Synthesis and evaluation of novel chiral stationary phases based on N-cyclobutylcarbonyl chitosan derivatives

Five halo-containing chitosan 3,6-bis(phenylcarbamate)-2-(cyclobutylformamide) derivatives were synthesized with well-deacetylated chitosan and halo-substituted phenyl isocyanates. The structures of the derivatives were characterized by IR, elemental analysis, and H-1 NMR spectrum. After being coated on silica gel, five new CSPs were obtained and their enantioseparation abilities were evaluated, and the enantioseparation abilities were compared with that of commercial CSP of Chiralcel OD-H. The results demonstrated that all the prepared CSPs showed satisfactory enantioseparation ability. The performance of CSP 2 with 3,4-dichloro substituent on the phenyl group was the best with 11 analytes being baseline separated and 2 analytes being partially separated among 15 tested analytes. Besides, the influence of mobile phase composition, substituent on the phenyl moieties of the chitosan derivatives, as well as structure of analytes on enantioseparation ability was also discussed. In this study, the prepared CSPs exhibited excellent tolerance to unusual solvents, and some of them even could work in pure tetrahydrofuran. Therefore, the CSPs bear a universal solvent compatibility in comparison with coated-type CSPs of cellulose/amylose derivatives.