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Krzemoorganiczne pochodne B-diketonów : synteza, właściwości i główne zastosowania

Urbaniak W.

Wiadomości Chemiczne

2001

[Z] 55, 9-10

859-882

Organosilicon derivatives of b-diketones of a general formula (1) have a wide range of possible applications, mainly because of the presence of b-diketonate moiety showing excellent properties of metal ion chelation and relatively easily undergoing conversion to other groups, as shown in Scheme 1. A particularly interesting subject of study are the compounds whose substituent R contains silyl groups (see formula (3)), capable of reacting with surface hydroxyl groups of inorganic support, e.g. silica, or of formation of polysilioxane polymers, as shown in Scheme 2. In the paper, two most often used methods of synthesis of this group of compounds: hydrosilylation and halogen substitution are discussed on the example of derivatives of acetylacetone, the most common representatives of 1,3-diketones. Catalytic hydrosilylation of the derivatives containing unsaturated carbon-carbon bond in the substituent is usually non-selective and proceeds on both -C=C- bond and carbonyl groups. More effective method is substitution of halogens in the organic group of an appropriate organosilicon compound, usually of the type described by formula. This reaction is also non-selective, since besides the desired products of C-alkylation a substantial amounts of the products of O-alkylation appears. However, a careful choice of solvents and other reagents e.g. a considerable amount of NaI, increases the selectivity towards the C-alkylation products and allows obtaining them in high yields. In the article the problems related to the products purification and identification by spectroscopic methods are also presented. Exemplary applications of the support modified with b-diketonate moiety for immobilisation of amino acids and metal ions are discussed in detail. The immobilised metal complexes have been applied as stationary phases in gas chromatography and as the starting material for composites containing nanometer-sized metal particles of a controllable and uniform size in an inorganic matrix for magnetic and electronic applications and for use as heterogeneous catalysts or oxygen absorbers.