Complex aluminates

A commercial process which uses hydrothermal leaching on a large scale is the Bayer process for production of aluminum oxide (see Aluminum compounds). This process is used to extract and precipitate high grade alurninum hydroxide (gibbsite [14762-49-3]) from bauxite [1318-16-7] ore. The hydrothermal process step is the extraction step in which concentrated sodium hydroxide is used to form a soluble sodium aluminate complex ... 

The lithium 2-butenyl(triethyl)aluminate complex, prepared in situ from 2-butenyllithium and triethylaluminum, displayed poor diastereoselectivity in a reaction with benzaldehyde (anti/syn 56 44)7. (Z)-3-Alkoxy-substituted aluminate complexes such as A-C, however, give good diastereoselectivity in aldehyde addition reactions8. The reactions of A with aldehydes at —100 °C give the jyw-diol monoether with >95% diastereoselectivity and >80-95% regiose-... 

The rubidium aluminate complex RbAlMe2(SC6H3-2,6-Trip2)2155 has also been prepared by the reaction of the rubidium terphenylthiolate with AIMe3 [Eq. (17)]. 

The immobilization of Nd tetramethyl aluminate complexes on porous silica supports (MCM-48) was reported by Fischbach et al. [406,407]. In this study activation was accomplished by DEAC. The polymerization of IP in hexane yielded IR with high cis- 1,4-contents (> 99%). 

Lappert and coworkers also found that such rare-earth metal aluminate complexes can be readily transformed into methyl derivatives by addition of equimolar amounts of donor Lewis base molecules such as pyridine or tetrahydrofuran (Lappert s concept of donor-induced aluminate cleavage, Scheme 1) [10]. Depending on the Lewis acidity of the Ln(III) center homo-... 

In the course of these studies key features such as olefin coordination [19,20], olefin insertion (propagation) [16,21,22], /(-hydrogen elimination [16,21,22], and /3-alkyl elimination [23] could be spectroscopically and structurally proven. In particular, yttrium aluminates have been proposed to model isoelectronic cationic homo- and heterobridged Zr/Al heterobimetallic complexes as dormant species and potential polymer chain transfer candidates [24]. Such zirconium aluminate complexes seem to be elusive [25], while the first structurally characterized titanium alumi-... 

In polar solvents, however, the tetrahedral intermediate A of Figure 14.53 decomposes faster than it is generated, with formation of an aldehyde and ROAl(tBu)2. This solvent effect is explained in Figure 14.53, using THF as an example. The tetrahedral intermediate A contains a trivalent A1 and forms a Lewis acid-Lewis base complex with the solvent. The intermediate A is thus converted into the aluminate complex B, which contains tetravalent Al. The A1 atom in A is bonded to only one O atom, which... 

For the experimental spectrum of first-scan, the result in Figure 15.4 indicates that the network structure of aluminate which consists of Al and O atoms partly remains, although aluminate dissolves in the water and is divided into aluminate complex anions and Na cations. Other chemical species in the aqueous solution is presumed to be [Al(OH)4] and the hydrated ions produced by the hydrolysis of aluminate. The XANES spectral shape of powder of /i-aluminate has been... 

In some rather neat organometallic chemistry, new Sc and Y tetramethyl aluminate complexes supported by a ferrocene 1,1 diamide ligand, [35] have been shown not only to ring-open and link methylimidazole groups, but also to couple pairs of pyridines to generate bipy complexes. The chemistry proceeds by a series of a-bond metathesis steps.77... 

Chiral modification is not limited to boronate and aluminate complexes. Boranes or alanes are partially decomposed with protic substances such as chiral amines, alcohols or amino alcohols to form useful reagents for enantioselective reduction of carbonyl compounds. For example, reduction of acetophenone with borane modified with the amines (65) to (67) gives (5)-l-phenylethyl alcohol with 3.5-20%... 

Materials which have extremely low volatility and the potential to serve therefore as non-reactive substrates and supports include zirconia, titania, and alumina. The rare earth oxides, represented by lanthana and ceria, also show very low volatility and can be expected to resist vapor-transport-assisted sintering and corrosion. Of the alkaline earth oxides, MgO is superior to all others, although the alkaline earth aluminate complex oxides can be much more stable (e. g., by a factor of 1000 for BaO) than the alkaline earth oxides. 

Attempts to prepare AI(SiPh3)j from KSiPhj and AlClj fail. In liq NH3 no compound with an Al—Si bond can be isolated. In tetrahydrofuran (THF) a potassium aluminate complex is obtained in 50% yield ... 

By the reaction of Li, Al and Me3SiCl in the presence of Hg, persilylated compounds are formed in high yields. In a mixture of boiling DME and THF, an aluminate complex is formed ... 

As discussed in 5.3.8.4, Li tetrakis(trimethylsilyl)aluminate complexes are available by the Hg-catalyzed reaction of McjSiCl with Li metal and Al. But the analogous Na and K compounds cannot by synthesized in this direct way. These compounds are formed by ... 

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