| abstract |
compounds of the general formula wherein ring A is saturated or aromatic and an optionally present saturated ring A is trans-linked to the second ring; R 'denotes a straight chain alkyl or alkoxy group having 1 to 11 carbon atoms; R 2 cyano, a straight-chain alkyl group having 1 to 11 carbon atoms, an ester group of the general formula or, if ring A is saturated, additionally denotes a straight-chain alkoxy group having 1 to 11 carbon atoms; in the ester group of formula II, ring B is either aromatic and X denotes oxygen or sulfur and R 3 cyano or a straight-chain alkyl or alkoxy group having 1 to 10 carbon atoms, or ring B denotes a trans-1,4-disubstituted cyclohexane ring and X oxygen and R 3 represents cyano or a straight chain alkyl group having 1 to 10 carbon atoms; and the total number of carbon atoms in the alkyl and / or alkoxy groups is at most 12, their production and use in electro-optical devices, liquid-crystalline mixtures and new intermediates are described.n n n The new compounds of formula I are particularly valuable as components in liquid crystal mixtures. |