Chapter

Heterogenized Homogeneous Catalysts for Fine Chemicals Production

Volume 33 of the series Catalysis by Metal Complexes pp 283-359

Date:

Chemoselective and Enantioselective Hydrogenations on Immobilized Complexes

  • Agnes ZsigmondAffiliated withDepartment of Organic Chemistry, University of Szeged Email author 
  • , Ferenc NotheiszAffiliated withDepartment of Organic Chemistry, University of Szeged
  • , Petr KlusonAffiliated withDepartment of Organic Chemistry, University of Szeged
  • , Tomas FlorisAffiliated withDepartment of Organic Chemistry, University of Szeged

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Abstract

Homogeneous catalysts, which are mixed with the reactants at the molecular level, typically show the highest activity and selectivity as they offer chemically well-defined active sites and are not limited by heat and mass transport. However, an inherent disadvantage of the homogeneous catalysis is the need to separate the catalyst from a product after the reaction. Therefore, solid or immobilized homogeneous catalysts are preferred in industry. In this contribution we pay attention to chemoselectivity, regioselectivity and enantioselectivity in the synthesis of fine chemicals by means of hydrogenation reactions with immobilised homogeneous complexes. Preferential hydrogenation of one functional group in a molecule over another is the chemoselective process, while regioselective hydrogenation is the preferential formation of one constitutional isomer of the product in a reaction in which other isomers may also be formed, and the stereoselective hydrogenation is the formation of an excess of one stereoisomer over others. Homogeneous and heterogeneous catalytic transfer hydrogenations (CTH) were additionally introduced as alternative methods to the classical hydrogenation processes. They utilise a different hydrogen source from molecular hydrogen and can find their use for reduction of any type of groups.