Advances in thermomorphic liquid/liquid recycling of homogeneous transition metal catalysts

One decisive disadvantage of homogeneous transition metal catalysis is the loss of the transition metal during the work-up of the product mixture. Especially when precious metals are involved the catalytic process is no more economic. Therefore considerable effort has been done with various concepts to overcome the loss of the homogeneous catalyst. In recent years several reports have been published on an integrated downstream processing for catalyst recycling using temperature dependent multi-component solvent systems. In the present contribution this concept has been improved and extended by optimisation of solvent selection and simplification. Potential solvent combinations have been found by using the upper critical solution temperature as selection criterion in addition to the concept of HANSEN solubility parameters. Furthermore a new type of temperature dependent solvent systems consisting of only two solvents has been investigated. (c) 2008 Elsevier B.V. All rights reserved.