Copper salt reduction

Atomized 5 % sodium chloride, pH 3.2 with acetic acid, 0.025 % cupric chloride-dihydrate, 35°C. Galvanic coupling due to copper salt reduction to copper metal. More severe than ASTM B 117. 

A flow diagram for the system is shown in Figure 5. Feed gas is dried, and ammonia and sulfur compounds are removed to prevent the irreversible buildup of insoluble salts in the system. Water and soHds formed by trace ammonia and sulfur compounds are removed in the solvent maintenance section (96). The pretreated carbon monoxide feed gas enters the absorber where it is selectively absorbed by a countercurrent flow of solvent to form a carbon monoxide complex with the active copper salt. The carbon monoxide-rich solution flows from the bottom of the absorber to a flash vessel where physically absorbed gas species such as hydrogen, nitrogen, and methane are removed. The solution is then sent to the stripper where the carbon monoxide is released from the complex by heating and pressure reduction to about 0.15 MPa (1.5 atm). The solvent is stripped of residual carbon monoxide, heat-exchanged with the stripper feed, and pumped to the top of the absorber to complete the cycle. 

Dialkyldiaziridines react with acidic iodide solution only on heating catalysis by traces of copper salts permits quantitative reduction at room temperature in these cases also. 

Ruthenium-copper and osmium-copper clusters (21) are of particular interest because the components are immiscible in the bulk (32). Studies of the chemisorption and catalytic properties of the clusters suggested a structure in which the copper was present on the surface of the ruthenium or osmium (23,24). The clusters were dispersed on a silica carrier (21). They were prepared by wetting the silica with an aqueous solution of ruthenium and copper, or osmium and copper, salts. After a drying step, the metal salts on the silica were reduced to form the bimetallic clusters. The reduction was accomplished by heating the material in a stream of hydrogen. 

The key intermediate in another total synthesis of secoquettamine (234), elaborated by Stevenson et al. (185), was 2-arylbenzofuran 241 prepared by a coupling reaction of the copper salt of 4-benzyloxyphenylacetylene with bromoisovanillin (Scheme 37). In the next step condensation with nitro-methane and reduction gave amine 242, which when N-methylated and debenzylated resulted in secoquettamine (234). 

Fig. 14.16 Nanobell formation through catalytic reduction of copper from loaded copper salt.

The reduction of silver ion in a sulfite solution is catalyzed by silver, (Sheppard, 3 James, 12) but the catalysis is less pronounced than that operating in the reactions of the developing agents already considered. The sulfite reaction is very slow at 20°, even in the presence of large amounts of colloidal silver. Data obtained at 59.8° indicate a dependence of rate upon the 0.75 power of the silver ion concentration and upon the first power of the sulfite ion concentration. The reaction, even in the presence of silver catalyst, is further catalyzed by copper salts. 

Certain of the salts in solution have a stronger colour than the acid, and in some cases are more stable thus, a deep blue solution of the copper salt may be obtained by the reduction of nitrosulphonic acid (in sulphuric acid) by mercury in the presence of copper. A suggestion has been made7 that the colour in the brown ring test for a nitrate is due to the formation of the ferrous salt of purple acid, but this is improbable.8... 

Of the several methods described for the production of thiosalicylic acid, only the following are of preparative interest heating of o-halogenated benzoic acids with an alkaline hydrosulfide at i50-200° in the presence of copper or copper salts,1 5 or by substitution of sodium sulfide at 200° 2 by reduction of dithiosalicylic add with glucose,3 or metals 4,5 in alkaline solution. The dithiosalicylic add is prepared by treating diazo-tized anthranilic acid with sodium disulfide in alkaline solution.4... 

Peptide aldehydes can be synthesized via hydrolysis of thiazolidine precursors with mercury or copper salts (Scheme 10). 56 The Phe-thiazolidine derivative 27 was prepared from reduction of dihydrothiazole ring in 26, which was formed from a (5-hydroxy thioamide cyclization of 25 using the Mitsunobu reaction. N-Terminal Boc and Z groups on thiazolidine pseudopeptides such as Boc-Ala-Phe-thiazolidine and Z-Phe-Tyr-thiazolidine are stable to hydrolysis that affords Boc-Ala-Phe-H and Z-Phe-Tyr-H. 56 ... 

Dimethyl carbonate is an interesting material which can be used instead of toxic dimethyl sulfate as a multipurpose alkylating reagent.438-578 Its synthesis can be performed in one step from cheap methanol, CO and oxygen materials in the presence of copper salts (e.g. copper(ll) methoxychloride or CuCl/py) at ca. 100 °C and 15-70 atm (equation 290).578,62S This reaction is thought to proceed in two steps 578 (a) formation of copper(II) methoxychloride from the reaction of copper(I) chloride, 02 and methanol (equation 291) and (b) reduction of copper(II) methoxychloride with CO to form dimethyl carbonate and regenerate copper(I) chloride (equation 292).626... 

He said that hydroxynitrosylsulphonic acid is produced by the action of sulphur dioxide on nitrous acid in 70 per cent, sulphuric acid as a direct product of the interaction of nitrous and sulphurous acids, and not by the reduction of chamber crystals—nitroxylsulphonic acid—because he supposed that the latter cannot exist in less than 80 per cent, sulphuric acid. This assumption was shown, by W. C. Reynolds and W. H. Taylor, to be unfounded nitroxylsulphonic acid can exist in the presence of even 60 per cent, sulphuric acid. Further, the blue colour produced by the action of sulphurous acid, or other reducing agent, on a nitrite in the presence of a cone, sulphuric acid soln. of a copper salt, was supposed by F. Raschig to be the copper salt of P. Sabatier s acid, whereas, according to W. C. Reynolds and W. H. Taylor, the product is the complex which nitric acid forms with copper sulphate, and studied by W. Manchot, V. Kohlschiitter, etc.— vide supra. The existence of F. Raschig s nitrosylsulphonic acid may therefore be questioned, and the same remark applies to his statement of the identity of P. Sabatier s blue acid with the product of the reaction of nitrous and sulphurous acids in the presence of a copper salt. 

Reductive aldol reaction of an allenic ester (52) to a ketone such as acetophenone can give y- (53-y) or a-product (53-cy).159 Using as catalysts a copper salt and a range of chiral phosphines, together with phosphine additives such as the triphenyl or tricy- clohexyl compounds, a highly selective set of outcomes can be achieved, e.g. (53-y) almost exclusively cis- with 99% ee, or - without additive - significant amounts of (53-a) can be formed (as a syn-anti mixture). A diastereoselective implementation of the latter has also been developed. 

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