Aluminium ethoxide

Ethanol [64-17-5] M 46.1, b 78.3 , d 0.79360, d 0.78506, n 1.36139, pK 15.93. Usual impurities of fermentation alcohol are fusel oils (mainly higher alcohols, especially pentanols), aldehydes, esters, ketones and water. With synthetic alcohol, likely impurities are water, aldehydes, aliphatic esters, acetone and diethyl ether. Traces of benzene are present in ethanol that has been dehydrated by azeotropic distillation with benzene. Anhydrous ethanol is very hygroscopic. Water (down to 0.05%) can be detected by formation of a voluminous ppte when aluminium ethoxide in benzene is added to a test portion. Rectified... 

This view is supported by the fact that aldehydes are actually condensed to esters by aluminium ethoxide (Tistschenko). 

Related to the Cannizzaro reaction there is a reaction discovered by Meerwein,1 in which an aldehyde is converted into an alcohol by the action of aluminium ethoxide. 

An X-ray single crystal study of the repeatedly reported crystals of iron ethoxide has shown that this compound (as well as isomorphous to it crystalline aluminium ethoxide ) is actually an oxocomplex- [Fe502(0Et)11]2,3Et0H (Fig. 6.4) [1365, 1785], The fragmentation products of such big molecules... 

Dispersion polymerization has also been applied to the ring opening polymerization of e-caprolactone and lactide in heptane-dioxane (4/1 v/v) with poly(dodecyl methacrylate)-g-poly(e-caprolactone) as stabilizer [97]. Diethyl-aluminium ethoxide and tin(II) 2-ethylhexanoate were used as initiators in these two systems, respectively, to obtain functional microspheres with a narrow particle size distribution and a narrow molecular weight distribution [98]. Table 2 provides an overview of microspheres obtained by living dispersion polymerization. 

Tishchenko reaction When aldehydes are treated with aluminium ethoxide, one molecule is reduced while the other is oxidised, and the product is the resulting ester.This reaction involves a hydride anion transfer. With more basic alkoxides, aldehydes with an a-hydrogen undergo the aldol reaction. 

It is prepared by the interaction of a solution of bromine with aluminium ethoxide or preferably aluminium isopropoxide. 

In Europe, acetaldehyde has also been largely displaced as a feedstock for acetic acid, though some producers have sought to retain a share indirectly by producing ethyl acetate (ethyl ethanoate) via the low-temperature Tishchenko reaction catalysed by aluminium ethoxide ... 

As the product Al(OPr )(OBu )2 is found to be dimeric it was suggested that aluminium atoms on being surrounded by bulky isopropoxy and tert-butoxy groups in a structure of the type (2-1), are shielded so effectively that the lone pair orbital of the oxygen atom of another tert-butyl alcohol molecule cannot approach sufficiently close to the d orbitals of aluminium for the interaction to be initiated. A finer difference in susceptibilities to steric factors was further demonstrated by the fact that with aluminium ethoxide, some further (albeit extremely slow) replacement was possible. 

Oliver and Worrall also investigated the mass spectrum of aluminium ethoxide and the proposed mass fragmentation pattern appears to indicate that in addition to tetrameric and other lower species, some pentameric species are also present and the fragmentation scheme of Fig. 2.9 can be deduced for different mass ion peaks ... 

In view of the earlier observation that the aldehydes react with nitroparaflins to form nitroalcohols in the presence of catalysts such as NaOH, NaHC03, KOH, K2CO3, and Na, Villani and Nord observed that the reaction could also be catalysed with the weakly acidic aluminium ethoxide or the weakly basic Mg[Al(OEt)4]2. 

A new catalyst in which chromocene was supported on silica gel was developed by Union Carbide" for use in gas-phase polymerization reactions. A typical catalyst contained about 2.5% by weight of chromium, and was activated by the addition of small amounts of alkylaluminium alkoxides, such as diethyl-aluminium ethoxide. Use of such a catdyst formulation gave rise to a polymer with much narrower molecular weight distributions. The average molecular weight could be controlled by the addition of hydrogen, which caused termination of the growing chain. 

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