Equations Cuprous oxide

It must be borne in mind that the equations (11), etc., hold good only when the condensed phases are chemically homogeneous. Thus Foote and Smith, who determined the dissociation pressure of cuprous oxide ... 

Kinetics of reaction must be considered when attempting to postulate mechanisms, but kinetic equations alone are unreliable in fixing mechanism. For example, in the oxidation of propylene to acrolein, cuprous oxide and bismuth molybdate have very different kinetics, yet the studies of Voge, Wagner, and Stevenson (18), and especially of Adams and Jennings (1, 2) show that in both cases the mechanism is removal of an H atom from the CH3 group to form an allylic intermediate, from which a second H atom is removed before the O atom is added. The orders of the reactions and the apparent optimum catalysts (16) are as follows ... 

Copper is not attacked by water at ordinary temperatures, or at 100° C., and only slightly at white heat but very prolonged immersion in sea-water produces a superficial coating of cuprous oxide.4 It is insoluble in dilute sulphuric acid of 5 to 10 per cent, strength,5 but reacts with the concentrated acid in accordance with the equations 6... 

How much cuprous oxide is formed by boiling 100 gm. of copper sulphate with potassium hydroxide and grape sugar (The equation is 2CUSO1.5H2O + 4KOH = Cup + O + 12 HP + 2K.,SOp... 

As a second example of an endothermic, but spontaneous process, we shall discuss the decomposition of cupric oxide to cuprous oxide and oxygen. The equation for the reaction and relevant data are ... 

Isotherms for propene adsorption on NiO, vanadium pentoxide, and cuprous oxide at 100° are shown in Fig. 2. All isotherms are described by Freundlich s equation and correspond to a heterogeneous surface with exponential distribution as to heats of adsorption. 

The oxidation of copper metal in a low partial pressure of oxygen produces cuprous oxide, CU2O, by a mechanism involving diffusion of Cu cations and electrons. The reaction is described by the chemical equation ... 

As a further example of how the presence of several defect types can influence the results, let us consider the oxidation of copper to CU2O. Cuprous oxide is a metal-deficit p-type semiconductor forming cation vacancies and electron holes. The formation of these defects may be represented by Equation (3.70) ... 

Single phase cuprous oxide (14 nm) was prepared by °Co gamma irradiation of deoxygenated aqueous solutions containing copper sulfate, propan-2-ol, surfactant sodium dodecyl sulfate, and acetate buffer at pH 4-4.5 (Zhu et al. 1994). In the absence of buffer (pH 3-3.5), mixture of copper and cuprous oxide was observed. Most probably, three competitive reactions occur radiation reduction (Equations (4.6) and (4.8)), dismntation of cuprous ions (Equation 4.9), and the formation of cuprous hydroxide, which decomposes to cuprous oxide (Equation 4.10). In buffered solutions, the reduction and dismntation of cnprons ions are completely suppressed. Since cuprous hydroxide is very unstable, it decomposes rapidly to cnprous oxide immediately after its formation. On the other hand, the precipitate of cupric hydroxide Cu(OH)2 forms in the solution of pH >5. 

Copper is not expected to follow Cabrera-Mott inverse logarithmic kinetics since its oxide is a modifier according to Table 4.1. In fact, copper follows direct logarithmic kinetics. This was emphasized by results (Table 4.2) from the analysis of experimental data [5e,9] including the results shown in Figure 4.2. No attempt is made here to apply the Fehlner-Mott direct logarithmic expression (Equation 4.5). This is because the evidence for oxide recrystallization with time is very complex. Onay [52] reported on the formation of multiphase, multilayer scales on copper at 300°C. He foimd that they result from the dissociation of compact cuprous oxide scale that has lost contact with the copper substrate. 

In the manufacture of printed circuit boards, the unwanted copper is etched away by acid solutions of cupric chloride (Equation 1.1). As the copper dissolves, the effectiveness of the solution tails and it must be regenerated. The traditional way of doing this is to oxidize the cuprous ion produced with acidified hydrogen peroxide. During the process the volume of solution increases steadily and the copper in the surplus liquor is precipitated as copper oxide and usually landfilled. 

The reaction is carried out by slowly adding the 1-bromoalkyne to a solution containing the terminal alkyne, amine, copper(i) chloride and hydroxylamine hydrochloride. The amine, usually ethylamine, is used in excess, e.g. 1-8 moles/mole of alkyne, and catalytic quantities (1-5 mol %) of copper(i) chloride are used. One of the side-reactions is the self-coupling of the bromoalkyne induced by Cu(i) which in turn is oxidized to Cu(ii) (equation 11). The hydroxylamine salt serves to reduce the copper back to the cuprous state. 

Terminal alkenes containing hydrogen linked to the triple bond undergo oxidative coupling to diacetylenes by cupric salts [5cuprous salts [59, 66] (equation 139). Copper salts are solubilized by complexing with tertiary amines, most frequently pyridine [59, 357] and tetramethylethylenediamine [66]. The coupling can also be carried out with cuprous salts of acetylenes [5 S]. 

Belousov et al. (115, 153) studied the kinetics of propene oxidation to acrolein on a cuprous-copper catalyst, using the flow-circulating method. The reaction products were shown to exert a considerable effect on the reaction rate, and this permitted the derivation of a more precise kinetic equation for this reaction. Over the temperature range of 305-365° the rates of propene oxidation to acrolein (wact) and carbon dioxide (wc0i) are fairly well described by equations... 

The first method involves oxidative homocoupling of bis(terminal alkynyl) complexes in the presence of a catalytic amount of cuprous halides and O2 as the oxidizing agent (Scheme 16, Equation (58)). The use of this catalyst system in organic synthesis is extensive and is better known as Hay s coupling reaction. Extension of this methodology to organometallic synthesis was demonstrated by the conversion of... 

Oxidation of phenol, Tsuji et al. have found that catechol is cleaved to monomethyl muconate in high yield by oxygen catalyzed by cuprous chloride in Py-CHpOH. Even more interesting from the biochemical standpoint is that phenol itself can be oxidized in the same way (equation I). The reaction is slow ... 

The catalyst formed dien oxygen is added to copper(I) chloride in pyridine has found considerable utility in the oxidation of a large number of nitrogen compounds. The preparation of unsaturated nitriles from unsaturated amines can be accomplished in a catalytic manner using cuprous chloride in pyridine [IS]. The oxidative cleavage of o-phenylenediamine catalyzed by cuprous chloride in pyridine takes place at room temperature to give cu,cis-mucononitrile, equation (113) [152]. 

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