I Oxide

Copper(I) oxide (KOPP-er one OK-side) is also known as cuprous oxide, red copper oxide, copper protoxide, copper hemi-oxide, and copper suboxide. It is a yellowish, red, or brown crystalline substance, depending on its method of preparation. It does not burn and is stable in dry air. In moist air, it slowly changes to copper(II) oxide (CuO). The compound has been used by humans for thousands of years, first as a pigment in glazes, and later in fungicides, electronic components, and industrial reactions. 

In 1883, copper(I) oxide was the first substance found to have semiconducting properties. A semiconductor conducts an electric current, although not nearly as efficiently as a conductor like copper, gold, or silver. Semiconductor components are now widely used in computer chips, although they are now made from silicon rather than copper(I) oxide. 

Copper(I) oxide occurs naturally as the mineral cuprite. It forms when native copper (copper as an element) is exposed 

Copper(l) oxide. Red atom is oxygen and turquoise atoms are copper, publishers 

Copper oxide is used in photoelectric cells, which are cells that generate an electric current when exposed to light. 

Chlorine (I) oxide was first prepared by Gay-Lussac1 by the reaction of chlorine with dry yellow mercury(II) oxide, protected on the surface by a layer of sand. The procedure given here is one of the many reported variations.2 

Caution. Adequate safety shields and only small quantities of material should be used as precautions against explosions. Air containing mercury (II) oxide dust should not be inhaled. Contact of the hands with yellow mer- 

The basic mercury (II) chlorides produced are suspended in water at 15° and treated with excess sodium hydroxide solution. The yellow precipitate is washed and dried at 120°. 

Chlorine(I) oxide resembles bromine in appearance. It boils at 2° and freezes at —120.6°. It is very soluble 

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Alonso C, Salvarezza R C, Vara J M and Arvia A J 1990 The meohanism of silver (I) oxide formation on polyorystalline silver in alkaline solution. Determination of nuoleation and growth rates Electrochim. Acta 35 489-96... 

In the absence of oxygen, gallium and indium are unaffected by water. Thallium, the most metallic element in Group III, reacts slowly with hot water and readily with steam to produce thallium(I) oxide, TI2O. 

By warming either copper(I) oxide or a mixture of copper(II) chloride and copper with concentrated hydrochloric acid, until a deep brown solution is formed ... 

Copper(l) sulphate, CU2SO4, is obtained as a white powder by heating together dimethyl sulphate and copper(I) oxide ... 

Addition of an alkali hydroxide to a solution of a silver(I) salt gives a brown solid, silver(I) oxide, AgjO when wet, this behaves as silver hydroxide AgOH, for example... 

The oxide is soluble in ammonia to give the complex [AglNHjlj] (linear). On heating, silver(I) oxide loses oxygen to give the metal (all the coinage metal oxides have low thermal stability and this falls in the order Cu > Ag > Au). 

I. Oxidation to benzoic acid. Boil a mixture of i ml. of benzyl chloride, 50 ml. of saturated aqueous KMn04 solution and 2 g. of anhydrous Na.jCOj under reflux for 30 minutes. Acidify with cone. HCl and then add 25% Na SOj solution until the brown precipitate of MnOj has dissolved. On cooling, benzoic acid crystallises out. Filter through a small Buchner funnel, wash with water and identify (P 347) When recrystallised from water, benzoic acid has m.p. 121 . 

Dissolve 65 g. of hydrazine sulphate in 400 ml. of 2 5. V sodium liyd i oxide solution contained in a 1-htre three-necked flask, equipped with a thermometer, mechanical stirrer and dropping funnel. Immerse the flask in an ice bath and when the temperature reaches 15° (some sodium sulphate... 

It is found in practice that for a number of compounds reacting ma the predominant species an almost horizontal plot is obtained. For compounds presumed to be nitrated via the free bases, such as 2,6-lutidine i-oxide and 3- and 5-methyl-2-pyridone, slopes of approximately unity are obtained. Since this type of plot allows for the incomplete ionisation of nitric acid, it can be used at higher acidities than plots using — ( H + logio Hjo) which break down when the condition is no longer true. 

These arguments were originally applied to the 4-nitration of 2,6-lutidine i-oxide and quinoline i-oxide, and use of the data available... 

Because of these difficulties, special mechanisms were proposed for the 4-nitrations of 2,6-lutidine i-oxide and quinoline i-oxide, and for the nitration of the weakly basic anilines.However, recent remeasurements of the temperature coefficient of Hq, and use of the new values in the above calculations reconciles experimental and calculated activation parameters and so removes difficulties in the way of accepting the mechanisms of nitration as involving the very small equilibrium concentrations of the free bases. Despite this resolution of the difficulty some problems about these reactions do remain, especially when the very short life times of the molecules of unprotonated amines in nitration solutions are considered... 

The interest attaching to the nitration of pyridine i-oxide and its derivatives has already been mentioned ( 8.2.5). Some data for these reactions are given in tables 8.1, 8.2 and 8.4. The 4-nitration of pyridine I-oxide is shown to occur through the free base by comparison with the case of i-methoxypyridinium cation ( 8.2.2), by the nature of the rate profile ( 8.2.1), and by consideration of the encounter rate ( 8.2.3). - Some of these criteria have been used to show that the same is true for... 

Any attempt to calculate partial rate factors for the i-oxides being The encounter rate criterion ( 8.2.3) is ambiguous for these compounds. 

With the oxides which are nitrated as the cations the difficulties are much less serious for the use of an acidity function is not involved. Comparison of 2,6-dimethoxy- and 3,5-dimethoxy-pyridine i-oxide with wt-dimethoxybenzene (which is nitrated at the encounter rate)... 

The nitration of phenylpyridines and related compounds has attracted attention for a long time, and measurements of isomer proportions have been made for several compounds of this type. Nitration occurs in the phenyl ring. For 2-phenylpyridine and 2-phenylpyridine i-oxide measurements of the dependence of rate of nitration upon acidity in 75-81 % sulphuric acid at 25 °C show that both compounds are nitrated as their cations (table 8.1). The isomer distribution did not depend significantly upon the acidity, and by comparison with the kinetic data for quinolinium ( 10.4.2) the partial rate factors illustrated below were obtained.They should be compared with those for the nitration of 2-nitrobiphenyl ( 10.1). The protonated heterocyclic groups are much... 

Ochiai and Okamoto showed that nitration of quinoline i-oxide in sulphuric acid at o °C gave 5- and 8-nitroquinoline i-oxides with a trace of the 4-isomer, but that at 60-100 °C 4-nitration became overwhelmingly dominant. The orientation depends not only upon temperature but also upon acidity, and kinetic studies (table 8.4 table 10.3) show that two processes are occurring the nitration of the free base (vil, R = O at C(4), favoured by low acidities and high temperatures, and the nitration of the cation (vil, R = OH), favoured by high acidities and low temperatures. ... 

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