The fluorous phase: organic chemistry with highly fluorinated reagents and solvents

Abstract

A review with 41 refs. is given. Perfluorinated hydrocarbons and related ethers and amines have emerged only recently as unique solvents with interesting applications in org. synthesis. Since they are immiscible with water and with many common org. solvents, they represent a third liq. phase commonly called the fluorous phase. Their high soly. for oxygen allows some efficient and selective aerobic oxidn. reactions under mild conditions. Individual components of a reaction mixt. (products and byproducts, excess of substrates and reagents), which bear perfluoralkyl substituents of sufficient size and no., can be selectively extd. into the fluorous phase. This is the basis of the so-called fluorous synthesis, a new sepn. and purifn. technique taking advantage of org./fluorous and fluorous/org. phase switches. A technique called fluorous biphase catalysis exploits not only this principle but also the ability of certain perfluorocarbon/hydrocarbon (aroms.) biphase mixts. to form a homogeneous soln. at elevated temp. A highly fluorinated catalyst can thus be applied under homogeneous conditions and can be recovered from the fluorous phase after phase sepn. at lower temps. [on SciFinder (R)]