Nickel acetate, decomposition

A further isothermal study [30] confirmed the autocatalytic character of the nickel acetate decomposition. The variation with temperature of the rate of decomposition... 

An early report by Meldola and Streatfeild (146) described an impure sample of Ni(ArNNNAr)2 (Ar = P-C6H4-NO2). Formation of nickel(II) diaryltriazenide complexes Ni(ArNNNAr)2py2 by treatment of nickel acetate with triazenes and pyridine followed by base (Na2C03), and the subsequent thermal decomposition of these products to leave the pyridine-free complexes Ni(ArNNNAr)2, was first reported by Dwyer and Mellor in 1941 (74). Prolonged, vigorous treatment of the latter products with pyridine, ethy-lenediamine (en), and o-phenanthroline (o-phen) gave the adducts... 

Though salt dehydration was not accompanied [27] by particle disintegration, the anhydrous pseudomorph was shown by X-ray diffiaction measurements to be very poorly crystallized (a characteristic feature of many nickel carboxylates). Decomposition in air (554 to 631 K) proceeded at a constant rate (0.1 < nr < 0.8 and = 96 kJ mol" ), ascribed to the operation of an autocatalytic mechanism. The reaction in vacuum (562 to 610 K) gave a sigmoid ar-time curve which was fitted by the Prout-Tompkins equation. Because the activation energy was the same as that for reaction in air, it was concluded that the same mechanism operated. The reaction in air yielded residual nickel oxide, while reaction in vacuum gave the carbide with excess carbon and some oxide. In addition to carbon dioxide, the volatile products of decomposition included water and acetic acid. 

Sulfur-free catalyst is generally obtained by treating nickel nitrate with alkali carbonate, hydroxide, or hydrogen carbonate. The alkali salts formed during the precipitation must be removed so far as possible from the product. The nickel hydroxide or basic carbonate is then reduced, without prior conversion into the oxide. Nickel oxide is usually prepared by decomposition of nickel acetate or nitrate. 

This equilibrium has been studied. Using a catalyst consisting of 73 per cent charcoal and 27 per cent nickel, which resulted from carbonizing a mixture of sugar and nickel acetate, the decomposition of carbon monoxide into carbon and carbon dioxide was entirely suppressed and the catalyst maintained its activity for months in producing methane. Ferric oxide, vanadium pentoxide, and cerium oxide are promoters for the nickel-charcoal catalyst. Studies have also been made of the various reactions involved in the reduction of carbon monoxide and dioxide. ... 

Nickel nanorods (diameter 12 to 15 nm length, 50 to 100 nm) have been synthesized by a solvothermal decomposition of nickel acetate in the presence of n-octylamine (nickel acetate to w-octylamine molar ratio is 1 300) at 250°C (104). The formation of Ni nanorods is favored by the presence of n-octyl amine it reduces, under solvothermal conditions, the Ni ions to Ni° and also acts as a shape-controlling agent to produce metallic nickel nanorods. In the absence of linear alkyl amines, only NiO nanoparticles are produced. Using a similar approach, in the presence of w-octylamine, nanorods of ruthenium and rhodium metals have been produced starting from corresponding acetyl acetonate precursors, Ru(acac)3 and Rh(acac)3. The metallic nanorods are stable in air because of the amine coating and can be redispersed in hydrocarbon solvents. 

A mixture of Ni°/NiO, produced by thermal decomposition of nickel acetate, dispersed on either silica or cordierite supports, was found to be catalytically active for the decomposition of methane without the need for any pre-treatment. Other authors used Ni catalysts supported on zirconia to produce H2 and a high yield of multiwalled carbon nanotubes. Raman spectroscopy suggested that carbon nanotubes formed at temperatures higher that 973 K had more graphite-like structure than those obtained at lower temperatures. They also reported that feed gas containing methane and hydrogen caused slow deactivation of the catalyst, and carbon yield increased with increasing Hg partial pressure in the feed gas. For a commercial Ni catalyst (65% wt Ni supported on a mixture of silica and alumina) it was found that catalyst deactivation depends on the... 

The features of the thermal analysis data show that metal acetate hydrazines decompose exothermically, in three steps, to their respective metal oxides. Manganese, cobalt, zinc, and cadmium complexes decompose through the formation of their corresponding metal acetates, while the nickel complex decomposes through a mixture of nickel metal and nickel acetate (Figure 3.5). The zinc complex however, loses both hydrazine molecules in a single step, while Mn, Co, and Cd complexes lose hydrazine in two steps. The metal oxide formation temperatures from the decomposition of metal acetate hydrazine complexes occur at 275-385 °C. These are lower than those reported for metal acetate hydrates, which occur at 350-400 °C. 

The higher iodides, however, tend to be unstable and decomposition occurs to the lower iodide (PI5 -> PI3). Anhydrous chlorides and bromides of some metals may also be prepared by the action of acetyl (ethanoyl) halide on the hydrated ethanoate (acetate) in benzene, for example cobalt(II) and nickel(II) chlorides ... 

Reduction. Just as aromatic amine oxides are resistant to the foregoing decomposition reactions, they are more resistant than ahphatic amine oxides to reduction. Ahphatic amine oxides are readily reduced to tertiary amines by sulfurous acid at room temperature in contrast, few aromatic amine oxides can be reduced under these conditions. The ahphatic amine oxides can also be reduced by catalytic hydrogenation (27), with 2inc in acid, or with staimous chloride (28). For the aromatic amine oxides, catalytic hydrogenation with Raney nickel is a fairly general means of deoxygenation (29). Iron in acetic acid (30), phosphoms trichloride (31), and titanium trichloride (32) are also widely used systems for deoxygenation of aromatic amine oxides. 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

E. P. Alvarez 2 found that the pemitrates react with soln. of lead acetate (white precipitate), silver nitrate (white precipitate), mercurous nitrate (white precipitate with rapid decomposition), mercuric chloride (red precipitate), copper sulphate (blue precipitate), zinc and cadmium sulphates (white precipitate), bismuth nitrate (white precipitate), gold chloride (slight effervescence and escape of oxygen), manganous chloride (pink precipitate), nickelous chloride or sulphate (greenish-white precipitate), cobaltous nitrate and chloride (pink precipitate), ferrous sulphate (green or bluish-green precipitate), ferric chloride (red ferric hydroxide), and alkaline earth chlorides (white precipitates). The precipitates are all per-salts of the bases in question. 

The characteristic colours and solubilities of many metallic sulphides have already been discussed in connection with the reactions of the cations in Chapter III. The sulphides of iron, manganese, zinc, and the alkali metals are decomposed by dilute hydrochloric acid with the evolution of hydrogen sulphide those of lead, cadmium, nickel, cobalt, antimony, and tin(IV) require concentrated hydrochloric acid for decomposition others, such as mercury(II) sulphide, are insoluble in concentrated hydrochloric acid, but dissolve in aqua regia with the separation of sulphur. The presence of sulphide in insoluble sulphides may be detected by reduction with nascent hydrogen (derived from zinc or tin and hydrochloric acid) to the metal and hydrogen sulphide, the latter being identified with lead acetate paper (see reaction 1 below). An alternative method is to fuse the sulphide with anhydrous sodium carbonate, extract the mass with water, and to treat the filtered solution with freshly prepared sodium nitroprusside solution, when a purple colour will be obtained the sodium carbonate solution may also be treated with lead nitrate solution when black lead sulphide is precipitated. 

SAFETY PROFILE Confirmed human carcinogen. Poison by ingestion and intraperitoneal routes. Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes. See also NICKEL(II) ACETATE and NICKEL COMPOUNDS. 

Raney nickel can be purchased in a form which is ready for use (W-2), or can be prepared by published procedures which furnish catalysts with a range of activities. The increase in selectivity of Raney Ni catalysts upon aging apparently results from the formation of CO by the decomposition of the ethanol under which the catalyst is usually stored. Highly regio- and stereo-selective catalysts are prepared as slurries by the reduction of the metal acetates, and are used in situ or stored for later use. P-2 nickel is prepared by reducing an aqueous alcoholic solution of Ni(OAc)2 with NaBH4. More recently, highly selective Ni and Pd catalysts were prepared by the reduction of Ni(OAc)2 or Pd(OAc)2 with NaH and f-pentyl alcohol in THF. ... 

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