Copper(II) acetate monohydrate, with the chemical formula Cu(C2H3O2)2·H2O and CAS number 13990-98-2, is a crystalline solid compound that plays a significant role in various chemical and industrial processes. This copper salt, which is a hydrated form of copper acetate, is commonly encountered in laboratories, industrial processes, and even in artistic practices. Despite being less well-known than other copper compounds such as copper sulfate, copper acetate monohydrate has several important applications that are integral to chemical synthesis, analytical chemistry, and material science.
This article will explore the key properties, synthesis methods, uses, and safety considerations of Copper(II) acetate monohydrate, providing a comprehensive understanding of this versatile chemical.
Chemical Structure and Physical Properties
Molecular Formula:
Copper(II) acetate monohydrate has the molecular formula Cu(C2H3O2)2·H2O. This indicates that each formula unit consists of one copper (Cu) ion, two acetate ions (C2H3O2−), and one water molecule of crystallization (H2O).
Molecular Weight:
The molecular weight of Copper(II) acetate monohydrate is approximately 199.64 g/mol.
Appearance:
Copper(II) acetate monohydrate is typically found as a blue-green crystalline solid. The color can vary slightly depending on the concentration and form of the compound. It is soluble in water, which allows it to be used in aqueous solutions for various applications.
Solubility:
- Solubility in water: Copper(II) acetate monohydrate is soluble in water, forming a blue solution.
- Solubility in organic solvents: It is less soluble in organic solvents, which limits its use in non-aqueous reactions.
Melting Point:
The melting point of Copper(II) acetate monohydrate is typically around 160°C, where it decomposes, releasing acetic acid and copper oxides.
Density:
The density of Copper(II) acetate monohydrate is around 2.0 g/cm³, which is typical for many metal salts.
Synthesis and Manufacturing
Copper(II) acetate monohydrate is synthesized through the reaction of copper(II) oxide (CuO) or copper(II) carbonate (CuCO3) with acetic acid (CH3COOH). The most common method for producing this compound involves the following general reaction:
CuO + 2 CH3COOH → Cu(CH3COO)2 + H2O
The copper acetate is often crystallized from the resulting solution. In this process, water molecules are incorporated into the crystal lattice, resulting in the monohydrate form of the compound.
An alternative method of synthesis involves the use of copper(II) sulfate (CuSO4) in the presence of sodium acetate (NaOAc), which also leads to the formation of copper acetate. Once the reaction is complete, the product is purified and dried to obtain the monohydrate form.
Uses of Copper(II) Acetate Monohydrate
Copper(II) acetate monohydrate has a range of important applications across various industries. These uses include roles in organic synthesis, electroplating, and as a catalyst in chemical reactions. Below are some key areas where Copper(II) acetate monohydrate is employed:
1. Catalysis in Organic Synthesis:
Copper(II) acetate monohydrate is an effective catalyst in a wide variety of organic reactions, particularly in the synthesis of carbon-carbon bonds. It is often used in coupling reactions such as the Sonogashira coupling, which is an important reaction in the production of organic compounds for pharmaceuticals, agrochemicals, and materials science. Copper acetate acts as a catalyst in reactions involving alkynes and aryl halides, helping to form complex organic molecules.
2. Chemical Synthesis:
Copper(II) acetate monohydrate is used in the preparation of other copper-based compounds. One of its main applications is in the production of copper(I) compounds, such as copper(I) iodide (CuI), through reduction processes. The acetate also serves as a precursor in the synthesis of copper complexes that can be used in various research and industrial applications.
3. Electroplating and Metal Surface Treatment:
In the field of electroplating, Copper(II) acetate monohydrate is used as a source of copper ions for electroplating processes. Copper acetate solutions are employed to deposit copper coatings onto metal surfaces. This technique is commonly used in the production of electronic components and in decorative applications.
4. Textile Industry (Dyeing and Pigment Production):
Copper acetate is used in the textile industry to fix dyes onto fabrics. It acts as a mordant in dyeing processes, improving the color intensity and stability of the dyes. Additionally, copper acetate is sometimes used as a pigment in its own right, contributing to the blue-green color in various artistic and industrial applications.
5. Laboratory Reagents and Chemical Analysis:
Copper(II) acetate monohydrate is widely used in laboratories for analytical purposes. It is a useful reagent for the detection of various substances, particularly in tests related to acetate ions and other organic compounds. The compound’s ability to participate in redox reactions makes it valuable for qualitative analysis in inorganic chemistry.
6. Fungicide and Agricultural Use:
Copper salts, including Copper(II) acetate monohydrate, have fungicidal properties and are sometimes used in agricultural practices. Copper is an essential micronutrient for plants, and copper-based compounds are employed as fungicides to protect crops from fungal infections. However, due to concerns about copper toxicity to the environment, the use of copper acetate as a fungicide is more limited compared to other copper compounds like copper sulfate.
7. Art and Patinas:
Copper(II) acetate is frequently used in artistic applications, particularly in the creation of patinas for copper and bronze sculptures. When copper acetate reacts with the metal surface, it produces a characteristic blue-green patina that is highly prized in decorative arts. Artists and metalworkers use copper acetate as a part of their patination process to give copper-based sculptures and objects an aged appearance.
Safety and Handling
Like many copper salts, Copper(II) acetate monohydrate must be handled with care due to its chemical properties and potential hazards. Below are key safety considerations:
1. Toxicity:
Copper(II) acetate monohydrate is toxic if ingested or inhaled in large quantities. It can cause gastrointestinal distress, nausea, vomiting, and diarrhea. Prolonged exposure to copper compounds can lead to liver and kidney damage. Handling the substance in a controlled environment with proper safety precautions is essential to minimize health risks.
2. Environmental Impact:
Copper is an essential element in trace amounts for many organisms, but excessive concentrations of copper in the environment can be toxic to aquatic life. Copper(II) acetate, like other copper salts, can pose risks to water bodies and aquatic ecosystems if it is not disposed of properly.
3. Protective Measures:
- Personal protective equipment (PPE) such as gloves, goggles, and lab coats should be worn when handling Copper(II) acetate monohydrate.
- Work with Copper(II) acetate should be done in well-ventilated areas, preferably under a fume hood, to avoid inhalation of dust or vapors.
- Avoid contact with skin and eyes, as copper salts can cause irritation.
4. Storage and Disposal:
Copper(II) acetate monohydrate should be stored in a cool, dry place, away from incompatible materials such as strong acids or bases. When disposing of copper-containing waste, it is essential to follow proper waste disposal protocols to prevent environmental contamination.
Conclusion
Copper(II) acetate monohydrate (CAS 13990-98-2) is a versatile and important compound used in a variety of industries, from organic synthesis and catalysis to electroplating and artistic applications. Its ability to form copper-based complexes and act as a catalyst in numerous reactions makes it an invaluable reagent in the laboratory. Despite its utility, Copper(II) acetate monohydrate must be handled with care due to its toxicity and environmental impact.
