An exploration of Silsesquioxanes and Zeolites using High-Speed experimentation

Abstract

Combinatorial Chemistry and High-Speed Experimentation techniques allow the rapid preparation and testing of large numbers of samples by using automated workstations. These techniques are increasingly applied to various fields of chemical research and particularly to catalysis. In this project, High-Speed Experimentation techniques were used to study two families of compounds with a silicon-oxygen framework: silsesquioxanes and zeolites. Silsesquioxanes are inorganic-organic hybrid materials with broad applications as model compounds for silica surfaces and as ligands in coordination chemistry and catalysis. Here, the synthesis of incompletely condensed silsesquioxanes as precursors for titanium catalysts active in the epoxidation of alkenes was optimised by means of High-Speed Experimentation techniques. This thorough study led to the identification of a number of trends, to new and more efficient methods to synthesise known silsesquioxanes and to the discovery of new silsesquioxane precursors for active catalysts. The most interesting results were reproduced at a conventional laboratory scale and the silsesquioxane products were fully characterised. One of these silsesquioxane structures was used to prepare an osmium complex that proved to be a useful model compound for a known heterogeneous catalyst and an active and safe homogenous catalyst for the dihydroxylation of alkenes. Zeolites are microporous crystalline materials with applications as heterogeneous catalysts, ion-exchangers and molecular sieves. The synthesis of aluminium-rich zeolite beta was investigated by means of High-Speed Experimentmation techniques in order to identify the lowest Si/Al ratio to obtain pure zeolite beta with hydrothermal methods.Applied Science