Editing Copper(II) chloride (section)

==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}}]] [[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>

Copper(II) chloride is also used in high school [[Scientific demonstration|demos]], such as reacting with [[Aluminium|aluminum]] to create [[Aluminium chloride|aluminum chloride]] and [[copper]], and learning how to measure [[Mole (unit)|moles]].<ref>{{Cite web |last=Flinn Scientific, Inc. |date=2016 |title=Aluminum and Copper Demonstration and Inquiry |url=https://www.flinnsci.com/api/library/Download/4a4b759462d74590b1ce25d1dcb6cfe6?srsltid=AfmBOopW6xB-Z-_V17IFrXDeFdZfFO5PC4hlFkivyNe3xmSxSVNHKCRe |access-date=Jan 14, 2025 |website=Flinn Scientific}}</ref>