Cadmium chloride

Cadmium chloride is a white crystalline compound of cadmium and chlorine, with the formula CdCl2. It is a hygroscopic solid that is highly soluble in water and slightly soluble in alcohol. Although it is considered to be ionic, it has considerable covalent character to its bonding. The crystal structure of cadmium chloride (described below), composed of two-dimensional layers of ions, is a reference for describing other crystal structures. Also known are CdCl2•H2O and CdCl2•5H2O.[2]

Cadmium chloride
Ball-and-stick model of cadmium chloride
Cadmium chloride in polyhedron shape
Names
IUPAC name
Cadmium dichloride
Other names
Cadmium(II) chloride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.030.256
EC Number
  • 233-296-7
912918
KEGG
RTECS number
  • EV0175000
UNII
UN number 2570
Properties
CdCl2
Molar mass 183.31 g·mol−1
Appearance White solid, hygroscopic
Odor Odorless
Density 4.047 g/cm3 (anhydrous)[1]
3.327 g/cm3 (Hemipentahydrate)[2]
Melting point 568 °C (1,054 °F; 841 K)
at 760 mmHg[2]
Boiling point 964 °C (1,767 °F; 1,237 K)
at 760 mmHg[2]
Hemipentahydrate:
79.5 g/100 mL (−10 °C)
90 g/100 mL (0 °C)
Monohydrate:
119.6 g/100 mL (25 °C)[2]
134.3 g/100 mL (40 °C)
134.2 g/100 mL (60 °C)
147 g/100 mL (100 °C)[3]
Solubility Soluble in alcohol, selenium(IV) oxychloride, benzonitrile
Insoluble in ether, acetone[1]
Solubility in pyridine 4.6 g/kg (0 °C)
7.9 g/kg (4 °C)
8.1 g/kg (15 °C)
6.7 g/kg (30 °C)
5 g/kg (100 °C)[1]
Solubility in ethanol 1.3 g/100 g (10 °C)
1.48 g/100 g (20 °C)
1.91 g/100 g (40 °C)
2.53 g/100 g (70 °C)[1]
Solubility in dimethyl sulfoxide 18 g/100 g (25 °C)[1]
Vapor pressure 0.01 kPa (471 °C)
0.1 kPa (541 °C)[2]
−6.87·10−5 cm3/mol[2]
Viscosity 2.31 cP (597 °C)
1.87 cP (687 °C)[1]
Structure
Rhombohedral, hR9 (anhydrous)[4]
Monoclinic (hemipentahydrate)[3]
R3m, No. 166 (anhydrous)[4]
3 2/m (anhydrous)[4]
a = 3.846 Å, c = 17.479 Å (anhydrous)[4]
α = 90°, β = 90°, γ = 120°
Thermochemistry
74.7 J/mol·K[2]
115.3 J/mol·K[2]
−391.5 kJ/mol[2]
−343.9 kJ/mol[2]
Hazards
Safety data sheet External MSDS
GHS pictograms [5]
GHS Signal word Danger
H301, H330, H340, H350, H360, H372, H410[5]
P210, P260, P273, P284, P301+310, P310[5]
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
4
0
Lethal dose or concentration (LD, LC):
94 mg/kg (rats, oral)[1]
60 mg/kg (mouse, oral)
88 mg/kg (rat, oral)[6]
NIOSH (US health exposure limits):
PEL (Permissible)
 [1910.1027] TWA 0.005 mg/m3 (as Cd)[7]
REL (Recommended)
 Ca[7]
IDLH (Immediate danger)
 Ca [9 mg/m3 (as Cd)][7]
Related compounds
Other anions
 Cadmium fluoride
Cadmium bromide
Cadmium iodide
Other cations
 Zinc chloride
Mercury(II) chloride
Calcium chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Structure

Cadmium chloride forms crystals with rhombohedral symmetry. Cadmium iodide, CdI2, has a very similar crystal structure to CdCl2. The individual layers in the two structures are identical, but in CdCl2 the chloride ions are arranged in a CCP lattice, whereas in CdI2 the iodide ions are arranged in an HCP lattice.[8][9]

Chemical properties

Cadmium chloride dissolves well in water and other polar solvents. In water, its high solubility is due in part to formation of complex ions such as [CdCl4]2−. Because of this behavior, CdCl2 is a mild Lewis acid.[8]

CdCl2 + 2 Cl− → [CdCl4]2−

With large cations, it is possible to isolate the trigonal bipyramidal [CdCl5]3− ion.

Preparation

Anhydrous cadmium chloride can be prepared by the action of anhydrous chlorine or hydrogen chloride gas on heated cadmium metal.

Cd + 2 HCl → CdCl2 + H2

Hydrochloric acid may be used to make hydrated CdCl2 from the metal, or from cadmium oxide or cadmium carbonate.

Uses

Cadmium chloride is used for the preparation of cadmium sulfide, used as "Cadmium Yellow", a brilliant-yellow stable inorganic pigment.

CdCl
2 + H
2S → CdS + 2 HCl

In the laboratory, anhydrous CdCl2 can be used for the preparation of organocadmium compounds of the type R2Cd, where R is an aryl or a primary alkyl. These were once used in the synthesis of ketones from acyl chlorides:[10]

CdCl
2 + 2 RMgX → R
2Cd + MgCl
2 + MgX
2
R
2Cd + 2R'COCl → 2R'COR + CdCl
2

Such reagents have largely been supplanted by organocopper compounds, which are much less toxic.

Cadmium chloride is also used for photocopying, dyeing and electroplating.

References
  1. Anatolievich, Kiper Ruslan. "cadmium chloride". chemister.ru. Retrieved 2014-06-25.
  2. Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
  3. Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand Company. p. 169.
  4. "Cadmium Chloride - CdCl2". chem.uwimona.edu.jm. Mona, Jamaica: The University of the West Indies. Retrieved 2014-06-25.
  5. Sigma-Aldrich Co., Cadmium chloride. Retrieved on 2014-05-23.
  6. "Cadmium compounds (as Cd)". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  7. NIOSH Pocket Guide to Chemical Hazards. "#0087". National Institute for Occupational Safety and Health (NIOSH).
  8. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  9. A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
  10. J. March, Advanced Organic Chemistry, 4th ed., p. 723, Wiley, New York, 1992.
Salts and covalent derivatives of the chloride ion
HCl He
LiCl BeCl2 BCl3
B2Cl4		 CCl4 NCl3
ClN3		 Cl2O
ClO2
Cl2O7		 ClF
ClF3
ClF5		 Ne
NaCl MgCl2 AlCl
AlCl3		 SiCl4 P2Cl4
PCl3
PCl5		 S2Cl2
SCl2
SCl4		 Cl2 Ar
KCl CaCl
CaCl2		 ScCl3 TiCl2
TiCl3
TiCl4		 VCl2
VCl3
VCl4
VCl5		 CrCl2
CrCl3
CrCl4		 MnCl2 FeCl2
FeCl3		 CoCl2
CoCl3		 NiCl2 CuCl
CuCl2		 ZnCl2 GaCl2
GaCl3		 GeCl2
GeCl4		 AsCl3
AsCl5		 Se2Cl2
SeCl4		 BrCl KrCl
RbCl SrCl2 YCl3 ZrCl3
ZrCl4		 NbCl3
NbCl4
NbCl5		 MoCl2
MoCl3
MoCl4
MoCl5
MoCl6		 TcCl3
TcCl4		 RuCl3 RhCl3 PdCl2 AgCl CdCl2 InCl
InCl2
InCl3		 SnCl2
SnCl4		 SbCl3
SbCl5		 Te3Cl2
TeCl4		 ICl
ICl3		 XeCl
XeCl2
XeCl4
CsCl BaCl2   HfCl4 TaCl5 WCl2
WCl3
WCl4
WCl5
WCl6		 Re3Cl9
ReCl4
ReCl5
ReCl6		 OsCl4 IrCl2
IrCl3
IrCl4		 PtCl2
PtCl4		 AuCl
AuCl3		 Hg2Cl2,
HgCl2		 TlCl PbCl2,
PbCl4		 BiCl3 PoCl2,
PoCl4		 AtCl RnCl2
FrCl RaCl2   RfCl4 Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
↓
LaCl3 CeCl3 PrCl3 NdCl2,
NdCl3		 PmCl3 SmCl2,
SmCl3		 EuCl2,
EuCl3		 GdCl3 TbCl3 DyCl2,
DyCl3		 HoCl3 ErCl3 TmCl2
TmCl3		 YbCl2
YbCl3		 LuCl3
AcCl3 ThCl4 PaCl5 UCl3
UCl4
UCl5
UCl6		 NpCl4 PuCl3 AmCl2
AmCl3		 CmCl3 BkCl3 CfCl3 EsCl3 Fm Md No LrCl3
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