Other Aluminium Compounds

Other Aluminium Compounds.—The new tetragonal ternary tellurides MM Te (M = Sr or Ba M = Al, Ga, or In), Ba7AleTeig, NaInTe2, and KlnTeg have been synthesized, and crystal parameters determined.  

body-centred-cubic structure V3AI has been prepared from the elements at high temperature and pressure.  

The phase CU3AI2 has a crystal structure of the partially filled NiAs type, and CuAl has a structure which may be described as a vacancy variant of the CsCl structure.  

Mass-spectrometric analysis of the species present in the vapour above an Al-Cu alloy in the range 1157—1882 K has led to a value for the dissociation energy of AlCu (AHo = 50.9 2.5 kcal mol ).  

The dissociation energies (Aq) for the gaseous metallic species AlAg and AlAu have been obtained by Knudsen-cell mass spectrometry. The values were 180 9 and 325 13 kJ mol , respectively, in line with relative bond strengths in the alloys. Similar data have been obtained by this technique for AlAua (506.3 25.1 kJ mol ) and AlsAu (460.2 20.9 kJ mol ).  

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Critical investigations (2) (25-27) have shown that none of these processes are sufficiently selective. It has been found that certain aluminium-oxygen compounds are converted partially in exactly the same manner as metallic aluminium. Other aluminium compounds, particularly in aluminium-silicon alloys, remain in the isolation residues to a certain extent and are thus incorrectly determined as oxygen. Residues of metallic aluminium must also be expected in the fractions isolated. 

Many of the uses of boron and aluminium compounds have already been discussed. The elements and a number of other compounds also have important applications. 

Antimony and other inorganic compounds (tin, molybdenum, aluminium, magnesium, iron, boron, with ATH accounting for about 40 % in volume of FR shipments in Europe). 

Dry mixtures of picric acid and aluminium powder are inert, but addition of water causes ignition after a delay dependent upon the quantity added. Other nitro compounds and nitrates are discussed in this context. 

Interaction with aluminium carbide is incandescent, and with caesium acetylide at 350°C is explosive. Other related compounds may be expected to be oxidised violently if unmoderated. 

ETL materials that are used most often are emissive metal complexes, especially aluminium but also beryllium and lanthanides such as europium and terbinm, of ligands such as 8-hydroxyquinoUne, benzoquinolines and phenanthroUne, whilst other effective compounds inclnde extended conjugated compounds, e.g. distyrylarylene derivatives. Some ETL materials are chosen because they are non-emissive to act as combined ET and hole blocking layers. A selection of these ETL materials is illustrated in Figure 3.35. 

Last, but not least, the development of ternary catalyst systems consisting of a metallocene, an organoborate, and an aluminium compound will reduce the manufacturing costs of mPE and will improve its ability to compete with other polymers. 

Under conditions of diffusion control, the TiAl3 layer, known to be the first to occur between titanium and aluminium, consumes all the aluminium atoms diffusing across its bulk exclusively for its own growth, not sharing them with the other intermetallic compound layers. Therefore, those or at least one of them can grow only at the expense of diffusion of the titanium atoms. 

Note that only ca 1% of the titanium atoms introduced with TiCl3 into the system give rise to the formation of surface active sites (since most of the titanium atoms remain inside the solid TiCl3 particles) [40], However, such active sites exhibit rather low stereospecificity in propylene polymerisation. The activity and stereospecificity of catalysts based on the / -TiCl3 modification also depend on the type of alkyl aluminium compound used as the activator. The application of triethylaluminium leads to a catalyst of much higher activity but of much lower stereospecificity, and on account of this diethylaluminium chloride is used for the polymerisation of propylene and other a-olefins, while triethylaluminium (and also triisobutylaluminium) is used for ethylene polymerisation [28],... 

In systems containing no anion other than fluoride, mixed aqua-fluorometalates mainly with [MF5(H20)] and [MF4(H20)2] are frequently formed. Therefore the possibility of H-bond formation plays an important role see Hydrogen Bonding Dihydrogen Bonding). The most investigated systems contain Al , Fe , Mn (surveys in Refs. 18, 113), and Aluminium compounds are... 

Other chromium catalysts for ethylene polymerization employ chromo-cene [246] and bis(triphenylsilyl) chromate [247] deposited on silica-alumina. The catalyst support is essential for high activity at moderate ethylene pressures (200—600 p.s.i.). The former catalyst is activated further by organo-aluminium compounds. Polymerization rates are proportional to ethylene pressure and molecular weight is lowered by raising the temperature or with hydrogen (0.1—0.5 mole fraction) in the monomer feed wide molecular weight distributions were observed. 

The only other alkyl compounds known are derivatives of methylene iodide or bromide, aluminium powder reacting with these compounds to produce the type AIX, which are heavy liquids. 

Instead of using a complex metal hydride as the source of the hydride anion, the hydride anion may be donated from a carbon atom. In such a case, the reaction is called the Meerwein-Ponndorf-Verley reduction, or MPV reduction. In contrast to the reduction by a complex metal hydride, the MPV reduction is reversible. It is performed by heating aluminium isoproproxide with an excess of propan-2-ol. Two different routes compete one involves one molecule of the aluminium isoproproxide for each molecule containing a carbonyl group to be reduced, while the other route uses two. Suggest the mechanism that involves only one molecule of the aluminium compound. 

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