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The synthesis of cuprous oxide (Cu₂O) is a fascinating chemical process that has intrigued scientists for centuries due to its wide range of applications in fields such as catalysis, solar energy conversion, and electronic devices^[].

The thermal breakdown of copper(I) salts or compounds is one of the conventional processes for producing cuprous oxide. A typical method is to heat a copper(II) salt solution, such as copper(II) chloride (CuCl₂), in the presence of a reducing agent, usually glucose or ascorbic acid, which is a weak reducing agent. As the temperature rises, this reaction reduces copper(II) ions to copper(I) ions, which is followed by the precipitation of cuprous oxide particles^[]:

2CuCl2​+2CH2​OH(CHOH)4​CHO+2H2​O → 2Cu2​O+2HCl+2CH3​COOH

Another technique is the direct thermal interaction of copper metal with oxygen^[]. This can be accomplished by thermally breaking down copper compounds in an environment high in oxygen or by carefully oxidizing copper metal. For example, cuprous oxide can be formed when copper metal is heated to temperatures exceeding 300°C in air or oxygen.

4Cu+O₂​→ 2Cu2O

Because cuprous oxide nanoparticles have different characteristics from bulk cuprous oxide, their production has attracted a lot of research. High surface area-to-volume ratios in nanoparticles can improve their catalytic activity and reactivity. Cuprous oxide nanoparticles with regulated size, shape, and crystallinity have been created using a variety of processes, including electrodeposition, chemical vapor deposition, and sol-gel approaches.

Green synthesis techniques have become viable substitutes for conventional methods in the manufacture of cuprous oxide in recent times. As precursors, these techniques usually make use of biomolecules, natural extracts, or ecologically safe reducing agents. For instance, under mild reaction conditions, plant extracts including polyphenols and flavonoids have been employed to convert copper ions to cuprous oxide nanoparticles. In addition to having positive effects on the environment, green synthesis gives the ability to modify the characteristics of cuprous oxide by selecting certain natural reducing agents and reaction parameters^[].
Additional characterisation of the produced cuprous oxide materials may be achieved by means of methods like Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD)^[]. These techniques for characterizing cuprous oxide particles aid in the comprehension of their shape, chemical makeup, surface characteristics, and crystal structure. This understanding enables the production of customized materials for particular uses and the optimization of synthesis parameters.

Reference

1. Sawant, S. S., Bhagwat, A. D., & Mahajan, C. M. (2016). Synthesis of cuprous oxide (Cu2O) nanoparticles–a review. Журнал нано-та електронної фізики, (8,№ 1), 01035-1.
2. Farghali, A. A., Bahgat, M., Allah, A. E., & Khedr, M. H. (2013). Adsorption of Pb (II) ions from aqueous solutions using copper oxide nanostructures. Beni-Suef University Journal of Basic and Applied Sciences, 2(2), 61-71.
3. Bera, P., Priolkar, K. R., Sarode, P. R., Hegde, M. S., Emura, S., Kumashiro, R., & Lalla, N. P. (2002). Structural investigation of combustion synthesized Cu/CeO2 catalysts by EXAFS and other physical techniques: formation of a Ce1-x Cu x O2-δ solid solution. Chemistry of Materials, 14(8), 3591-3601.
4. Bale, V.K., & Katreddi, H.R. (2022). Green synthesis, characterization and antimicrobial activity of nanosized Cuprous Oxide fabricated using aqueous extracts of Allium Cepa and Raphanus Sativus.
5. Seifi, S., & Masoum, S. (2019). Preparation of copper oxide/oak-based biomass nanocomposite for electrochemical hydrogen storage. International Journal of Hydrogen Energy, 44(23), 11979-11988.

1.1 Physcial Properties

The crystalline solid form of cobalt acetate is usually pink or red in color. At room temperature and pressure, it is often found in solid form. The anhydrous form of cobalt acetate has a melting point of around 140–150°C (284–302°F)^[], however this might vary depending on the hydration state. Its solubility rises with temperature and it is soluble in both water and polar solvents, this solubility is a key feature that facilitates its use in various solutions and mixtures for industrial applications. 1.71 g/cm^3 is the approximate density of anhydrous cobalt acetate. Because unpaired electrons exist in the cobalt ion’s d orbitals, some cobalt acetate complexes behave paramagnetically^[]. Cobalt acetate, particularly in its hydrated forms, has a propensity to take in moisture from the surrounding air. It has a vinegar-like odor, which is typical for acetate salts^[5].

 Figure 3: Cobalt acetate in its crystalline solid form

1.2 Chemical Properties

In an aqueous solution, cobalt acetate dissociates to produce cobalt ions (Co^2+) and acetate ions (CH3COO^-). In acidic environments, it is quite stable^[]. The synthesis of different cobalt complexes, which usually involve the coordination of cobalt ions with acetate ligands and other auxiliary ligands, begins with cobalt acetate. Under the right circumstances, cobalt(II) may be oxidized to cobalt(III) in cobalt acetate and related complexes. Because cobalt acetate and its derivatives may coordinate with reactant molecules and engage in redox processes, they are utilized as catalysts in organic transformations, This catalytic activity is leveraged in the production of polymers, specialty chemicals, and in the pharmaceutical industry for the synthesis of various drugs. The ability of cobalt acetate to promote desired reactions and increase reaction rates makes it a valuable component in these processes^[7]. When cobalt acetate is heated, it may become anhydrous by dehydrating and absorbing water from the environment to create hydrated complexes^[]. A number of variables, including pH, temperature, and ligand type, affect how stable cobalt acetate complexes are^[]. Cobalt acetate complexes have the capacity to interact with a wide range of ligands and substrates, affecting their stability, reactivity, and structure.

These chemical properties, combined with its physical characteristics, make cobalt acetate a versatile and valuable compound in various industrial and chemical applications

References

1. Beattie, James K., et al. “The chemistry of cobalt acetate. VIII. New members of the family of oxo-centred trimers,[Co3 (μ3-O)(μ-O2CCH3) 5− p (μ-OR) pL5] 2+(R= H, alkyl, L= ligand, p= 0–4). The preparation and characterisation of the trimeric tetrakis (μ-acetato)-(μ-hydroxo)-μ3-oxo-pentakis (pyridine)-tri-cobalt (III) hexafluorophosphate, [Co3 (μ3-O)(μ-O2CCH3) 4 (μ-OH)(C5H5N) 5][PF6] 2, and the preparation and crystal structure of the trimeric tris (μ-acetato)-(μ-hydroxo)-(μ- methoxo)-μ3-oxo-pentakis (pyridine)-tri-cobalt (III ….” Polyhedron 22.7 (2003): 947- 965.
2. Diemente, Damon. An electron paramagnetic resonance study of some cobalt complexes and their adducts with molecular oxygen. Northwestern University, 1971.
3. Thabede, P. M. The effect of carboxylic acids on the size and shape of Co3O4 nanoparticles: used as capping molecules and ligands in the preparation method. Diss. Vaal University of Technology, 2017.
4. Shen, Chaojun, et al. “Four new cobalt (ii) coordination complexes: thermochromic switchable behavior in the process of dehydration and rehydration.” CrystEngComm 14.9 (2012): 3189-3198.
5. Yang, Luqin, et al. “Cobalt (II) and cobalt (III) dipicolinate complexes: solid state, solution, and in vivo insulin-like properties.” Inorganic Chemistry 41.19 (2002): 4859-4871.

China is one of the largest consumers and producers of copper in the world. The country’s demand for copper is driven by its rapid industrialization, urbanization, and infrastructure development. China uses copper extensively in construction, power generation and transmission, electronics, transportation, and many other industries.

China has significant copper reserves, although the quality of the deposits varies. The largest copper mining operations in China are located in the provinces of Inner Mongolia, Xinjiang, Tibet, Yunnan, and Jiangxi. The major mining companies in China include Jiangxi Copper Corporation Limited, Tongling Nonferrous Metals Group Co., Ltd., and Zijin Mining Group Co., Ltd.

In addition to domestic production, China imports a substantial amount of copper to meet its demand. The country sources copper ore and concentrates from countries like Chile, Peru, Australia, and Mongolia, among others. It also imports refined copper and copper products from various countries.

The Chinese government closely monitors and regulates the copper industry to ensure a stable supply and manage prices. It has implemented measures such as import quotas, export restrictions, and environmental regulations to control the flow of copper in the country.