| abstract |
Compounds of the formula ##STR1## wherein R 1 is straight-chain alkyl of 1 to 12 carbon atoms, R 2 is 1-alkynyl and the 1-alkynyl group in R 2 is a straight-chain group of 1 to 10 carbon atoms, their manufacture, liquid crystalline mixtures containing said compounds as well as their use for electro-optical purposes are described. The novel compounds are valuable components for liquid crystalline mixtures and have a negative dielectric anisotropy. |