Studies On Synthesis Of N-oxazoline Phenylacrylamides Bonded Chiral Stationary Phases And Evalution Of Their Chiral Resolution Ability

Chirality is one of intrinsic properties for the nature. All the reactions relative to the living activity carry out in highly asymmetric environment. Biomacromolecules, including protein, amylase, and nucleic acid, are of chiral. In our daily life, most drugs with activity are also of chiral. More and more attention has been paid to utilizing the high performance liquid chromatography (HPLC) chiral stationary phases (CSPs) to separate enantiomers. Studies on both the synthesis of CSPs and the structure-property relationship have become an active topic in the polymer science, which allow the development of novel CSPs with excellent resolution performance.Polyacrylamides have significantly contributed to the area of polymer-based CSPs. In this paper, the optically active polymers of N-(oxazolinylphenyl)acrylamide derivatives (poly(PhOPAM), and poly(MeOPAM)) have been synthesized by radical polymerization. The corresponding polymer modified CSPs were prepared by immobilizing the polymers to silica gel via "grafting to" method. The structure was characterized by elemental analysis (EA), thermogravimetry analysis (TGA), and FT-IR for the novel CSPs.The chiral resolution ability of the CSPs was evaluated on HPLC. In this study, four racemates, including binaphthol, benzoin, 2-amino-1-butanol, and loxoprofen sodium, were selected for the chiral separation under the positive chromatography conditions. It was found that racemic benzoin and 2-amino-l-butanol could be successfully separated on both polymer-based CSPs. The poly(MeOPAM)-bonded CSP showed most effective resolution performance for benzoin.The chiral separation performance of poly(PhOPAM)-bonded silica gel was examined in a chiral ligand exchange chromatography (CLEC) mode for α-amino acids, including (D,L)-phenylalanine, (D,L)-serine, (D,L)-aspartic acid, and (D,L)-valine. The effects of flow rate, pH of the mobile phase and the concentration of the center ion Cu²⁺ were studied. The results indicate that all of the four amino acids could be separated under the given conditions. The optimum operationparameters for the effective separation of (D,L)-aspartic acid covered the followings: flow rate = 0.5 ml/min, pH = 7.0, Cu(OAc)₂-H₂O eluent with [Cu²⁺] of 0.1 mmol/L.