Fluorous medium

Fluorous media and supercritical CO2 are, like water and all organic solvents, molecular reaction media. In contrast, ionic liquids are salts formed by mismatched associations of cations and anions. It is usually assumed that salts are solid under normal conditions and that they melt only at very high temperatures for example, NaCl has to be heated to 803 C before it becomes liquid. However, it has been discovered that special pairings of cations and anions can lead to salts that are liquid around room temperature. These salts, called ionic liquids, constitute very promising media as they display many interesting properties. 

The advantages and disadvantages of these solvents are shown in Table 1.1. A number of interesting and useful properties of ionic liquids can be exploited, and a summary of the most important physical and chemical properties of ionic liquids, along with their applications in synthetic chemistry, is shown in Table 1.2. Ionic liquids are sometimes described in the literature using other terms, including 

No vapor pressure Purification difficult, quality variable Non-flammable High viscosity Highly tunable Commercially expensive Easy separation of products and Toxicity not fully understood recycling of catalysts Potential for high solubility of gases Reacts with strong nucleophiles  

Perfluorocarbons (PFCs) came to public notice in the 1960s with the publication of an account of a mouse breathing in this medium. As well as the fact that they dissolve gases (such as oxygen), PFCs have the important property of being easily 

The use of fluorous solvents has proliferated as a result of their attractive features. 

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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. 

L. V. Dinh, J. Gladysz, Transition Metal Catalysis in Fluorous Media Extension of a New Immobilization Principle to Biphasic and Monophasic Rhodium-Catalyzed Hydrosilylations of Ketones and Enones , Tetrahedron Lett. 1999, 40,8995. 

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. 

Syntheses of perfluoroalkylated Xantphos derivatives have been reported normal-sclcctiYC hydroformylation in fluorous media is anticipated to be disclosed. 

Allylzinc halides, with polymer-supported imines, 2, 398 [(7t-Allyl)zirconoxyl]carbenes, preparation, 4, 921 a-Activation, metal fluoroalkyls and fluoroaryls, 1, 735 Altemaric acid, via Alder-ene reactions, 10, 595 Alternative solvents, for green organometallic chemistry fluorous media, 12, 844 ionic liquids, 12, 846... 

Fluoromethylbenzoic acids, metallation, 9, 26-27 Fluoro(phenyl) complexes, with platinum(II), 8, 482 Fluorosilanes, elimination in fluorinated alkene activation, 1, 732 in fluorinated aromatic activation, 1, 731 and hydrodefluorination, 1, 748 Fluorosilicate anions, hypercoordinated anions, 3, 484 Fluorotoluenes, metallation, 9, 21 Fluorous alkylstannanes, preparation, 3, 820 Fluorous biphasic system, as green solvent, 12, 844 Fluorous ligands, with supercritical carbon dioxide, 1, 82 Fluorous media... 

Green chemistry alternative solvents fluorous media, 12, 844 ionic liquids, 12, 846... 

Figure 4.8 Baeyer-Villiger reaction of cyclobutanone in fluorous media [196],...

Catalytic oxidations with hydrogen peroxide have also been performed in fluorous media (Fig. 7.19) [67]. 

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