene-Styrene), with nitrile-butadiene rubber, or NBR (acronym of the English Nitrile Butadiene Rubber).

CoCl was incorporated_two to the ABS-NBR mixture and the whole was hot compressed. The results indicate that the NBR was uniformly dispersed in the ABS and that the CoCl_two tends to be distributed in the NBR phase.

The coordination reaction between the cations Co^two+'and -CN groups have a positive impact on mechanical properties. By increasing the CoCl content_two increases tensile strength and ease of bending.

However, a decrease in thermal stability and problems with the absorption of water from CoCl were observed._two, Therefore, this type of mixture will continue to be studied..

Harmful or lethal administration to horses

The CoCl_two has been used in very small quantities in horse feed.

Cobalt is an important element (in traces) for the diet of horses, since the bacteria in their intestinal tract use it to synthesize vitamin B12 (cobalamin).

However, recent studies (2019) indicate that cobalt supplementation in horse feed is neither useful nor necessary and that it can be potentially lethal for these animals.

References

1. Wenzel, R.G. et al. (2019). Cobalt accumulation in horses following repeated administration of cobalt chloride. Australian Veterinary Journal 2019, Early View, August 16, 2019. Recovered from onlinelibrary.wiley.com.
2. Muñoz-Sánchez, J. and Chánez-Cárdenas, M. (2018). The use of cobalt chloride as a chemical hypoxia model. Journal of Applied Toxicology 2018, 39 (4): 1-15. Recovered from onlinelibrary.wiley.com.
3. Liu, H. et al. (2015). Homogeneous Photochemical Water Oxidation with Cobalt Chloride in Acidic Media. ACS Catalists 2015, 5, 4994-4999. Recovered from pubs.acs.org.
4. Shao, C. et al. (2018). Acrylonitrile-butadiene-styrene / nitrile butadiene rubber blends enhanced by anhydrous cobalt chloride. Journal of Applied Polymer Science 2018, Volume 135, Issue 41. Recovered from onlinelibrary.wiley.com.
5. Zou, W. et al. (2001). Cobalt Chloride Induces PC12 Cells Apoptosis Through Reactive Oxygen Species ad Accompanied by AP-1 Activation. Journal of Neuroscience Research 2001, 64 (6): 646-653. Recovered from onlinelibrary.wiley.com.
6. Urteaga, L. et al. (1994). Kinetic Study of the Synthesis of n-Octyl Octanoate Using Cobalt Chloride as Catalyst. Chem. Eng. Technol. 17 (1994) 210-215. Recovered from onlinelibrary.wiley.com.
7. Murdock, H.R.Jr. (1959). Studies on the Pharmacology of Cobalt Chloride. Journal of the American Pharmaceutical Association 1959, Volume 48, Issue 3, pages 140-142. Recovered from onlinelibrary.wiley.com.
8. Bowie, E.A. and Hurley, P.J. (1975). Cobalt Chloride in the Treatment of Refractory Anaemia in Patients undergoing Long-term Haemodialysis. Australian and New Zealand Journal of Medicine 1975, Volume 5, Issue 4, pp. 306-314. Recovered from onlinelibrary.wiley.com.
9. Cotton, F. Albert and Wilkinson, Geoffrey. (1980). Advanced Inorganic Chemistry. Fourth Edition. John Wiley & Sons.
10. Dean, J.A. (editor) (1973). Lange's Handbook of Chemistry. Eleventh Edition. McGraw-Hill Book Company.
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