| Chiral liquid-liquid extraction technology has the advantages of simple operation,low equipment requirements and mild reaction conditions,which has a good application prospect in the industrial production of optical pure drugs.The key of chiral liquid-liquid extraction is the selection of chiral extractants,but the few kinds of chiral extractants limit the wide application of this technology to a certain extent.In order to further study and develop more kinds of chiral extractants,the following work is carried out in this paper:Liquid-liquid extraction of amino acid enantiomers with(S)-SDP metal complexes.4-nitrophenylalanine enantiomer(Nphe)was separated by liquid-liquid extraction with(S)-SDP as chiral extractant.The effects of metal ions,p H,concentration of extractant and temperature on extraction performance were investigated.The separation factor(α),enantiomer excess factor(ee)and performance factor(pf)were used to evaluate the chiral resolution.The results showed that(S)-SDP-Pd was suitable for the separation of 4-nitrophenylalanine enantiomers,and the highestαvalue was 3.32.L-4-nitrophenylalanine was prefered by(S)-SDP-Pd in extraction.The optimal extraction conditions were p H 7.1,(S)-SDP-Pd concentration2.2 mmol/L and temperature 14.0~oC.Under this optimal condition,the maximum pf value is 0.08536.In addition,the mechanism of(S)-SDP-Pd resolution of4-nitrophenylalanine enantiomer was discussed.Liquid-liquid extraction of amino acid enantiomers with Mandyphos metal complexes.The 3-chloro-phenylglycine enantiomer(Cpheg)was separated by liquid-liquid extraction with ferrocene bisphosphine ligand Mandyphos-Pd as metal complex.The effects of metal ions,p H,concentration of extractant and temperature on extraction were investigated.The separation factor(α),enantiomer excess factor(ee)and performance factor(pf)were used to evaluate the chiral resolution.The results showed that Mandyphos-Pd had good separation ability for3-chloro-phenylglycine enantiomers,and the separation factor was 2.64.The enantioselectivity was significantly affected by the concentration of Mandyphos-Pd and p H,while the extraction temperature had little effect on the enantioselectivity.Therefore,the extraction experiment can be carried out at room temperature(20~oC),which has the advantage of energy saving.After optimization,the highest performance factor(pf)was 0.08376.The optimal extraction conditions were p H 7.8 and the concentration of Mandyphos-Pd was 1.2 mmol/L.In addition,the resolution mechanism of 3-chloro-phenylglycine enantiomers by Mandyphos-Pd was discussed.Liquid-liquid extraction of amino acid enantiomers with Taniaphos metal complexes.Taniaphos,a chiral ligand with rotatable spatial configuration,was used as chiral extractant to separate amino acid enantiomers.The extraction efficiency was evaluated with phenylalanine(Phe),homophenylalanine(Hphe),4-nitro-phenylalanine(Nphe)and 3-chloro-phenylglycine(Cpheg)as substrates.The results showed that Taniaphos-Cu had good enantiomer separation ability for Phe,Hphe,Nphe and Cpheg,and the separation factorsαwere 3.13,2.10,2.32 and 2.14,respectively.Taniaphos-Cu was more likely to bind to D-amino acid.The effects of p H value,extraction concentration and extraction temperature on extraction efficiency were evaluated by single factor experiment and response surface methodology.Under the optimal extraction conditions,the performance factors(pf)of Phe,Hphe,Nphe and Cpheg were 0.08892,0.1250,0.09621 and 0.08021,respectively.In addition,the separation mechanism of Phe,Hphe,Nphe and Cpheg by Taniaphos-Cu was discussed.Liquid-liquid extraction of amino acid enantiomers with Garphos metal complexes.Garphos was used as chiral extractant for liquid-liquid extraction of phenylalanine enantiomers.The effects of metal ions,p H,concentration of extractant and temperature on extraction were investigated.The separation factor(α),enantiomer excess factor(ee)and performance factor(pf)were used to evaluate the chiral resolution.The results showed that theαvalue of Garphos-Pd to phenylalanine was 1.54,and Garphos-Pd was more likely to complex with D-phenylalanine in extraction.The effects of p H,concentration of extractant and extraction temperature on extraction efficiency were evaluated by single factor experiment and response surface methodology.The enantioselectivity was significantly affected by the concentration of Mandyphos-Pd and p H,while the extraction temperature had little effect on the enantioselectivity.Therefore,the extraction experiment can be carried out at room temperature(20~oC),which has the advantage of energy saving.In addition,after optimization by response surface method,the optimal pf value 0.07732 was obtained at p H 8.2 and concentration 1.1 mmol/L,and the predicted pf was 0.07649with a relative error of 1.07%under this condition.Therefore,the model optimized by response surface method can better predict the actual situation.In addition,the mechanism of separation of phenylalanine enantiomers by Garphos-Pd was discussed. |
