Preparation And Chiral Recognition Of Cellulose And Amylose Derivatives-based Chiral Stationary Phases For HPLC

Demonstrating high chiral recognition to various chiral compounds,chiral stationary phases(CSPs)based on polysaccharide derivatives has been used widely as CSPs for direct discrimination of enantiomers in high-perfomance liquid chromatography(HPLC).In the thesis,two immobilized polysaccharide derivatives-based CSPs,seven coated regioselectively modified polysaccharide derivatives-based CSPs and one novel coated cellulose derivative CSP based on click reaction were synthesized,characterized,and their chiral discrimination abilities were evaluated.Cellulose or amylose was directly coated onto silica gel after its dissolution in a mixture of N,N-dimethylacetamide/LiCl/pyridine and then nonregioselectively immobilized onto silica gel via intermolecular polycondensation of triethoxysilyl groups introduced by(3-glycidoxypropyl)triethoxysilane,the relevant immobilized CSPs based on 3,5-dimethylphenylcarbamates of cellulose and amylose were obtained by derivatization of the remaining hydroxyl groups of the polysaccharideswith 3,5-dimethylphenyl isocyanate.Compared with the regioselective immobilization method,the present one avoided the protection and deprotection of 6-position hydroxyl groups on glucose unit during the preparation of 2,3-bis(3,5-dimethylphenylcarbamates)of cellulose and amylose,exhibiting rapidness and convenience for preparation of immobilized CSPs.Investagtions indicated that the immobilized cellulose3,5-dimethylphenylcarbamate CSPs exhibited chiral recognition comparable to that of Chiralpak IB.While in comparison with Chiralpak IA,the immobilized amylose 3,5-dimethylphenylcarbamate CSPs exhibited decreased enantioseparation.Also,the obtained CSPs demonstrated good solvent compatibility(Solvents such as chloroform and tetrahydrofuran which are strictly forbidden for coated CSPs);So with these solvents used,better resolutions of some of the tested chiral compounds were obtained.Three regioselectively modified cellulose derivatives and four regioselectively modified amylose derivatives were prepared and their chiral recognition under reversed-phase liquid conditions was evaluated.Investigations showd that the obtained CSPs exhibited particular enantioseparation towards neutral chiral compounds,and low enantioseparation for acidic and basic chiral compounds,which might be ascribed to the poor chiral separation of the CSPs under reversed-phase conditions with different mobile phase compositions.A new cellulose derivative CSP was prepared by cyclizating afive-membered ring of the azide and alkynyl groups based on click chemistry.The method exhibited big advantages,such as easy operation,easy purification of the product,less side products and the product having better stereoselectivity and regioselectivity.Investigations showd the CSP demonstrated particular chiral recognition and its enantioseparation was affected by mobile phase compositions.