| abstract |
Compounds of the formula <IMAGE> I wherein n is 0 or 1; one of X1 and X2 is -COO- or -OOC- and the other is a single covalent bond or -CH2CH2-; X3 and X4 individually are a single covalent bond or -CH2CH2-, with the proviso that at most one of X1, X2, X3 and X4 is -CH2CH2-; rings A1 and A5 individually are a group of the formula <IMAGE> II or trans-1,4-cyclohexylene; rings A2, A3 and A4 individually are a group of formula II or, when ring A2, A3 or A4 is not linked with at least one of the other two of these rings by a single covalent bond then such ring also can be trans-1,4-cyclohexylene, with the proviso that at least one of rings A1 through A5 is a group of formula II; Y is hydrogen, or when Y is attached to a ring of formula II which is not linked with another ring via a single covalent bond, Y also can be fluorine, chlorine or methyl; and R1 and R2 individually are straight-chain alkyl of 1-7 carbon atoms, or when R1 or R2 is attached to a ring of formula II such R1 or R2 also can be straight-chain alkoxy of 1 to 7 carbon atoms; their manufacture and use for electro-optical and chromatographical purposes and liquid crystalline mixtures containing these compounds are described. |