Abstract
Completely deacetylated chitosan was prepared by the treatment of commercial chitosan with 50% aqueous NaOH, and then derivatized into several new chitosan phenylcarbamate derivatives having a urea and an imide moiety at the 2‐position of the glucosamine ring by the reaction with isocyanate and phthalic anhydride/isocyanate, respectively. The chitosan derivatives were coated on macroporous silica gel and evaluated as chiral stationary phases (CSPs) for high‐performance liquid chromatography. The chiral recognition ability of the chitosan derivative was improved using the completely deacetylated chitosan. Among the novel chitosan derivatives, the 3,5‐dimethyl‐, 3,5‐dichloro‐, and 3,4‐dichlorophenylcarbamate derivatives were found to possess relatively high chiral resolution abilities. The CSPs based on the chitosan phenylcarbamate‐urea and ‐imide derivatives were stable in the presence of chloroform and ethyl acetate as a component of the eluents, and some racemates were better resolved by such eluents. The dichlorophenylcarbamate‐imide derivatives showed a high chiral recognition for metal acetylacetonate complexes. The enantiomerization of Al(acac)~3~ was performed on the chitosan 3,5‐dichlorophenylcarbamate‐imide derivative CSP and the resulting chromatogram showed a 26% (+)‐isomer enrichment. Chirality, 2008. © 2007 Wiley‐Liss, Inc.