3,5-DIMETHYLPHENYLCARBAMATES OF CELLULOSE AND AMYLOSE REGIOSELECTIVELY BONDED TO SILICA-GEL AS CHIRAL STATIONARY PHASES FOR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

3,5-Dimethylphenylcarbamates of amylose (ADMPC) (1) and cellulose (CDMPC) (2) chemically bonded to 3-aminopropylsilica gel were prepared with 4,4'-diphenylmethane diisocyanate as a spacer and their optical resolution abilities were evaluated as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). To investigate the influence of the position of the glucose unit in immobilization on chiral recognition, the polysaccharide derivatives were regioselectively bonded to the silica surface. ADMPC regioselectively bonded at the B-position to silica gel possesses a higher optical resolving power than that bonded at the 2- or 3-position. The chiral recognition ability of the former CSP was almost comparable to that of ADMPC coated an silica gel. For CDMPC, the position of glucose in immobilization on silica gel hardly affected the chiral recognition. The enantioselectivities of these CSPs were also influenced by the amount of the diisocyanate used for immobilization. These chemically bonded-type CSPs were able to be used with eluents such as CHCl3, in which the polysaccharide derivatives are soluble or swollen. A few racemates which were not or poorly separated on the coated-type CSP were more efficiently resolved on the chemically bonded-type CSP using CHCl3, as a component of the mobile phase.