
Copper(I) chloride, commonly called cuprous chloride, is the lower
chloride
The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride s ...
of
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...
, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dig ...
. Impure samples appear green due to the presence of
copper(II) chloride
Copper(II) chloride is the chemical compound with the chemical formula CuCl2. The anhydrous form is yellowish brown but slowly absorbs moisture to form a blue-green dihydrate.
Both the anhydrous and the dihydrate forms occur naturally as the ve ...
(CuCl
2).
History
Copper(I) chloride was first prepared by
Robert Boyle
Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of ...
in the mid-seventeenth century
from
mercury(II) chloride ("Venetian sublimate") and copper metal:
:HgCl
2 + 2 Cu → 2 CuCl + Hg
In 1799,
J.L. Proust characterized the two different chlorides of copper. He prepared CuCl by heating CuCl
2 at red heat in the absence of air, causing it to lose half of its combined chlorine followed by removing residual CuCl
2 by washing with water.
An acidic solution of CuCl was formerly used for analysis of carbon monoxide content in gases, for example in Hempel's gas apparatus.
This application was significant
during the nineteenth and early twentieth centuries when
coal gas
Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. It is produced when coal is heated strongly in the absence of air. Town gas is a more general term referring to manufactured gaseous ...
was widely used for heating and lighting.
Synthesis
Copper(I) chloride is produced industrially by the direct combination of copper metal and chlorine at 450–900 °C:
:
2 Cu + Cl2 -> 2 CuCl
Copper(I) chloride can also be prepared by
reducing copper(II) chloride with
sulfur dioxide
Sulfur dioxide ( IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic ...
, or with ascorbic acid (
vitamin C
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) a ...
) that acts as a
reducing sugar
A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a react ...
:
:
2 CuCl2 + SO2 + 2 H2O -> 2 CuCl + H2SO4 + 2 HCl
:
2 CuCl2 + C6H8O6 -> 2CuCl + 2HCl + C6H6O6
Many other reducing agents can be used.
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
Properties
Copper(I) chloride has the cubic
zincblende
Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Va ...
crystal structure at ambient conditions. Upon heating to 408 °C the structure changes to hexagonal. Several other crystalline forms of CuCl appear at high pressures (several GPa).
[
Copper(I) chloride is a ]Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
, which is classified as soft according to the Hard-Soft Acid-Base concept. Thus, it forms a series of complexes with soft Lewis base
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
s such as triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists ...
:
: CuCl + 1 P(C6H5)3 → 1/4 4
: CuCl + 2 P(C6H5)3 → CuCl 6H5)3)">(C6H5)3)sub>2
: CuCl + 3 P(C6H5)3 → CuCl 6H5)3)">(C6H5)3)sub>3
Although CuCl is insoluble
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution.
The extent of the solub ...
in water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...
, it dissolves in aqueous solution
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would ...
s containing suitable donor molecules. It forms complexes with halide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a f ...
ions, for example forming H3O+ CuCl2− in concentrated hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dig ...
. Chloride is displaced by CN− and S2O32−.
Solutions of CuCl in HCl HCL may refer to:
Science and medicine
* Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia
* Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development
* Hollow-cathode lamp, a s ...
or NH3 absorb carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
to form colourless complexes such as the chloride-bridged dimer uCl(CO)sub>2. The same hydrochloric acid solutions also react with acetylene
Acetylene ( systematic name: ethyne) is the chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in its pur ...
gas to form 2H2)">uCl(C2H2) Ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...
cal solutions of CuCl react with acetylenes to form the explosive copper(I) acetylide
Copper(I) acetylide, or cuprous acetylide, is a chemical compound with the formula Cu2 C2. Although never characterized by X-ray crystallography, the material has been claimed at least since 1856. One form is claimed to be a monohydrate with for ...
, Cu2C2. Alkene complex
In organometallic chemistry, a transition metal alkene complex is a coordination compound containing one or more alkene ligands. Such compounds are intermediates in many catalytic reactions that convert alkenes to other organic products.Elschenbro ...
es o can be prepared by reduction of CuCl2 by sulfur dioxide
Sulfur dioxide ( IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic ...
in the presence of the alkene in alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
solution. Complexes with diene
In organic chemistry a diene ( ) (diolefin ( ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nomenclature ...
s such as 1,5-cyclooctadiene
Cycloocta-1,5-diene is a cyclic hydrocarbon with the chemical formula , specifically .
There are three configurational isomers with this structure, that differ by the arrangement of the four C–C single bonds adjacent to the double bonds. Eac ...
are particularly stable:[Nicholls, D. (1973) ''Complexes and First-Row Transition Elements'', Macmillan Press, London.]
In absence of other ligands, its aqueous
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula. For example, a solution of table salt, or sodium chloride (NaCl), in water would ...
solutions are unstable with respect to disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term ca ...
:
: 2 CuCl → Cu + CuCl2
In part for this reason samples in air assume a green coloration.
Uses
The main use of copper(I) chloride is as a precursor to the fungicide copper oxychloride
Dicopper chloride trihydroxide is the chemical compound with the formula Cu2(OH)3Cl. It is often referred to as tribasic copper chloride (TBCC), copper trihydroxyl chloride or copper hydroxychloride. It is a greenish crystalline solid encounte ...
. For this purpose aqueous copper(I) chloride is generated by comproportionation
Comproportionation or synproportionation is a chemical reaction where two reactants containing the same element but with different oxidation numbers, form a compound having an intermediate oxidation number. It is the opposite of disproportionation. ...
and then air-oxidized:
: Cu + CuCl2 → 2 CuCl
: 4 CuCl + O2 + 2 H2O → Cu3Cl2(OH)4 + CuCl2
Copper(I) chloride catalyzes a variety of organic reactions
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical re ...
, as discussed above. Its affinity for carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
in the presence of aluminium chloride
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contam ...
is exploited in the COPureSM process.
In organic synthesis
CuCl is used with carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...
, aluminium chloride
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contam ...
, and hydrogen chloride
The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride g ...
in the Gatterman-Koch reaction
The Gattermann reaction, (also known as the Gattermann formylation and the Gattermann salicylaldehyde synthesis) is a chemical reaction in which aromatic compounds are formylated by a mixture of hydrogen cyanide (HCN) and hydrogen chloride (HCl) ...
to form benzaldehydes.
In the Sandmeyer reaction
The Sandmeyer reaction is a chemical reaction used to synthesize aryl halides from aryl diazonium salts using copper salts as reagents or catalysts.
It is an example of a radical-nucleophilic aromatic substitution. The Sandmeyer reaction provides ...
.[Wade, L. G. (2003) ''Organic Chemistry'', 5th ed., Prentice Hall, Upper Saddle River, New Jersey, p. 871. .] Treatment of an arenediazonium salt
Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide.
General propert ...
with CuCl leads to an aryl chloride, for example:
The reaction has wide scope and usually gives good yields.
Early investigators observed that copper(I) halides catalyse 1,4-addition of Grignard reagents to alpha,beta-unsaturated ketones led to the development of organocuprate
A Gilman reagent is a lithium and copper ( diorganocopper) reagent compound, R2CuLi, where R is an alkyl or aryl. These reagents are useful because, unlike related Grignard reagents and organolithium reagents, they react with organic halides to ...
reagents that are widely used today in organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
:[Jasrzebski, J. T. B. H.; van Koten, G. (2002) ''Modern Organocopper Chemistry'', N. Krause (ed.). Wiley-VCH, Weinheim, Germany. p. 1. .]
This finding led to the development of organocopper chemistry
Organocopper compounds is the chemistry of organometallic compounds containing a carbon to copper chemical bond. Organocopper chemistry is the study of organocopper compounds describing their physical properties, synthesis and reactions. They a ...
. For example, CuCl reacts with methyllithium
Methyllithium is the simplest organolithium reagent with the empirical formula CH3Li. This s-block organometallic compound adopts an oligomeric structure both in solution and in the solid state. This highly reactive compound, invariably used in so ...
(CH3Li) to form "Gilman reagent
A Gilman reagent is a lithium and copper ( diorganocopper) reagent compound, R2CuLi, where R is an alkyl or aryl. These reagents are useful because, unlike related Grignard reagents and organolithium reagents, they react with organic halides t ...
s" such as (CH3)2CuLi, which find extensive use in organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
. Grignard reagents form similar organocopper compounds. Although other copper(I) compounds such as copper(I) iodide
Copper(I) iodide is the inorganic compound with the formula CuI. It is also known as cuprous iodide. It is useful in a variety of applications ranging from organic synthesis to cloud seeding.
Copper(I) iodide is white, but samples often appear ...
are now more often used for these types of reactions, copper(I) chloride is still recommended in some cases:[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. .]
Here, Bu indicates an n-butyl
In organic chemistry, butyl is a four-carbon alkyl radical or substituent group with general chemical formula , derived from either of the two isomers (''n''-butane and isobutane) of butane.
The isomer ''n''-butane can connect in two ways, giv ...
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 C closer to the C=O).
Copper(I) chloride is also an intermediate formed from copper(II) chloride
Copper(II) chloride is the chemical compound with the chemical formula CuCl2. The anhydrous form is yellowish brown but slowly absorbs moisture to form a blue-green dihydrate.
Both the anhydrous and the dihydrate forms occur naturally as the ve ...
in the Wacker process
The Wacker process or the Hoechst-Wacker process (named after the chemical companies of the same name) refers to the oxidation of ethylene to acetaldehyde in the presence of palladium(II) chloride as the catalyst. This chemical reaction was one of ...
.
In polymer chemistry
CuCl is used as a catalyst in Atom Transfer Radical Polymerization Atom transfer radical polymerization (ATRP) is an example of a reversible-deactivation radical polymerization. Like its counterpart, ATRA, or atom transfer radical addition, ATRP is a means of forming a carbon-carbon bond with a transition metal ...
(ATRP).
Niche uses
Copper(I) chloride is also used in pyrotechnics
Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarry ...
as a blue/green coloring agent. In a flame test
A flame test is an analytical procedure used in chemistry to detect the presence of certain elements, primarily metal ions, based on each element's characteristic flame emission spectrum (which may be affected by the presence of chloride ...
, copper chlorides, like all copper compounds, emit green-blue.
Natural occurrence
Natural form of CuCl is the rare mineral nantokite.
References
External links
National Pollutant Inventory – Copper and compounds fact sheet
{{good article
Chlorides
Copper(I) compounds
Metal halides
Coordination complexes
Pyrotechnic colorants
Zincblende crystal structure