Separation Of Enantiomers Via High-speed Counter-current Chromatography With β-cyclodextrin Derivatives As Chiral Selectors

A method of high-speed counter-current chromatography(HSCCC)was applied in separation of enantiomers by employing hydrophilic β-cyclodextrin derivatives as chiral selector.The mechanism of reaction extraction and the related theory in separation of enantiomers were studied.Factors influencing the chiral separation efficiency of 2-phenylbutyric acid and brompheniramine enantiomers were investigated.Under the optimal conditions,the separation of racemic 2-phenyl butyric acid,brompheniramine enantiomers,pheniramine enantiomer and chlorpheniramine enantiomers was successfully achieved through HSCCC.The main studied work and experimental results obtained were as follows:(1)Separation of 2-butylbutyric acid enantiomers by HSCCC.The mathematical model was established through the mechanism of reaction extraction of acidic enantiomers and detail related theory,which was used to optimize the separation conditions.Results showed that model predictions were in good agreement with the experimental results.The optimal conditions of separated 2-phenylbutyric acid were as follows: the organic phase composed of n-hexane and butyl acetate with a volume ratio of 7:3,HE-β-CD of chiral selector,HE-β-CD concentration of 0.1 mol/L,pH of aqueous phase of 3.0 and temperature of 5 °C.Under the above conditions,the resolution of 2-phenylbutyric acid enantiomer was successfully obtained by HSCCC.In addition,The effect of amount of 2-phenylbutyric acid on resolution was investigated by HSCCC.It was found that the maximum sample amount of 2-phenylbutanoic acid enantiomer was about 100 mg which was dissolved in 20 ml of stationary phase.(2)Separation of basic enantiomers by HSCCC.Several influencing factors,such as types of organic phase and chiral selector,concentrations of chiral selector,pH of aqueous phase and temperature on separation result,were investigated.The suitable conditions of separated brompheniramine were as follows: the organic phase composed of n-hexane and isobutyl acetate with a volume ratio of 2:4,CM-β-CD of chiral selector,CM-β-CD concentration of 0.01 mol/L,pH of aqueous phase of 7.50 at temperature of 5 °C.Under the optimal conditions,racemic bromophenamine enantiomer,pheniramine enantiomers and chlorpheniramine enantiomers through recycling HSCCC.In addition,the separation conditions of pheniramine enantiomer were optimized on the basis of separation system of bromophenamine enantiomer,and the effect of separation of pheniramine enantiomer was greatly improved.