N-ACYL-BETA-D-GLYCOPYRANOSYLAMINES AND 2-ALKYLAMIDO-2-DEOXY-ALPHA BETA-D-GLUCOPYRANOSES - RELATIONSHIP BETWEEN MOLECULAR-STRUCTURE AND MESOMORPHISM/

A variety of N-acyl-beta-D-glucopyranosylamines, N-acyl-beta-D-mannopy ranosylamines and 2-alkylamido-2-deoxy-alpha/beta-D-glucoses has been prepared regiospecifically and in good yield in a one step reaction of the appropriate acid chloride with D-mannosylamine, 2-amino-2-deoxy-D -glucopyranose (prepared in one step from glucose and mannose accordin g to literature methods) and D-glucosamine liberated in situ from the commercially available hydrochloride. The dependence of the liquid cry stal transition temperatures and mesophase formation on the degree and nature of intermolecular hydrogen bonding has been studied by choosin g two different carbohydrate cores and by attaching aliphatic terminal chains via an amide linkage in two different positions. Comparison is made with related compounds reported in the literature. Whereas the N -acyl-beta-D-mannopyranosylamines and N-acyl-beta-D-glucopyranosylamin es possess wide-range smectic A phases, the corresponding 2-alkylamid o-2-deoxy-beta-D-glucopyranoses do not exhibit observable mesomorphism . Although some homologues of the compounds synthesized have already b een reported in the literature, their liquid crystalline behaviour was not reported. These investigations confirm the general view that it i s the number and type of hydrogen bonding groups on the carbohydrate m oiety and the aliphatic chain length that primarily determine thermotr opic mesophase behaviour, as well as the absolute values of the transi tion temperatures.