Copper salts, decompositions

Coppet(II) oxide [1317-38-0] CuO, is found in nature as the black triclinic tenorite [1317-92-6] or the cubic or tetrahedral paramelaconite [71276-37 ]. Commercially available copper(II) oxide is generally black and dense although a brown material of low bulk density can be prepared by decomposition of the carbonate or hydroxide at around 300°C, or by the hydrolysis of hot copper salt solutions with sodium hydroxide. The black product of commerce is most often prepared by evaporation of Cu(NH2)4C02 solutions (35) or by precipitation of copper(II) oxide from hot ammonia solutions by addition of sodium hydroxide. An extremely fine (10—20 nm) copper(II) oxide has been prepared for use as a precursor in superconductors (36). 

The pyrolysis of perfluoro carboxylic salts can result both in mono and bimolecular products At 210-220 °C, silver salts give mostly the coupled products, at 160-165 °C in A -methylpyrrolidinone, the corresponding copper salts also give the simple decarboxylated compounds in nearly equal amounts The decomposition of the copper salts m the presence of lodobenzene at 105-125 °C results m a phenyl derivative, in addition to the olefin and coupled product [94] (equations 60-62)... 

Many of the early workers who studied the thermal decomposition reactions of diazocarbonyl compounds found that the addition of copper metal or copper salts allowed the reaction to be achieved at a lower temperature,<63AG(E)565, 64CB2628, 73JOU431> although no detailed study of this catalytic effect was undertaken. Alonso and Jano studied the copper-salt reaction of ethyl diazopyruvate 26 with acetonitrile and benzonitrile. The... 

Metal-Catalyzed. Cyclopropanation. Carbene addition reactions can be catalyzed by several transition metal complexes. Most of the synthetic work has been done using copper or rhodium complexes and we focus on these. The copper-catalyzed decomposition of diazo compounds is a useful reaction for formation of substituted cyclopropanes.188 The reaction has been carried out with several copper salts,189 and both Cu(I) and Cu(II) triflate are useful.190 Several Cu(II)salen complexes, such as the (V-f-butyl derivative, which is called Cu(TBS)2, have become popular catalysts.191... 

In a printed circuit board etching line using copper(II) chloride solution, 45 wt% hydrogen peroxide solution was used to recover the copper salts. The peroxide header tank became contaminated with trace amounts of the etching solution, and catalytic decomposition of the peroxide led to a pressure burst of the tank. 

Aziridines have been synthesized, albeit in low yield, by copper-catalyzed decomposition of ethyl diazoacetate in the presence of an inline 260). It seems that such a carbenoid cyclopropanation reaction has not been realized with other diazo compounds. The recently described preparation of 1,2,3-trisubstituted aziridines by reaction of phenyldiazomethane with N-alkyl aldimines or ketimines in the presence of zinc iodide 261 > most certainly does not proceed through carbenoid intermediates rather, the metal salt serves to activate the imine to nucleophilic attack from the diazo carbon. Replacement of Znl2 by one of the traditional copper catalysts resulted in formation of imidazoline derivatives via an intermediate azomethine ylide261). 

Insertion of a carbene unit into the N—H bond of primary or secondary amines by copper salt catalyzed decomposition of diazo compounds has been known for a number of years14). The copper chelate promoted reaction of diazodiphenyl-methane 291) or 2-diazo-1,2-diphenyl-1-ethanone 292) with primary benzylamines or... 

A somewhat unusual copper catalyst, namely a zeolite in which at least 25% of its rhodium ions had been exchanged by Cu(II), was active in decomposition of ethyl diazoacetate at room temperature 372). In the absence of appropriate reaction partners, diethyl maleate and diethyl fumarate were the major products. The selectivity was a function of the zeolite activation temperature, but the maleate prevailed in all cases. Contrary to the copper salt-catalyzed carbene dimer formation 365), the maleate fumarate ratio was found to be relatively constant at various catalyst concentrations. When Cu(II) was reduced to Cu(I), an improved catalytic activity was observed. 

The Sandmeyer reaction utilizes a diazonium salt to produce an aryl halide. The process begins by converting an amine to a diazonium salt. Decomposition of the diazonium salt in the presence of a copper halide places the halide ion into the position originally occupied by the amine. The most useful copper halides are CuCl and CuBr in addition, the copper pseudohalides, such as CuCN, also works by placing a nitrile in the position originally occupied by the amine. Figure 13-27 shows an example of the Sandmeyer reaction. 

In aqueous solutions, copper(II) nitrate undergoes many double decomposition reactions with soluble salts of other metals, forming precipitates of insoluble copper salts. 

Ahphatic diazo compounds are convenient starting materials for the generation of carbenes by photolytic or thermal methods. Decomposition of diazo compounds can be catalyzed by some metals or metal salts (63,64). Whereas copper salts were first used, rhodium(ll) acetate has recently become recognized as one of the most efficient catalysts and is now used almost exlusively (65). 

Preparation of Metal Sulphides by an Exchange Decomposition Reaction. Precipitation with Ammonium Sulphide. Pour 2 ml each of solutions of iron(ll), manganese(II), zinc, cadmium, lead, antimony, and copper salts into separate test tubes. Add 2 ml of an ammonium sulphide solution to each tube. Note the colour of the formed precipitates. Write the equations of the reactions and the values of the solubility products of the sulphides of these metals (see Appendix 1, Table 12). Using the concept of the solubility product, explain the process of precipitation of sulphides under these conditions. 

Many of the heavier thiosulphates when heated with water give rise to the corresponding sulphides. 3 To this ready decomposition of the thiosulphate is due the precipitation of sulphides when hot acid-containing solutions of various metals are treated with sodium thiosulphate solution.8 When a solution of alkali thiosulphate is boiled with a copper salt, the yellow precipitate of sodium cuprous thiosulphate first formed undergoes decomposition to produce cuprous and cupric sulphides and free sulphur, the relative amounts of these products depending on the thiosulphate concentration, the duration of boiling, and the acidity of the solution.4... 

The cyclopropanation of alkenes, alkynes, and aromatic compounds by carbenoids generated in the metal-catalyzed decomposition of diazo ketones has found widespread use as a method for carbon-carbon bond construction for many years, and intramolecular applications of these reactions have provided a useful cyclization strategy. Historically, copper metal, cuprous chloride, cupric sulfate, and other copper salts were used most commonly as catalysts for such reactions however, the superior catalytic activity of rhodium(ll) acetate dimer has recently become well-established.3 This commercially available rhodium salt exhibits high catalytic activity for the decomposition of diazo ketones even at very low catalyst substrate ratios (< 1%) and is less capricious than the old copper catalysts. We recommend the use of rhodium(ll) acetate dimer in preference to copper catalysts in all diazo ketone decomposition reactions. The present synthesis describes a typical cyclization procedure. 

Martin, J. P., Ervin, J. O., and Shepherd, R. A. (1966). Decomposition of the iron, aluminium, zinc and copper salts or complexes of some microbial and plant polysaccharides in soil. Soil Sci. Soc. Am. Proc. 30,196-200. 

The formation of by-products appears to predominate with annelated derivatives, and the desired phenanthridone is, at best, only a minor product of the copper-catalyzed decomposition of the appropriate diazonium salt. Typically (and contrary to an earlier report123), the decomposition of iV-methyl-2-naphthanilide-l -diazonium fluoro-borate (96) gives poor yields of four products 2-naphthanilide (2%), jN7-methyl-9,10-benzophenanthridone (97) (3%), 2-methyl-6,7-benziso-indoline-l-spirocyclohexa-2, 5 -diene-3,4,-dione (98) (5%), and bi-(2 - methyl - 3 - oxo - 6,7 - benzisoindoline -1 - spirocyclohexa - 2, 5 - dien-4 -yl) (99) (15%).132 133... 

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