Reactions in Fluorous Media

The term fluorous was coined as an analogy to aqueous for highly fluorinated alkanes, ethers and tertiary amines [1], These compounds differ markedly from the corresponding hydrocarbon compounds to the extent that such compounds commonly give bilayers with conventional organic solvents. In this chapter, we will discuss the different approaches towards carrying out reactions in fluorous media and describe how reactants and catalysts can be engineered to be preferentially soluble in fluorous solvents. 

Chemistry in Alternative Reaction Media D. Adams, P. Dyson and S. Tavener 2004 John Wiley Sons, Ltd ISBNs 0-471-49848-3 (Cloth) 0-471-49849-1 (Paper) 

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Chapters 1 and 2 have been reorganised and updated in line with recent developments. A new chapter on the Future of Purification has been added. It outlines developments in syntheses on solid supports, combinatorial chemistry as well as the use of ionic liquids for chemical reactions and reactions in fluorous media. These technologies are becoming increasingly useful and popular so much so that many future commercially available substances will most probably be prepared using these procedures. Consequently, a knowledge of their basic principles will be helpful in many purification methods of the future. 

Figure 7.9 Rate enhancement of a Diels-Alder reaction in fluorous media.

A fluorous acetylacetonate ligand, C7F15COCH2COC7F15, was introduced into metal-catalyzed aerobic oxidation reactions in fluorous media, which appears to be useful for two reasons (1) catalyst recycling is easy (2) the gas is highly soluble... 

Most of the reported work on Mizoroki-Heck reactions in fluorous media applies palladium salts and free ligands. There are only five reports on the usage of preformed fluorous palladium complexes (Table 15.1, entries 1 ) [64-68]. They all used a biphasic system with an organic solvent and a fluorous catalyst that dissolved only at elevated temperatures. Gladysz and coworkers [64, 65] recovered the catalyst 22 in the only patent on Mizoroki-Heck reactions in fluorous media by simple filtration (Table 15.1, entries 1, 2). The first two runs with iodobenzene and methyl acrylate at 100 °C in DMF were almost quantitative after 2 h reaction time (TON 5251), but after the third run at 100 °C the activity decreased (TON 2500-2900) and the authors changed the reaction time in the fourth run to 10 h to receive again quantitative conversion and yield (TON 5251). 

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