Aluminum powders, preparation

Production of both monobasic aluminum diformate, (HO)Al(OOCH)2, and monobasic aluminum formoacetate, (HO)Al(OOCH) (OOCCH ), has declined. One reason could be the ready substitution of inexpensive aluminum formate solution (17—19) for soHd aluminum acetate in formoacetate in most of the common commercial appHcations. Monobasic aluminum formoacetate, mol wt 148.05, mp 350°C, is a fine crystalline powder, prepared from aluminum metal. It is used for fabric water repeUency and in the tanning of coUagen tape for surgical sutures (10). 

Aluminum acetylsaHcylate is a tasteless, nonbasic, stable, alternative therapeutic salt to aspirin (83). Also called aluminum aspirin, it is an insoluble white to off-white powder prepared by reaction of aluminum isopropoxide with sodium acetylsaHcylate in an organic solvent. The product precipitates from the reaction mixture (83). Standards requke that aluminum aspirin contain not less than the equivalent of 80% aspirin, corresponding to 90% purity on an anhydrous basis. The aluminum oxide assay must be 12—17% (81). 

Aluminum powder—Cl Pigment Metal 1, Cl No. 77000, EEC No. E 173. Finely divided particles of aluminum prepared from virgin aluminum [7429-90-5]. It is free from admixture with other substances. 

Triethylaluminum is prepared from aluminum powder, ethylene, and hydrogen according to the reaction sequence ... 

The preparation of ferrovanadium by this route is carried out batchwise in refractory-lined open reactors, with vanadium pentoxide, aluminum powder, iron scrap and lime or fluorspar constituting the charge. The reactions once initiated, proceed briskly to completion. The reaction heat is sufficient to melt the ferrovanadium and the alumina-lime/fluor-spar slag, which readily separate due to density difference. The aluminothermic ferroalloy product contains practically no carbon. 

Although several phenyl derivatives of the lanthanides and actinides have been characterized, only one re-arene complex of the / transition metals is known to date. This is the uranium(III) benzene complex, U(AlCl4)s CeHe 153), prepared by the combination of uranium tetrachloride, aluminum trichloride and aluminum powder in refluxing benzene, the Fischer-Hafner method [154). The molecular geometry of the complex is shown in Fig. 18. 

Niobium was prepared in the metallic state for the first time by Blomstrand in 1866, later by Moissan, and still later, by Goldschmidt. While Blomstrand reduced niobium chloride with hydrogen to form niobium, Moissan and Goldschmidt reduced the oxide with carbon (in an electrical furnace) and aluminum powder, respectively. 

Figure 5.82 The strength of different dispersion-strengthened alloys relative to the pure metal strength as a function of relative temperature. Preparation techniques include sintered aluminum powder (SAP), internal oxidation, and salt decomposition. Reprinted, by permission, from A. Kelly, Composite Materials, p. 62. Copyright 1966 by American Elsevier, Inc.

Ten grams of the prepared chromium (III) chloride, 8g of aluminum powder, 30g of aluminum chloride, and 27g of biphenyl are intimately mixed by shaking in a clean, dry, stoppered 250ml bottle. The mixture ia rapidly poured into a 150ml beaker and covered with an even layer of three to four grams of biphenyl. 

Aluminum oxide sols are successfully used for application of films [1794, 1793], such as high area films for hybrid circuits [1236]. The same technique was used for the preparation of J-A1203 (NaAlnO,7) in this case alcoholic solutions of NaOR were added to aluminum alkoxide solutions [1795, 1038]. To increase the stability of sols, aluminum alkoxides are frequently modified with acetic acid [1570] or (3-diketones [1659]. Alumina sheets are commercially produced by the sintering of high-purity fine A1203 powders prepared by hydrolysis of modified Al(OPr )3 [1236]. To prepare powders with spherical species from dilute solutions, hydroxopropylcellulose was added to prevent... 

This technique for preparing diethylaluminumchloride presents few problems. However, aluminum powder should be activated, otherwise the formation of triethylaluminum sesquichloride starts much later but proceeds autocatalytically, releasing a lot of heat, which greatly increases the pressure in the reactor and even causes explosions. The formation stage of diethylaluminumchloride is not so active however, the process should be strictly controlled (because the reaction releases heat) and the ion should be supplied from the components gradually. 

As in the previous procedures, to prepare aluminum oxide, all you need to do is place the dried mass of hydrated aluminum hydroxides (prepared in step 1) into a crucible and then heat at 600 to 800 Celsius using a typical Bunsen burner for about 3 to 4 hours. During the heating process, water is volatized and removed, and the hydrate aluminum hydroxides are dehydrated forming a white powder. After the roasting process, the aluminum oxide is cooled, and then stored in any suitable container. This aluminum oxide is well suitable for use as a filtering aid, and for use in silica gel columns for filtration purification. 

SENSITIVITY - 25 g. of dynamite are required for detonation when prepared with small particle size aluminum powder (300 mesh). Larger aluminum powder yields an explosive that requires more than 100 g. dynamite for detonation. 

Reduction with aluminum powder, for example, in the preparation of benzanthrone, or of quinizarin from purpurin (seldom used). 

Tris(trimethylsilyl)aluminum, AllSifCHOj] (1). The reagent is obtained as the THE complex by reaction of Hg(Si(CH,),]i with aluminum powder in THE (90% yield). Nonsolvated reagent is prepared by reaction of sodium tetrakis(trimethylsilyl)aluminate with AlCl, in pentane. It ignites spontaneously in air dec. at 50°."... 

Chloroaluminate complexes of the general formula Ln( -Arene)( ] -AlCl4)3 (equation 20) were prepared by reacting AICI3 with LnCb in the corresponding aromatic solvent. In some cases, the reactions proceed only with addition of aluminum powder. The first compound of this type, Sm(jj -C6Me6)(AlCl4)3, was reported in 1986. 

Dehydration of cyanohydrins to a, /3-olefinic nitriles has been accomplished by thionyl chloride, phosphorus pentoxide, or anhydrous potassium carbonate. A typical example is the preparation of 1-cyano-1-cyclopentene from cyclopentanone cyanohydrin (75%). Aluminum powder is the best of many catalysts studied for the dehydration of ethylene cyanohydrin to acrylonitrile, HjC=CHCN (80%). ... 

The most advantageous reaction conditions for the preparation are as follows a reaction temperature of 150° 5°, minimum hydrogen pressure of 70 atm, a final concentration of the product of 50-55%, and a 50% theoretical excess of the finest aluminum powder. 

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