Copper(II) chloride, dihydrate (1:2:2) (13933-17-0) Physical and Chemical Properties
Copper(II) chloride, dihydrate (1:2:2)
Hydrated copper(II) chloride supplied as the dihydrate crystalline salt for industrial synthesis, catalyst preparation, electroplating formulations and analytical/R&D use.
| CAS Number | 13933-17-0 |
| Family | Inorganic chlorides |
| Typical Form | Powder or crystalline solid |
| Common Grades | EP, USP |
Copper(II) chloride dihydrate is an inorganic crystalline salt of the divalent transition metal copper and chloride counterions, with coordinated water of crystallization. Its empirical molecular formula is \(\ce{Cl2CuH4O2}\), equivalently represented as \(\ce{CuCl2.2H2O}\). Structurally it is a coordination compound in which \(\ce{Cu^{2+}}\) centers are surrounded by oxygen donor ligands (water) and chloride ligands; the \(\ce{Cu^{2+}}\) (d9) electronic configuration commonly produces Jahn–Teller distortions in octahedral coordination geometries and gives rise to characteristic blue‑green colors in aqueous solutions and solid-state hydrates.
Electronically the compound behaves as a typical Lewis acidic metal salt: in aqueous solution it dissociates to give solvated \(\ce{Cu^{2+}}\) and \(\ce{Cl-}\), with the hydrated metal ion subject to hydrolysis and to ligand exchange with coordinating anions or neutral donors. The salt is ionic and polar, with significant water solubility and a propensity to form chloro‑complexes at elevated chloride concentration (e.g., \(\ce{CuCl+}\), \(\ce{CuCl2}\), \(\ce{CuCl3^-}\) species under specific conditions). Redox chemistry is important for copper(II) salts: \(\ce{Cu^{2+}}\) is reducible to copper(I) under reducing conditions and can participate in one‑electron and two‑electron redox processes relevant to catalysis and preparative chemistry.
Industrially and in laboratory practice, copper(II) chloride dihydrate is widely used as a reagent and catalyst (organic transformations, coupling reactions, oxidation chemistry), a precursor to other copper compounds, and as a component in pigments, wood‑treatment and fungicidal formulations. Its combination of Lewis acidity, redox activity and solubility in aqueous media makes it a convenient copper source across chemical manufacturing, analytical, and research applications.
Common commercial grades reported for this substance include: EP, USP.
Basic Physical Properties
Density
No experimentally established value for this property is available in the current data context.
Qualitative note: as a crystalline inorganic hydrate, the bulk density depends on crystal habit and packing; hydrates typically have higher solid‑state densities than comparable anhydrous salts per mole of metal due to the mass contribution of coordinated water.
Melting or Decomposition Point
No experimentally established value for this property is available in the current data context.
Qualitative note: hydrated inorganic salts frequently decompose or lose crystallization water on heating before exhibiting a clean melting point; copper(II) chloride dihydrate commonly dehydrates upon heating to yield the anhydrous salt and ultimately will undergo thermal decomposition at higher temperatures.
Solubility in Water
No experimentally established value for this property is available in the current data context.
Qualitative behavior: the compound is readily soluble in water and dissociates to solvated \(\ce{Cu^{2+}}\) and \(\ce{Cl-}\). Aqueous solutions are typically blue to green depending on concentration and speciation; increasing chloride concentration shifts speciation toward chloro‑complexes.
Solution pH (Qualitative Behavior)
No experimentally established value for this property is available in the current data context.
Qualitative behavior: aqueous solutions of copper(II) salts are mildly acidic due to hydrolysis of the hydrated \(\ce{Cu^{2+}}\) ion (\(\ce{[Cu(H2O)6]^2+}\) ⇌ \(\ce{[Cu(H2O)5(OH)]^+}\) + \(\ce{H+}\)). Solution pH depends on concentration, buffer capacity, and the presence of coordinating anions or bases which can suppress hydrolysis.
Chemical Properties
Acid–Base Behavior
Copper(II) chloride dihydrate behaves as a source of the Lewis acidic \(\ce{Cu^{2+}}\) center in solution. The hydrated metal ion undergoes ligand exchange and hydrolysis; coordination equilibria with chloride and other ligands produce a distribution of species influenced by chloride concentration and solvent. In the presence of strong bases, copper(II) will precipitate as hydroxide (\(\ce{Cu(OH)2}\)) under typical aqueous conditions; further complex formation or redox reactions may follow depending on pH and ligands present.
Reactivity and Stability
The solid dihydrate is stable under normal laboratory conditions but will lose water upon heating and can be reduced to copper(I) species under strongly reducing conditions. The compound is incompatible with strong reducing agents and active metals; mixtures containing organometallic reagents and oxygen that also include copper(II) salts have been associated with formation of peroxides and energetic decomposition in documented incidents. Contact with strong bases, sulfides, or agents that complex or reduce copper can lead to precipitation, complex formation, or reduction to copper metal or copper(I) compounds. Standard inert‑atmosphere practices should be applied where reductions or organometallic reagents are used.
Molecular and Ionic Parameters
Formula and Molecular Weight
- Molecular formula: \(\ce{Cl2CuH4O2}\)
- Common structural representation: \(\ce{CuCl2.2H2O}\)
- Molecular weight: 170.48 \(\mathrm{g}\,\mathrm{mol}^{-1}\)
- Exact mass (monoisotopic): 168.888432
Additional computed descriptors: hydrogen bond donor count = 2; hydrogen bond acceptor count = 4; rotatable bond count = 0; topological polar surface area = 2 (computed descriptors as reported).
Constituent Ions
Primary ionic constituents in aqueous solution: - \(\ce{Cu^{2+}}\) (hexaaqua and other solvated coordination forms) - \(\ce{Cl-}\)
Crystalline form contains coordinated water commonly described as \(\ce{2H2O}\) per formula unit.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS Registry Number: 13933-17-0
- UNII: S2QG84156O
- DSSTox Substance ID: DTXSID1049564
- InChI:
InChI=1S/2ClH.Cu.2H2O/h2*1H;;2*1H2/q;;+2;;/p-2 - InChIKey:
MPTQRFCYZCXJFQ-UHFFFAOYSA-L - SMILES:
O.O.[Cl-].[Cl-].[Cu+2]
Synonyms and Common Names
Reported synonyms (selected from available depositor names and listings) include: - Copper(II) chloride, dihydrate - Cupric chloride dihydrate - Copper chloride dihydrate - Copper chloride; Copper chloride dihydrate; Copper dichloride dihydrate - Cupric Chloride, dihydrate - Copper Chloride (CuCl2), dihydrate
(Several additional depositor and legacy synonyms exist in source annotations.)
Industrial and Commercial Applications
Functional Roles and Use Sectors
Copper(II) chloride dihydrate functions principally as a source of soluble copper(II) for: - Synthetic and preparative chemistry (catalysis, reagent for oxidation and coupling reactions) - Analytical chemistry as a reference and reagent for inorganic and wet chemical methods - Manufacture and intermediate production of other copper compounds and coordination complexes - Pigment and dye processing, and as a component in certain wood‑treatment and antifouling/fungicidal formulations where copper salts are employed
Its combined Lewis acidity, solubility, and redox activity make it a common laboratory and industrial copper source.
Typical Application Examples
- Use as a homogeneous catalyst or catalyst precursor in organic coupling and halogenation protocols.
- Use as a soluble copper source for synthesis of coordination complexes and for generating copper(I) species in situ by controlled reduction.
- Use as an analytical reagent for qualitative and quantitative assays requiring copper(II).
- Use as an intermediate for manufacturing copper‑containing pigments and specialty chemicals.
If specific application specifications or validated formulations are required, selection should be based on the described physicochemical properties and compatibility with process conditions.
Safety and Handling Overview
Health and Environmental Hazards
Copper(II) salts are irritants to skin, eyes and mucous membranes and can be harmful if ingested in sufficient amounts; copper is toxic to aquatic organisms and environmental discharge should be minimized and controlled. The compound can participate in redox and complexation chemistries that may produce hazardous by‑products under inappropriate conditions. There are documented cases in which mixtures containing copper(II) salts, organolithium reagents and oxygen led to formation of peroxides and explosive outcomes; avoid combining strong reducing organometallic reagents, oxidants and copper(II) salts in the presence of protic solvents or oxygen without appropriate risk controls.
For detailed hazard, transport and regulatory information, users should refer to the product‑specific Safety Data Sheet (SDS) and local legislation.
Storage and Handling Considerations
Store in a tightly closed container in a cool, dry, well‑ventilated area away from incompatible materials such as strong reducing agents, alkali metals, and strong bases. Avoid dust generation and control exposures by engineering controls and appropriate personal protective equipment (gloves, eye protection, lab coat). When used in processes involving reactive organometallic reagents or strong oxidants, implement inert‑atmosphere handling and validated procedures to minimize the risk of peroxide formation, runaway reactions, or gas evolution. Waste containing copper should be collected and disposed of in accordance with environmental regulations to prevent aquatic toxicity.
