Ruthenium/Nitrogen-doped Carbon Nanocages Catalysts For Catalytic Asymmetric Hydrogenation Of Acetophenone

Phenethyl alcohol is an important intermediate product in the synthesis of drugs, which can be obtained by the catalytic asymmetric hydrogenation of acetophenone. Hydrogenation of acetophenone can carry out in homogenous or heterogeneous process. Homogenous catalysts exhibit high catalytic activity and selectivity but need high preparation cost, harsh experimental conditions. In addition, it is also difficult to separate catalyst and purify products. The heterogeneous catalyst can be separated from products by simple filtration or sedimentation and also recycled. Due to the advantages of heterogeneous catalyst, research interests are focused on seeking heterogeneous catalyst with high activity, selectivity and stability. Therefore, my scheme includes:1. Develop a simple method to synthesize nitrogen-doped carbon nanocages (NCNC) using in-situ formed MgO as the template. The synthesis temperature strongly affected the property of NCNCs. With the synthesis temperature increasing, surface area and pore volume decreased, pore size significantly increased, the content of nitrogen decreased.2. Prepare Ru/NCNC by means of the microwave-assisted ethylene glycol reduction. The Ru nanoparticals were highly dispersed on the surface of NCNC with small size of ca.1-2.5nm.3. Compare the catalytic hydrogenation performance of acetophenone of Ru/NCNC and Ru/AC. The conversion of acetophenone was up to99%and the selectivity of phenethyl alcohol was up to95%using Ru/NCNC as catalyst. To Ru/AC catalyst, the conversion was only0.69%but the selectivity was100%. The doped nitrogen atoms embedded in the NCNC were responsible for improving catalytic performance of Ru/NCNC as well as special cage-like structure and good graphitized degree of NCNC.4. Preliminarily investigate the catalytic asymmetric hydrogenation performance of acetophenone of Ru/NCNC as catalyst. BINAP and (1S,2S)-DPEN were used as modifier. The e.e. value of phenethyl alcohol is ca.12-14%. Then several typical effect factors were investigated, i.e., reaction temperature, reaction time, catalyst, solvent, base, and reaction pressure. The catalyst was recycled for4times. The conversions were prior to95%for the first three times. Selectivities were in the range of88-92%and e.e. value remained in12-14%.