Liqiud Crystal Materials with Sulfur Atoms Incorporated in the Principal Structure III. Trans and Cis Isomers of New Liquid Crystal Material: 2-(p-Substituted phenyl)-5-alkyl-1,3-dithianes

Article abstract of DOI:10.1246/bcsj.58.477

Trans and cis isomers of 2,5-disubstituted 1,3-dithianes were synthesized by the acid-catalyzed thioacetalization of p-substituted benzaldehydes and dithiols.The results of identifications of trans and cis isomers made by means of 13C NMR chemical shifts indicate that the isomerism occurred at the 5 position in the 1,3-dithiane ring.Benzaldehydes with electrondonating p-substituents produced less cis isomers than that with the cyano group, which seems to indicate the establishment of an equilibrium in the formation reaction between trans and cis isomers.Several electro-optic properties of trans- and cis-2-(p-cyanophenyl)5-alkyl-1,3-dithianes were determined by using them as a dopant of mixture of liquid crystals.Mixture added with trans isomers was superior to that added with cis isomers in several points.