Substituted benzonitriles, their preparation, liquid crystal compositions containing them and display devices employing such compositions.

摘要

Novel compounds which are 4-alkylcyclohexenes having at the 1-position a 4-cyanophenyl or 4"-cyanobiphenyl-4'-yl group and which are expressed by the general formula:
<Chemistry id="chema01" num="0001"><Image id="ia01" he="12" wi="74" file="IMGA0001.TIF" imgContent="chem" imgFormat="TIFF" inline="no" /></Chemistry>(wherein R represents a straight-chain alkyl group having 1 to 9 carbon atoms and n is 1 or 2) are liquid crystal materials which can be used in Np liquid crystal display devices. The compounds of formula (I) wherein n = 1 can be employed as the main component of a liquid crystal composition, while the compounds of formula (I) wherein n=2 can be used to broaden the nematic temperature range of other liquid crystal compounds including those of formula (I) wherein n=1.

The compounds are typically prepared by a 3-stage process in which a 4-bromophenyl or 4'-bromobiphenyl substituent is introduced at the 1-position of a 4-alkylcyclohexanone by a grignard or organolithium reaction giving the corresponding substituted 4-alkylcyclo-hexanol which without separation of the cis-and trans-isomers is dehydrated to the corresponding cyclohexene and the bromo substituent is then converted to a cyano group.

The compounds of formula (I) have a lower viscosity than conventinal liquid crystal compounds, a short response time when used in display devices, good compatability with other liquid crystal compounds to form mixtures with particularly effective properties, and are easier to prepare than the recently reported 4-(trans-4-alkylcyclohexyl)benzoni- triles.