Aluminium catalysts

Polymerisations in alkyl chlorides. In Figure 3 of Reference 43 it was shown that the DP of the polymers at first increased with monomer concentration, and then fell off steeply to a quite low value characteristic of the polymerisation of undiluted monomer. The exact nature of the diluent ( alkyl halide ) and catalyst were not disclosed, but it is now known that the diluent was methyl chloride and the catalyst aluminium chloride. Kennedy and Thomas have investigated in some detail this interesting phenomenon [56] Experiments were carried out at -78° in a dry-box To 7.1 g of isobutene and the appropriate quantity... 

Finally, we believe that theory can play a significant role in the design of new aluminium catalysts. Aluminium compounds are more amenable to high-level calculations than transition metal complexes. Because of the lower coordination numbers involved the catalysts tend to be smaller, which also simplifies calculations. As a result, it is frequently possible to carry out reasonably accurate calculations on a real catalyst , so that theory can at times really guide or at least assist experiment. 

Obara et al. (95) co-carbonized a petroleum pitch which gave a coke of mosaic size of optical texture with the strong Lewis acid catalyst, aluminium chloride,which promoted the size of the optical texture and extents of hydrogen transfer to added anthracene. A correlation was established between size of optical texture of the resultant cokes and extents of formation of 9,10-dihydroanthracene plus evolved hydrogen gas. 

The following test materials have often been used FCC catalysts, aluminium oxide, silica gel, glass beads, silica or quartz sand, sea sand, coal and coal ash, petroleum coke, metal powders, resin particles, boric acid, and magnesite powder. Mean particle size ranges from 11 /un to 1,041 /rm, and particle density, from 384 kg/m3 to 7,970 kg/m3. According to Geldart s classification (1973), most of these materials belongs to Class A, some to Class B, and a few to Class D or C, as listed in Table II. 

In the study of catalysts, aluminium NMR is used in order to identify and quantify the various co-ordination states of this nucleus, with some restrictions which will be examined here. 

Solving these equations gives xn-0.18 and X = 0.82. The fact that the iso-form predominates in the equilibrium mixture has been verified by direct observation of the equilibrium at high pressures in the presence of a suitable catalyst, aluminium bromide. 

Without catalyst, we do not obtain at this temperature any fluorinated derivatives (Table 2, entry 1). Several catalysts (Table 1) are suitable for the fluorodecarboxylation of phenylchloroformate to fluorobenzene such as oxyfluoride (Al, entry 2 Cr, entry 4 Zr, entry 5 Ti, entry 10) or fluorides (Al, entry 3 La, entry 6 Ce entry 7 Mg entry 9). The best activity and selectivity is observed using as catalyst aluminium fluoride or oxyfluoride (entries 2 and 3). 

Liquid phase aldol condensation reaction between heptanal and benzaldehyde is studied over two series of oxynitride catalysts aluminium phosphate oxynitrides AlPON and mixed aluminium gallium phosphate oxynitrides AlGaPON , with increasing nitrogen contents (0-14 wt.% for AlPON and 0 - 16 wt. % for AlGaPON ). The main products are jasminaldehyde and 2-pentyl-2-nonenal. Jasminaldehyde is formed via the cross-aldol condensation reaction between heptanal and benzaldehyde and 2-pentyl-2-nonenal is formed via the self-condensation reaction of heptanal. 

Benzene is alkylated by reaction with an halogenoalkane, in the presence of a catalyst. For example, chloroethane reacts with benzene in the presence of the catalyst aluminium chloride to form ethylbenzene ... 

A.3 Lewis Acid/Metal Salt Superacids. - Superacid active catalysts may be obtained by the grinding of aluminium bromide or chloride with some salts. The reaction of AlBr with titanium, copper, iron, aluminium, nickel sulphates, aluminium or titanium chlorides results in catalytic systems able to initiate n-pentane isomerization even at room temperature.The soluble complex of AlBr-j with salts is a true catalyst. Aluminium trichloride... 

Porous carbon electrodes coated with catalysts Aluminium-vanadium mixed oxides H2SO4 Oxidation Wiesener (1973)... 

Titanium is the real catalyst aluminium serves only at the beginning to initiate the reaction by alkylation. The alkylated titanium surface-complex produced in this way has a ligand vacancy (empty orbital) oriented in a cavity for an olefin to make a Ti-complex (Fig. 4.2). 

The hemilabile nature of amine sidearm may play a role in the catalytic cycle since it could reversibly coordinate to the Ti center, thus stabilizing a highly reactive intermediate. Recently, several catalyst systems are reported to be able to effectively catalyze the hydroamination of carbodiimides and offer good yields, which includes alkaline metal catalysts,aluminium catalysts," and rare earth metal catalysts. The mechanisms are also proposed to undergo the similar insertion-protonation pathway. All of these mechanisms are significantly different from that is proposed for imido catalyst systems. The latter involves Ti=N species (Scheme 21.8). 

Many catalysts have been used but the standard catalysts are generally mixtures of silica and alumina or natural or synthetic aluminium silicate zeolites. 

Besides stmctural variety, chemical diversity has also increased. Pure silicon fonns of zeolite ZSM-5 and ZSM-11, designated silicalite-l [19] and silicahte-2 [20], have been synthesised. A number of other pure silicon analogues of zeolites, called porosils, are known [21]. Various chemical elements other than silicon or aluminium have been incoriDorated into zeolite lattice stmctures [22, 23]. Most important among those from an applications point of view are the incoriDoration of titanium, cobalt, and iron for oxidation catalysts, boron for acid strength variation, and gallium for dehydrogenation/aromatization reactions. In some cases it remains questionable, however, whether incoriDoration into the zeolite lattice stmcture has really occurred. 

Aluminium chloride is used extensively in organic chemistry as a catalyst, for example in the Friedel-Crafts reaction ... 

Halogen derivatives of silanes can be obtained but direct halogena-tion often occurs with explosive violence the halogen derivatives are usually prepared by reacting the silane at low temperature with a carbon compound such as tetrachloromethane, in the presence of the corresponding aluminium halide which acts as a catalyst. 

Hydrogen bromide may also be prepared by dropping bromine into benzene containing aluminium powder, which acts as a catalyst to the reaction ... 

The halogen carriers or aromatic halogenation catalysts are usually all electrophilic reagents (ferric and aluminium haUdes, etc.) and their function appears to be to increase the electrophilic activity of the halogen. Thus the mechanism for the bromination of benzene in the presence of iron can be repre-sfflited by the following scheme ... 

By passing a mixture of carbon monoxide and hydrogen chloride into the aromatic hydrocarbon in the presence of a mixture of cuprous chloride and aluminium chloride which acts as a catalyst (Gattermann - Koch reaction). The mixture of gases probably reacts as the equivalent of the unisolated acid chloride of formic acid (formyl chloride) ... 

The effect of ligands on the endo-exo selectivity of Lewis-acid catalysed Diels-Alder reactions has received little attention. Interestingly, Yamamoto et al." reported an aluminium catalyst that produces mainly exo Diels-Alder adduct. The endo-approach of the diene, which is normally preferred, is blocked by a bulky group in the ligand. 

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