Thermotropic liquid-crystalline properties of some novel hexuronic acid derivatives bearing a single or two alkyl chains

We have recently developed a new method for O-glycosidation of totally O-unprotected aldoses and uronic acids. Either pyranosides or the corresponding furanosidic isomers are thus obtained in one step from natural carbohydrates. This paper is concerned with the thermotropic liquid-crystalline phases of alkyl beta-D-galacto-(or gluco)-furanosiduronic acids bearing a saturated alkyl chain at the anomeric position and of some dialkylated derivatives. Phase identifications and measurements of phase transition data were carried out by differential scanning calorimetry (DSC), polarizing optical microscopy and small angle X-ray diffraction studies. Uronic derivatives have quite crystalline structures; upon heating, these compounds exhibit a smectic A* transformation.