ctivation, Tuning, and Immobilization of Homogeneous Catalysis in an Ionic Liquid/Compressed CO_2 Continuous-Flow System

摘要

The quest for new strategies to immobilize organometallic catalysts is one of the major challenges in homogeneous catalysis. Ionic liquids (ILs) are emerging as excellent solvents for transition metal catalysts. In many applications they are used for multiphasic reaction systems because of their miscibility gap with the reaction products.[!] Supercritical carbon dioxide (scCOz) is also of increasing interest because it combines an environmentally benign character with favorable physico-cher:nical properties for chemical synthesis.[z.3] cata- lyst separation schemes have been devised on the basis of the tuneable phase behavior of scCOz (CESS process). [4] We report here anew continuous-flow catalytic system based on the combination of these two solvents systems, which are at the extreme ends of the volatility and polarity scale. We provide convincing evidence that the interplay of their complementary properties offers new intriguing possibilities for catalytic synthesis.