(2'-Cyano-4'-alkylphenyl)-3-cyano-4-alkoxybenzoates and liquid crystal
申请人:Kabushiki Kaisha Suwa Seikosha
公开号:US04287085A1
公开(公告)日:1981-09-01
Ester compounds suitable for use in liquid crystal compositions are provided. The ester compounds are (2'-cyano-4'-alkylphenyl)-3-cyano-4-n-alkoxybenzoates represented by the general formula: ##STR1## wherein R and R' each is a straight-chain alkyl group having one to eight carbon atoms. The ester compounds alone do not exhibit a liquid crystal phase, but have a relatively low melting point. Addition of at least one such ester compound to a liquid crystal composition lowers the value of the dielectric anisotropy of the composition at frequencies higher than the critical frequency, and lowers it at frequencies lower than the critical frequency. Such compositions are particularly well suited for the two-frequency matrix-addressing drive in a display of complex characters or graphic displays. The ester compounds in accordance with the invention are prepared by condensing a 3-bromo-4-n-alkoxybenzoyl chloride having the general formula: ##STR2## and a 2-cyano-4-n-alkylphenol having the general formula: ##STR3## to prepare a (2'-cyano-4'-n-alkylphenol)-3-bromo-4-n-alkoxybenzoate having the general formula: ##STR4## wherein R and R' each is a straight-chain alkyl group having from one to eight carbon atoms, and reacting the benzoate (IV) with cuprous cyanide to yield the desired ester (I).