HYDROGENATION OF C6 DIENIC COMPOUNDS USING RUTHENIUM CATALYSTS

Leaf alcohol ((Z)-hex-3-en-1-ol) can be prepared by hydrogenation of sorbic acid, sorbic alcohol or butyl ester of sorbic acid. Selective hydrogenation of mentioned C6 compounds was performed with high selectivity in the presence of a ruthenium half sandwich complexes with the structure [Cp*Ru(diene)] CF3SO3. The influence of the reaction conditions (temperature, pressure, catalyst amount, solvent type) on the reaction rate and selectivity in the hydrogenation of dienic compounds have been studied in details. The influence of various diene ligands and type of supporting materials, when heterogenized catalysts were used, on the process of hydrogenation has not been studied yet. This work was focused on the preparation of model ruthenium complexes of the type [Cp*Ru(butyl sorbate)] CF3SO3, [Cp*Ru(COD)] CF3SO3 and [Cp*Ru(NBD)] CF3SO3 (COD = 1,5 - cyclooctadiene, NBD = bicyclo [2.2.1] hepta-5-diene) and its immobilization on various smectite minerals (hektorite, montmorillonite, bentonite) by means of ion exchange. The dependence of the immobilized amount of the complex on the support type was monitored. Montmorillonite is the best support material. In all cases more than 70 wt. % of complex was immobilized (15 mg/250 mg). Prepared complexes were then used for the hydrogenation of butyl sorbate in homogeneous and heterogeneous arrangement. The hydrogenations were carried out at 50 degrees C, 4 MPa. Influence of the support type on the activity and selectivity of the catalysts was studied. Best results were obtained using ruthenium complexes immobilized on montmorillonite. The selectivity to the desired butyl (Z)-hex-3-enoate was in a range 90-98%.