Mikroemulsionen als Reaktionsmedien für Suzuki-Kupplungen

Banu Yesilyurt, 2013

Due to their environmental safety and immensely large interface, microemulsions are suitable as a medium for organic synthesis reactions for the ecological and efficient synthesis of fine chemicals. By setting up a three–phase system, it is possible to isolate products, catalysts and by–products through phase separation from each other. However, due to the different extraction tendencies of the various homologs of a technical surfactant, multiple applications of the catalyst containing microemulsion phase drives, with each reaction cycle, a continuous shift of the phase boundaries to higher temperatures. Therefore, the influence of the extraction on the phase behavior of the technical system H₂O – n–heptane – Marlipal^® 24/50 was examined in this work. The consequent phase shift to higher temperatures resulting from extraction was counteracted by two approaches. On the one hand, the phase shift was compensated for by addition of more hydrophobic technical co-surfactants. On the other hand, this effect can be avoided through the use of homologous pure short-chain surfactants. For this purpose, the phase behaviors of the system H₂O – n–decane – C₄E₁ and the system H₂O – n–heptane – Marlipal^® 24/50 were characterized. Subsequently, the speed of the phase separation in the three–phase region of the systems H₂O – n–decane – C₄E₁ and H₂O – n–heptane – Marlipal^® 24/50 was investigated at their mean temperature by eye and using an apparatus to visualize phase separations.