Preparation Of Polystyrene-based Chiral Stationary Phase And Application Of Enantiomeric Separation

At present,the demand for optically pure chiral drugs is increasing,and people pay more and more attention to the effective separation and preparation of chiral drugs.The chiral stationary phase(CSP)method in high performance liquid chromatography(HPLC)has been widely used for the separation of chiral drugs due to its high efficiency,high sensitivity and reproducibility.And because of its high column capacity,CSP has a good industrial application prospect.Although there are many commercially available CSP,the required type of chiral stationary phase is also very large due to the various kinds of chiral drugs.Therefore,the preparation of efficient and diverse CSP is the important development direction in the field of chiral drug resolution.In this study,L-leucine(L-Leu)as a chiral source was loaded onto a 10-micron chloromethylated polystyrene microspheres to prepare novel CSP.The chiral resolution of the novel CSP was explored by using DL-Phenylalanine(DL-Phe)as the object of separation.The main work is as follows:(1)Determination of load chiral source : using the template compound Benzyl chloride instead of chloromethylated polystyrene microspheres to load different L-amino acids,and explored the degree of racemization.Results show that there is not a significant racemization in the reaction product of L-leucine and Benzyl chloride in the environment of strong alkali.Meanwhile,significant racemizations were found in the reaction products of L-tryptophan(L-Trp)and L-proline(L-Pro)with Benzyl chloride.These indicate that L-Leu is more suitable than the other two L-amino acids as a chiral source for chiral stationary phases.(2)Preparation of CSP: ten micrometers of chloromethylated crosslinked polystyrene microspheres were prepared by using a polymerization method between dispersion polymerization and suspension polymerization,with styrene(St)and chloromethylated styrene(CMS)as the comonomer in the mixed reaction medium of anhydrous ethanol and water.The chlorine content of the prepared chlorine microspheres is about 5.91%.The polystyrene-based CSP was successfully prepared by loading the L-Leu onto the chlorine microspheres by using the phase transfer catalysis method with L-Leu as the chiral source,and the degree of nucleophilic substitution reaction under this condition is about 62.8%.(3)Preliminary application of chiral separation : the DL-Phe was separated by liquid chromatography,and the chiral resolution of polystyrene-based CSP was preliminarily explored.The effects of the composition and velocity of the mobile phase on the DL-Phe splitting were investigated.The results show that the DL-Phe is not separated when the mobile phase is water or petroleum ether.When the mobile phase is anhydrous methanol,there is unobvious separation;when the mobile phase is anhydrous methanol / petroleum ether,the separation of the DL-Phe is better.The effects of the ratio of anhydrous methanol and petroleum ether in the mobile phase were investigated.The results show that when the ratio of anhydrous methanol to petroleum ether is 7/3,the resolution was better.The effects of the mobile phase flow rate on the resolution were investigated by setting the flow rates to 1.0~3.0 mL / min respectively.The results show that with the increase of mobile phase velocity,the degree of separation decreases.