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

Abstract

Liquid-crystal 5-phenylpyrmidine derivatives having S.sub.c or S.sup.*.sub.c phases and a process for preparing them. The new liquid-crystal 5-phenylpyrimidine derivatives have an S.sub.c or S.sup.*.sub.c phase and are described by the general formula (I) ##STR1## in which the symbols have the following meaning: R.sup.1 and R.sup.2 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 --CH.sub.2 -- groups can be replaced by --O-- and /or --S----A and --B each denote ##STR2## in which the radicals R.sup.1, R.sup.2, 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 R.sup.2 the --CH.sub.2 -- 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 R.sup.2 the --CH.sub.2 -- group adjacent to the phenyl nucleus is replaced by --O--.

Dependencies are inferred from the claim text.