Impregnation, onto clays

Recently this approach has been extended to parallel combinatorial library synthesis. One example is the solvent-free synthesis of a 96-member library of substituted pyridines via a one-step Hantzsch-3CC conducted in 96-weU micro titer filter plates (Scheme 2.3-12). Here the p-ketoester and aldehyde reagents were impregnated onto a 5 1 bentonite clay-ammonium nitrate mixture. Irradiation for 5 min in a domestic MW oven, followed by washing the product off the support into a receiver daughter plate gave substituted-pyridine products in >70% purity overall. 

Kaminsky [92] was the first to report a method in which the filler surfaces were treated with metallocene-based catalyst for the production of filled polyolefins. In this method, at first under inert atmosphere, the clay surface is treated with an alkylaluminum compound to reduce the residual water content. In the second step, the catalyst or cocatalyst solution is impregnated onto the clay surface followed by washing with an anhydrous solvent to avoid excess catalyst leaching from the support during the polymerization. Additional alkylaluminum compounds may be used during the course of polymerization. This polymerization-filling technique is a widely used procedure for the synthesis of polymer/clay nanocomposites using coordination catalysts [60, 93, 94]. 

Reactants are first impregnated as neat liquids onto solid supports such as aluminas, silicas and clays or via their solutions in an adequate organic solvent and further solvent removal in the case of solids. Reaction in dry media is performed between individually impregnated reactants, followed by a possible... 

Denecke MA, Reich T, Pompe S, Bubner M, Heise KH, Nitsche H, Allen PG Bucher JJ, Edelstein NM, Shuh DK, Czerwinski KR (1998b) EXAFS investigations of the interaction of humic acids and model compounds with uranyl cations in sohd complexes. Radiochim Acta 82 103-108 Dent AJ, Ramsay JDF, Swanton SW (1992) An EXAFS study of uranyl ions in solutions and sorbed onto sihca and montmorillonite clay colloids. J Colloid Interface Sci 150 45-60 d Espinose de la Caillerie J-B, Kermarec M, Clause (1995a) Impregnation of y-alumina with ( ) and ( ) ions at neutral pH Hydrotalcite-type coprecipitate formation and characterization J Am Chem Soc 117 11471-11481... 

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