Preparation And Enantionseparation Ability Of Immobilized Chiral Stationary Phases Based On Cellulose Benzoates

Polysaccharide derivatives have excellent enantioseparation ability,which are currently the most widely used chiral stationary phase materials.Among them,the cellulose tris(4-methyl benzoate)share a high enantioseparation ability,and its coated chiral stationary phase has been commercialized.However,the structural stability of the benzoate derivatives is relatively poor,resulting in the ability of the chiral stationary phase to be affected by the coating solvent,so that its application is subject to great restrictions.In addition,the conventional coated CSPs,although having a good chiral recognition,prepared through adsorbing on surface of the carrier by physical interaction,so that the material is susceptible to the polarity of the solvent used,Therefore,there are some limitations in the selection of the mobile phase,and some polar solvents can not be used as the mobile phase.These polar solvents help to improve the solubility of some chiral compounds,which may lead to more efficient resolution or reversal of the enantiomeric elution order,which is important for the resolution of chiral compounds.To solve the above problem,in this paper,a series of cellulose tris(4-methylbenzoate)derivatives containing a small proportion of 3-triethoxysilane groups were synthesized,and prepared the coated and immobilized chiral stationary phase,based on the synthesized derivatives were prepared.Then the enantioseparation performance of the obtained CSPs were futher evaluated.First,a series of cellulose-tris(4-methylbenzoate)derivatives having different proportions of 3-triethoxysilane groups were synthesized using the transesterification method.The structure of the synthesized derivatives were characterized by FT-IR and ~1H NMR.Secondly,the coated CSPs were prepared by coating method based on the synthetic derivatives,and the immobilized chiral stationary phase was prepared by polycondensation of triethoxysilane groups.And the coating efficiency and bonding efficiency of two kinds of stationary phases were determined by thermogravimetric analysis(TGA).Finally,chiral resolution of 9 racemic compounds was carried out by high performance liquid chromatography(HPLC).The enantioseparation ability of the coated and immobilized chiral stationary phase were evaluated and the recognition mechanism was further studied.The results show that the immobilized CSPs based on cellulose-tris(4-methylbenzoate)containing a small amount of 3-triethoxysilane groups can achieve efficient baseline separation for a variety of chiral compounds,especially for the Troger base enantiomer,which exhibits an efficient chiral resolution.At the same time,the enantioseparation performance of the immobilized CSPs is slightly lower than that of the corresponding coated CSPs,which may be due to the fact that the introduction of 3-triethoxysilane groups affects the structural regularity of cellulose to a certain extent,which has a certain impact on their enantioseparation and recognition performance.