Copper-ammonium-salt solutions regeneration

Regeneration of the copper-ammonium-salt solution is accomplished primarily by pressure reduction and the application of heat. Unfortunately, these operations have other effects, e.g., the vaporization of ammonia and the production of side reactions, which result in the requirement for a somewhat complex regenerator design. The regeneration temperature should be below 180°F in order to minimize the vaporization of ammonia and occurrence of side reactions. The pressure of regeneration should be as low as economically feasible. Operation at 1 atm is probably most common. 

The copper-ammonium-salt solutions are generally not corrosive to mild steel however, the gases evolved during regeneration can be quite corrosive due to the presence of carbon dioxide. To prevent corrosion in the vapor zones, it is good practice to use stainless steel (vessels or liners) in the exhaust-gas scrubber section and above the liquid in the evaporator section. 

Oxidation of the a-hydroxyketone with concentrated nitric acid, or by catalytic amounts of copper(n) salts in acetic acid solution which are regenerated continuously by ammonium nitrate, yields the diketone (e.g. benzil and furil, Expt 6.143). 

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