Synthesis Of Novel Chiral Chelating Extractants And Study On Extraction Resolution Of D/L-amino Acid

Six types of chiral extractants were synthesized and L-Phenylalanine methyl ester as the chiral pools in this paper which included four chiral secondary amine extractants: N-n-butyl-L-Phenylalanine methyl ester(BuPhe), N-n-octyl-L-Phenylalanine methyl ester(OcPhe), N-n-dodecyl-L-Phenylalanine methyl ester(DoPhe) and N-(2-Pyri-dylmethyl)-L-Phenylalanine methyl ester(PyMPhe); one chiral tertiary amine extractants: N,N'-di-n-octyl-L-Phenylalanine methyl ester(DiOcPhe); one chiral amide extractants: N-benzoyl-L-Phenylalanine methyl ester(BePhe). The extractants were characterized by nuclear magnetic resonance(1H NMR), infrared spectrum(IR), element analysis and high performance liquid chromatography(HPLC) and etc. Their extract ability for copper ions was studied, and the extraction behavior of the extraction separation of D/L-phenylalanine was researched. The main contents were listed as follows:1. L-phenylalanine methyl ester and aldehydes as the raw material for Schiff base reaction, and the C=N was reduced by the catalytic hydrogenation of NaBH4, then three secondary amine N-alkylation-L-phenylalanine methyl ester was obtained. The products were characterized and the results showed that the purity of all the products was over 96%, and the yield was above 80%.2. It was found that OcPhe could be attained directly when n-Octyl aldehyde was excess during the synthesis of OcPhe. And the yield was related to the reaction ratios. OcPhe or OcPhecan be synthsised selectively by adjusting the reaction ratios.3. BePhe and PyMPhe were synthetized and characterized. The results showed that BePhe was the white solid and the yield was about 77.5%, m.p. 84-85℃, the purity was over 96%; and PyMPhe was bright yellow liquid with the yield of 72.3%.,the purity was over 95%.4. The extraction behavior of BePhe,DiOcPhe and PyMPhe on extract copper ion was researched. It was found that the extraction distribution ratio is very low due to their spatial structure. Due to its water solublity, PyMPhe isn't suited to act as Chiral extracting agent.5. The extraction behavior of Cu(Ⅱ) ion with BuPhe,OcPhe and DoPhe was investigated. The effects of the diluents, the concentration of extractant and salt, and temperature on extraction distribution ratio were studied. The conclusions were as following:(1) The extraction capacity of three extractants for copper ions reduced in the order: BuPhe > OcPhe > DoPhe. The order was reverse after adding NaCl to water phase and the extraction capacity increased , which showed that extraction mechanism had changed when NaCl was added.(2) The extraction distribution ratio increased rapidly with an increase of the concentration of NaCl. The extraction ratio was more than 98% when the concentration of NaCl was 3.0 mol/L. It can meet the requirements of extractant binded to copper ions tightly enough to make the extracted complex enter the water phase difficultly.(3) The extraction distribution ratio increased with an increase in the concentration of extractant. Each copper ion were extracted into organic phase and coordinated with one extraction molecular in the extracted complex.(4) The extraction distribution ratio decreased with the increase of the temperature, which demonstrated that the extraction reaction is exothermic. Increasing the temperature would decrease the reaction.(5) By studying the impact of diluents on the extraction rate, the studies gave the result that the extraction capacity is the in dichloromethane system. It showed that the extraction capacity of this kind extractants was greatly influenced by the diluent.6. The conventional reaction of amino acid and ninhydrin was improved and the best conditions were obtained in this paper. The interference of copper ions in aqueous phase was eliminated by adding Sn powder.7. The complex which was formed of OcPhe extracted transition metal Cu (Ⅱ) ion acted as the extraction separation agent. The extraction separation of D/L-phenylalanine was studied. The conclusions were as follows:(1) The extraction distribution ratio had no change with an increase in the concentration of phenylalanine, which suggested that this process is a normal extraction process.(2) The extraction distribution ratio increased with the increase of Cu (Ⅱ) ion concentration in the organic phase. If the concentration of Cu (Ⅱ) ion is too high, it will exceed the load capacity of the organic phase to lead to the formation of the third phase. So the extraction capacity of D/L-phenylalanine can be improved by controlling the amount of Cu (Ⅱ) ions.(3) The extraction capacity of chiral extractants for L-phenylalanine is higher than that for D-phenylalanine and the separation factor reached 1.28, which can provided an important theoretical and experimental basis for further study on chiral solvent extraction separation technology.(4) The impact of temperature on the extraction distribution ratio was researched. It was found that the extraction reaction is exothermic.(5) The effect of the diluents on the extraction distribution ratio was studied, and the results suggested that the extraction distribution ratio was influenced by the diluents obviously.