Synthesis And Application Of The Composite Chitosan Of Chiral Stationary Phase

With the fast development of analytical chemistry, enantioseparation plays the importantrole in the application fild of drugs, agriculture and food. Especially, in the field of medicine,obtaining single enantiomer drugs and presenting higher optically pure and smaller toxic sideeffects, has become an important aspect of medical research. At present, chromatographicenantioseparation depending on the development of chiral stationary phases (CSPs) by highperformance liquid chromatograph (HPLC) has become the most powerful and popularmethod. Therefore, developing all kinds of CSPs, which are low-cast, more effective, andcommercial are the goal of the research. So far, polysaccharide-derived CSPs playsignification roles in enantioseparation during recent dacades. Chitosan has the (1-4)linkage, just like cellulose, but it has an amino groups at the2-position on the glucosaminering instead of the hydroxyl groups that is present in the cellulose. It is also one of the mostabundant optically active polymers. Moreover, inherent chiral chitosan can be convenientlychemically modified at the hydroxyl and amino groups. In order to resolve the ehiralcompound better, more new CSPs have been attraeting much.In this paper, the synthesis involved the protection and deprotection of6-position usingtriphenylmethyl chlorides, which can predominantly react with6-OH of chitosan, the newphenylcarbamate derivaritive chitosan-[6-(3-chloropheny)-2,3-(4-chloropheny)] carbamateswere synthesized and used as the chiral stationary phase(CSPs-1) for high-performance liquidchromatography (HPLC) after coating on5m aminopropyl silica gal, and it wascharacterized using IR and1HNMR. The chiral recognition ability of obtained derivatives wasevaluated using9racemates at the condition of conventional eluent and triad eluent, and thereare five kinds of racemates achieved baseline separations or near-baseline. The result showedthat most of racemates were better retention time on the new derivatives than on the typicalhomogeneously substituted phenylcarbamate derivatives, chitosan-tri-(3-chloropheny-carbamates), chitosan-tri-(4-chloropheny carbamates).Abstract two coated-type composite chiral stationary phases (CSPs-2, CSPs-3) wereprepared based on chitosan-tri-(3-chloropheny carbamates) and chitosan-tri-(4-chlorophenycarbamates) by coating the corresponding derivatives onto5m aminopropyl silica gelseparately and then mixing or by coating the mixed derivatives coating on silica gel. Thechiral recognition ability of CSPs-2and CSPs-3was evaluated using9racemates at thecondition of nomal phase eluent and adding polar modifier mobile phase.The result showedthat the CSPs-3show chiral recognition abilities better CSPs-2,5racemates achieved baselineseparations or near-baseline on the composite CSPs-3.In addition, chitosan with the acetyl group at the2position of glucosamine ring wasdeacetylated with50%aqueous NaOH,3,5-dimethylphenylisocyanate as derivatizationreagent, chitosan-(3,5-dimethylphenylcarbamate-urea) were synthesized and used as the ochiral stationary phase(CSPs-4) for high-performance liquid chromatography (HPLC) aftercoating on5m aminopropyl silica gal.. The chiral recognition ability of obtained derivativeswas evaluated using18racemates at the condition of normal phase eluent and acidic or basicwas additived.