Compounds of the formula ##STR1## wherein A.sup.1 denotes a single covalent bond and A.sup.2 denotes 1,4-phenylene or trans-1,4-cyclohexylene or A.sup.1 denotes trans-1,4-cyclohexylene and A.sup.2 denotes a single covalent bond; X.sup.1 signifies fluorine or chlorine; X.sup.2 represents fluorine or, when X.sup.1 signifies chlorine, also hydrogen or chlorine; and R.sup.1 signifies 1E-alkenyl with 2 to 12 carbon atoms, their manufacture, liquid crystalline mixtures which contain such compounds and their use for electro-optical purposes.
化学式为##STR1##的化合物,其中A.sup.1表示单个共价键,A.sup.2表示1,4-苯撑基或trans-1,4-环己撑基,或者A.sup.1表示trans-1,4-环己撑基,A.sup.2表示单个共价键;X.sup.1表示
氟或
氯;X.sup.2表示
氟或者当X.sup.1表示
氯时,还表示氢或
氯;R.sup.1表示具有2至12个碳原子的1E-烯基,其制造,液晶混合物包含这种化合物和它们用于电光目的的用途。