2-(p-Substituted phenyl)-5-alkyl-1,3-dithianes, newliquidcrystals, were synthesized by the thioacetalization of the corresponding aldehydes and dithiols. These compounds have characteristic supercooling states, exhibit monotropic liquidcrystal phases even in the case of long terminal alkyl substituents. The mesomorphic characteristics of these compounds were different from those of the corresponding