Synthesis, Characterization And Application In The Field Of Asymmetric Catalysis Of Chiral Ligands Immobilized On The Titanium Phosphonate

Tetravalent metal phosphates, phosphonates and hybrid phosphate-phosphonates are of interest because of their practical application in areas such as ion exchange, catalysis, intercalation chemistry and proton conduction. Being members of the layered metal phosphates family, layered titanium phosphates of tetravalent metals have been of considerable interest recently. In this paper chiral amino alcohol was immobilized on titanium phophate frame to form a new type of chiral titanium phophonate. It was indicated that chiral titanium phophonate led to the active heterogeneous catalysis for asymmetric additions of diethylzinc to benzaldehyde in 88.5 % yield and e.e. value of up to 40.8 % which decreased at 16 % e.e. lower than those in homogeneous asymmetric catalysis. The catalyst TiP-Pd had been prepared by the complexation of the titanium phosphonate with PdCl₂ and suggested its potential as one-phase catalysis and two-phase separation. In the hydrogenation of acetophenone under mild conditions, the chemical selectivities of acetophenone to phenylethanol and ethylbenezene are up to 93.3 % and 100 % respectively, and can be reused eleven times with above 97 % recycle and without the leaching of palladium and the sharp loss of catalytic activities.