Cuprous ammonium complex

Another approach to separate butadiene from other hydrocarbons is to use a solution containing cuprous ammonium acetate that forms a weak copper(I) complex with butadiene (243,244). The latter process has been used in a number of plants. 

Copper—Liquor Scrubbing. Cuprous ammonium salts of organic acids form complexes with carbon monoxide. 

The main advantages of the Cosorb process over the older copper ammonium salt process are low corrosion rate, abiHty to work in carbon dioxide atmospheres, and low energy consumption. The active CuAlCl C H CH complex is considerably more stable than the cuprous ammonium salt, and solvent toluene losses are much lower than the ammonia losses of the older process (94). 

CAA [Cuprous ammonium acetate] A general process for separating alkenes, di-alkenes, and alkynes from each other by extraction of their cuprous complexes from aqueous cuprous ammonium acetate into an organic solvent. Exxon used it for separating C4 fractions containing low concentrations of butadiene. The liquid-liquid extraction processes for butadiene have all been replaced by extractive distillation processes. 

A solution of 24 g of 4-(N,N-dimethylaminoethoxy)bromobenzene was added dropwise over 45 min to magnesium in 90 ml of anhydrous tetrahydrofuran. 2 ml of 1,2-dibromoethane were added as catalyst. After the addition, the mixture was stirred at 25°C for one hour to obtain a solution of 0.7 M of 4-(N,N-dimethylaminoethoxy)-benzene magnesium bromide which was then added to a solution of 6.16 g of dimethylsulfide-cuprous bromide complex in 20 ml of tetrahydrofuran. The mixture was stirred at room temperature for 20 min and a solution of 3.7 g of 3,3-[l,2-(ethanediyl-bisoxy)]-5a,10a-epoxy-17a-prop-l-ynyl-8(9(1 L))-estrene-17p-ol in 50 ml of tetrahydrofuran was added thereto dropwise over a few minutes. The mixture was stirred under an inert atmosphere for one hour and was then poured into a solution of 15 g of ammonium chloride in 20 ml of iced water. The mixture was extracted with ether and the organic phase was washed with aqueous saturated sodium chloride solution, was dried and evaporated to dryness under reduced pressure. The 18.3 g of oil were chromatographed over silica gel and eluted with chloroform to obtain 4.5 g of 3,3-[l,2-ethanediyl-bisoxy]-lip-[4-(N,N-dimethylaminoethoxy)phenyl]-17a-(prop-l-ynyl)-89-estrene-5a,17p-diol with a specific rotation of [a]D20 =-44(+/-)1.5° (c = 1% in chloroform). 

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. 

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-... 

Ammonia complexation has also been employed, primarily for nickel-copper separations but also for copper recovery, when this is from native copper or copper oxide ores [15]. The dissolving process is thought to involve formation of soluble cuprous ammonium carbonate [53] (Eqs. 13.51 and 13.52). 

The cuprous complex ion then reacts to form tarnish (Eq 7.10). The zinc concentration of the tarnish is very small due to the greater stability of the zinc ammonium complex in solution relative to zinc oxide that would coexist with the Cu20 in the tarnish. These effects of increasing zinc concentration of the brass are consistent with the fact that tarnishing occurs less readily on copper. It is also consistent with the greater susceptibility of the high-zinc brasses (20 to 30 wt% Zn), which more readily tarnish, to IGSCC. 

Carbon monoxide was initially separated by means of aqueous solutions of cuprous ammonium chloride by the formation of a complex according to the following reversible reaction ... 

The interaction between 2, 4, 5-trichlorophenyl propagyl ether and iodine, in the presence of cuprous chloride, ammonium carbonate to form cupro-ammonium complex salt, plus potassium iodide to solubilize iodine as its water-soluble complexes (as KI2, KIg, KI. ) ulti-... 

Aluminum, coordination compounds, 446 Aminopolycarboxylates, lanthanide, complexation, 346-358 Ammine cupric ions, complexity constant determination, 101-106 Ammine cuprous ions, complexity constant determination, 106-107 Ammonium ion-hydrogen-bonding receptor complexes, schematic representation, 150,151/... 

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... 

In the above examples, both the feed and the permeate phases were gaseous and aqueous liquid membranes were used. Cahn and Li (1976) have demonstrated facilitated transport separation of the olefin 1-hexene from n-heptane through an aqueous membrane containing cuprous ammonium acetate the permeate phase was made up of n-octane. Kuo and Gregor (1983) have illustrated facilitated transport of acetic acid from an aqueous solution through an organic membrane of decaUn containing trioctylphosphine oxide (TOPO (0113(012)7)31 )), which complexed with acetic acid. 

The use of aqueous cuprous-ammonium carbonate and formate solutions was first described in a patent to Badische Anilin and Soda Fabrik (1914). Subsequently, the aqueous process was utilized in many plants and the chemistry of the process was studied extensively. More recently, a process based on the use of cuprous aluminum chloride in an aromatic solvent carrier (the COSORB process) has been developed. The new process is reported to have the advantages of greater complex stability and a lower corrosion rate. Both the aqueous and non-aqueous processes are discussed in the following sections. Although the aqueous process is now seldom used, it is included in the discussion because of its historical and technical interest. A more detailed discussion of the aqueous process is given in previous... 

The cupric ion displays a characteristic power of forming complex derivatives with ammonia2 and substituted ammonias, an example being the cupric ammonium hydroxides mentioned on p. 254. A great number of other complex derivatives are derived from cuprous or cupric ions. In certain of these compounds both kinds of copper ions are present simultaneously, examples being the complex cupric-cuprous... 

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