Fluorous metallic catalysis catalysts

These critical aspects of the classical fluorous biphasic catalysis led in recent works to the development of protocols for the conversions with modified catalyst systems in non-fluorinated hydrocarbons as solvents. As part of the BMBE lighthouse project, Gladyzs and coworkers appHed this concept to C - C coupHng reactions (Suzuki reaction) and other metal-catalyzed addition reactions (hydrosilylation, selective alcoholysis of alkynes), which have direct relevance for the synthesis of fine chemicals and specialties [74]. 

The value of perfluoroalkyl-derivatised ligands in FBS catalysis depends on the preferential solubility of the catalyst in a fluorous solvent. Initially, this was established, qualitatively, by 31P NMR spectroscopic studies [37,49], but very recently [52] the fluorous partition coefficients of metal complexes of the trialkyl phosphine (la) have been measured analytically, from which both a fluorine content of > 60% and the number of perfluoroalkyl groups, which shield the hydrocarbon domain of the complex, are crucial for a high fluorous partition. 

Adsorption on silica gel surfaces or silica gels coated with water or thin layers of ionic liquids has been used to immobilize transition metal complexes % ionic interactions and hydrogen bonding. Reversed-phase silica gels were used to retain catalysts by hydrophobic interactions. Support of catalysts on fluorous reversed-phase silica gel by the solvophobic nature of perfluoroalkyl chains is a new and promising approach with potential in catalysis and combinatorial chemistry. 

Another attractive line of application of macromolecular complexes as catalysts is the so-called fluorous catalysis, whose idea was proposed in the early 1990s [163-168]. The main idea of such catalysis is that a catalyst is soluble (immobilized) in the perfluorocarbon phase, whereas the product is soluble in an organic solvent. If a suitable solvent for substrates, e.g. toluene or benzene, is used, then the system at sufficiently high temperature is homogeneous, and on cooling, there is phase separation. As a result, the solution of the metal complex in fluorocarbon is readily separable from the reaction products and can be reused. 

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