Study On The Chirality Purity Analysis Methods Of Valine

Natural valine has L configuration,while synthesized valine can be L configuration or D configuration.Valine with different configurations is used to form different active pharmaceutical ingredients.So it is important to establish an exact and effective analysis method for the chirality purity measurement of valineThere were two methods,chiral stationary phase chromatography and non-chiral stationary phase chromatography,were used to characterize the chiral purity of valine in this paper.The first method is to characterize the chiral purity of valine by non chiral stationary phase chromatography.D-camphorsulfonyl chloride was used as the chiral derivatizing reagent to functionalize valine.The enantiomers of(DL)-valine were transformed into the two kinds of different diastereoisomers including D-camphorsulfonyl-L-valine methyl ester and D-camphorsulfonyl-D-valine methyl ester.As these two diastereoisomers belong to two different compounds,they do not have the characteristics of enantiomers,which enables them to be separated via the non chiral stationary phase chromatography.Meanwhile,after derivatization,the UV absorption of valine is enhanced,and the sensitivity of determining the chiral purity of valine is improved.The chiral purity of(DL)-valine can be characterized according to the peak area difference of the two kinds of diastereoisomers on the common reversed phase chromatography.The specific derivatization process is to use valine as the raw material.The product valine methyl ester was synthesized by methylesterification.The process for the preparation of D-camphorsulfonyl-L-valine methyl ester and D-camphorsulfonyl-D-valine methyl ester were valine methyl ester and D-camphorsulfonyl chloride were as raw materials by derivatization.The maximum absorption wavelength of D-camphorsulfonyl-L-valine methyl ester and D-camphorsulfonyl-D-valine methyl ester were 224 nm.Through a lot of experimental research,the optimal liquid phase conditions for the separation of the two diastereoisomers were determined to be:The mobile phase were 60%methanol and 40%20 mmol/L potassium dihydrogen phosphate aqueous solution(adjusted pH=4.0 by potassium dihydrogen phosphate),diamonsil column C18(250 mm×4.60 mm,5μm),column box temperature of 30 ℃,flow rate of 1 m L/min.Under this optimal condition,the retention times of D-camphorsulfonyl-D-valine methyl ester and D-camphorsulfonyl-L-valine methyl ester were 6.793 min and 9.485 min respectively.The two kinds of diastereoisomers have a good separation effect,and the degree of separation was 2.015.The appearance of D-camphorsulfonyl-L-valine methyl ester is white solid,but D-camphorsulfonyl-D-valine methyl ester is liquid.The melting range of D-camphorsulfonyl-L-valine methyl ester is 93.68℃-99.68℃ measured by differential scanning calorimeter.In this dissertation,the structure of D-camphorsulfonyl-L-valine methyl ester was characterized by FTIR and ~1H NMR.The second method is to characterize the chiral purity of valine by chiral stationary phase chromatography.The value of valine e.e.was determined by HPLC-UV.Through many experiments and explorations,the liquid phase conditions for the separation of(DL)-valine were obtained as follows:10%tetrahydrofuran+90%2 mmol/L copper sulfate,SUMICHIRAL OA-6100 chromatographic column,detection wavelength of 220 nm,column temperature of 30 ℃,flow rate of 1 m L/min.The retention time of D and L-valine was 10.361 min and 16.872 min.The resolution of the two enantiomers is 3.688.The novelty of this dissertation involves the use of D-camphorsulfonyl chloride as a chiral derivatizing reagent for the derivatization of valine.The d.e.value was determined by non chiral stationary phase chromatography,which indirectly characterized the chiral purity of valine and reducing the dependence of characterizing the chiral purity of chiral stationary phase chromatographic column.There is no relevant literature reported on this point at present.