Multiphase Systems for the Recycling of Alkoxycarbonylation Catalysts

Abstract

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 CO 2 /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 CO 2 or selective dissolution in a fluorous phase, has received only scant attention but offers many opportunities for further improvement.

ILs in Transition Metal-Catalysed Alkoxy- and Aminocarbonylation

“…In these procedures, valuable carboxylic acids, such as linear fatty acids or branched 2-arylpropanoic acids (the latter used as nonsteroidal anti-inflammatory agents (ibuprofen, naproxen and ketoprofen)), can be obtained. As a consequence, a significant research effort has been devoted to find adequate catalyst recycling methods [9] to facilitate largescale applications. Amongst immobilisation methodologies, the use of ILs can be particularly interesting.…”

Synthesis of MCM-41 Immobilized (Phenoxy)Imine Palladium(II) Complexes as Recyclable Catalysts in the Methoxycarbonylation of 1-Hexene

“…Heterogeneous catalysts, on the other hand, are easily recoverable, but they too have several drawbacks, mainly associated with low catalytic activities and poor selectivity [2]. This has necessitated a search for catalyst systems that can exploit the advantages and limit the disadvantages of both homogeneous and heterogeneous catalysts [3,4]. Thus, the immobilization of homogeneous catalysts to give a hybrid system which is recoverable and selective is currently of much interest in catalyst design and development [5,6].…”

Palladium–Bis(carbene) Catalysts for the Bisalkoxycarbonylation of Olefins to Succinic Diesters

“…Pd complexes bearing various ligands have been employed in the coupling of olefins to carbon monoxide (CO) to afford polyketones and mono‐ and diesters . Depending on the structure of the ligands and the reaction conditions, two reaction pathways are possible, that is, polymerization and monomer formation (Scheme ).…”