Ester compounds, liquid crystal composition including same and method of production

摘要

Ester compounds suitable for use in liquid crystal compositions are provided. The ester compounds are (2'-chloro-4'-n-alkylphenyl)-3-cyano-4-n-alkoxybenzoates represented by the general formula: <IMAGE> (I) wherein R and R' are straight-chain alkyl groups having from one to eight carbon atoms. The ester compounds alone do not exhibit a liquid crystal phase, but have a relatively high value of dielectric anisotropy. Addition of minor amounts of at least one such ester compound to a liquid crystal composition lowers the value of the dielectric anisotropy of the composition in the high frequencies range. Such compositions are particularly well suited for the two-frequency matrix-addressing drive in a display of complex characters or graphic displays by reducing the driving voltage. The ester compounds in accordance with the invention are prepared by condensing a 3-bromo-4-n-alkoxybenzoyl chloride having the general formula: <IMAGE> (II) and a 2-chloro-4-n-alkylphenol having the general formula: <IMAGE> (III) to prepare a (2'-chloro-4'-n-alkylphenyl)-3-bromo-4-n-alkoxybenzoate having the general formula: <IMAGE> (IV) wherein R and R' are straight-chain alkyl groups having from one to eight carbon atoms, and reacting the benzoate (IV) with cuprous cyanide to yield the desired ester (I).