Cobalt chloride Chemical Properties

Melting point:

724 °C(lit.)

Boiling point:

1049 °C

Density 

3.35

vapor pressure 

40 mm Hg ( 0 °C)

Flash point:

500°C

storage temp. 

Store below +30°C.

solubility 

585.9g/l soluble

form 

beads

color 

Pale blue

Specific Gravity

3.356

PH

pH (50g/l, 25℃) : >=3.0

Water Solubility 

soluble

Crystal Structure

CdCl2 type

Sensitive 

Hygroscopic

crystal system

Three sides

Sublimation 

500 ºC

Merck 

14,2437

Space group

R3m

Lattice constant

a/nm	b/nm	c/nm	α/o	β/o	γ/o	V/nm3
0.355	0.355	1.74	90	90	120	0.19

Exposure limits

ACGIH: TWA 0.02 mg/m3

Stability:

hygroscopic

CAS DataBase Reference

7646-79-9(CAS DataBase Reference)

NIST Chemistry Reference

Cobalt dichloride(7646-79-9)

EPA Substance Registry System

Cobalt chloride (CoCl2) (7646-79-9)

Safety Information

Hazard Codes 

T,N

Risk Statements 

49-42/43-52/53-50/53-22-68-41-60-51/53

Safety Statements 

53-23-36/37-45-60-61-22-39-26

RIDADR 

UN 2923 8/PG 3

WGK Germany 

2

RTECS 

GF9800000

F 

9-21

TSCA 

Yes

HazardClass 

8

PackingGroup 

III

HS Code 

28273930

Hazardous Substances Data

7646-79-9(Hazardous Substances Data)

Toxicity

LD50 in mice, rats (mg/kg): 360.0, 171.0 orally; 92.6, 36.9 i.p.; 23.3, 4.3 i.v. (Singh, Junnarkar)

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS
• Language:English Provider:ALFA

Cobalt chloride Usage And Synthesis

Uses

Cobalt(II) chloride has several applications. It is used in hygrometers; as a
humidity indicator; as a temperature indicator in grinding; as a foam stabilizer in beer; in invisible ink; for painting on glass; in electroplating; and a catalyst in Grignard reactions, promoting coupling with an organic halide. It also is used to prepare several other cobalt salts; and in the manufacture of synthetic vitamin B12.
The vapor-phase co-reductions with other metal halides by hydrogen results in finely divided intermetallics with applications as structural materials or compounds with useful thermoelectric, magnetic, and oxidation-resistance properties.

Preparation

Cobalt(II) chloride is prepared by the action of cobalt metal or its oxide, hydroxide, or carbonate with hydrochloric acid:
Co(OH)2 + 2HCl → CoCl2 + 2H2O
The solution on concentration and cooling forms crystals of hexahydrate which on heating with SOCl2 dehydrates to anhydrous cobalt(II) chloride.
Alternatively, the hexahydrate may be converted to anhydrous CoCl2 by dehydration in a stream of hydrogen chloride and dried in vacuum at 100–150°C.
The anhydrous compound also may be obtained by passing chlorine over cobalt powder.

Description

blue crystals (anhydrous)
violet-blue (dihydrate)
rose red crystals (hexahydrate)
Sinks and mixes with water. Pale blue leaflets, turns pink upon exposure to moist air.

Chemical Properties

(1) Blue, (2) ruby-red crystals.Soluble in water, alcohol, and acetone.

Physical properties

Blue leaflets; turns pink in moist air; hygroscopic; the dihydrate is violet blue crystal; the hexahydrate is pink monoclinic crystal; density 3.36, 2.48 and 1.92 g/cm3 for anhydrous salt, dihydrate and hexahydrate, respectively; anhydrous salt melts at 740°C and vaporizes at 1,049°C; vapor pressure 60 torr at 801°C; the hexahydrate decomposes at 87°C; the anhydrous salt and the hydrates are all soluble in water, ethanol, acetone, and ether; the solubility of hydrates in water is greater than the anhydrous salt.

Uses

Cobalt(II) chloride is used in humidity indicator in weather instruments. In the anhydrous form, it finds use in electroplating of cobalt, in organic chemistry and is a precursor to cobaltocene, (bis(cyclopentadienyl)cobalt(II), which is a good reducing agent. It also serves as a Lewis acid. Cobalt chloride is an indicator for water in desiccants, owing to the reversible hydration/dehydration coupled with distinct color change. Cobalt chloride is useful for producing invisible ink as it turns blue when heated and becomes invisible once it gets cooled. Cobalt(II) chloride catalyzes cross coupling of aryl halides or vinyl halides with aryl grignard reagents in excellent yields.

Uses

Cobalt chloride (CoCl2) is used to manufacture vitamin B12, even though the compound itself can cause damage to red blood cells. It is also used as a dye mordant (to fix the dye to the textile so that it will not run). It is also of use in manufacturing solid lubricants, as an additive to fertilizers, as a chemical reagent in laboratories, and as an absorbent in gas masks, electroplating, and the manufacture of vitamin B12.

Uses

Absorbent for ammonia, gas masks, electroplating, sympathetic inks, hygrometers, manufacture of vitamin B 12, flux for magnesium refining, solid lubricant, dye mordant, catalyst, barometers, laboratory reagent, fertilizer additive.

Definition

ChEBI: A cobalt salt in which the cobalt metal is in the +2 oxidation state and the counter-anion is chloride. It is used as an indicator for water in desiccants.

General Description

Cobalt(II) chloride is an anhydrous cobalt salt. Cobalt(II) chloride participates in the synthesis of various esters in the presence of acetonitrile.

Air & Water Reactions

Hygroscopic. Soluble in water.

Reactivity Profile

A 0.2 molar aqueous solution has a pH of 4.6. Cobalt chloride acts as a weakly acidic inorganic salt, which is soluble in water. The resulting solutions contain moderate concentrations of hydrogen ions and have pH's of less than 7.0. They react as acids to neutralize bases. These neutralizations generate heat, but less or far less than is generated by neutralization of inorganic acids, inorganic oxoacids, and carboxylic acid. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible. Many of these compounds catalyze organic reactions. Potassium or sodium metals act to reduce metal halides, producing exothermic reactions, even explosions [Bretherick, 5th Ed., 1995].

Hazard

May not be used in food products (FDA). Can cause blood damage.

Health Hazard

Inhalation causes respiratory disease, shortness of breath, and coughing; permanent disability may occur. Ingestion causes pain, vomiting, and diarrhea. Contact causes irritation of eyes and may cause skin rash.

Fire Hazard

Special Hazards of Combustion Products: Toxic cobalt oxide fumes may form in fire.

Flammability and Explosibility

Not classified

Biochem/physiol Actions

Cobalt chloride induces hypoxia condition in cells by upregulating hypoxia-inducible factor-1α (HIF-1α), erythropoietin and glycolytic enzymes. It is also responsible for mitochondrial DNA damage in rat neuronal PC12 cells. It is also responsible for the induction of apoptosis.Cobalt chloride 0.1M solution is an additive screening solution of Additive Screening Kit. Additive Screen kit is designed to allow rapid and convenient evaluation of additives and their ability to influence the crystallization of the sample. The Additive Kit provides a tool for refining crystallization conditions.

Safety Profile

Suspected carcinogen with experimental carcinogenic data. Poison experimentally by ingestion, skin contact, intraperitoneal, intravenous, and subcutaneous routes. Moderately toxic to humans by ingestion. Human systemic effects by ingestion: anorexia, goiter (increased thyroid size), and weight loss. Experimental teratogenic and reproductive effects. Human mutation data reported. Incompatible with metals (e.g., sodmm and potassium). See also COBALT. When heated to decomposition it emits toxic fumes of Cl-.

Purification Methods

A saturated aqueous solution at room temperature is fractionally crystallised by standing overnight. The first half of the material that crystallises in this way is used in the next crystallisation. The process is repeated several times, water being removed in a dry-box using air filtered through glass wool and dried over CaCl2 [Hutchinson J Am Chem Soc 76 1022 1954]. It has also been crystallised from dilute aqueous HCl. The hexahydrate m 86o forms pink to red deliquescent crystals. It loses 4H2O on heating at 52-56o and forms the violet dihydrate which loses a further H2O at 100o to form the violet monohydrate which loses the last H2O at 120-140o to give the pale blue anhydrous deliquescent salt m 735o and b 1049o. A pink solution of CoCl2 in H2O becomes blue on heating to 50o or adding conc HCl which may precipitate the mono or dihydrate. The solid dihydrate gives a blue-purple solution with EtOH. Note: CoCl2 in H2O is a “sympathetic ink”, i.e. writing using an aqueous solution is almost invisible on paper, but becomes blue on warming the paper. On cooling or standing, the writing becomes invisible again. The anhydrous salt is soluble in H2O, EtOH, Et2O, Me2CO and pyridine. [Glemser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1515 1965.]

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