Copper oxides, decomposition

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. 

Properties of T2O. Some important physical properties of T2O are Hsted in Table 2. Tritium oxide [14940-65-9] can be prepared by catalytic oxidation of T2 or by reduction of copper oxide using tritium gas. T2O, even of low (2—19% T) isotopic abundance, undergoes radiation decomposition to form HT and O2. Decomposition continues, even at 77 K, when the water is fro2en. Pure tritiated water irradiates itself at the rate of 10 MGy/d (10 rad/d). A stationary concentration of tritium peroxide, T2O2, is always present (9). AH of these factors must be taken into account in evaluating the physical constants of a particular sample of T2O. 

Copper metal surface area was determined by nitrous oxide decomposition. A sample of catalyst (0.2 g) was reduced by heating to 563 K under a flow of 10 % H2/N2 (50 cm min"1) at a heating rate of 3 deg.min 1. The catalyst was then held at this temperature for 1 h before the gas flow was switched to helium. After 0.5 h the catalyst was cooled in to 333 K and a flow of 5 %N20/He (50 cm3mirr ) passed over the sample for 0.25 h to surface oxidise the copper. At the end of this period the flow was switched to 10 % H2/N2 (50 entitlin 1) and the sample heated at a heating rate of 3 deg.min"1. The hydrogen up-take was quantified, from this a... 

The effect of metal oxides in sensitising the thermal decomposition and explosion of the salt is in the order manganese dioxide > copper oxide > nickel oxide. 

In a review of the course and mechanism of the catalytic decomposition of ammonium perchlorate, the considerable effects of metal oxides in reducing the explosion temperature of the salt are described [1], Solymosi s previous work had shown reductions from 440° to about 270° by dichromium trioxide, to 260° by 10 mol% of cadmium oxide and to 200°C by 0.2% of zinc oxide. The effect of various concentrations of copper chromite , copper oxide, iron oxide and potassium permanganate on the catalysed combustion of the propellant salt was studied [2], Similar studies on the effects of compounds of 11 metals and potassium dichromate in particular, have been reported [3], Presence of calcium carbonate or calcium oxide has a stabilising effect on the salt, either alone or in admixture with polystyrene [4],... 

Contact with copper oxide, lead(II) oxide, lead(IV) oxide, mercury(II) oxide, tin(IV) oxide or iron(II,III) oxide causes violent decomposition and ignition. Dry powdered silver oxide causes an explosion. 

Note All the above should be checked by analysing the evolved gases and residual solids. Above 400°C further decomposition occurs with loss of S02 and S03 to give copper oxide. 

According to the authors cited above, equation (16) holds for the decomposition of hydrogen iodide on platinum and of nitrous oxide on gold, and furthermore, according to Schwab and Drikos (12), for the oxidation of carbon monoxide to carbon dioxide on copper oxide. 

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

Thermal decomposition—Thermal decomposition methods may be used to prepare metal oxide fumes. An aerosol of a precursor to the metal oxide (i.e., a substance that is readily decomposed, thermally, to yield the oxide) is first generated and then is heated by passing it through a heated tube to decompose it to the oxide. Metal formates, oxalates, and the like, which readily yield the oxides and do not produce objectionable side products, are commonly used precursors. In this program, fumes of iron oxide, vanadium oxide, and copper oxide were generated using this method. 

Phenol can also be prepared by the decomposition of benzoic acid prepared by the oxidation of toluene.927,978 The process is an oxidative decarboxylation catalyzed by copper(II). An interesting feature of this reaction is that the phenolic hydroxyl group enters into the position ortho to the carboxyl group as was proved by 14C labeling.979 In the Dow process980 molten benzoic acid is transformed with steam and air in the presence of Cu(II) and Mg(II) salts at 230-240°C. A copper oxide catalyst is used in a vapor-phase oxidation developed by Lummus.981... 

Intramolecular cyclopropanation of diazoketones to furnish [3.1.0] and [4.1.0] bicyclic systems are the most common and effective reactions in this category. Two recent examples are shown in equations 48 and 49. The bicyclic ketone 34 has been used in the synthesis of polycyclic cyclobutane derivatives77, whereas ketone 35 is the key intermediate in the total synthesis of ( )-cyclolaurene78. When the olefinic double bond is attached to, or is part of, a ring system, the cyclopropanation process also works well. Copper oxide catalysed decomposition of diazoketone 36 produces the strained tricyclic ketone 37 in 86% yield (equation 50)79. In another case, in which the cyclopropanation of diazoketone 38 gave stereospecifically the cyclopropyl ketone 39, copper sulphate catalysis was used. The cyclopropyl ketone 39 is the key intermediate in the total synthesis of ( )-albene 40 (equation 51). ... 

On introducing nitroglycerine in the nitrocellulose, the effect of copper oxide sharply decreases, and at more than 40% NG it disappears completely. In the thermal decomposition of NG much more CO than C02 is formed, and in the decomposition of NC more C02 than CO is formed. Hence, on introducing NG into NC, the proportion of CO in the decomposition products is increased. The C0/C02 ratio in the decomposition products of NC, NG, and their mixtures (V = 20cm3/g at STP) is as follows ... 

Decomposition of NzO on a copper oxide catalyst in adiabatic circulating reactor Hugo (46) X ... 

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