Copper(II) chloride may be synthesized by heating elemental copper with chlorine:
Cu + Cl2 CuCl2
Alternatively, it may be prepared by treating copper carbonate with hydrochloric acid followed by crystallization:
CuCO3 + 2HCl → CuCl2 + CO2 + H2O
In the above preparation, the hydrate of the salt crystallizes, precipitates, and may be dehydrated by heating under vacuum.
Copper(II) chloride is used as a mordant in dyeing and printing of fabrics; as an ingredient of isomerization and cracking catalysts; and as a desulfurizing and deodorizing agent in petroleum industry.
Other important applications are in copper plating of aluminum; preparation of copper standard solutions; test for molybdenum; in tinting-baths for iron and tin; in pigments for ceramics and glasses; as a fixer and desensitizer reagent in photography; in mercury extraction from ores; in laundry-marking and invisible inks; and in manufacture of several copper salts.
Copper (II) chloride dihydrate is used in the preparation of copper oxychloride and as a catalyst in many organic chlorination reactions such as vinyl chloride and 1,2-dichloroethane. Copper chloride dihydrate may be also used as catalyst to cleave tetrahydropyranyl (THP) ethers and t-butyldimethylsilyl (TBDMS) ethers and to chemoselectively hydrolyze semicarbazones to carbonyl compounds. Solution of copper (II) chloride is used for plating on aluminum and for tinting germanium and tin.
Moist blue crystals.
Supplement (trace mineral).
 H. Wayne Richardson, Handbook of Copper Compounds and Applications, 1997
 Ram N. Ram and Kiran Varsha, Regeneration of carbonyl compounds from semicarbazones by copper (II) chloride dihydrate, Tetrahedron Letters, 1991, vol. 32, 5829-5832
 Z. P. Tan, L. Wang, J. Bo. Wang, Deprotection of t- Butyldimethylsiloxy (TBDMS) Protecting Group with Catalytic Copper (II) Chloride Dihydrate, Chinese Chemical Letters, 2000, vol. 11, 753-756