Perfluoroalkanes, biphasic catalysis using

A second approach to biphasic catalysis uses a fluorous (i.e. perfluoroalkane) phase instead of an aqueous phase. We must immediately draw a distinction between the higher C perfluoroalkanes used in fluorous biphasic catalysis and the low-boiling CFCs that have been phased out under the Montreal Protocol (see Box 13.7). The principle of fluorous biphasic catalysis is summarized in scheme 26.22. 

The miscibility of perfluoroalkanes and other perfluoro solvents is low with corresponding hydrocarbon solvents and is exploited in fluorous organic biphasic catalysis.27 In some cases, apolar reactants may be dissolved in the fluorous phase and on conversion to higher polarity products a second immiscible phase is formed. Notable examples of catalyzed reactions that are effectively carried out using the fluorous biphase approach are hydroformylations28 and oxidations.29 It should be noted that fluorous solvents are damaging to the environment, however, as with other catalyst immobilization solvents, if they are not lost from the system no damage to the environment takes place. Fluorous biphase systems have not, as yet, been used on an industrial scale. 

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