Cyclohexane derivatives of formula I ##STR1## wherein R is an alkyl group which has 1-12 C atoms and in which one or two non-adjacent CH.sub.2 groups can also be replaced by O, --CO--O-- or --OCO--,A.sup.1 and A.sup.2 each independently of one another are trans-1,4-cyclohexylene or unsubstituted or fluorine-substituted 1,4-phenylene, and one of the groups A.sup.1 and A.sup.2 can also be a single bond,X is --CN, halogen, OH, --COOR.sup.1, --OOCR.sup.1, --COR.sup.1, --OR.sup.1 or R.sup.1 andR.sup.1 is an alkyl group which has 1-12 C atoms and in which one or two CH.sub.2 groups can also be replaced by O, but excluding direct links between two O atoms,with the proviso that, in the case of X=CN, A.sup.2 is trans-1,4-cyclohexylene or fluorine-substituted, 1,4-phenylene, are suitable as components of liquid-crystalline phases.