Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Copper(II) chloride: Difference between pages

{{good article}}

| verifiedrevid = 476995602

| ImageCaption = Anhydrous{{legend|rgb(256, 128, 80)|[[Copper]], Cu}}{{legend|lime|[[Chlorine]], Cl}}

| ImageCaption1 = Anhydrous

| IUPACName = Copper(II) chloride

|Section1={{Chembox Identifiers

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 1200553

| CASNo2_Ref = {{cascite|correct|CAS}}

| CASNo2 = 10125-13-0

| CASNo2_Comment= (dihydrate)

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = P484053J2Y

| UNII2_Ref = {{fdacite|correct|FDA}}

| UNII2 = S2QG84156O

| UNII2_Comment = (dihydrate)

| Gmelin = 9300

| Beilstein = 8128168

| DrugBank = DB09131

| UNNumber = 2802

| EC_number = 231-210-2

|Section2={{Chembox Properties

| Formula = {{chem2|CuCl2

}}

| MolarMass = 134.45 g/mol (anhydrous)<br />170.48 g/mol (dihydrate)

| Appearance = yellow-brown solid (anhydrous)<br />blue-green solid (dihydrate)

| Solubility = 70.6 g/(100 mL) (0 °C) <br> 75.7 g/(100 mL) (25 °C) <br> 107.9 g/(100 mL) (100 °C)

| SolubleOther = ''methanol:''<br>68 g/(100 mL) (15 °C)

<br/>''ethanol:''<br>53 g/(100 mL) (15 °C) <br> soluble in [[acetone]]

| MeltingPtC = 630

| MeltingPt_notes = (extrapolated)<br /> 100 °C (dehydration of dihydrate)

| BoilingPtC = 993

| BoilingPt_notes = (anhydrous, decomposes)

| MagSus = +1080·10⁻⁶ cm³/mol

| Structure_ref = <ref>{{cite journal |author1=A. F. Wells |title=The crystal structure of anhydrous cupric chloride, and the stereochemistry of the cupric atom |journal=Journal of the Chemical Society |date=1947 |pages=1670–1675 |doi=10.1039/JR9470001670 |language=en}}</ref><ref>{{cite journal |author1=Sydney Brownstein |author2=Nam Fong Han |author3=Eric Gabe |author4=Yvon LePage |title=A redetermination of the crystal structure of cupric chloride dihydrate |journal=Zeitschrift für Kristallographie |date=1989 |volume=189 |issue=1 |pages=13–15 |doi=10.1524/zkri.1989.189.1-2.13 |bibcode=1989ZK....189...13B |language=en}}</ref>

| CrystalStruct = [[monoclinic crystal structure|monoclinic]] (β = 121°) (anhydrous) <br> [[orthorhombic crystal structure|orthorhombic]] (dihydrate)

| SpaceGroup = C2/m (anhydrous) <br> ''Pbmn'' (dihydrate)

| PointGroup =

| LattConst_a = 6.85&nbsp;Å (anhydrous) <br> 7.41&nbsp;Å (dihydrate)

| LattConst_b = 3.30&nbsp;Å (anhydrous) <br> 8.09&nbsp;Å (dihydrate)

| LattConst_c = 6.70&nbsp;Å (anhydrous) <br> 3.75&nbsp;Å (dihydrate)

| UnitCellVolume =

| UnitCellFormulas =

| MolShape =

| OrbitalHybridisation =

| Dipole =

}}

|Section7={{Chembox Hazards

| ExternalSDS = [https://fscimage.fishersci.com/msds/05625.htm Fisher Scientific]

| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS07}}{{GHS09}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|301|302|312|315|318|319|335|410|411}}

| PPhrases = {{P-phrases|261|264|270|271|273|280|301+310|301+312|302+352|304+340|305+351+338|310|312|321|322|330|332+313|337+313|362|363|391|403+233|405|501}}

| 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(II) fluoride]]<br />[[Copper(II) bromide]]

| OtherCations = [[Copper(I) chloride]]<br />[[Silver chloride]]<br />[[Gold(III) chloride]]

'''Copper(II) chloride''', also known as '''cupric chloride''', is an [[inorganic compound]] with the [[chemical formula]] {{chem2|CuCl2|auto=1}}. The [[monoclinic crystal system|monoclinic]] yellowish-brown [[anhydrous]] form slowly absorbs moisture to form the orthorhombic blue-green [[hydrate|dihydrate]] {{chem2|CuCl2*2H2O}}, with two [[water of crystallization|water molecules of hydration]]. It is industrially produced for use as a [[catalyst|co-catalyst]] in the [[Wacker process]].

Both the anhydrous and the dihydrate forms occur naturally as the rare minerals '''tolbachite''' and '''eriochalcite''', respectively.

==Structure==

[[File:Copper(II)-chloride-dihydrate-xtal-3D-balls.png|150px|left|thumb|Structure of copper(II) chloride dihydrate{{legend|rgb(256, 128, 80)|[[Copper]], Cu}}{{legend|red|[[Oxygen]], O}}{{legend|lime|[[Chlorine]], Cl}}{{legend|white|[[Hydrogen]], H}}]]

Anhydrous copper(II) chloride adopts a distorted [[cadmium iodide]] structure. In this structure, the [[copper]] centers are [[octahedral molecular geometry|octahedral]]. Most copper(II) compounds exhibit distortions from idealized [[Octahedral molecular geometry|octahedral geometry]] due to the [[Jahn-Teller effect]], which in this case describes the localization of one [[electron|d-electron]] into a [[molecular orbital]] that is strongly [[antibonding molecular orbital|antibonding]] with respect to a pair of chloride ligands. In {{chem2|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 [[bridging ligand|bridge]] asymmetrically to other Cu centers.<ref>{{Cite book |last=Wells |first=A.F. |title=Structural Inorganic Chemistry |publisher=Clarendon Press |year=1984 |isbn=0-19-855370-6 |location=Oxford |page=253}}</ref><ref name="greenwood" />

Copper(II) chloride is [[Paramagnetism|paramagnetic]]. Of historical interest, {{chem2|CuCl2*2H2O}} was used in the first [[electron paramagnetic resonance]] measurements by [[Yevgeny Zavoisky]] in 1944.<ref>{{cite book|url=https://books.google.com/books?id=FldqbSffUMgC&pg=PA167|page=167|title=Mechanochemistry in Nanoscience and Minerals Engineering|author=Peter Baláž|publisher=Springer|year=2008|isbn=978-3-540-74854-0}}</ref><ref>{{cite book|url=https://books.google.com/books?id=l3F9yUSk-rgC&pg=PA3|page=3|title=Electron paramagnetic resonance: a practitioner's toolkit|author=Carlo Corvaja|publisher=John Wiley and Sons|year=2009|isbn=978-0-470-25882-8}}</ref>

==Properties and reactions==

[[File:CuCl2 equilibrium.JPG|thumb|left|Aqueous solutions of copper(II) chloride. Greenish when high in {{chem2|Cl−}}, more blue when lower in {{chem2|Cl−}}.]]

Aqueous solutions prepared from copper(II) chloride contain a range of copper(II) [[coordination complex|complexes]] depending on [[concentration]], temperature, and the presence of additional [[chloride|chloride ions]]. These species include the blue color of {{chem2|[Cu(H2O)6](2+)}} and the yellow or red color of the halide complexes of the formula {{chem2|[CuCl_{2+''x''}]^{''x''−}|}}.<ref name="greenwood">Greenwood, N. N. and Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. p. 1183–1185 {{ISBN|0-7506-3365-4}}.</ref>

===Hydrolysis===

When copper(II) chloride solutions are treated with a [[base (chemistry)|base]], a [[precipitation (chemistry)|precipitation]] of [[copper(II) hydroxide]] occurs:<ref name="Ullmann" />

:{{chem2|CuCl2 + 2 NaOH → Cu(OH)2 + 2 NaCl}}

Partial hydrolysis gives [[dicopper chloride trihydroxide]], {{chem2|Cu2(OH)3Cl}}, a popular fungicide.<ref name="Ullmann" /> When an aqueous solution of copper(II) chloride is left in the air and isn't stabilized by a small amount of acid, it is prone to undergo slight hydrolysis.<ref name="greenwood" />

===Redox and decomposition===

Copper(II) chloride is a mild [[oxidizing agent|oxidant]]. It starts to decompose to [[copper(I) chloride]] and [[Chlorine|chlorine gas]] around {{convert|400|C}} and is completely decomposed near {{convert|1000|C}}:<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><ref name="tgdta">{{cite journal |author1=Shuiliang Zhou |author2=Shaobo Shen |author3=Dalong Zhao |author4=Zhitao Zhang |author5=Shiyu Yan |title=Evaporation and decomposition of eutectics of cupric chloride and sodium chloride |journal=Journal of Thermal Analysis and Calorimetry |date=2017 |volume=129 |issue=3 |pages=1445–1452 |doi=10.1007/s10973-017-6360-y |s2cid=99924382 |language=en}}</ref><ref name="Kirk">{{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="cucl">{{cite journal |author1=Z. Wang |author2=G. Marin |author3=G. F. Naterer |author4=K. S. Gabriel |title=Thermodynamics and kinetics of the thermal decomposition of cupric chloride in its hydrolysis reaction |journal=Journal of Thermal Analysis and Calorimetry |date=2015 |volume=119 |issue=2 |pages=815–823 |doi=10.1007/s10973-014-3929-6 |s2cid=93668361 |url=https://research.library.mun.ca/13446/1/2015-JTAC.pdf |language=en}}</ref>

:{{chem2|2 CuCl2 → 2 CuCl + Cl2}}

The reported [[melting point]] of copper(II) chloride of {{convert|498|C}} is a melt of a mixture of copper(I) chloride and copper(II) chloride. The true melting point of {{convert|630|C}} can be extrapolated by using the melting points of the mixtures of CuCl and {{chem2|CuCl2}}.<ref>{{cite journal |author1=Wilhelm Biltz |author2=Werner Fischer |title=Beiträge zur systematischen Verwandtschaftslehre. XLIII. Über das System Cupro-/Cuprichlorid |journal=Zeitschrift für anorganische und allgemeine Chemie |date=1927 |volume=166 |issue=1 |pages=290–298 |doi=10.1002/zaac.19271660126 |language=de}}</ref><ref name="group">{{cite book |author1=A. G. Massey |author2=N. R. Thompson |author3=B. F. G. Johnson |title=The Chemistry of Copper, Silver and Gold |date=1973 |publisher=Elsevier Science |isbn=9780080188607 |language=en |page=42}}</ref> Copper(II) chloride reacts with several metals to produce copper metal or copper(I) chloride (CuCl) with oxidation of the other metal. To convert copper(II) chloride to copper(I) chloride, it can be convenient to reduce an aqueous solution with [[sulfur dioxide]] as the [[reducing agent|reductant]]:<ref name="Ullmann" />

:{{chem2|2 CuCl2 + SO2 + 2 H2O → 2 CuCl + 2 HCl + H2SO4}}

===Coordination complexes===

{{chem2|CuCl2}} reacts with HCl or other [[chloride]] sources to form complex ions: the red {{chem2|[CuCl3]−}} (found in [[potassium trichloridocuprate(II)]] {{chem2|K[CuCl3]}}) (it is a [[dimerization (chemistry)|dimer]] in reality, {{chem2|[Cu2Cl6](2−)}}, a couple of tetrahedrons that share an edge), and the green or yellow {{chem2|[CuCl4](2−)}} (found in [[potassium tetrachloridocuprate(II)]] {{chem2|K2[CuCl4]}}).<ref name="greenwood" /><ref name="tetra">{{cite book|author=Naida S. Gill |author2=F. B. Taylor |series=Inorganic Syntheses |year=1967 |volume=9 |pages=136–142 |doi=10.1002/9780470132401.ch37 |title=Tetrahalo Complexes of Dipositive Metals in the First Transition Series |isbn=978-0-470-13240-1}}</ref><ref name="handbook" />

:{{chem2|CuCl2 + Cl- ⇌ [CuCl3]-}}

:{{chem2|CuCl2 + 2 Cl- ⇌ [CuCl4](2-)}}

Some of these complexes can be crystallized from aqueous solution, and they adopt a wide variety of structures.<ref name="tetra" />

Copper(II) chloride also forms a variety of [[complex (chemistry)|coordination complexes]] with [[ligand]]s such as [[ammonia]], [[pyridine]] and [[triphenylphosphine oxide]]:<ref name="Ullmann" /><ref name="greenwood" /><ref>{{cite journal |author1=W. Libus |author2=S. K. Hoffmann |author3=M. Kluczkowski |author4=H. Twardowska |title=Solution equilibriums of copper(II) chloride in pyridine and pyridine-diluent mixtures |journal=Inorganic Chemistry |date=1980 |volume=19 |issue=6 |pages=1625–1632 |doi=10.1021/ic50208a039 |language=en}}</ref>

:{{chem2|CuCl2 + 2 C5H5N → [CuCl2(C5H5N)2]}} (tetragonal)

:{{chem2|CuCl2 + 2 (C6H5)3P\dO → [CuCl2((C6H5)3P\dO)2]}} (tetrahedral)

However "soft" ligands such as [[phosphine]]s (e.g., [[triphenylphosphine]]), iodide, and [[cyanide]] as well as some tertiary [[amine]]s induce [[Redox|reduction]] to give copper(I) complexes.<ref name="greenwood" />

==Preparation==

Copper(II) chloride is prepared commercially by the action of [[chlorination reaction|chlorination]] of copper. Copper at red heat (300-400°C) combines directly with chlorine gas, giving (molten) copper(II) chloride. The reaction is very [[exothermic process|exothermic]].<ref name="Ullmann" /><ref name="handbook">{{cite book |author1=H. Wayne Richardson |title=Handbook of Copper Compounds and Applications |date=1997 |publisher=CRC Press |isbn=9781482277463 |language=en |pages=24–68}}</ref>

:{{chem2|Cu(s) + Cl2(g) → CuCl2(l)}}

A solution of copper(II) chloride is commercially produced by adding chlorine gas to a circulating mixture of [[hydrochloric acid]] and copper. From this solution, the dihydrate can be produced by evaporation.<ref name="Ullmann" /><ref name="Kirk" />

Although copper metal itself cannot be oxidized by hydrochloric acid, copper-containing bases such as the hydroxide, [[copper(II) oxide|oxide]], or [[basic copper carbonate|copper(II) carbonate]] can react to form {{chem2|CuCl2}} in an [[Acid–base reaction|acid-base reaction]] which can subsequently be heated above {{convert|100|C}} to produce the anhydrous derivative.<ref name="Ullmann" /><ref name="Kirk" />

Once prepared, a solution of {{chem2|CuCl2}} may be purified by [[crystallization]]. A standard method takes the solution mixed in hot dilute hydrochloric acid, and causes the crystals to form by cooling in a [[calcium chloride]] ({{chem2|CaCl2}}) ice bath.<ref name = bertz>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. 220–223, Wiley, New York, 1738.</ref><ref>{{cite book|title = Purification of Laboratory Chemicals|author1=W. L. F. Armarego |author2=Christina Li Lin Chai |pages = 461|url = https://books.google.com/books?id=PTXyS7Yj6zUC&pg=PA461|format = [[Google Books]] excerpt|edition = 6th|isbn = 978-1-85617-567-8|publisher = Butterworth-Heinemann|date = 2009-05-22}}</ref>

There are indirect and rarely used means of using copper ions in solution to form copper(II) chloride. [[Electrolysis]] of aqueous sodium chloride with copper [[electrode|electrodes]] produces (among other things) a blue-green [[foam]] that can be collected and converted to the hydrate. While this is not usually done due to the emission of toxic chlorine gas, and the prevalence of the more general [[chloralkali process]], the electrolysis will convert the copper metal to copper ions in solution forming the compound. Indeed, any solution of copper ions can be mixed with hydrochloric acid and made into a copper chloride by removing any other ions.<ref>{{cite journal |author1=J. Ji |author2=W. C. Cooper |title=Electrochemical preparation of cuprous oxide powder: Part I. Basic electrochemistry |journal=Journal of Applied Electrochemistry |date=1990 |volume=20 |issue=5 |pages=818–825 |doi=10.1007/BF01094312 |s2cid=95677720 |language=en}}</ref>

==Uses==

=== 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, [[Palladium(II) chloride|{{chem2|PdCl2}}]] is [[Redox|reduced]] to [[Palladium|Pd]], and the {{chem2|CuCl2}} serves to re-oxidize this back to {{chem2|PdCl2}}. Air can then oxidize the resultant [[Copper(I) chloride|CuCl]] back to {{chem2|CuCl2}}, completing the cycle.<ref name="org">{{cite journal |author1=Nicholas D. P. Cosford |author2=Pauline Pei Li |author3=Thierry Ollevier |title=Copper(II) Chloride |journal=Encyclopedia of Reagents for Organic Synthesis |date=2015 |pages=1–8 |doi=10.1002/047084289X.rc214.pub3 |isbn=9780470842898 |language=en}}</ref>

# {{chem2|C2H4 + PdCl2 + H2O → CH3CHO + Pd + 2 HCl}}

# {{chem2|Pd + 2 CuCl2 → 2 CuCl + PdCl2}}

# {{chem2|4 CuCl + 4 HCl + O2 → 4 CuCl2 + 2 H2O}}

The overall process is:<ref name="org" />

:{{chem2|2 C2H4 + O2 → 2 CH3CHO}}

=== In organic synthesis ===

Copper(II) chloride has some highly specialized applications in the [[organic synthesis|synthesis of organic compounds]].<ref name="bertz" /> It affects the [[chlorination reaction|chlorination]] of [[aromatic hydrocarbons]]&mdash;this is often performed in the presence of [[aluminium oxide]]. It is able to chlorinate the [[locant#Greek letter locants|alpha position]] of [[carbonyl]] compounds:<ref name="org" /><ref>{{cite journal |author1=C. E. Castro |author2=E. J. Gaughan |author3=D. C. Owsley |year=1965 |title=Cupric Halide Halogenations |journal=[[Journal of Organic Chemistry]] |volume=30 |issue=2 |pages=587 |doi=10.1021/jo01013a069}}</ref>

:[[File:CuCl2 alpha chlorination.png|400px|Alpha chlorination of an aldehyde using {{chem2|CuCl2}}.]]

This reaction is performed in a polar solvent such as [[dimethylformamide]], often in the presence of [[lithium chloride]], which accelerates the reaction.<ref name="org" />

{{chem2|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]]:<ref>{{cite journal |author1=J. Brussee |author2=J. L. G. Groenendijk |author3=J. M. Koppele |author4=A. C. A. Jansen |year=1985 |title=On the mechanism of the formation of s(−)-(1, 1'-binaphthalene)-2,2'-diol via copper(II)amine complexes |journal=[[Tetrahedron (journal)|Tetrahedron]] |volume=41 |issue=16 |pages=3313 |doi=10.1016/S0040-4020(01)96682-7}}</ref><!--this methodology is obsolete and the citations are too specialized for wikipedia-->

:[[File:CuCl2 naphthol coupling.png|400px|Coupling of beta-naphthol using {{chem2|CuCl2}}.]]

Such compounds are intermediates in the synthesis of [[BINAP]] and its derivatives.<ref name="org" />

Copper(II) chloride dihydrate promotes the hydrolysis of [[Acetonide|acetonides]], i.e., for deprotection to regenerate diols<ref name="Chandrasekhar2003">{{cite journal |last=Chandrasekhar |first=M. |author2=Kusum L. Chandra |author3=Vinod K. Singh |year=2003 |title=Total Synthesis of (+)-Boronolide, (+)-Deacetylboronolide, and (+)-Dideacetylboronolide |journal=[[Journal of Organic Chemistry]] |volume=68 |issue=10 |pages=4039–4045 |doi=10.1021/jo0269058 |pmid=12737588}}</ref> or [[Amino alcohols|aminoalcohols]], as in this example (where TBDPS = [[tert-Butyldiphenylsilyl|''tert''-butyldiphenylsilyl]]):<ref name="Krishna2007">{{cite journal |last=Krishna |first=Palakodety Radha |author2=G. Dayaker |year=2007 |title=A stereoselective total synthesis of (−)-andrachcinidine via an olefin cross-metathesis protocol |journal=[[Tetrahedron Letters]] |publisher=Elsevier |volume=48 |issue=41 |pages=7279–7282 |doi=10.1016/j.tetlet.2007.08.053}}</ref>

:[[File:CuCl2 DeprotectionOfAminoAlcohol.png|350px|Deprotection of an acetonide using {{chem2|CuCl2*2H2O}}.]]

{{chem2|CuCl2}} also catalyses the [[free radical]] addition of [[sulfonyl chloride]]s to [[alkene]]s; the alpha-chlorosulfone may then undergo [[Elimination reaction|elimination]] with a base to give a vinyl [[sulfone]] product.<ref name="org" />

=== Catalyst in production of chlorine ===

Copper(II) chloride is used as a [[catalyst]] in a variety of processes that produce chlorine by [[oxychlorination]]. The [[Deacon process]] takes place at about 400 to 450&nbsp;°C in the presence of a copper chloride:<ref name="Ullmann" />

:{{chem2|4 HCl + O2 → 2 Cl2 + 2 H2O}}

Copper(II) chloride catalyzes the chlorination in the production of [[vinyl chloride]] and [[dichloromethane]].<ref name="Ullmann" />

Copper(II) chloride is used in the [[copper–chlorine cycle]] where it reacts with steam into copper(II) oxide dichloride and hydrogen chloride and is later recovered in the cycle from the [[electrolysis]] of copper(I) chloride.<ref name="cucl" />

===Niche uses===

Copper(II) chloride is used in [[pyrotechnics]] as a blue/green coloring agent. In a [[flame test]], copper chlorides, like all copper compounds, emit green-blue light.<ref>{{cite web | title = Flame Tests | url = http://www.chemguide.co.uk/inorganic/group1/flametests.html | first = Jim | last = Clark | date = August 2018 | website = chemguide.co.uk | archive-url = https://web.archive.org/web/20201127013520/http://www.chemguide.co.uk/inorganic/group1/flametests.html | url-status = live | archive-date = November 27, 2020 | access-date = January 10, 2021}}</ref>

In [[humidity indicator card]]s (HICs), cobalt-free brown to azure (copper(II) chloride base) HICs can be found on the market.<ref>{{cite patent| number =US 20150300958 A1| title =Adjustable colorimetric moisture indicators | pubdate=2015| inventor =Evan Koon Lun Yuuji Hajime| url =https://www.google.com/patents/US20150300958?cl=en}}</ref> In 1998, the [[European Community]] classified items containing cobalt(II) chloride of 0.01 to 1% [[mass fraction (chemistry)|w/w]] as T (Toxic), with the corresponding [[R phrase]] of R49 (may cause cancer if inhaled). Consequently, new cobalt-free humidity indicator cards containing copper have been developed.<ref>{{cite web |title=Cobalt dichloride |url=https://echa.europa.eu/substance-information/-/substanceinfo/100.028.718 |website=European Chemicals Agency |publisher=ECHA |access-date=30 May 2023}}</ref>

Copper(II) chloride is used as a [[mordant]] in the textile industry, [[petroleum]] [[copper sweetening|sweetener]], [[Wood preservation|wood preservative]], and [[water purification|water cleaner]].<ref name="Ullmann" /><ref>{{cite book |author1=B.H. Patel |editor1-last=Clark |editor1-first=M. |title=Handbook of Textile and Industrial Dyeing |date=2011 |publisher=Woodhead Publishing |isbn=9781845696955 |pages=412–413 |url=https://www.sciencedirect.com/book/9781845696955/handbook-of-textile-and-industrial-dyeing |access-date=2 June 2023 |language=en |chapter=11 - Natural dyes}}</ref>

==Natural occurrence==

[[File:Eriochalcite-88986.jpg|thumb|Eriochalcite]]

Copper(II) chloride occurs naturally as the very rare anhydrous mineral tolbachite and the dihydrate eriochalcite.<ref name="xray18">Marlene C. Morris, Howard F. McMurdie, Eloise H. Evans, Boris Paretzkin, Harry S. Parker, and Nicolas C. Panagiotopoulos (1981) ''Copper chloride hydrate (eriochalcite)'', in ''[https://nvlpubs.nist.gov/nistpubs/Legacy/MONO/nbsmonograph25-18.pdf Standard X-ray Diffraction Powder Patterns] National Bureau of Standards, Monograph 25, Section 18; page 33.</ref> Both are found near [[fumarole]]s and in some copper mines.<ref>{{cite web |title=Tolbachite |url=https://www.mindat.org/min-3990.html |website=mindat.org |access-date=24 August 2023 |language=en}}</ref><ref>{{cite web |title=Eriochalcite |url=https://www.mindat.org/min-1398.html |website=mindat.org |access-date=24 August 2023}}</ref><ref>{{cite web |title=The New IMA List of Minerals |url=http://cnmnc.units.it/imalist.htm |website=Università degli studi di Trieste |publisher=International Mineralogical Association |access-date=24 August 2023 |language=en}}</ref> Mixed oxyhydroxide-chlorides like [[atacamite]] ({{chem2|Cu2(OH)3Cl}}) are more common, arising among Cu ore beds oxidation zones in arid climates.<ref>{{cite web |title=Atacamite |url=https://www.mindat.org/min-406.html |website=mindat.org |access-date=30 May 2023}}</ref>

==Safety and biological impact==

Copper(II) chloride can be toxic. Only concentrations below 1.3 [[parts-per notation|ppm]] of aqueous copper ions are allowed in drinking water by the [[United States Environmental Protection Agency|US Environmental Protection Agency]].<ref>{{cite web |title=National Primary Drinking Water Regulations |url=https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations#Inorganic |website=EPA |date=30 November 2015 |access-date=29 May 2023}}</ref> If copper chloride is absorbed, it results in headache, diarrhea, a drop in [[blood pressure]], and fever. Ingestion of large amounts may induce [[copper poisoning]], [[CNS disorders]], and [[haemolysis]].<ref name="CopperHealth">{{cite web |title=Copper: Health Information Summary |work=Environmental Fact Sheet |publisher=New Hampshire Department of Environmental Services |id=ARD-EHP-9 |year=2005 |url=http://des.nh.gov/organization/commissioner/pip/factsheets/ard/documents/ard-ehp-9.pdf |archiveurl=https://web.archive.org/web/20170120014307/http://www.des.nh.gov/organization/commissioner/pip/factsheets/ard/documents/ard-ehp-9.pdf |archivedate=20 January 2017}}</ref><ref>{{cite web |title=Safety Data Sheet |url=https://www.sigmaaldrich.com/US/en/sds/aldrich/203149 |website=Sigma Aldrich |access-date=30 June 2023}}</ref>

Copper(II) chloride has been demonstrated to cause [[chromosome abnormality|chromosomal aberrations]] and [[mitosis|mitotic]] cycle disturbances within [[onion|A. cepa]] (onion) cells.<ref>{{cite journal | last1=Macar | first1=Tuğçe Kalefetoğlu | title=Resveratrol ameliorates the physiological, biochemical, cytogenetic, and anatomical toxicities induced by copper (II) chloride exposure in Allium cepa L. | url=https://link.springer.com/article/10.1007/s11356-019-06920-2 | journal=Environmental Science and Pollution Research | year=2020 | volume=27 | issue=1 | pages=657–667 | doi=10.1007/s11356-019-06920-2 | pmid=31808086 | s2cid=208649491}}</ref> Such cellular disturbances lead to [[genotoxicity]]. Copper(II) chloride has also been studied as a harmful environmental pollutant. Often present in irrigation-grade water, it can negatively affect water and soil microbes.<ref>{{cite journal | last1=Shiyab | first1=Safwan | title=Phytoaccumulation of copper from irrigation water and its effect on the internal structure of lettuce. | journal=Agriculture | year=2018 | volume=8 | issue=2 | pages=29 | doi=10.3390/agriculture8020029 | doi-access=free}}</ref> Specifically, [[denitrifying bacteria]] were found to be very sensitive to the presence of copper(II) chloride. At a concentration of 0.95 mg/L, copper(II) chloride was found to cause a 50% inhibition (IC50) of the metabolic activity of denitrifying microbes.<ref>{{cite journal | last1=Ochoa-Herrera | first1=Valeria | title=Toxicity of copper (II) ions to microorganisms in biological wastewater treatment systems. | url=https://www.sciencedirect.com/science/article/pii/S0048969711011065 | journal=Science of the Total Environment | year=2011 | volume=412 | issue=1 | pages=380–385 | doi=10.1016/j.scitotenv.2011.09.072 | pmid=22030247 | bibcode=2011ScTEn.412..380O}}</ref>

==See also==

* [[Copper(I) chloride]]

==References==

{{Reflist}}

==Further reading==

* {{Greenwood&Earnshaw|ref=none}}

* {{cite book |author=Lide, David R. |title=CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data |url=https://archive.org/details/handbookofchemis00crcp |url-access=registration |publisher=CRC Press |location=Boca Raton |year=1990 |isbn=0-8493-0471-7|ref=none}}

* ''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.&nbsp;723, Wiley, New York, 1992.

* ''Fieser & Fieser Reagents for Organic Synthesis'' Volume 5, p158, Wiley, New York, 1975.

* {{cite journal

| title = Chlorocuprates(II)

| author = D. W. Smith

| journal = Coordination Chemistry Reviews

| year = 1976

| volume = 21

| issue = 2–3

| pages = 93–158

| doi = 10.1016/S0010-8545(00)80445-2

|ref=none}}

==External links==

{{Commons category|Copper(II) chloride}}

* [http://www.periodicvideos.com/videos/mv_copper_chloride.htm Copper Chloride] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)

* [https://web.archive.org/web/20150907141353/http://www.amazingrust.com/Experiments/background_knowledge/CuCl2.html Copper (II) Chloride – Description and Pictures]

* [https://web.archive.org/web/20130530211504/http://www.npi.gov.au/substances/copper/index.html National Pollutant Inventory – Copper and compounds fact sheet]

{{Copper compounds}}

{{Chlorides}}

[[Category:Copper(II) compounds]]

[[Category:Chlorides]]

[[Category:Metal halides]]

[[Category:Semiconductor materials]]

[[Category:Coordination complexes]]

[[Category:Pyrotechnic colorants]]