Silver oxide, decomposition

The decomposition of silver oxide was one of the earhest solid reactions studied. It is smoothly reversible below 200°C (392°F) with equation for partial pressure of oxygen,... 

The diazo ketone 3, when treated with silver oxide as catalyst, decomposes into ketocarbene 5 and dinitrogen Na. This decomposition reaction can also be achieved by heating or by irradiation with uv-light. The ketocarbene undergoes a Wolff rearrangement to give a ketene 6 ... 

An a-diazo ketone 1 can decompose to give a ketocarbene, which further reacts by migration of a group R to yield a ketene 2. Reaction of ketene 2 with water results in formation of a carboxylic acid 3. The Woljf re arrangement is one step of the Arndt-Eistert reaction. Decomposition of diazo ketone 1 can be accomplished thermally, photochemically or catalytically as catalyst amorphous silver oxide is commonly used ... 

Ammoniacal silver oxide is as dangerous as the previous similar compounds. Thus, the clear solution, which is obtained after centrifuging ammoniacal silver oxide leaves a very explosive compound as a residue to which was attributed the AgaN4 formula. It seems that the decomposition of this nitride is inhibited by ammonium salts. A similar situation was created after treating this ammoniacal oxide with silver nitrate until a solid started to precipitate, and this detonated 10 to 14 days after being prepared. It was assumed that this solid was AggNH. 

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. 

What does this imply Suppose some silver metal and silver oxide is sealed in a closed silica ampoule, under a complete vacuum, and the ampoule is heated to a temperature somewhat below the decomposition temperature of 230°C. As there is no oxygen in the ampoule, some of the silver oxide will decompose and oxygen will be released. This will continue until the equilibrium decomposition pressure is reached. Provided that there is both silver and silver oxide in the tube, the oxygen pressure will be fixed (Fig. 7.5a). If the temperature is raised or lowered, either more silver... 

Contact with metal oxides increases the sensitivity of nitromethane, nitroethane and 1-nitropropane to heat (and of nitromethane to detonation). Twenty-four oxides were examined in a simple quantitative test, and a mechanism was proposed. Cobalt, nickel, chromium, lead and silver oxides were the most effective in lowering ignition temperatures [1]. At 39 bar initial pressure, the catalytic decomposition by chromium or iron oxides becomes explosive at above 245° C [2],... 

The iodide, [Cr en2pn]I3.2H20, is obtained in lustrous yellow needles by decomposition of the thiocyanate with potassium iodide. The iodide is more soluble in water than triethylencdiamino-chromic iodide, and is insoluble in alcohol and ether. The aqueous solution is decomposed by moist silver oxide, giving a strongly alkaline solution containing the base, [Cr en2pn](OII)3. 

Tripropylenediamino-chromic Iodide, [Cr pn3]X3.II20, may be prepared, for instance, by the decomposition of trichloro-tripyridino-ehromium with propylenediamine monohydrate. It crystallises in small yellow needles, soluble in water, and is decomposed by moist silver oxide with liberation of the base, [Cr pn3](OH)3. 

Aquo-pentammino-cobaltic Hydroxide.—A hydroxide, possibly of formula [Co(XH3)5H20](OH)3, has been formed in solution either by the decomposition of the chloride, [Co(NH3)5H20]C13, of the series with moist silver oxide, or by the decomposition of a cold aqueous solution of the sulphate with barium hydroxide thus ... 

The hydroxo-compound, [Pd(NH3)2(OH)2], is obtained on treating the ehloro-derivative with moist silver oxide, or by precipitation from a solution of the sulphato-compound with the calculated quantity of barium hydroxide. The solution is filtered and evaporated in vacuo or in air free from carbon dioxide, when a yellow residue of microscopic octahedra is obtained. The aqueous solution is strongly alkaline, rapidly absorbs carbon dioxide from the air, and combines with evolution of heat with acids, forming the corresponding aeido-derivatives. In the dry state it may be heated to 105° C. without decomposition. Prolonged boiling with water causes it to lose ammonia, as in the case of the dibromo-derivative, leaving a brown residue. It precipitates the hydroxides of the metals copper and silver from solutions of their salts, and liberates ammonia from ammonium salts.2... 

Chloro-pentammino-iridium Hydroxide, [Ir(NH3)5Cl](OH)2, may be obtained by decomposition of the chloride with freshly precipitated silver oxide, or by warming the chloride with sodium hydroxide on a water-batli. The base is stable, absorbs carbon dioxide from the air, and only slowly decomposes on boiling with water. 

A. J. Balard,9 in 1821, also prepared hypobromous acid in a similar manner, namely, by the gradual addition of mercuric oxide of bromine water, and thoroughly shaking the mixture after each addition. Further, quantities of bromine and mercuric oxide can be added until the yellow fluid contains between 6 and 7 parts of HOBr per 100 c.c. The mercuric oxide can be replaced by silver oxide, silver or mercuric nitrate, mercuric acetate, etc. The soln. with 6-7 parts of HOBr per 100 c.c. decomposes at 30°, but more dil. soln. when distilled under ordinary atm. press, give a distillate of bromine followed by a straw-yellow fraction which is a dil. aq. soln. of hypobromous acid. The decomposition is not so pronounced if it be conducted at 40° under a press, of, say, 50 mm. of mercury. 

The higher decomposition points were obtained when adrenochrome methyl and ethyl ethers were prepared by oxidation of the appropriate catecholamine in methanol with silver oxide. The BOlid aminochromes were then obtained as microcrystalline solids on addition of dry ether and cooling the resultant solution to — 80°. The slightly less pure products were obtained when the oxidation was carried out in acetonitrile. [R. A. Heacock and B. D. Scott, loc. cit. (footnote c )]. 

Hydrogen trisulphide is much more easily combustible than the crude parent hydrogen polysulphide. Exposure to light tends to accelerate its decomposition. It slowly reduces concentrated sulphuric acid to sulphur dioxide, whilst on contact with dry silver oxide, cupric oxide, lead dioxide or mercuric oxide, it bursts into explosive combustion,2 a residue of the metallic sulphide being obtained. Many other metallic oxides and most salts bring about a less vigorous decomposition metals in the massive condition only react with it slowly. With potassium permanganate or dichromate the reaction is violent. 

Towards alkalis the disulphide is much less stable than the trisulphide and decomposes almost explosively in an untreated glass flask. Distilled water induces rapid decomposition, whilst contact with alkali causes explosive formation of hydrogen sulphide. When placed on paper or on the skin, rapid decomposition occurs, in the latter case with formation of a white fleck, resembling the effect of hydrogen peroxide. The disulphide resembles the trisulphide in its behaviour with sulphuric acid and with silver oxide it is more readily inflamed than the trisulphide. 

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