Fluorous Solvents and Catalysts

In their seminal publication Horvath and Rabai [121] introduced the term ''fluorous'' in analogy with ''aqueous'' to emphasize the peculiar properties of perfluorohydrocarbons (and related perfluoroalkylethers and amines) as reaction media and quickly the word was extended to perfluoroalkyl-labeled organic compounds, that have today broad application in synthesis and separation techniques [122]. Fluorous solvents, some of which are shown in Scheme 3.17, display

F3CaCCCCF3 F2 F2

Perfluorohexane FC-72

F2 O

HFE-7200

ponytail _A_

spacer fluorous m = 0,1...m alkyl chain

CnF2n+2

2F HFE-7500

'CF3

F-626

Me Me

Me Me

Silica HO

Fluorous silica gel

Silica HO

Fluorous silica gel

Scheme 3.17 Fluorous solvents, ponytails and silica gel

(a) biphasicl iquid-liquid separation organic S R solvent S R

fluorous Cf solvent cf heating

SS Cf cooling

S=substrate

R=reagent

P=product

Cf= fluorous catalyst

(b) temperature-dependent solubility of fluorous catalysts organic S R

solvent S

heating cooling

(c) fluorous solid-phase extraction organic R solvent S

reaction mixture residue

Cf f Cf

0 0

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