Cuprous-ammonium-salt solutions

The salt process employs scrubbing of the gas with cuprous ammonium salt solution. Carbon monoxide forms a complex with the solution at high pressure and low temperature in the absorption column. The absorbed pure carbon monoxide is released from the solution at low pressure and high temperature in the regenerator/stripper section. Any carbon monoxide that is liberated in the stripper section is removed by subsequently washing the gas with caustic. Sulfur has to be removed in the pretreatment stage to prevent the formation of solid sulfide. 

Absorphon of CO2 in aqueous solutions of MEA absorption of H2S and mercaptans in aqueous soluhons of alkanolatnines and caushc soda absorption of carbon monoxide in aqueous cuprous ammonium chloride solutions absorphon of lower olefins in aqueous soluhons of cuprous ammonium compounds absorption of pure chlorine in aqueous solutions of sodium carbonate or sodium hydroxide conversion of dithiocarbamates to thiuram disulfides sulfonation of aromatic compounds with lean SO3 recovery of bromine from lean aqueous solutions of bromides reactions of importance in pyrometallurgy absorphon of CO2 in aqueous solutions of caustic alkahes and amine absorption of O2 in aqueous solutions of sodium dithionite absorphon of O2 in aqueous sodium sulfite soluhons absorption of O2 in alkaline solutions containing the sodium salt of 1,4-napthaquinone- 2-sulfonic acid (NQSA) special case role of diffusion in the absorption of gases in blood in the human body. 

The COSORB solvent has a number of advantages over the aqueous solution of cuprous ammonium salts used in the early copper scrubbing process. It operates at low pressure, is unaffected by carbon dioxide and... 

Extraction exploits the ability of cuprous ammonium acetate to form a complex selectively with butadiene, which is retained preferentially in the cuprous salt solution. The absorption of butenes is 10 to 50 times less. On the other hand, acetylenic compounds are complexed first and the process is not easily reversible. The effectiveness of the method thus depends heavily on their concentration in the feedstock, which must not exceed 5(X) ppm in practice. However, steam-cracked C4. cuts do not directly meet this specification, and prior selective hydrogenation is therefore indispensable. This require-... 

Cuprous ammonium acetate extraction. Butadiene is purified by aqueous CAA extraction in a liquid-gas countercurrent process developed by Exxon (67-69). The cuprous salt forms a soluble addition complex with butadiene, which is decomposed by heat thus the process is adaptable to countercurrent multistage equipment. Typically, the C4 hydrocarbon mixture with a butadiene content of 30-40% contacts the CAA solution in a countercurrent fashion in a series of mixer-settlers. Cooling to ca -15°C is required to promote complex formation. The more saturated hydrocarbons, butanes, and butenes are first removed by distillation. Butadiene is released from the complex by further heating to 80° C. After ammonia is removed by washing with water, distillation produces butadiene that is 98-99% pure. Acetylenes and allenes are extracted with the butadiene but must... 

Water-Insoluble Salts. Many important salts for 7r-complexation are water-insoluble. The best examples are cuprous (Cu+) salts, e.g., CuCl. The most practical technique for preparing monolayer CuCl is by a two-step process incipient wetness impregnation of CuCE followed by reduction to CuCl. This process also applies to other cuprous salts, as the cupric salts are generally water-soluble. Attempts have also been made for direct impregnation of CuCl. This could be accomplished by two ways using acid or basic solutions or dissolving CuCl with the aid of ammonium chloride. These two techniques will be first briefly described, and the two-step process will be then discussed in more details. 

Great care should be exercised in these preparations, in order to exclude traces of moisture. To a stirred solution of the alkyne (6 mmol) in dichloromethane (50 ml) was added butyl lithium (2.4 ml of a 2.5 M solution in hexane) at - 70°C, under a positive pressure of nitrogen. After 10 min, cuprous cyanide (0.27 g, 3 mmol) was added and stirring continued for 2 h at — 40°C. The mixture was cooled to - 70°C and the iodonium salt (1 mmol) was added this mixture was allowed to warm to room temperature slowly and stirred for another 10 h. Then it was poured into a saturated aqueous solution of ammonium chloride (100 ml), extracted with dichloromethane and the organic layer was dried and concentrated. The residue was purified by filtration through a short silica column (hexane, then dichloromethane) solvent evaporation afforded pure bicyclic enediynes, in 36-69% yield. 

When suspended in a solution containing both ammonia and ammonium (or other) salts, air at atmospheric pressure oxidizes cuprous sulphide to cupric sulphate and thiosulphate, the reaction being slower than with cupric sulphide. In suspension in neutral or acidic solutions, cupric sulphate is produced, the reaction being less energetic than in presence of ammonia, and up to 160° C. requiring compressed air.3... 

Cuprous cyanide is a white solid, and is soluble with difficulty in water. It is dissolved readily by cold, concentrated hydrochloric acid, and is reprecipitated from this solvent by addition of an aqueous solution of potassium hydroxide. In contact with air, its colourless solution in ammonium hydroxide develops a blue tint. The salt is also dissolved by aqueous solutions of ammonium chloride, sulphate, and nitrate, and by warm, dilute sulphuric acid. None of its solutions has the power of absorbing carbon monoxide.13 The heat of formation of... 

Cuprous thiocyanate, CuCNS.—The thiocyanate is produced by dissolving cuprous oxide or carbonate in thiocyanic acid, and by the interaction of solutions of potassium thiocyanate and a cupric salt in presence of a reducer, such as ferrous sulphate or sulphurous acid.2 It is a white substance, its solubility at 18° C. being 0 23 mg. in 1 litre of water.3 It dissolves in ammonium hydroxide and concentrated hydrochloric acid, and also in concentrated nitric acid with formation of cupric sulphate. It is employed in the preparation of aromatic thiocyanates.4... 

Cupric thiocyanate, Cu(CNS)2.—The thiocyanate is formed as a velvet-black precipitate by adding basic cupric carbonate or cupric hydroxide to a solution of thiocyanic acid, and by the interaction of potassium thiocyanate and concentrated solutions of cupric salts.8 It is very unstable, being transformed by contact with water into cuprous thiocyanate.9 With ammonium hydroxide it yields blue, aeicular crystals of ammonio-cupric ihiocyanaie, Cu(CNS)2,2NHs, also produced by dissolving cupric hydroxide in ammonium thiocyanate.10... 

Ammonium cuproferrocyanide, (NH4)2Cu2Fe(CN)6, results1 when cuprous cyanide is boiled with a solution of ammonium ferrocyanide containing ammonium sulphite, and hydrogen passed through the mixture. It may also be obtained by double decomposition of the sodium salt with ammonium nitrate. It crystallises in small, colourless six-sided prisms, which readily decompose both under water and on mere exposure to air or in a vacuum. 

Procedure II. A drop of the test solution is precipitated with the reagent, either on a spot plate or on filter paper, and then a few drops of dilute hydrochloric acid or ammonium chloride are added. The mercury compound dissolves while the red silver precipitate remains. Procedure II is recommended when copper as well as mercury is present, since the cuprous cyanide is sufficiently dissociated (when potassium cyanide is used) to react with the reagent to give a red insoluble cuprous salt, which resembles the silver compound. 

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