Atsushi Sawatari

Chiral discrimination with regioselectively substituted cellulose esters as chiral stationary phases

Four kinds of cellulose derivatives, including two regioselectively substituted cellulose esters (6-O-acetyl-2,3-di-O-benzoyl cellulose and 2,3-di-O-acetyl-6-O-benzoyl cellulose), were synthesized so that the effects of their functional group distribution on their chiral discrimination ability could be examined. The degree of substitution by functional groups appeared to have a critical effect on the separation in most cases, but the type of the functional group at the C-6 position also significantly influenced chiral discrimination when a series of neutral arylalcohol derivatives were used as racemates. Copyright 2000 Wiley-Liss, Inc.

Studies on the thermal properties and structures of deoxyhalocelluloses

The thermal properties and structures of deoxyhalocelluloses were studied using thermogravimetric and differential scanning calorimetric analyses and an X-ray diffraction method. The X-ray diffraction curves of the cellulose derivatives were obtained after subjecting them to a specific treatment that was supposed to render a specific cellulose allomorph from the amorphous state cellulose; all of the cellulose derivatives examined without such treatment exhibited no crystalline features. Only deoxyfluorocellulose was found to give a diffraction pattern similar to that of the corresponding cellulose allomorph, which was cellulose IV in this case. On the basis of the thermal analyses, it was confirmed that chlorodeoxycellulose has a flameretardant property, whereas deoxyfluorocellulose was found not to be flame-retardant. The difference is supposedly due to the difference in the bonding energy between C-Cl and C-F.