Copper(I) chloride is also produced hydrometallurgically by the reduction of copper(II) in the presence of chloride ions [71]
2 CuCl2 + Na2SO3 + H2O ---> 2 CuCl + Na2SO4 + 2 HCl :
Other reducing agents can be used, such as metallic copper, sulfurous acid, hydroxylamine, hydrazine, or phosphorous acid. The copper(I) chloride solution is produced, for example, by mixing a copper(II) chloride solution with metallic copper in the presence of hydrochloric acid or sodium chloride. The colorless to brown solution is stable only in the absence of air. Continuous preparations of copper(I) chloride solutions have been developed [72] , [73]. When they are diluted with water, a white crystalline material precipitates which can be vacuum dried or washed with sulfurous acid, then with alcohol and ether, and carefully dried. Zinc has also been used as a reducing agent in a more recent process [74].
Production of copper(I) chloride by treatment of ores with iron(III) chloride solutions [75] , [76] and recovery of the product through chlorination in pit furnaces above 800 °C [77] have also been attempted.
[71] R. Keller, H. Wycoff, Inorg. Synth. 2 (1946) 1 – 4.
[72] Schering, DE 1 080 088, 1958 (H. Niemann, K. Herrmann).
[73] Harshaw, US 2 367 153, 1945 (C. Swinehart).
[74] Goldschmidt, DE 3 305 545, 1983 (E. Mack, L. Witzke).
[75] Cyprus Metallurg., DE 2 607 299, 1976 (D. Goens, P. Kruesi).
[76] Cyprus Metallurg., US 3 972 711, 1976 (D. Goens, P. Kruesi).
[77] Metallgesellschaft, DE 1 174 996, 1963 (K. Meyer, H. Ransch, H. Pietsch); DE 1 180 946, 1963; DE 1 160 622, 1963.