Copper(I) chloride
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2008-06-09T21:49:03Z
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{{Chembox new
| Name = Copper(I) chloride
| ImageFile = Copper(I)-chloride-sample.jpg
<!-- | ImageSize = 170px -->
| ImageName = Copper(I) chloride
| ImageFile1 = Nantokite-unit-cell-3D-balls.png
<!-- | ImageSize1 = 130px -->
| ImageName1 = Unit cell of nantokite
| IUPACName = Copper(I) chloride
| OtherNames = Cuprous chloride
| Section1 = {{Chembox Identifiers
| CASNo = 7758-89-6
| RTECS = GL6990000
}}
| Section2 = {{Chembox Properties
| Formula = CuCl
| MolarMass = 98.99 g/mol
| Appearance = white powder, slightly<br />green from oxidized impurities
| Density = 4.140 g/cm<sup>3</sup>, solid
| Solubility = 0.0062 g/100 mL (20 °C)
| MeltingPt = 430 °C (703 K)
| BoilingPt = 1490 °C (1760 K),<br />decomposes
}}
| Section3 = {{Chembox Structure
| CrystalStruct = [[Tetrahedral]] [[close packed]]<br />([[Zinc blende]] structure)
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS = [http://sciencelab.com/msds.php?msdsId=9923602 ScienceLab.com]
| MainHazards = Irritant
| NFPA-H = 3
| NFPA-R = 0
| NFPA-F = 0
| FlashPt =
| RSPhrases = R: 22, 50, 53 S: 22, 60/61
}}
| Section8 = {{Chembox Related
| OtherAnions = [[Copper(I) bromide]]<br />[[Copper(I) iodide]]
| OtherCations = [[Copper(II) chloride]]<br />[[Silver(I) chloride]]
}}
}}
'''Copper(I) chloride''', commonly called cuprous chloride, is the lower [[chloride]] of [[copper]], with the formula CuCl. This colorless solid is a versatile precursor to other copper compounds, including some of commercial significance. It occurs naturally as the rare mineral [[nantokite]]. Unlike other first-row transition metal halides, it forms stable [[Complex (chemistry)|complexes]] with [[carbon monoxide]]. It crystallizes in a [[diamondoid]] motif, reflecting the tendency of copper(I) to form tetrahedral complexes.
==Chemical properties==
CuCl is more affordable and less toxic than other soft Lewis acids. In addition, copper can exist in multiple redox states, including I, II, and III. This combination of properties define some of the useful features of copper(I) chloride. It is a soft [[Lewis acid]], classified as soft according to the [[HSAB concept|Hard-Soft Acid-Base concept]]. Thus, it tends to form stable [[Complex (chemistry)|complexes]] with soft [[Lewis base]]s such as [[triphenylphosphine]]:
:CuCl + [[triphenylphosphine|P(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>]] → [CuCl(P(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>)]<sub>4</sub>
Although CuCl is insoluble in water, it dissolves in aqueous solutions containing suitable donor molecules. It forms complexes with [[halide]] ions, for example forming [[hydronium|H<sub>3</sub>O<sup>+</sup>]] CuCl<sub>2</sub><sup>-</sup> with concentrated [[hydrochloric acid]]. It also dissolves in solutions containing [[cyanide|CN<sup>-</sup>]], [[thiosulfate|S<sub>2</sub>O<sub>3</sub><sup>2-</sup>]], and [[ammonia|NH<sub>3</sub>]] to give complexes.
Solutions of CuCl in [[hydrochloric acid|HCl]] or [[ammonia|NH<sub>3</sub>]] absorb [[carbon monoxide]] to form colourless complexes such as the chloride-bridged dimer [CuCl(CO)]<sub>2</sub>. The same hydrochloric acid solutions also react with [[acetylene]] gas to form [CuCl(C<sub>2</sub>H<sub>2</sub>)]. [[ammonia]]cal solutions of CuCl react with acetylenes to form the explosive [[copper(I) acetylide]]. Complexes of CuCl with [[alkene]]s can be prepared by reduction of [[copper(II) chloride|CuCl<sub>2</sub>]] by [[sulfur dioxide]] in the presence of the alkene in alcohol solution. Complexes with [[diene]]s such as [[1,5-cyclooctadiene]] are particularly stable:<ref name="Nicholls">Nicholls, D. ''Compleses and First-Row Transition Elements'', Macmillan Press, London, 1973.</ref>
[[Image:CuCl COD dimer.gif|400px|Structure of COD complex of CuCl]]
Although only poorly soluble in water, its [[aqueous]] solution are unstable with respect to [[disproportionation]] into [[Copper|Cu]] and [[Copper(II) chloride|CuCl<sub>2</sub>]].<ref name="">Greenwood, N.N.; Earnshaw, A. ''Chemistry of the Elements'', 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.</ref> In part for this reason samples assume a green coloration (see photograph in upper right).
==Uses==
The main use of copper(i) chloride is as a precursor to the [[fungicide]] copper oxychloride. For this purpose aqueous copper(I) chloride is generated by [[comproportionation]] and then air-oxidized:
: Cu + CuCl<sub>2</sub> → 2 CuCl
: 6 CuCl + 3/2 O<sub>2</sub> + 3 H<sub>2</sub>O → 2 Cu<sub>3</sub>Cl<sub>2</sub>(OH)<sub>4</sub> + CuCl<sub>2</sub>
Copper(I) chloride catalyzes a variety of organic reactions, as discussed above. Its affinity for carbon monoxide in the presence of [[aluminium chloride]] is exploited in the COPure<sup>SM</sup> process.
===In organic synthesis===
In the [[Sandmeyer reaction]].<ref name="Sandmeyer">(a) Wade, L. G. ''Organic Chemistry'', 5th ed., p. 871, Prentice Hall, Upper Saddle RIver, New Jersey, 2003. (b) March, J. ''Advanced Organic Chemistry'', 4th ed., p. 723, Wiley, New York, 1992.</ref> Treatment of an [[arenediazonium salt]] with CuCl leads to an aryl chloride, for example:
[[Image:CuCl Sandmeyer.gif|400px|(Example Sandmeyer reaction using CuCl)]]
The reaction has wide scope and usually gives good yields.
Early investigators observed that copper(I) halides catalyse 1,4-addition of [[Grignard reagent]]s to alpha,beta-unsaturated ketones<ref name="Kharasch">Kharasch, M. S.; Tawney, P. O. ''Journal of the American Chemical Society'', '''63''', 2308 (1941).</ref> led to the development of [[organocuprate]] reagents that are widely used today in [[organic synthesis]]:<ref name="">Jasrzebski, J. T. B. H.; van Koten, G. in ''Modern Organocopper Chemistry'', (N. Krause, ed.), p. 1, Wiley-VCH, Weinheim, Germany, 2002.</ref>
[[Image:CuCl Kharasch reaction.gif|500px|(Addition of RMgX to C=C-C=O mediated by CuCl)]]
This finding led to the development of [[organocopper|organocopper chemistry]]. For example, CuCl reacts with [[methyllithium]] (CH<sub>3</sub>Li) to form "[[Gilman reagent]]s" such as (CH<sub>3</sub>)<sub>2</sub>CuLi, which find extensive use in [[organic synthesis]]. [[Grignard reagent]]s react similarly. Although other copper(I) compounds such as [[copper(I) iodide]] are now more often used for these types of reactions, copper(I) chloride is still recommended in some case:<ref name="">(a) Bertz, S. H.; Fairchild, E. H. 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. (b) Munch-Petersen, J., et al., ''Acta Chimica Scand.'', '''15''', 277 (1961).</ref>
[[Image:CuCl sorbate ester alkylation.gif|500px|(Alkylation of sorbate ester at 4-position mediated by CuCl)]]
Here, Bu indicates an n-[[butyl]] group. Without CuCl, the [[Grignard reagent]] alone gives a mixture of 1,2- and 1,4-addition products (i.e., the butyl adds at the closer to the C=O).
===In polymer chemistry===
Copper(I) chloride is also an intermediate formed from [[copper(II) chloride]] in the [[Wacker process]]. CuCl is used as a catalyst in [[ATRP (chemistry)|Atom Transfer Radical Polymerization]] (ATRP).
==References==
{{reflist|1}}
==External links==
*[http://www.npi.gov.au/database/substance-info/profiles/27.html National Pollutant Inventory - Copper and compounds fact sheet]
*[http://www.rccostello.com/copure.html The COPure<sup>SM</sup> Process for purifying CO utilizing a copper chloride complex]
[[Category:Chlorides]]
[[Category:Copper compounds]]
[[Category:Metal halides]]
[[Category:Coordination compounds]]
[[Category:Pyrotechnic colorants]]
[[ar:كلوريد نحاس أحادي]]
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[[it:Cloruro rameoso]]
[[hu:Réz(I)-klorid]]
[[nl:Koper(I)chloride]]
[[ja:塩化銅(I)]]
[[pl:Chlorek miedzi(I)]]
[[sr:Купро-хлорид]]
[[zh:氯化亚铜]]