Studies On The Preparation And Properties Of Cellulose Type Chiral Stationary Phases

Chirality is omnipresent in nature, and chiral drugs are closely related tothe health of human beings. High-performance liquid chromatography（HPLC）based on the application of chiral stationary phases（CSPs）, whichwas developed rapidly in recent decades, is a very effective technique toobtain optical isomers and separate the enantiomers of chiral compounds inbulk. Therefore, developing a novel CSP is of importance. In this work, aseries of CSPs of composite beads were designed and prepared usingcellulose as the chiral material, for the reason that the CSPs of cellulosederivatives have high loadings for chiral compounds. The enantioseparationability and stability of the as-prepared CSPs were evaluated. In addition, akind of composite CSP coated with cellulose derivatives has also beenprepared in order to study the trends in consistency or anti-consistency of thederivatives for the separation. The works can be summarized as follows:1. The optimal conditions for the preparation of cellulose-SiO₂compositebeads by emulsion-solidification were investigated, in order to obtainappropriate particle size for conventional chromatography. The capacity ofSiO₂in composite beads was determined. The cellulose-SiO₂compositebeads were then modified by phenyl isocyanate and the hydroxyls of thesilica gel were capped with trimethoxysilane to afford two CSPs ofcomposite beads with different capacity of SiO₂. The composite beads andthe CSPs were characterized by FT-IR, element analysis and scanningelectronic microscope （SEM）. The particle size and the surface area of thecomposite beads were deceted. The chromatographic results demonstratedthat the stability of these two CSPs were not satisfactory.2. The optimal conditions for the preparation of cellulose-BaSO₄compositemicrospheres by emulsion-solidification were studied. Partial of hydroxylsin cellulose were then, respectively, modified by benzoyl chloride and 4-methyphenyl isocyanate to obtain corresponding CSPs of cellulose-BaSO₄composite microsphere. Appropriate substitution degrees wereachieved by adjusting the composition of the solvent, the reactiontemperature and the reaction time of the modification reactions. Thecomposite microspheres and the CSPs were characterized by FT-IR,element analysis and scanning electronic microscope （SEM）. The particlesize and the surface area of the composite microspheres were deceted. Thechiral recognition properties and stability of these stationary phases wereevaluated by using HPLC. The chromatographic results demonstrated thatthe CSPs derived from cellulose-BaSO₄composite microspheres hadsatisfactory stability.3. A kind of composite CSP was prepared by coating a mixture of cellulosetris（4-methylphenylcarbamate） and cellulose tris（3,5-dimethyphenylcarba-mate） at an equal molar ratio of glucose unit on3-aminopropyl silica gel.Besides, these two cellulose derivatives were coated on3-aminopropylsilica gel separately to give two CSPs of single chiral selector. Theenantioseparation properties of the composite CSP were evaluated withHPLC. The enantioseparation results revealed that the two selectors of thecomposite CSP exhibited consistency for the enantioseparation of someracemates, and exhibited anti-consistency for the enantioseparation ofother racemates. However, the enantioseparation capacities of thecomposite CSP generally intermediated between those of the twoindividual phases. Therefore, whether the composite CSP performsconsistency or anti-consistency depends on the structure of chiral analysts.