Copper(I) chloride

{{Chembox | Watchedfields = changed | verifiedrevid = 470447484 | ImageFile = Copper(I) chloride pure.jpg | ImageSize = 230px | ImageName = Sample of copper(I) chloride | ImageFile1 = Copper(I)-chloride-from-xtal-unit-cell-3D-bs-17.png | ImageClass1 = bg-transparent | ImageSize1 = 180px | ImageName1 = Unit cell of nantokite | IUPACName = Copper(I) chloride | OtherNames = Cuprous chloride |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 56403 | InChI = 1/ClH.Cu/h1H;/q;+1/p-1 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 53472 | SMILES = Cl[Cu] | InChIKey = OXBLHERUFWYNTN-REWHXWOFAC | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/ClH.Cu/h1H;/q;+1/p-1 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = OXBLHERUFWYNTN-UHFFFAOYSA-M | CASNo = 7758-89-6 | CASNo_Ref = {{cascite|correct|CAS}} | UNII_Ref = {{fdacite|correct|FDA}} | UNII = C955P95064 | PubChem = 62652 | RTECS = GL6990000 | EINECS = 231-842-9 | Gmelin = 13676 | Beilstein = 8127933 | DrugBank = DB15535 }} |Section2={{Chembox Properties | Formula = CuCl | MolarMass = 98.999&nbsp;g/mol<ref name=crc>{{RubberBible92nd|page=4.61}}</ref> | Appearance = white powder, slightly green from oxidized impurities | Density = 4.14&nbsp;g/cm³<ref name=crc/> | Solubility = 0.0047&nbsp;g/100 mL (20 °C)<ref name=crc/> | SolubilityProduct = 1.72×10⁻⁷ | MeltingPtC = 423 | MeltingPt_ref = <ref name=crc/> | BoilingPtC = 1490 | BoilingPt_notes = (decomposes)<ref name=crc/> | SolubleOther = insoluble in ethanol, <br> acetone;<ref name=crc/> soluble in concentrated HCl, NH₄OH | RefractIndex = 1.930<ref>Patnaik, Pradyot (2002) ''Handbook of Inorganic Chemicals''. McGraw-Hill, {{ISBN|0-07-049439-8}}</ref> | MagSus = −40.0·10⁻⁶ cm³/mol<ref>{{RubberBible92nd|page=4.132}}</ref> | BandGap = 3.25 eV (300 K, direct)<ref>{{cite journal|doi=10.1016/0038-1098(96)00020-8|title=Electron-phonon interaction at the direct gap of the copper halides|journal=Solid State Communications|volume=98|pages=27–30|year=1996|last1=Garro|first1=Núria|last2=Cantarero|first2=Andrés|last3=Cardona|first3=Manuel|last4=Ruf|first4=Tobias|last5=Göbel|first5=Andreas|last6=Lin|first6=Chengtian|last7=Reimann|first7=Klaus|last8=Rübenacke|first8=Stefan|last9=Steube|first9=Markus|issue=1|bibcode=1996SSCom..98...27G}}</ref> }} |Section3={{Chembox Structure | CrystalStruct = Zincblende, cF20 | SpaceGroup = F{{overline|4}}3m, No. 216<ref name=str>{{cite journal|doi=10.1103/PhysRevB.50.5868|title=High-pressure polymorphism of the copper(I) halides: A neutron-diffraction study to ~10 GPa|journal=Physical Review B|volume=50|issue=9|pages=5868–5885|year=1994|last1=Hull|first1=S.|last2=Keen|first2=D. A.|pmid=9976955|bibcode=1994PhRvB..50.5868H}}</ref> | PointGroup = | LattConst_a = 0.54202 nm | UnitCellFormulas = 4 | UnitCellVolume = 0.1592 nm³ }} |Section7={{Chembox Hazards | ExternalSDS = [http://hazard.com/msds/mf/baker/baker/files/c5949.htm JT Baker] | GHSPictograms = {{GHS07}}{{GHS09}} | GHSSignalWord = Warning | HPhrases = {{H-phrases|302|410}} | PPhrases = {{P-phrases|264|270|273|301+312|330|391|501}} | NFPA-H = 3 | NFPA-R = 0 | NFPA-F = 0 | FlashPt = Non-flammable | LD50 = 140 mg/kg | PEL = TWA 1 mg/m³ (as Cu)<ref name=PGCH>{{PGCH|0150}}</ref> | REL = TWA 1 mg/m³ (as Cu)<ref name=PGCH/> | IDLH = TWA 100 mg/m³ (as Cu)<ref name=PGCH/> }} |Section8={{Chembox Related | OtherAnions = Copper(I) fluoride<br>Copper(I) bromide<br/>Copper(I) iodide | OtherCations = Silver(I) chloride<br>Gold(I) chloride | OtherCompounds =Copper(II) chloride }} }} '''Copper(I) chloride''', commonly called '''cuprous chloride''', is the lower chloride of copper, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated hydrochloric acid. Impure samples appear green due to the presence of copper(II) chloride (CuCl₂).

==Occurrence== CuCl occurs as the rare mineral nantokite.<ref>{{Cite web|url=https://www.mindat.org/min-2840.html|title=Nantokite}}</ref><ref>{{Cite web|url=https://www.ima-mineralogy.org/Minlist.htm|title=List of Minerals|date=21 March 2011}}</ref>

==Structure== Copper(I) chloride has the cubic zincblende crystal structure at ambient conditions. Upon heating to 408&nbsp;°C the structure changes to hexagonal. Several other crystalline forms of CuCl appear at high pressures (several GPa).<ref name=str/>

==Synthesis== Copper(I) chloride is produced industrially by the direct combination of copper metal and chlorine at 450–900&nbsp;°C:<ref>{{Cite book|title=Kirk-Othmer Encyclopedia of Chemical Technology|last=Richardson|first=H. W.|year=2003|isbn=0471238961|chapter=Copper Compounds|doi=10.1002/0471238961.0315161618090308.a01.pub2}}</ref><ref name="Ullmann">{{Cite book|title=Ullmann's Encyclopedia of Industrial Chemistry|author1=Zhang, J. |author2=Richardson, H. W.|year=2016|isbn=978-3-527-30673-2|chapter=Copper Compounds|pages=1–31 |doi=10.1002/14356007.a07_567.pub2}}</ref> :{{chem2|2 Cu + Cl2 -> 2 CuCl}} Copper(I) chloride can also be prepared by reducing copper(II) chloride with sulfur dioxide, or with ascorbic acid (vitamin C) that acts as a reducing sugar:<ref>{{cite book |last1= Glemser |first1= O. |last2= Sauer |first2= H. |year= 1963 |chapter= Copper(I) Chloride |title= Handbook of Preparative Inorganic Chemistry |edition= 2nd |editor-first= G. |editor-last= Brauer |publisher= Academic Press |location= New York |volume= 1 |page= 1005 }}</ref><ref>{{cite journal |author1=Tuğba Akbıyık |author2=İnci Sönmezoğlu |author3=Kubilay Güçlü |author4=İzzet Tor |author5=Reşat Apak |title=Protection of Ascorbic Acid from Copper(II)−Catalyzed Oxidative Degradation in the Presence of Fruit Acids: Citric, Oxalic, Tartaric, Malic, Malonic, and Fumaric Acids |journal=International Journal of Food Properties |date=2012 |volume=15 |issue=2 |pages=398–411 |doi=10.1080/10942912.2010.487630 |s2cid=85408826 |language=en}}</ref> :{{chem2|2 CuCl2 + SO2 + 2 H2O -> 2 CuCl + H2SO4 + 2 HCl}} :{{chem2|2 CuCl2 + C6H8O6 -> 2CuCl + 2HCl + C6H6O6}} Many other reducing agents can be used.<ref name="Ullmann" />

==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:<ref name="Ullmann" /> : Cu + CuCl₂ → 2 CuCl : 4 CuCl + O₂ + 2 H₂O → Cu₃Cl₂(OH)₄ + CuCl₂

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^SM process.<ref>{{cite journal |author1=Xiaozhou Ma |author2=Jelco Albertsma |author3=Dieke Gabriels |author4=Rens Horst |author5=Sevgi Polat |author6=Casper Snoeks |author7=Freek Kapteijn |author8=Hüseyin Burak Eral |author9=David A. Vermaas |author10=Bastian Mei |author11=Sissi de Beer |author12=Monique Ann van der Veen |title=Carbon monoxide separation: past, present and future |journal=Chemical Society Reviews |date=2023 |volume=52 |issue=11 |pages=3741–3777 |doi=10.1039/D3CS00147D |pmid=37083229 |pmc=10243283 |url=https://pubs.rsc.org/en/content/articlepdf/2023/cs/d3cs00147d |language=en}}</ref>

===In organic synthesis=== CuCl is used as a co-catalyst with carbon monoxide, aluminium chloride, and hydrogen chloride in the Gatterman-Koch reaction to form benzaldehydes.<ref>{{Cite journal|last1=Dilke|first1=M. H.|last2=Eley|first2=D. D.|date=1949|title=550. The Gattermann–Koch reaction. Part II. Reaction kinetics|url=http://xlink.rsc.org/?DOI=JR9490002613|journal=J. Chem. Soc.|language=en|pages=2613–2620| doi=10.1039/JR9490002613|issn=0368-1769|url-access=subscription}}</ref>

In the Sandmeyer reaction, the treatment of an arenediazonium salt with CuCl leads to an aryl chloride. For example:<ref name="Sandmeyer">Wade, L. G. (2003) ''Organic Chemistry'', 5th ed., Prentice Hall, Upper Saddle River, New Jersey, p. 871. {{ISBN|013033832X}}.</ref><ref name="sand">March, J. (1992) [http://rushim.ru/books/mechanizms/march6ed.pdf ''Advanced Organic Chemistry''], 4th ed., Wiley, New York. p. 723. {{ISBN|978-0-470-46259-1}}</ref>

class=skin-invert-image|400px|(Example Sandmeyer reaction using CuCl)

The reaction has wide scope and usually gives good yields.<ref name="sand" />

Early investigators observed that copper(I) halides catalyse 1,4-addition of Grignard reagents to alpha,beta-unsaturated ketones<ref name="Kharasch">{{cite journal | title = Factors Determining the Course and Mechanisms of Grignard Reactions. II. The Effect of Metallic Compounds on the Reaction between Isophorone and Methylmagnesium Bromide | journal = J. Am. Chem. Soc. | volume = 63 | pages = 2308 | year = 1941 | doi = 10.1021/ja01854a005 | author1 = Kharasch, M. S. | author2 = Tawney, P. O. | issue = 9}}</ref> led to the development of organocuprate reagents that are widely used today in organic synthesis:<ref name="Jasrzebski">Jasrzebski, J. T. B. H.; van Koten, G. (2002) ''Modern Organocopper Chemistry'', N. Krause (ed.). Wiley-VCH, Weinheim, Germany. p. 1. {{doi|10.1002/3527600086.ch1}} {{ISBN|9783527600083}}.</ref>

class=skin-invert-image|500px|(Addition of RMgX to C=C-C=O mediated by CuCl)

This finding led to the development of organocopper chemistry. For example, CuCl reacts with methyllithium (CH₃Li) to form "Gilman reagents" such as (CH₃)₂CuLi, which find use in organic synthesis. Grignard reagents form similar organocopper compounds. 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 cases:<ref name="BertzAndMunchPetersen">Bertz, S. H.; Fairchild, E. H. (1999) ''Handbook of Reagents for Organic Synthesis, Volume 1: Reagents, Auxiliaries and Catalysts for C-C Bond Formation'', R. M. Coates, S. E. Denmark (eds.). Wiley, New York. pp. 220–3. {{ISBN|978-0-471-97924-1}}.</ref>

class=skin-invert-image|500px|(Alkylation of sorbate ester at 4-position mediated by CuCl)

Cuprous chloride also catalyzes the dimerization of acetylene to vinylacetylene, once used as a precursor to various polymers such a neoprene.<ref>{{cite journal |doi=10.1021/cr400357r |title=Catalytic Reactions of Acetylene: A Feedstock for the Chemical Industry Revisited |date=2014 |last1=Trotuş |first1=Ioan-Teodor |last2=Zimmermann |first2=Tobias |last3=Schüth |first3=Ferdi |journal=Chemical Reviews |volume=114 |issue=3 |pages=1761–1782 |pmid=24228942 |doi-access=free }}</ref>

===Niche uses=== CuCl is used as a catalyst in atom transfer radical polymerization (ATRP). It is also used in pyrotechnics as a blue/green coloring agent. In a flame test, copper chlorides, like all copper compounds, emit green-blue.<ref>{{Cite journal |last1=Barrow |first1=R F |last2=Caldin |first2=E F |date=1949-01-01 |title=Some Spectroscopic Observations on Pyrotechnic Flames |url=https://iopscience.iop.org/article/10.1088/0370-1301/62/1/305 |journal=Proceedings of the Physical Society. Section B |volume=62 |issue=1 |pages=32–39 |doi=10.1088/0370-1301/62/1/305 |issn=0370-1301|url-access=subscription }}</ref>

==Reactions== Upon contact with water, copper(I) chloride slowly undergoes disproportionation:<ref name="GreenwoodEarnshaw">{{Greenwood&Earnshaw2nd|page=1185}}</ref> : 2 CuCl → Cu + CuCl₂ In part for this reason, samples in air assume a green coloration.<ref>Pastor, Antonio C. (1986) {{US Patent|4582579}} "Method of preparing cupric ion free cuprous chloride" Section 2, lines 4–41.</ref>

Copper(I) chloride is a Lewis acid. It is classified as soft according to the hard-soft acid-base concept. Thus, it forms a series of complexes with soft Lewis bases such as triphenylphosphine: : CuCl + 1 P(C₆H₅)₃ → 1/4 {CuCl[P(C₆H₅)₃]}₄ : CuCl + 2 P(C₆H₅)₃ → CuCl[P(C₆H₅)₃)]₂ : CuCl + 3 P(C₆H₅)₃ → CuCl[P(C₆H₅)₃)]₃

CuCl also forms complexes with halides. For example H₃O⁺ CuCl₂⁻ forms in concentrated hydrochloric acid.<ref>{{cite journal |author1=J. J. Fritz |title=Chloride complexes of copper(I) chloride in aqueous solution |journal=J. Phys. Chem. |date=1980 |volume=84 |issue=18 |pages=2241–2246 |doi=10.1021/j100455a006 |language=en}}</ref> Chloride is displaced by CN⁻ and S₂O₃²⁻.<ref name="Ullmann" />

Solutions of CuCl in HCl absorb carbon monoxide to form colourless complexes such as the chloride-bridged dimer [CuCl(CO)]₂. The same hydrochloric acid solutions also react with acetylene gas to form [CuCl(C₂H₂)]. Ammoniacal solutions of CuCl react with acetylenes to form the explosive copper(I) acetylide, Cu₂C₂. Alkene complexes of CuCl can be prepared by reduction of CuCl₂ by sulfur dioxide in the presence of the alkene in alcohol solution. Complexes with dienes such as 1,5-cyclooctadiene are particularly stable:<ref name="Nicholls">Nicholls, D. (1973) ''Complexes and First-Row Transition Elements'', Macmillan Press, London.</ref>

class=skin-invert-image|400px|Structure of COD complex of CuCl

==History== Copper(I) chloride was first prepared by Robert Boyle and designated '''rosin of copper''' in the mid-seventeenth century from mercury(II) chloride ("Venetian sublimate") and copper metal:<ref name="Boyle1666">{{cite book|last=Boyle|first=Robert|title=Considerations and experiments about the origin of forms and qualities|year=1666|place=Oxford|url=https://quod.lib.umich.edu/e/eebo/A29017.0001.001?rgn=main;view=fulltext|pages=286–288}}</ref> :HgCl₂ + 2 Cu → 2 CuCl + Hg

In 1799, Joseph Proust first differentiated two different chlorides of copper. He prepared CuCl (which he called '''white muriate of copper''') by heating CuCl₂ at red heat in the absence of air, causing it to lose half of its combined chlorine followed by removing residual CuCl₂ by washing with water.<ref name="Proust1799">{{cite journal |last=Proust |first=J. L. |year=1799 |title=Recherches sur le Cuivre |url=https://books.google.com/books?id=ZBki5255ZXgC&pg=PA47 |journal=Annales de chimie |volume=32 |pages=26–54}}</ref>

An acidic solution of CuCl was formerly used to analyze carbon monoxide content in gases, for example in Hempel's gas apparatus where the CuCl absorbs the carbon monoxide.<ref name="martin">{{cite book|last = Martin|first = Geoffrey|year = 1922|title = Industrial and Manufacturing Chemistry|url = https://archive.org/details/in.ernet.dli.2015.73073/|edition = Part 1, Organic|location = London|publisher = Crosby Lockwood|pages=408}}</ref> This application was significant during the nineteenth and early twentieth centuries when coal gas was widely used for heating and lighting.<ref name="Lewes1891">{{cite journal|last=Lewes|first=Vivian H.|journal=Journal of the Society of Chemical Industry|year=1891|title=The Analysis of Illuminationg Gases|volume=10|pages=407–413|url=https://books.google.com/books?id=oSEAAAAAMAAJ&pg=PA408}}</ref>

==Gallery== <gallery> Image:Copper(I)chloride crystal 01.jpg|White copper(I) chloride crystals on copper wire File:Copper(I) chloride.jpg|Copper(I) chloride partially oxidized in air File:IR Spectrum of Copper(I) chloride.png|IR absorption spectrum of copper(I) chloride </gallery>

==References== {{Reflist|30em}}

==External links== {{Commons category|Copper(I) chloride}} *[https://web.archive.org/web/20080302034606/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^SM Process for purifying CO utilizing a copper chloride complex]

{{Copper compounds}} {{Chlorides}}

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Category:Chlorides Category:Copper(I) compounds Category:Metal halides Category:Coordination complexes Category:Pyrotechnic colorants Category:Zincblende crystal structure