Cadmium chloride is a white crystalline compound of
cadmium and
chloride, with the formula CdCl
2. This salt is a
hygroscopic solid that is highly soluble in water and slightly soluble in
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
. The
crystal structure of cadmium chloride (described below), is a reference for describing other crystal structures. Also known are CdCl
2•H
2O and CdCl
2•5H
2O.
Structure
Cadmium chloride forms a layered structure consisting of octahedral Cd
2+ centers linked with chloride ligands.
Cadmium iodide, CdI
2, has a similar structure, but the
iodide ions are arranged in a
HCP lattice, whereas in CdCl
2 the
chloride ions are arranged in a CCP lattice.
[N. N. Greenwood, A. Earnshaw, ''Chemistry of the Elements'', 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.]
Chemical properties
Cadmium chloride dissolves well in water and other polar solvents. It is a mild
Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
.
[
:CdCl2 + 2 Cl− → dCl4sup>2−
Solutions of equimolar cadmium chloride and potassium chloride give potassium cadmium trichloride.
With large cations, it is possible to isolate the trigonal bipyramidal dCl5sup>3− ion.
]
Preparation
Anhydrous cadmium chloride can be prepared by the reaction of hydrochloric acid and cadmium metal.
: Cd + 2 HCl → CdCl2 + H2
The anhydrous salt can also be prepared from anhydrous cadmium acetate using hydrogen chloride or acetyl chloride.
Uses
Cadmium chloride is used for the preparation of cadmium sulfide, used as "cadmium yellow
Cadmium pigments are a class of pigments that contain cadmium. Most of the cadmium produced worldwide has been for use in rechargeable nickel–cadmium batteries, which have been replaced by other rechargeable nickel-chemistry cell varieties ...
", a brilliant-yellow stable inorganic pigment.
: + → + 2 HCl
In the laboratory, anhydrous CdCl2 can be used for the preparation of organocadmium compound
An organocadmium compound is an organometallic compound containing a carbon to cadmium chemical bond. Organocadmium chemistry describes physical properties, synthesis, reactions and use of these compounds. Cadmium shares group 12 with zinc and mer ...
s of the type R2Cd, where R is an aryl or a primary alkyl. These were once used in the synthesis of ketone
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...
s from acyl chloride
In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...
s:[J. March, ''Advanced Organic Chemistry'', 4th ed., p. 723, Wiley, New York, 1992.]
: + 2 RMgX → + +
: + 2R'COCl → 2R'COR +
Such reagents have largely been supplanted by organocopper compound
Organocopper compounds is the chemistry of organometallic compounds containing a carbon to copper chemical bond. Organocopper chemistry is the study of organocopper compounds describing their physical properties, synthesis and reactions. They a ...
s, which are much less toxic.
Cadmium chloride is also used for photocopying
A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers u ...
, dyeing and electroplating
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be ...
.
Like all cadmium compounds, is highly toxic and appropriate safety precautions must be taken when handling it.
References
External links
International Chemical Safety Card 0116
{{Chlorides
Cadmium compounds
Chlorides
Metal halides
IARC Group 1 carcinogens