Controlled Synthesis And Chiral Recognition Of Cellulose Phenylcarbamate Derivatives Bearing Different Substituents

Polysaccharide derivatives are widely used for the preparation of chiral stationary phases(CSPs)for high-performance liquid chromatography(HPLC)due to their excellent chiral recognition abilities.Among them,the phenylcarbamate derivatives of cellulose and amylose show the highest recognition ability.Generally,the structure and property of substituent on the phenyl group has significant influence on their chiral recognition abilities.By far,the study on the chiral recognition ability and related recognition mechanism of the polysaccharide derivative bearing different substituents has been still desired.Based on this background,the synthesis and chiral recognition ability of cellulose phenylcarbamate derivatives bearing different groups at 2-,3-and 6-postions of a glucose unit have been systematically performed in this study.A series of cellulose phenylcarbamate derivatives bearing different groups at 2-,3-and6-postions of a glucose unit were synthesized by the regioselective procedures.The reaction process was monitored by FT-IR,the structure and the degree of substitution at different positions of glucose unit were confirmed by~1H NMR and FT-IR spectra,and the higher order structures was characterized by CD sepctra.The coated-type CSPs based on the obtained derivatives were then prepared by traditional coating method,and their thermostability and coating efficiency were analyzed by TGA.Finally,the chiral columns for HPLC were prepared by slurry method,and the chiral recognition abilities of derivatives were evaluated by enantioseparation of ten chiral compounds on the CSPs by normal-phase HPLC.Based on these results,the effect of the position,structure and property of the substituents on the chiral recognition ability of the cellulose derivatives was further investigated.It indicated that all of the obtained cellulose phenylcarbamates bearing regioselective substituents exhibited good chiral recognition abilities to racemates 2,5 and 6(The separation factor are higher than 1.2).Especially,the resolution of racemate 6 on all the obtained CSPs in the study were even higher than that on the commercial column,Chiralcel OD.On the other hand,the combination of the introduction of electronic donating substituents at 2-and3-positions and electronic withdrawing substituents at 6-position can improve the chiral recognition ability of this series of cellulose derivatives.Each derivative exhibited unique chiral resolution ability,which varied depending on the different structures of the racemates.