Enantiomeric resolution of ephedrine racemic mixture using molecularly imprinted carboxylic acid functionalized resin

In the current work, we prepared an enantio-selective imprinted resin adsorbent ((+)-EMIP) with remarkable affinity for (+)-ephedrine ((+)-Eph) enantiomer. The phenolic amide derived from 4-hydroxybenzoic acid (HBA) and (+)-Eph ((+)-Eph-HBA) was first synthesized via N,N'-diisopropylcarbodiimide (DIC) activation and then copolymerized with resorcinol and formalin. The template (+)-Eph was then expelled from the resin by alkaline degradation of the amide linkage and the finally obtained (+)-EMIP resin particles exhibited a considerable selectivity toward the (+)-Eph with a capacity reached 220 +/- 1 mg/g. Also, the selectivity studies indicated a higher affinity toward the imprinted (+)-Eph enantiomer as a result of the formation of configuration-matching receptor sites that were able to fit the targeted enantiomer better than its mirror-image. Moreover, the prepared resin was successfully employed in the chiral resolution of (+/-)-Eph racemate using batch technique with (+)-Eph 87.1% enantiomeric excess in the loading supernatant solution and (-)-Eph 44.6% excess in the recovery eluant solution.