- Copper(II) chloride
Identifiers CAS number ,
PubChem ChemSpider UNII ChEBI ChEMBL RTECS number GL7000000 Jmol-3D images Image 1
Properties Molecular formula CuCl2 Molar mass 134.45 g/mol (anhydrous)
170.48 g/mol (dihydrate)
Appearance yellow-brown solid (anhydrous)
blue-green solid (dihydrate)
Density 3.386 g/cm3 (anhydrous)
2.51 g/cm3 (dihydrate)
498 °C (anhydrous)
100 °C (dehydration of dihydrate)
993 °C (anhydrous, decomp)
Solubility in water 706 g/L (0 °C)
757 g/L (25 °C)
Structure Crystal structure distorted CdI2 structure Coordination
Octahedral Hazards MSDS Fischer Scientific EU classification Not listed NFPA 704 Flash point Non-flammable Related compounds Other anions Copper(II) fluoride
Other cations Copper(I) chloride
(what is: /?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Copper(II) chloride is the chemical compound with the formula CuCl2. This is a light brown solid, which slowly absorbs moisture to form a blue-green dihydrate. The copper(II) chlorides are some of the most common copper(II) compounds, after copper sulfate.
Anhydrous CuCl2 adopts a distorted cadmium iodide structure. In this motif, the copper centers are octahedral. Most copper(II) compounds exhibit distortions from idealized octahedral geometry due to the Jahn-Teller effect, which in this case describes the localization of one d-electron into a molecular orbital that is strongly antibonding with respect to a pair of chloride ligands. In CuCl2·2H2O, the copper again adopts a highly distorted octahedral geometry, the Cu(II) centers being surrounded by two water ligands and four chloride ligands, which bridge asymmetrically to other Cu centers.
Properties and reactions
Aqueous solution prepared from copper(II) chloride contain a range of copper(II) complexes depending on concentration, temperature,and the presence of additional chloride ions. These species include blue color of [Cu(H2O)6]2+ and yellow or red color of the halide complexes of the formula [CuCl2+x]x−.
- 2 CuCl2 → 2 CuCl + Cl2
Some of these complexes can be crystallized from aqueous solution, and they adopt a wide variety of structural types (Fig. 1).
Copper(II) hydroxide precipitates upon treating copper(II) chloride solutions with base:
- CuCl2 + 2 NaOH → Cu(OH)2 + 2 NaCl
- CuCl2 + 2 C5H5N → [CuCl2(C5H5N)2] (tetragonal)
- CuCl2 + 2 (C6H5)3P=O → [CuCl2((C6H5)3P=O)2] (tetrahedral)
However "soft" ligands such as phosphines (e.g., triphenylphosphine), iodide, and cyanide as well as some tertiary amines cause reduction to give copper(I) complexes. To convert copper(II) chloride to copper(I) derivatives it is generally more convenient to reduce an aqueous solution with sulfur dioxide as the reductant:
- 2 CuCl2 + SO2 + 2 H2O → 2 CuCl + 2 HCl + H2SO4
Hydrolysis give the copper oxychloride, Cu2Cl(OH)3, a popular fungicide.
Copper(II) chloride is prepared commercially by the action of chlorination of copper:
- Cu + Cl2 + 2 H2O → CuCl2(H2O)2
It can also be generated by treatment of the hydroxide, oxide, or copper(II) carbonate with hydrochloric acid. Electrolysis of aqueous sodium chloride with copper electrodes produces (among other things) a blue-green foam that can be collected and converted to the hydrate.
Anhydrous CuCl2 may be prepared directly by union of the elements, copper and chlorine.
Copper(II) chloride occurs naturally as the very rare mineral tolbachite and the dihydrate eriochalcite. Both are found near fumaroles. More common are mixed oxyhydroxide-chlorides like atacamite Cu2(OH)3Cl, arising among Cu ore beds oxidation zones in arid climate (also known from some altered slags).
Co-catalyst in Wacker process
A major industrial application for copper(II) chloride is as a co-catalyst with palladium(II) chloride in the Wacker process. In this process, ethene (ethylene) is converted to ethanal (acetaldehyde) using water and air. During the reaction, PdCl2 is reduced to Pd, and the CuCl2 serves to re-oxidize this back to PdCl2. Air can then oxidize the resultant CuCl back to CuCl2, completing the cycle.
- C2H4 + PdCl2 + H2O → CH3CHO + Pd + 2 HCl
- Pd + 2 CuCl2 → 2 CuCl + PdCl2
- 4 CuCl + 4 HCl + O2 → 4 CuCl2 + 2 H2O
The overall process is:
- 2 C2H4 + O2 → 2 CH3CHO
Other organic synthetic applications
Copper(II) chloride has a variety of specialized applications in the synthesis of organic compounds. It effects chlorination of aromatic hydrocarbons- this is often performed in the presence of aluminium oxide. It is able to chlorinate the alpha position of carbonyl compounds:
CuCl2, in the presence of oxygen, can also oxidize phenols. The major product can be directed to give either a quinone or a coupled product from oxidative dimerization. The latter process provides a high-yield route to 1,1-binaphthol:
Such compounds are intermediates in the synthesis of BINAP and its derivatives
It is toxic and only concentrations below 5 ppm are allowed in drinking water by the US Environmental Protection Agency.
- ^ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
- ^ Peter Baláž (2008). Mechanochemistry in Nanoscience and Minerals Engineering. Springer. p. 167. ISBN 3540748547. http://books.google.com/?id=FldqbSffUMgC&pg=PA167.
- ^ Marina Brustolon (2009). Electron paramagnetic resonance: a practitioner's toolkit. John Wiley and Sons. p. 3. ISBN 0470258829. http://books.google.com/?id=l3F9yUSk-rgC&pg=PA3.
- ^ Greenwood, N. N. and Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
- ^ Naida S. Gill et al. (1967). Tetrahalo Complexes of Dipositive Metals in the First Transition Series. "Inorganic Syntheses". Inorg. Synth.. Inorganic Syntheses 9: 136–142. doi:10.1002/9780470132401.ch37. ISBN 9780470132401.
- ^ a b S. H. Bertz, E. H. Fairchild, in Handbook of Reagents for Organic Synthesis, Volume 1: Reagents, Auxiliaries and Catalysts for C-C Bond Formation, (R. M. Coates, S. E. Denmark, eds.), pp. 220-3, Wiley, New York, 1999.
- ^ W. L. F. Armarego, Christina Li Lin Chai (2009-05-22) (Google Books excerpt). Purification of Laboratory Chemicals (6th ed.). Butterworth-Heinemann. pp. 461. ISBN 1856175677. http://books.google.com/?id=PTXyS7Yj6zUC&pg=PA461.
- ^ H.Wayne Richardson, "Copper Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim, doi:10.1002/14356007.a07_567
- ^ C. E. Castro, E. J. Gaughan, D. C. Owsley (1965). "Cupric Halide Halogenations". Journal of Organic Chemistry 30 (2): 587. doi:10.1021/jo01013a069.
- ^ J. Brussee, J. L. G. Groenendijk, J. M. Koppele, A. C. A. Jansen (1985). "On the mechanism of the formation of s(−)-(1, 1'-binaphthalene)-2,2'-diol via copper(II)amine complexes". Tetrahedron 41 (16): 3313. doi:10.1016/S0040-4020(01)96682-7.
- ^ Chandrasekhar, M.; Kusum L. Chandra, and Vinod K. Singh (2003). "Total Synthesis of (+)-Boronolide, (+)-Deacetylboronolide, and (+)-Dideacetylboronolide". Journal of Organic Chemistry 68 (10): 4039–4045. doi:10.1021/jo0269058. PMID 12737588.
- ^ Krishna, Palakodety Radha; G. Dayaker (2007). "A stereoselective total synthesis of (-)-andrachcinidine via an olefin cross-metathesis protocol". Tetrahedron Letters (Elsevier) 48 (41): 7279–7282. doi:10.1016/j.tetlet.2007.08.053.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 0080379419.
- Lide, David R. (1990). CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data. Boca Raton: CRC Press. ISBN 0-8493-0471-7.
- The Merck Index, 7th edition, Merck & Co, Rahway, New Jersey, USA, 1960.
- D. Nicholls, Complexes and First-Row Transition Elements, Macmillan Press, London, 1973.
- A. F. Wells, 'Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
- J. March, Advanced Organic Chemistry, 4th ed., p. 723, Wiley, New York, 1992.
- Fieser & Fieser Reagents for Organic Synthesis Volume 5, p158, Wiley, New York, 1975.
- D. W. Smith (1976). "Chlorocuprates(II)". Coordination Chemistry Reviews 21 (2–3): 93–158. doi:10.1016/S0010-8545(00)80445-2.
- Copper (II) Chloride - Description and Pictures
- National Pollutant Inventory - Copper and compounds fact sheet[dead link]
Wikimedia Foundation. 2010.