双水相手性萃取拆分扁桃酸外消旋体

研究了扁桃酸(MA)对映体在含β-环糊精(β-CD)手性选择剂的聚乙二醇(PEG)/(NH_4)_2SO_4双水相体系中的萃取分配行为.考察了pH、PEG和(NH_4)_2SO_4的质量分数、β-CD的浓度、MA的浓度与萃取温度等因素对拆分效果的影响.实验结果表明:双水相手性萃取具有很强的手性分离能力,β-CD对L-MA对映体的识别能力大于对D-MA对映体的识别能力;当温度为30℃、pH=1.0、PEG2000质量分数为30%、(NH_4)_2SO_4质量分数为20%、β-CD的浓度为0.008 mol/L、扁桃酸的浓度为0.05 mol/L时,分离因子(α)达到2.46,上、下相对映体过剩值(e.e.%)分别为42.13%和40.43%.

Aqueous Two Phase Extraction for the Enantioseparation of Mandelic Acid Enantiomers

The distribution behavior of D,L-mandelic acid(MA) was examined in aqueous two-phase systems composed of polyethylene glycol (PEG) and ammonium sulfate (NH_4)_2SO_4] containing β-cyclodextrin (β-CD) as chiral selector. The influence of the pH, the mass fractions of PEG and (NH_4)_2SO_4 , the molecular weight of PEG, the initial concentrations of β-CD, D,L-MA and extractive temperature on the distribution behavior were studied. The results showed that β-CD is inclined to recognize L-MA; the enantioselectivities reached at 2.46 and the enantiometric excess (e.e.%) is 42.13% in the top phase and 40.43% in the bottom phase, respectively. Under the condition of the extractive temperature of 30℃, the pH values of the bottom phase is 1.0, the mass fraction of PEG and (NH_4)_2SO_4 is 30% and 20%, the molecular weight of PEG is 2000, the initial concentration of β-CD and D,L-MA is 0.008 mol/L and 0.05 mol/L, respectively. Aqueous two-phase chiral-extraction has strong chiral separation ability, and has great significane for preparative separation of racemic compounds.