Liquid crystal compounds

1-(p-Cyanophenyl)-4-alkylcyclohexenes expressed by the general formula ##STR7## wherein R.sub.1 represents a straight alkyl group having 3.about.7 carbon atoms.

1-(4'-Cyano-4-biphenylyl)-4-alkylcyclohexenes expressed by the general formula ##STR8## wherein R.sub.2 represents a straight alkyl group having 3.about.5 carbon atoms.

A method for producing 1-(4'-cyano-4-biphenylyl)-4-alkylcyclohexenes expressed by the general formula ##STR10## wherein R represents a straight alkyl group having 1.about.9 carbon atoms, which method comprises:

• reacting a 4-alkylcyclohexanone (wherein the alkyl group has a straight chain of 1.about.9 carbon atoms) with 4-bromo-4'-biphenyllithium to prepare a mixture of cis- and trans-forms of 1-(4'-bromo-4-biphenylyl)-4-alkylcyclohexanols (the first step);
• subjecting said mixture of cis-and trans-forms to a dehydration reaction to form a 1-(4'-bromo-4-biphenylyl)-4-alkylcyclohexene (the second step);
• and replacing the Br group of the compound thus prepared by cyano group (the third step).

A nematic liquid crystal composition containing at least one member selected from the group consisting of 1-(p-cyanophenyl)-4-alkylcyclohexenes and 1-(4'-cyano-4-biphenylyl)-4-alkylcyclohexenes, expressed by the general formula ##STR11## wherein R represents a straight alkyl group having 1.about.9 carbon atoms and n represents 1 or 2.