Alkenylcyclohexane liquid crystalline compounds

Compounds of the general formula ##STR9## wherein Z.sup.1 denotes a single covalent bond or --CH.sub.2 --CH.sub.2 --;

• ring A.sup.1 represents 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl or, when Z.sup.1 stands for --CH.sub.2 --CH.sub.2 --, also trans-1,4-cyclohexylene;
• X.sup.1 stands for fluorine or chlorine;
• X.sup.2 signifies fluorine, chlorine or, when X.sup.1 stands for chlorine, also hydrogen;
• and R.sup.1 signifies 1E-alkenyl with 2 to 12 carbon atoms.

A liquid crystalline mixture having at least two components, wherein at least one component is a compound of the formula ##STR12## wherein R.sup.1 is 1E-alkenyl of 2 to 12 carbon atoms;

• Z.sup.1 is a single covalent bond or --CH.sub.2 CH.sub.2 --;
• ring A.sup.1 is 1,4-phenylene, pyrimidin-2,5-diyl, pyridin-2,5-diyl or, when Z.sup.1 is --CH.sub.2 CH.sub.2 --, A.sup.1 also can be trans-1,4-cyclohexylene;
• X.sup.1 is fluorine or chlorine;
• and X.sup.2 is fluorine or chlorine;
• or when X.sup.1 is chlorine, X.sup.2 also can be hydrogen;
• and when ring A.sup.1 is pyridin-2,5-diyl and Z.sup.1 is --CH.sub.2 CH.sub.2 --, X.sup.2 also can be hydrogen.

An electro-optical cell comprising:

• (a) two plate means;
• (b) liquid crystal means disposed between the two plate means and including a compound of the formula:
• ##STR14## wherein R.sup.1 is 1E-alkenyl of 2 to 12 carbon atoms;
• Z.sup.1 is a single covalent bond or --CH.sub.2 CH.sub.2 --;
• ring A.sup.1 is 1,4-phenylene, pyrimidin-2,5-diyl, pyridin-2,5-diyl or, when Z.sup.1 is --CH.sub.2 CH.sub.2 --, A.sup.1 also can be trans-1,4-cyclohexylene;
• X.sup.1 is fluorine or chlorine;
• and X.sup.2 is fluorine or chlorine;
• or when X.sup.1 is chlorine, X.sup.2 also can be hydrogen, and when ring A.sup.1 is pyridin-2,5-diyl and Z.sup.1 is --CH.sub.2 CH.sub.2 --, X.sup.2 also can be hydrogen;
• and
• (c) means for applying an electric potential to said plate means.