the phenol which yields a compound of formula i b the phenol is synthesized in a single step by condensation in ethanol of p hydroxybenzaldehyde with a para substituted u03b1 cyanotoluene str9 this condensation reaction is known as knoevenagel reaction described for instance as the condensation of an aldehyde with an active methylene compound in the presence of a base catalysed by amines in alcoholic solution compounds of formula i a or i b can be used as the sole liquid crystal compound in a liquid display device but preferably the liquid crystal compositions contain a mixture of at least two compounds of formula i generally the mixtures contain 2 4 compounds of formula i so as to provide eutectic mixtures having nematic properties over a broad temperature range a preferred characteristic of mixtures of compounds of formula i is that the mixtures have properties for use in twisted cell and are therefore highly desirable for use in liquid crystal display devices it will be understood that among the preferred liquid crystal devices in accordance with this invention are those adapted for electrooptical display without further elaboration it is believed that one skilled in the art can using the preceding description utilize the present invention to its fullest extent the following preferred specific embodiments are therefore to be construed as merely illustrative and not.