Recycling and Separation of Homogeneous Catalyst from Aqueous Multicomponent Mixture by Organic Solvent Nanofiltration.

Organic solvent nanofiltration (OSN) has evolved to an established recycling method for homogeneous catalysts. However, commercial availability has not circumvented the need for classification and the scoping of possible applications for specific solvent mixtures. Therefore, Evonik's DuraMem 300 was assessed for the recycling of magnesium triflate at two transmembrane pressures from a mixture of ethanol, ethyl acetate and water.

Highly Active N,O Zinc Guanidine Catalysts for the Ring-Opening Polymerization of Lactide.

New zinc guanidine complexes with N,O donor functionalities were prepared, characterized by X-Ray crystallography, and examined for their catalytic activity in the solvent-free ring-opening polymerization (ROP) of technical-grade rac-lactide at 150 °C. All complexes showed a high activity. The fastest complex [ZnCl (DMEGasme)] (C1) produced colorless poly(lactide) (PLA) after 90 min with a conversion of 52 % and high molar masses (M =69 100, polydispersity=1.

Concerning the Role of Supercritical Carbon Dioxide in S 1 Reactions.

A series of S 1-type reactions has been studied under various conditions to clarify the role of supercritical carbon dioxide (scCO ) as reaction medium for this kind of transformations. The application of scCO did not result in higher yields in any of the experiments in comparison to those under neat conditions or in the presence of other inert compressed gases. High-pressure UV/Vis spectroscopic measurements were carried out to quantify the degree of carbocation formation of a highly S 1-active alkyl halide as a function of the applied solvent.

Comprehensive monitoring of a biphasic switchable solvent synthesis.

Biphasic reactions were investigated in a specially designed high pressure set-up that allows simultaneous fibre-optic ATR IR and ATR UV-Vis measurements in both phases. The scope of quantitative spectroscopic measurements is tested on the absorption of CO(2) in hexanol and a biphasic switchable solvent synthesis. For both systems, all substances including dissolved and gaseous CO(2) can be quantified and a constant total mass balance over all phases can be achieved for every component in the reaction system.

Ceramic microreactors for heterogeneously catalysed gas-phase reactions.

The high surface to volume ratio of microchannel components offers many advantages in micro chemical engineering. It is obvious, however, that the reactor material and corrosion phenomena play an important role when applying these components. For chemical reactions at very high temperatures or/and with corrosive reactants involved, microchannel components made of metals or polymers are not suited.