Copper nitrate, decomposition

Catalysts. Cupric oxide was prepared by thermal decomposition of reagent grade copper nitrate (Wako Pure Chem.Inc.Ltd.) at 400°C in air for 4 hrs. Magnesium oxide was commercially available reagent grade powder (Kanto Chemical Co.Ltd.). The oxides powders were pressed into tablets and crushed and 24-42 mesh granules were used as catalysts. 

Catalysts suitable specifically for reduction of carbon-oxygen bonds are based on oxides of copper, zinc and chromium Adkins catalysts). The so-called copper chromite (which is not necessarily a stoichiometric compound) is prepared by thermal decomposition of ammonium chromate and copper nitrate [50]. Its activity and stability is improved if barium nitrate is added before the thermal decomposition [57]. Similarly prepared zinc chromite is suitable for reductions of unsaturated acids and esters to unsaturated alcohols [52]. These catalysts are used specifically for reduction of carbonyl- and carboxyl-containing compounds to alcohols. Aldehydes and ketones are reduced at 150-200° and 100-150 atm, whereas esters and acids require temperatures up to 300° and pressures up to 350 atm. Because such conditions require special equipment and because all reductions achievable with copper chromite catalysts can be accomplished by hydrides and complex hydrides the use of Adkins catalyst in the laboratory is very limited. 

The intermediate precipitate obtained by the reaction of copper nitrate with ammonium dichromate and ammonia has been shown to be Cu(0H)NH4Cr04,122 and the decomposition of the precipitate to give the catalyst to be formulated as in eq. 1.6, by an X-ray diffraction study by Stroupe, although the catalysts obtained by decomposition at sufficiently controlled low temperature (350°C) are amorphous.123 Catalysts previosly used in liquid-phase hydrogenation below 300°C often show crystalline cupric chromite to have been largely reduced to the cuprous chromite... 

Reaction of Copper Nitrate with Dimethyl Ether. In sharp contrast to the behavior of diethyl ether, dimethyl ether shows little reactivity with copper nitrate. Dimethyl ether was condensed onto copper nitrate at —70° C. on warming to —20° C. ether evaporated to leave a pale blue solid which melted to a green oil at —12°. This oil was stable up to 50° C., and analysis showed it to be a molecular addition compound, Cu(N03)2.1.5 Me20 on treatment with water the dimethyl ether was evolved. Some decomposition of the addition compound does occur on long standing under vacuum (16),... 

An alternate procedure involves the precipitation of mixed copper and chromium hydroxides from a solution of chromium nitrate and copper nitrate by the addition of an sodium bicarbonate and then heating the precipitate to 300°-500°C.30 In this procedure, the copperchromium ratio can be varied over a wide range. A ratio between four and eight was optimum for use in the hydrogenation of esters to alcohols (Eqn. 13.6).30 A related Zn-CrO catalyst prepared by the decomposition of precipitated zinc-copper hydroxides was effective in the hydrogenation of unsaturated esters to unsaturated alcohols (Eqn. 13.7). 0 The presence of a small amount of alumina increased catalyst activity and selectivity. Some of these catalysts, however, tend to become colloidal on use so they can present separation problems. O... 

Copper-Chnimlum oxide (Adkins cataiyst HJS 2). I he culalyst is prepared by stirring a solution of copper nitrate and barium nitrate into an aqueous solution of sodium dichromate and ammonium hydroxide. The orange precipitate is washed, dried, and stirred at 350° to effect decomposition. The cooled material is leached with 10% acetic acid, dried, and pulverized. The catalyst so obtained is brownish black. 

The influences of the ions Ca, Mg and Ba and of Mn02 crystals on the decomposition of Mn(N03)2 in the presence of water have been investigated [65]. From a FTIR product analysis coupled with TG, it was concluded [66] that basic copper nitrate, Cu2(OH)3N03, decomposes in one step between 430 and 500 K when heated at 10 K min. The reactant breaks down to yield CuO + H2O + HNO3,... 

We now report on the impact of NO on the low and high temperature decomposition steps of silica-supported first row d-metal nitrates, and the resrrltmg metal oxide dispersions. It was found that NO significantly lowered the decomposition temperatures of all investigated metal nitrates and changed the decomposition pathways of cobalt, nickel and copper nitrate. For the latter metal nitrates it was verified that an improved dispersion was obtained after thermal treatment in the preserrce of NO as corttpared to Ar. 

Chromia—alumina catalysts are prepared by impregnating T-alumina shapes with a solution of chromic acid, ammonium dichromate, or chromic nitrate, followed by gentie calciaation. Ziac and copper chromites are prepared by coprecipitation and ignition, or by thermal decomposition of ziac or copper chromates, or organic amine complexes thereof. Many catalysts have spiael-like stmctures (239—242). 

Copper(II) oxide is less often prepared by pyrometaHurgical means. Copper metal heated in air to 800°C produces the copper(II) oxide. Decomposition of nitrates, carbonates, and hydroxides at various temperatures also occurs. 

Attempts to prepare the anhydrous nitrate by dehydration always fail because of decomposition to a basic nitrate or to the oxide, and it was previously thought that Cu(N03)2 could not exist. In fact it can be obtained by dissolving copper metal in a solution of N2O4 in ethyl acetate to produce Cu(N03)2.N204, and then driving off the N2O4 by heating this at 85-100°C. The observation by C. C. Addison... 

The enthalpy of absorption of 1- and 2-nitropropane on breathing mask cartridges made with carbon is such that the decomposition of the nitrated derivative can cause its ignition. This accident is aggravated when the cartridge also contains metal oxides such as copper (II) oxide or manganese dioxide. 

Alone, or Metals, or Metal compounds Mellor, 1940, Vol. 8, 327 1967, Vol. 8, Suppl. 2.2, 84, 96 It is an explosive of positive oxygen balance, less stable than ammonium nitrate, and has been studied in detail. Stable on slow heating to 300°C, it decomposes explosively on rapid heating or under confinement. Presence of zinc, copper, most other metals and their acetylides, nitrides, oxides or sulfides cause flaming decomposition above the m.p. (70°C). Commercial cobalt (cubes) causes an explosion also. 

Ellis and coworkers studied the effect of lead oxide on the thermal decomposition of ethyl nitrate vapor.P l They proposed that the surface provided by the presence of a small amount of PbO particles could retard the burning rate due to the quenching of radicals. However, the presence of a copper surface accelerates the thermal decomposition of ethyl nitrate, and the rate of the decomposition process is controlled by a reaction step involving the NO2 molecule. Hoare and coworkers studied the inhibitory effect of lead oxide on hydrocarbon oxidation in a vessel coated with a thin fQm of PbO.P l They suggested that the process of aldehyde oxidation by the PbO played an important role. A similar result was found in that lead oxide acts as a powerful inhibitor in suppressing cool flames and low-temperature ignitions.P l... 

Ellis, W. R., Smythe, B. M., and The-harne, E. D., The Effect of Lead Oxide and Copper Surfaces on the Thermal Decomposition of Ethyl Nitrate Vapor,... 

The nitrate salt prepared by this method is hydrated. It cannot be dehydrated fully without decomposition. Anhydrous CuNOs may be prepared by dissolving copper metal in a solution of dinitrogen tetroxide, N2O4, in ethyl acetate. Upon crystaUization, an N2O4 adduct of Cu(N03)2 that probably has the composition [NO [Cu(N03)3] is obtained. This adduct, on heating at 90°C, yields blue anhydrous copper(II) nitrate which can be sublimed in vacuum at 150°C and coUected. 

Thermal decomposition of copper(II) nitrate produces copper oxides and nitrogen oxides. 

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

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