Optically active 1,3-dioxolane derivatives carrying a mesogenic radical in the 4-position, a process for their preparation and their use as doping agents in liquid-crystal mixtures

摘要

Optically active 1,3-dioxolane derivatives which carry a mesogenic radical in the 4-position and have the general formula (I) (I) are suitable for use as doping agents in liquid-crystal mixtures-in particular ferroelectric liquid-crystal mixtures. The symbols in the general formula have the following meanings: R1 is composed analogously to the part of the general formula on the right-hand side of X or is an alkyl or alkylene radical which can be substituted, R2, R3 and R4 are H or alkyl (R4 is also alkenyl) which can also be substituted [R2 and R3, together with the C(2) of the dioxolane ring are also a cycloaliphatic radical or a keto group], J, l and n are zero, 1 or 2 and k and m are zero or 1, subject to the proviso that, if k is zero n is zero and if n is zero m is zero and 1