Preparation And Application Of Mesoporous Alumina Supported KF Catalyst

The mesoporous alumina (denoted as m-Al2O3) were prepared by anionic and neutral synthesis routes, respectively. Catalysts(denoted as KF/m-Al2O3) were prepared by using m-Al2O3 as supports for deposition of Potassium fluoride via different methods of dipping and rubbing, respectively. The samples of supports and catalysts were characterized by XRD,FTIR,N2-adsorption, TEM and laser granularity analytical method. The mesoporous alumina samples synthesized by neutral pathway exhibited a wormhole channel motif .surface areas up to 374.5m2/g and average pore sizes being 7.2nm. Some new kinds of OH- group preserved on the surface of KF/m-Al2O3 ,and further research should be done to make sure if they were in the form of [Al—OH…F-] or not .Titration method analysis indicated that m-Al2O3 could support more amount of KF and produced effective alkaline centers on the surface than the commercial γ -Al2O3,and the catalyst with amount of 36.7% KF had basic intensity over 18.4 and basicity of 4.79 mmol/g.The catalytic activity of the KF/m-Al2O3 catalyst prepared by different KF loading amounts, the different supports and different reactive condition for 0-Alkylation of p,p'-Biphenol and N-benzylation of phthalimide are investigated. The results indicate that the catalytic activity is influenced strongly by the supports. The catalytic activity of KF/m-Al2O3 excelled that of KF/ γ -Al2O3,which is in good agreement with the order of the number of the surface basic sites on the catalyst measured by titration. The result is attributed to the larger surface and the regular pore distribution of mesoporous Al2O3. Various reaction factors affecting the yield have been studied. The optimal reaction conditions were, (1)molar ratio of phthalimide and benzylchloride 1 : 1.2, KF loading amounts of catalyst 36.7%,reaction temperature 90℃,reaction time 4h in DMF, and the yield of N-benzylation of phthalimide was 91.3%.(2) molar ratio of p,p'-Biphenol and Methyl iodide 1 : 2.5, KF loading amounts of catalyst 36.7%,reaction temperature 40℃ ,reaction time 3h in DMF,and the yield of 4,4'-Dimethoxybiphenyl was 89.3%.The m-Al2O3 supported KF catalysts were employed as highly active/selective and reusable catalysts for the semi-synthesis of stachydrine. The mild reactive condition and the simple subsequent disposal process made this synthsis method more competitive than others. Various reaction factors affecting the yield have been studied. The optimal reaction conditions were, molar ratio of L-proline and Methyl iodide 1 : 2.5, KF loading amounts of catalyst 36.7%,reaction temperature 40℃,reaction time 6h,and the yield of stachydrine was 91.3%. The structures of stachydrine were determined by TLC,FTIR, 1H-NMR ,13C-NMR and MS,et al.