Biphasic Recognition Chiral Extraction Separation Of Phenyl Succinic Acid Enantiomers

In this paper,phenylsuccinic acid(PSA) enantiomers were separated by biphasic recognition chiral extraction with synthesized L-,D- tartaric ester as chiral selector in organic phase and hydrophilicβ-cyclodextrin (β-CD) derivative in aqueous phase,respectively.The main contents can be summarized as follows:Enantiomeric separation of phenylsuccinic acid was studied by reversed phase high-performance liquid chromatography(RP-HPLC) withβ-cyclodextrin and its derivatives as chiral mobile phase additives, respectively.The enantiomers were separated at a baseline level.The separation factor(α) and resolution(Rs) are respectively 1.22 and 8.03. Analytic method was established.And a series of chiral selectors of L-, D- tartaric esters were synthesized by refluxing L-,D- tartaric acid together with fatty alcohol.The effects of mole ratio,solvent,types of catalyst and concentration of catalyst on the esterification were investigated.The structure of aimed product was studied by Infra-red spectrum.Finally,the resolution of phenylsuccinic acid enantiomers by enantioselective extraction with tartaric esters as chiral selector in organic phase and hydrophilicβ-cyclodextrin(β-CD) derivative in aqueous phase was studied.Distribution behavior of phenylsuccinic acid enantiomers was examined in two separation systems:systemⅠwas the system with tartaric ester as the chiral selector.The system with tartaric ester /β-cyclodextrin as chiral selector was systemⅡ.The effect of composition,concentration and pH of the separation system on the enantioselectivity was also examined.It can be found that,chiral selector can be well recognized on the enantiomers:S-enantiomer is easily extracted by L-(+)-iso-butyl tartrate and R- enantiomer is easily extracted by HP-β-CD.The extraction effect of PSA is optimum by one stage extraction,and the distribution ration for R-PSA(k_R) and for S-PSA(k_s) and separation factor(α) are 1.120,3.204 and 2.86,respectively.This law can be analysed with three point interacted recognition.In addition,the possible separation mechanism of PSA enantiomers with HP-β-CD was discussed.The inclusion stability constant ofβ-cyclodextrin derivatives with PSA enantiomers was studied by using UV spectrophotometry.The experimental results indicate the among the threeβ-cyclodextrin derivatives,HP-β-CD has strongest binding ability with PSA enantiomers in aqueous solution and host-guest complex with 1:1 molar ratio is formed.The inclusion process is a spontaneous and exothermic process, and lower temperature if of benefit to reaction.