A Study On The Catalytic Hydrogenation Of 3, 5-Dimethylpyridine

3,5-Dimethylpiperidine is an important starting material of tilmieosin, which is a semi-synthetic maerolide antibiotic developed for veterinary use. As an intermediate, 3,5-dimethylpiperidine is a mixture of 85% cis-isomer and 15% trans-isomer. Hydrog- enation of 3,5-dimethylpyridine is the best method to obtain 3,5-dimethylpiperidine.In this thesis, catalytic activities of various metal catalysts in the hydrogenation of 3,5-dimethylpyridine were investigated. The influence of reaction parameters such as temperature, pressure, time, and solvent on the hydrogenation was investigated. Catalyst III under the optimum reaction conditions:130℃, 9.5 MPa , 24 h, ethanol as the solvent, the conversion and the diastereoselective of 3,5-dimethylpyridine could be up to 82% and 91% respectively. Catalyst IV under the optimum reaction conditions:130℃, 9 MPa, 24 h, ethanol as the solvent, the conversion and the diastereoselective of 3,5-dimethylpyridine could be up to 92% and 70% respectively. The cyclic reuse of catalysts showed that the activity and diastereoselective did not decrease significantly. Mixture of two kinds of products was consistent with the goal product.Four proline-derived small chiral Br?nsted acids were synthesized using L-proline as the starting materials. The catalytic activity of the Br?nsted acid as organocatalyst was estimated. The results showed that the activity of these Br?nsted acids was high in the reduction of imines.