Copper(I) chloride

Copper(I) chloride
Sample of copper(I) chloride
Sample of copper(I) chloride
Unit cell of nantokite
Unit cell of nantokite
Names
IUPAC name
Copper(I) chloride
Other names
Cuprous chloride
Identifiers
3D model (JSmol)
8127933
ChEBI
ChemSpider
DrugBank
ECHA InfoCard 100.028.948 Edit this at Wikidata
EC Number
  • 231-842-9
13676
RTECS number
  • GL6990000
UNII
UN number 2802
  • InChI=1S/ClH.Cu/h1H;/q;+1/p-1 checkY
    Key: OXBLHERUFWYNTN-UHFFFAOYSA-M checkY
  • InChI=1/ClH.Cu/h1H;/q;+1/p-1
    Key: OXBLHERUFWYNTN-REWHXWOFAC
  • Cl[Cu]
Properties
CuCl
Molar mass 99.00 g·mol−1
Appearance white powder, slightly green from oxidized impurities
Density
  • 4.14 g/cm3
  • 3.69 g/cm3 (molten, 423 °C (793 °F))
Melting point 423 °C (793 °F; 696 K)
Boiling point 1,490 °C (2,710 °F; 1,760 K)
0.0047 g/100 mL (20 °C (68 °F))
1.72×10−7
Vapor pressure 10 Pa (0.0015 psi) (459 °C (858 °F))
Band gap 0.56 eV (300 K (27 °C; 80 °F), direct)
−40×10−6 cm3/mol
1.930[page needed]
Structure
Cubic, cF20
F43m, No. 216
3m
a = 3.81 Å, b = 3.81 Å, c = 9.16 Å
α = 90°, β = 90°, γ = 120°
115.23 Å3
3
Thermochemistry
48.5 J⋅mol−1·K-1
86.2 J⋅mol−1·K-1
−137.2 kJ⋅mol−1
−119.9 kJ⋅mol−1
Enthalpy of fusion (ΔfH⦵fus)
 7.08 kJ⋅mol−1
Hazards
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation markGHS09: Environmental hazard
Danger
H302+H312, H315, H318, H410
P264, P270, P273, P280, P301+P312+P330, P302+P352+P312, P305+P351+P338+P310, P332+P313, P362, P391, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
2
0
1
1 mg/m3 (TWA)
Lethal dose or concentration (LD, LC):
  • 336 mg/kg (rat, oral)
  • 1224 mg/kg (rat, dermal)
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 mg/m3 (as Cu)
REL (Recommended)
 TWA 1 mg/m3 (as Cu)
IDLH (Immediate danger)
 TWA 100 mg/m3 (as Cu)
Related compounds
Other anions
Other cations
Related compounds
 Copper(II) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkYX markN ?)

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.

Structure

Copper(I) chloride has the cubic zincblende crystal structure at ambient conditions. Upon heating to 408 °C (766 °F) the structure changes to hexagonal. Several other crystalline forms of CuCl appear at high pressures (several GPa).

Synthesis

Copper(I) chloride is produced industrially by the direct combination of copper metal and chlorine at 450–900 °C (842–1,652 °F):

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:

2 CuCl2 + SO2 + 2 H2O → 2 CuCl + H2SO4 + 2 HCl
2 CuCl2 + C6H8O6 → 2CuCl + 2HCl + C6H6O6

Many other reducing agents can be used.

Uses

The main use of copper(I) chloride is as a precursor to the fungicide copper oxychloride (Cu2(OH)3Cl). For this purpose aqueous copper(I) chloride is generated by comproportionation and then air-oxidized:

Cu + CuCl2 → 2 CuCl
12 CuCl + 3 O2 + 6 H2O → 4 Cu2(OH)3Cl + 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 process.

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.

In the Sandmeyer reaction, the treatment of an arenediazonium salt with CuCl leads to an aryl chloride. For example:

(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 reagents to alpha,beta-unsaturated ketones led to the development of organocuprate reagents that are widely used today in organic synthesis:

(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 (CuI) are now more often used for these types of reactions, copper(I) chloride is still recommended in some cases:

(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.

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.

Reactions

Upon contact with water, copper(I) chloride slowly undergoes disproportionation:

2 CuCl → Cu + CuCl2

In part for this reason, samples in air assume a green coloration.

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 the hydronium (H3O+) complex H3O+CuCl−2 forms in concentrated hydrochloric acid. Chloride is displaced by cyanide (CN−) and thiosulfate (S2O2−3).

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 copper(II) chloride (CuCl2) by sulfur dioxide in the presence of the alkene in alcohol solution. Complexes with dienes such as 1,5-cyclooctadiene are particularly stable:[page needed]

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:

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.

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. This application was significant during the nineteenth and early twentieth centuries when coal gas was widely used for heating and lighting.

References

  1. 1 2 Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 4–59, 4–124, 4–127, 5–11, 5–177, 6–103, 6–156. ISBN 9781498754293.
  2. ↑ Patnaik, Pradyot (2003). Handbook of inorganic chemicals. New York, NY: McGraw-Hill. ISBN 0-07-049439-8.
  3. ↑ "Materials Data on CuCl by Materials Project". next-gen.materialsproject.org. Berkeley, CA, US: Lawrence Berkeley National Laboratory Materials Project. 14 July 2020. doi:10.17188/1199079. OSTI 1199079. DOE Contract AC02-05CH11231, mp-22914. Retrieved 14 June 2026.
  4. ↑ Sigma-Aldrich Co., Copper(I) chloride.
  5. 1 2 3 "SDS - Copper(I) chloride". www.fishersci.com. ThermoFisher Scientific. 21 December 2025. pp. 3, 5. Retrieved 14 June 2026.
  6. ↑ "NIOSH Pocket Guide to Chemical Hazards".
  7. ↑ "Nantokite". mindat.org.
  8. ↑ Hull, S.; Keen, D. A. (1994). "High-pressure polymorphism of the copper(I) halides: A neutron-diffraction study to ~10 GPa". Physical Review B. 50 (9): 5868–5885. Bibcode:1994PhRvB..50.5868H. doi:10.1103/PhysRevB.50.5868. PMID 9976955.
  9. ↑ Richardson, H. W. (2003), "Copper Compounds", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, doi:10.1002/0471238961.0315161618090308.a01.pub2, ISBN 9780471238966
  10. 1 2 3 4 Zhang, J.; Richardson, H. W. (2016). "Copper Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. pp. 1–31. doi:10.1002/14356007.a07_567.pub2. ISBN 978-3-527-30673-2.
  11. ↑ Glemser, O.; Sauer, H. "19. Copper, Silver, Gold". In Brauer, Georg (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 2. Translated by Riley, Reed F. (2 ed.). New York, NY: Academic Press. p. 1005–6. doi:10.1016/B978-0-12-395591-3.50005-4. ISBN 978-0-12-395591-3.
  12. ↑ Tuğba Akbıyık; İnci Sönmezoğlu; Kubilay Güçlü; İzzet Tor; Reşat Apak (2012). "Protection of Ascorbic Acid from Copper(II)−Catalyzed Oxidative Degradation in the Presence of Fruit Acids: Citric, Oxalic, Tartaric, Malic, Malonic, and Fumaric Acids". International Journal of Food Properties. 15 (2): 398–411. doi:10.1080/10942912.2010.487630. S2CID 85408826.
  13. ↑ Xiaozhou Ma; Jelco Albertsma; Dieke Gabriels; Rens Horst; Sevgi Polat; Casper Snoeks; Freek Kapteijn; Hüseyin Burak Eral; David A. Vermaas; Bastian Mei; Sissi de Beer; Monique Ann van der Veen (2023). "Carbon monoxide separation: past, present and future". Chemical Society Reviews. 52 (11): 3741–3777. doi:10.1039/D3CS00147D. PMC 10243283. PMID 37083229.
  14. ↑ Dilke, M. H.; Eley, D. D. (1949). "550. The Gattermann–Koch reaction. Part II. Reaction kinetics". J. Chem. Soc.: 2613–2620. doi:10.1039/JR9490002613. ISSN 0368-1769.
  15. ↑ Wade, L. G. (2003). Organic chemistry (5th ed.). Upper Saddle River, N.J: Prentice Hall. p. 871. ISBN 978-0130338327.
  16. 1 2 Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (PDF) (6th ed.), New York: Wiley-Interscience, p. 984, ISBN 978-0-471-72091-1
  17. ↑ Kharasch, M. S.; Tawney, P. O. (1941). "Factors Determining the Course and Mechanisms of Grignard Reactions. II. The Effect of Metallic Compounds on the Reaction between Isophorone and Methylmagnesium Bromide". J. Am. Chem. Soc. 63 (9): 2308. doi:10.1021/ja01854a005.
  18. ↑ Jasrzebski, J.T.B.H.; van Koten, G. (2002). Modern organocopper chemistry. Weinheim, Germany: Wiley-VCH. p. 1. doi:10.1002/3527600086.ch1. ISBN 978-3-527-60008-3.
  19. ↑ Bertz, S.H.; Fairchild, E.H. (1999). Coates, R.M.; Denmark, S.E. (eds.). Handbook of Reagents for Organic Synthesis. New York, NY, US: Wiley. pp. 220–3. ISBN 978-0-471-97924-1.
  20. ↑ Trotuş, Ioan-Teodor; Zimmermann, Tobias; Schüth, Ferdi (2014). "Catalytic Reactions of Acetylene: A Feedstock for the Chemical Industry Revisited". Chemical Reviews. 114 (3): 1761–1782. doi:10.1021/cr400357r. PMID 24228942.
  21. ↑ Barrow, R F; Caldin, E F (1949-01-01). "Some Spectroscopic Observations on Pyrotechnic Flames". Proceedings of the Physical Society. Section B. 62 (1): 32–39. doi:10.1088/0370-1301/62/1/305. ISSN 0370-1301.
  22. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1185. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
  23. ↑ US patent 4582579A, Pastor, Antonio C., "Method for Preparing Cupric Ion-free Cuprous Chloride", published 1986-04-15, issued 1986-04-15, assigned to AT&T MVPD Group LLC
  24. ↑ J. J. Fritz (1980). "Chloride complexes of copper(I) chloride in aqueous solution". J. Phys. Chem. 84 (18): 2241–2246. doi:10.1021/j100455a006.
  25. ↑ Nicholls, David (1974). Complexes and first-row transition elements. London: Macmillan. ISBN 978-0333170885. LCCN 76353677. OCLC 1391286782. OL 4927215M.
  26. ↑ Boyle, Robert (1666). The Origine of Formes and Qualities, (according to the Corpuscular Philosophy,): Illustrated by Considerations and Experiments, (written Formerly by Way of Notes Upon an Essay about Nitre). Oxford. pp. 286–288.
  27. ↑ Proust, J. L. (1799). "Recherches sur le Cuivre - Sur le Muriate de Cuivre" [Research on Copper - On Copper Muriate]. Annales de chimie, ou, Recueil de mémoires concernant la chimie et les arts qui en dépendent [Annals of Chemistry, or, Collection of Memoirs Concerning Chemistry and the Arts Dependent Upon It] (in French). 32: 26–54. Ce muriate se laissedistiller à sec ans éprouver d'altération; mais si on force la chaleur, une partie de l'acidepasse en état d'acide marin oxigéné, tandis que le cuivre, ramené de 25 à 17 d'oxidation sur 100, forme, avec le reste, un muriate blanc particulier, dont j'ai fait mention dans mon mémoire sur l'étain. [This muriate can be distilled to dryness without undergoing alteration; but if the heat is forced, a portion of the acid is converted into oxygenated muriatic acid, while the copper—its level of oxidation reduced from 25 to 17 parts per 100—forms a distinctive white muriate with the remainder, which I mentioned in my paper on tin.]
  28. ↑ Martin, Geoffrey (1922). Industrial and Manufacturing Chemistry (Part 1, Organic ed.). London: Crosby Lockwood. p. 408. hdl:2027/umn.319510009400187. OCLC 13687566.
  29. ↑ Lewes, Vivian H. (1891). "The Analysis of Illuminating Gases". Journal of the Society of Chemical Industry. 10 (5): 407–413. doi:10.1002/jctb.5000100501.