Highly Selective Hydrogenation of Butyl Sorbate to Butyl cis-hex-3-Enoate Using Cp*-Ruthenium (II) Catalyst

Abstract

The Cp*–ruthenium half sandwich complex [Cp*Ru (butyl sorbate)]Tf (Tf = CF3SO 3 − ) was prepared and used as the catalyst for the hydrogenation of butyl sorbate to butyl cis-hex-3-enoate. The stability of the catalyst was increased by the immobilization of the catalyst to the clay material montmorillonite K10 by means of ionic exchange. Prepared material was characterized by XRD, XRF and TGA methods. Hydrogenation of butyl sorbate was carried out in homogeneous and heterogeneous arrangements. The influence of reaction conditions, especially the influence of the solvent type, on the reaction rate and the selectivity was studied. By-products were identified by GC-MS. The optimal conditions for the highest selectivity (up to 98%) were achieved in heterogeneous hydrogenation in methyl tert-butyl ether using the pressure 4 MPa, temperature 50 °C and 5 wt.% of the catalyst related to the butyl sorbate amount. Furthermore, it was demonstrated that the catalyst could be recovered and reused without loss of selectivity.