Multiphase systems for the recychug of alkoxycarbonylation catalysts

This review evaluates the various multiphasic systems that have been developed for catalyst recycling in the context of alkoxycarbonylation of alkenes and alkynes. Immobilization of the catalyst on an insoluble support, such as silica, alumina, clay or a polymer, as well as immobilization in the inorganic phase of several liquid/liquid biphasic systems (aqueous/organic, ionic liquid/organic, fluorous/organic or supercritical CO2/organic) has been described. In several cases detailed information on the efficiency of catalyst separation and recycling is available. Most of the work was focused on the alkoxycarbonylation reactions of alkenes, for which several efficient methods for catalyst recycling were demonstrated. The recycling of catalyst through specific precipitation from supercritical CO2 or selective dissolution in a fluorous phase, has received only scant attention but offers many opportunities for further improvement. 1 Introduction 2 Alkoxycarbonylation and Recycling using Catalysts Immobilized on Insoluble Supports 2.1 Immobilization on Silica and Montmorillonite 2.2 Immobilization on Insoluble Polymeric Supports 3 Alkoxycarbonylation Reactions and Catalysts that can be Recycled using Biphasic Systems 3.1 Use of Aqueous Biphasic Systems in Alkoxycarbonylation Reactions of Alkenes 3.2 Use of Ionic Liquids in Alkoxycarbonylation Reactions of Alkenes 3.3 Use of Supercritical CO2 in Alkoxycarbonylation Reactions 4 Conclusions