Alkoxy di- and tri-fluoro-tolan(s) - useful as components of LC media

摘要

Di- and tri-fluorotolans of formula (I) are claimed. In (I) R'1 = 1-9C alkyl, L = H or F. Pref. R'1 = Et, Pr, Bu or pentyl. (I) are prepd. e.g. by reaction of the corresp. p-substd. bromo-or iodo-benzene with the corresp. phenylacetylene in the presence of a Pd complex catalyst, or by reaction of p-alkoxyphenylacetylene with the di- or tri-fluoro-substd. bromo-or iodo-benzene. USE/ADVANTAGE - (I) are useful as components of LC media (claimed). Also claimed are LC media with at least 2 LC components, at least one of which is a cpd. (I) and LCDs contg. such media. (I) are colourless cpds. which are stable to chemicals, heat and light, and which form LC mesophases in a suitable temp. range for electro-optical applications. Media contg. (I) have low temp.-dependence of threshold voltage, high electrical resistance, good miscibility with other components and good low-temp. stability and a positive effect on the d/p window which is important for STN displays.