Synthesis Of New Chitosan Derivatives And Their Research Of Chiral Recognition Ability

Chirality is a ubiquitous feature in living systems. Chiral resolution has becomepharmacology study and pharmaceutical industry urgent to resolve. High-performance liquidchromatography (HPLC) has become the most powerful method not only for analyzingenantiomers, but also for obtaining them in a pure form. Among many chiral stationary phases(CSPs), the polysaccharide derivatives, such as the phenylcarbamayes of cellulose andamylose exhibit broad applicability to a wide range of compounds. Cellulosetris(3,5-dimethylphenylcarbamate)(commercial names, Chiralcel OD) and amylose tris(3,5-dimethylphenylcarbamate)(commercial names, Chiralpak AD) are the most frequently usedas CSPs.Completely deacetylated chitosan was prepared by the treatment of commercial chitosanwith50%aqueous NaOH, and then derivatized into several new chitosan phenylcarbamatederivatives having a urea and an imide moiety at the2-position of the glucosamine ring by thereaction with isocyanate, respectively. And learn about the influence on derivatization ofchitosan by Chitosan with different viscosity, different reaction solvents, different reactiontemperature, reaction time and the amount of isocyanate. Chitosan structure was characterizedby IR spectrum and1H spectrum NMR. Finally determine to use dimethyl sulfoxide(DMSO) as solvent, completely deacetylated Chitosan-B and Chitosan-C as reactants, reacteat80℃for12h. and then an excess of an isocyanate (2.5eq) were added into the system.Synthesis of a series of novel chitosan derivatives, including chitosan-4-chlorophenylcarbamate-urea derivatives,chitosan-3-methylphenylcarbamate-urea derivatives, and chitosan-3-chlorophenylcarbamate-urea derivatives and chitosan-4-bromophenylcarbamate-urea derivatives,Chitosan derivative structure was characterized by IR spectrum and1H spectrum NMR. Thechitosan derivatives were coated on macroporous silica gel and evaluated as chiral stationaryphases (CSPs) for high-performance liquid chromatography. Coating efficiency can becalculated by TG. The chiral recognition ability of the chitosan derivative was improved usingthe completely deacetylated chitosan.In our study, a series of new chitosan derivatives havebeen synthesized, and introducted an methyl or an halogen group at the m-and/or p-positionof the phenyl ring.This derivatives was used to separate7kinds racemates. Chitosanderivatives CSPs show a high chiral recognition. They can make some enantiomers getbaseline separation, and separating degree is high. Among the novel chitosan derivatives, the 4-chlorophenylcarbamate derivatives were found to possess relatively high chiral resolutionabilities.The CSPs based on the chitosan phenylcarbamate-urea and-imide derivatives werestable in the presence of chloroform as a component of the eluents, and some racemates werebetter resolved by such eluents.Chitosan derivatives can be used with eluents containingsolvents such as CHCl3，which cannot be used by other polysaccharides CSPs. Chitosanderivative structure was characterized by IR spectrum and1H spectrum NMR. Derivativeshave been used as CSPs for HPLC in oder to evaluate its chiral recognition ability. The resultsshow that, novel chitosan derivatives CSPs show a high chiral recognition to some chiralcompounds.