NEW LIQUID-CRYSTAL MATERIALS WITH CHIRAL 2-METHYLBUTYL GROUP - (+)-2-METHYLBUTYL 4-(5-ALKYL-1,3-DIOXAN-2-YL) CINNAMATE AND BENZOATE

New liquid crystal materials with chiral 2-methylbutyl group: (+)-2-methylbutyl 4-(5-alkyl-1,3-dioxan-2-yl) cinnamate and benzoate were synthesized. The mesomorphic behavior of these compounds were measured, and compared with those of the corresponding 1,3-oxathiane and 1,3-dithiane compounds. Though compounds (7) exhibited a liquid crystal phase; compounds (8) did not. The difference in the chemical structure between (7) and (8) is the existence of CH=CH in the former. So that, CH=CH seems to contribute to exhibit the liquid crystal phase in compound (7). Transition temperatures of the isotropic to the liquid crystal phase decrease in the order: 1,3-dithiane > 1,3-dioxane > 1,3-oxathiane. This result seems to originate in wider molecular width of 1,3-oxathiane compounds and larger dispersion force of 1,3-dithianes.