Hydrogenation of Organic Compounds 

Introduction

Hydrogenation is a process of major industrial importance. Gaseous H2 has relatively low solubility in conventional organic solvents, placing significant limitations on reactions such as hydrogenation, which involve addition of H2 to substrates. By contrast, H2 is completely miscible with supercritical fluids such as scCO2 (TC = 31.1°C, PC = 73.8 bar) or scPropane (TC = 96.8°C, PC = 42.6 bar). Our research group was one of the first to exploit this miscibility to synthesise highly labile organometallic dihydrogen compounds.

Continuous flow reactors provide a simple means of increasing the yield from a supercritical reaction without increasing the overall size of the apparatus. Our other web pages describe a miniature flow reactor for synthesis and isolation of organometallic compounds. In collaboration with Thomas Swan & Co. Ltd, we have now built a reactor which can be used for continuous catalytic hydrogenation of a wide range of organic compounds with high efficiency.

Continuous Supercritical Hydrogenation

Hydrogenation under supercritical fluid conditions has several advantages:-

Hydrogenation of Cyclohexane

Most of the reaction parameters (temperature, pressure, flow rate, concentration of H2, etc.) can be controlled independently. This allows conditions to be optimised to give high selectivity for a particular product in reactions where several products can be generated. A wide range of organic funtional groups can be hydrogenated with very high conversion and selectivity.

Other Hydrogenations carried out in Carbon Dioxide


 
 

The continuous flow reactor can also be used to investigate other continous reactions, such as Friedel-Crafts Alkylations, Etherifications and Hydroformylations.


Further Information

For further information please contact M. Poliakoff


Key Publications from Nottingham

  1. Continuous Hydrogenation of Organic Compounds in Supercriical Fluids, M. G. Hitzler and M. Poliakoff, Chem. Commun., 1997, 1667-8
  2. The Selective Catalytic Hydrogenation of Organic Compounds in Supercritical Fluids as a Continuous Process, M. G. Hitzler, F. R. Smail, S. K. Ross and M. Poliakoff, Organic Process Research & Development, 1998, 2, 137-46
  3. Continuous Hydrogenation in Supercritical Fluids, T. Tacke, C. Rehren, S. Wieland, P. Panster, S. K. Ross, J. Toler, M. G. Hitzler, F. R. Smail and M. Poliakoff in “Catalysis of Organic Reactions” (Ed. Herkes), Marcel Dekker, New York, 1998.

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Page created by: Simon Poliakoff


Created: July 1997
Last Revised: January 2001