Liquid-crystal 5-phenylpyrimidine derivatives having sc or sc* phases and a process for preparing them

摘要

Liquid-crystal 5-phenylpyrmidine derivatives having Sc or S*c phases and a process for preparing them. The new liquid-crystal 5-phenylpyrimidine derivatives have an Sc or S*c phase and are described by the general formula (I) <IMAGE> (I) in which the symbols have the following meaning: R1 and R2 denote identical or different, straight-chain or branched alkyl or alkenyl groups having from k to 16 carbon atoms, with or without an asymmetric carbon atom, in which one or more non-adjacent -CH2- groups can be replaced by -O- and /or -S--A and -B each denote <IMAGE> <IMAGE> in which the radicals R1, R2, in each case, are situated at the phenylene part of -A, -B and m and n denote 0 or 1, but m and n do not simultaneously denote 1, with the following provisos: (a) if m=n=0, k is 8, and in R2 the -CH2- group adjacent to the phenyl nucleus is replaced by -O-; (b) if m=1 and n=0, k is 2, and (c) if m=0 and n=1, k is 2 and in R2 the -CH2- group adjacent to the phenyl nucleus is replaced by -O-.