Aluminum alkoxides, with 0-diketones

Another example of derivatives with interesting structures formed in reactions 7 (147) of aluminum alkoxides with /3-diketones//3-ketoesters (262) may be cited. 

In addition to conventional aikoxide-based syntheses, Williams and Interrante [177] and Pouxviel et al. [175] investigated aluminosilicate gels prepared from organometallic precursors. Williams and Interrante reacted diketonate (chel) aluminum alkoxides with trimethylacetoxysilane forming heterocondensed products according to the following scheme ... 

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... 

The following tables are intended to include all the reductions with aluminum alkoxides which were reported prior to February, 1943, although some examples doubtless have been overlooked. Table I lists the reduction of aldehydes, which have been subdivided into (a) aliphatic aldehydes and (b) alicyclic and aromatic aldehydes. Table II lists the reduction of ketones, which have been classified as (a)-satu-rated and unsaturated aliphatic ketones, (b) aromatic ketones, (c) alicyclic ketones, (d) unsaturated alicyclic and aromatic ketones, (e) a- — halogen substituted ketones, (f) diketones, (g) protected diketones, (h) alcoholic and phenolic ketones (and ethers or esters of these), and (i) keto esters. 

Although formally involving the reaction with a C—H bond, metal alkoxides will react with -diketones and -keto esters to form six-membered chelates and alcohols. Hence the acetyl-acetonate (acac) derivatives of aluminum can be obtained (equation 63). ... 

It was shown (262) that whereas the tris-/3-diketonates are monomeric with hexacoordinated aluminum, the monoalkoxide bis-/3-diketonates dimerize with alkoxide bridges and can be represented by [(/3-dik)2Al(/i-OR)2Al(/3-dik)2], in which both aluminum atoms are hexacoordinated. The dialkoxide mono-/3-di-ketonate, instead of adopting a symmetric structure [(RO)(/3-dik)Al( -OR)2Al(/3-dik)(OR)] with both aluminum atoms in the five-coordinate state shows a structure that can be represented by the unsymmetric [((3-dik)2Al( -OR)2Al(OR)2], in which one of the aluminum atoms is six coordinate while the other is tetra-coordinate. Although higher (74) coordination for aluminum was reported in a number of glycol derivatives (263), the preferential formation of [ 3-dik)2Al(/i-0-i-Pr)2Al(0-/-Pr)2] may be considered to arise from the stability of Al(0-i-Pr)4 moiety, a very large number of derivatives of which were already described (4-8, 14-20, 25-30, 38, 39). 

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