Study On Enantioselective Chiral Extraction Of 4-mandelic Acid Enantiomers

In this paper,4-mandelic acid enantiomers was chosen as the research object,and the characteristics of chiral selective extraction of 4-mandelic acid enantiomers from two different systems were studied.The main contents can be summarized as follows:Firstly,the analytic method of enantiomeric resolution of 4-mandelic acid enantiomers was established using a reversed phase HPLC with hydroxypropyl-beta-cyclodextrin on C18 column.The influence of compositionmobile phase,concentration of chiral additive,content of buffer salt and other factors were investigated and optimized to obtain corresponding HPLC analysis condition.Under these conditions,the resolution of 4-mandelic acid enantiomers was greater than 1.5,and the baseline separation was achieved.The validity of this method was proven by precision,linearity,limit of detection and limit of quantification.Secondly,the resolution of 4-mandelic acid enantiomers was studied in aqueous/organic phase,and the chiral extractants were selected from tartaric acid derivatives and amino acid derivatives.Among tartaric acid derivatives,the separation factor was up to 1.22 by using Di-p-Toluoyl-D-tartaric acid(D-DTTA).Among amino acid derivatives,the separation factor was up to 3.06 by using 2-Cl-N-carbobenzyloxy-L-valine(2-Cl-Z-Valine).The effect of types of organic solvent,pH valueof aqueous phase,kinds of resolving agent and its concentration,4-chloromandelic acid concentration and extractive temperature on the distribution coefficient and separation factor were investigated.The laws of the experimental results were analyzed and the mechanisms were primary discussed.Finally,the distribution behavior of 4-chloromandelic acid enantiomers was studied in aqueous two phase system consisted of polyethylene glycol/ammonium sulfate with Hydroxypropyl-?-cyclodextrin.The mechanism of enantiomeric separation of 4-mandelic acid by aqueous two-phase system was studied.The influence of pH,molecular weight of polyethylene glycol,mass fraction of polyethylene glycol,mass fraction of ammonium sulfate,concentration of Hydroxypropyl-?-cyclodextrin,concentration of 4-chloromandelic acid and extractive temperature on enantiomeric separation were investigated.Under the optimized extraction conditions,the separation factor of 4-ClMA enantiomers was up to 1.61.