Journal of Thermal Analysis and Calorimetry, Vol. 63 (2001) 339–344 D-XYLOSE DERIVATIVE LIQUID CRYSTALS P. Martin, P. Godé, P. Villa and G. Goethals Laboratoire de Chimie Organique et Cinétique, Université de Picardie ‘Jules Verne’, 33 rue St. Leu, 80039 Amiens Cedex, France (Received February 21, 2000; in revised form July 15, 2000) Abstract We studied the phase transition temperatures of a series of amphiphilic D-xylopyranose and D-xylo- furanose derivatives in which the lipophilic part is an alkyl chain R(n-C n H 2n+1 ), regiospecifically linked to D-xylose, at different positions, by Z which is an atom or a functional group (O, S, O–(CH 2 ) 3 –S). The alkyl chain was moved from the C-1 to the C-5 position in the xylose moiety, thereby allowing us to compare directly the phase transition temperatures of the individual materials. These compounds give thermotropic and/or lyotropic liquid crystals. In some cases, we also ob- served solid–solid phase transitions. Keywords: amphiphile, DSC, D-xylose derivatives, lyotropy, thermotropy Introduction In 1983 Jeffrey and Bhattacharjee [1] showed that n-alkyl glucopyranosides exhibit thermotropic liquid crystalline properties. Subsequently, many studies were per- formed on liquid crystalline carbohydrates and related materials. The majority of the undertaken studies involved the investigation of substituted cyclic furanose and pyranose systems. However, no results have been reported involving D-xylose. Thus, this work is concerned with a systematic investigation of the effects of the linking group Z, alkyl chain length and its position, on liquid crystalline properties of D-xyl- ose derivatives. For this purpose we have selected to study the mesomorphic behav- iour of alkyl substituted D-xylose where the aliphatic chain is attached to the D-xyl- ose moiety via either an ether or a thioether linkage. Materials and methods Synthesis The D-xylose amphiphilic derivatives x-ZR-D-xylose (Table 1) in which R is an alkyl chain linked to the D-xylose moiety at the x position (C-1 to C-5) by Z=O, S, O–(CH 2 ) 3 –S, were described previously [2, 3]. 1418–2874/2001/ $ 5.00 © 2001 Akadémiai Kiadó, Budapest Akadémiai Kiadó, Budapest Kluwer Academic Publishers, Dordrecht