FLUESSIGKRISTALLINE PHASE

Heterocyclic compounds of the formula Iec R -A -A -CH2CH2-A -R in which R and R in each case independently of one another represent an alkyl group having 1-15 C atoms in which one or two non-adjacent CH2 groups can also be replaced by O atoms and/or -CO- groups and/or -O-CO- groups and/or -CO-O- groups and/or -O-COO- groups and/or -CHCN- and/or -CH-halogen- groups, and one of the radicals R and R can also be F, Cl, Br or CN, A , A and A in each case independently of one another are a 1,4-cyclohexylene group which is unsubstituted or mono- or polysubstituted by F and/or Cl atoms and/or CH3 and/or CN groups and in which one or two non-adjacent CH2 groups can also be replaced by O atoms and/or S atoms, or are a 1,4-bicyclo-(2.2.2)-octylene group or are a 1,4-phenylene group which is unsubstituted or monosubstituted or polysubstituted by F and/or Cl atoms and/or CH3 and/or CN groups and in which one or more CH groups can also be replaced by N, with the proviso that at least one of the groups A and A is a pyrazine-2,5-diyl group (Pa) or a pyridine-2,5-diyl group (Py).