Difluorophenyl pyrimidyl pyridine derivatives and the use thereof in liquid crystal mixtures

摘要

PCT No. PCT/EP96/05774 Sec. 371 Date Jan. 14, 1999 Sec. 102(e) Date Jan. 14, 1999 PCT Filed Dec. 20, 1996 PCT Pub. No. WO97/24351 PCT Pub. Date Jul. 10, 1997Difluorophenylpyrimidylpyridine derivatives of the formula (I) wherein X is N and Y is CH or X is CH and Y is N; R1 and R2 are identical or different and are a) an unbranched or branched alkyl chain having 1 to 20 carbon atoms, where aa) one or more non-adjacent and non-terminal CH2 groups may be replaced by -O-, -CO-O-, -O-CO-, -O-CO-O- or -Si(CH3)2-, and/or ab) one or more H atoms may be replaced by F, and/or ac) the terminal CH3 group may be replaced by one of the following chiral groups (optically active or racemic): R3, R4 and R5 are identical or different and are hydrogen or a straight-chain or branched alkyl radical having 1-16 carbon atoms (with or without an asymmetrical carbon atom), where, in addition, one or more non-adjacent non-terminal CH2 groups may be replaced by -O-, and/or where one or more H atoms of the alkyl radical may be substituted by -F; R4 and R5 may alternatively together be -(CH2)4- or -(CH2)5- if they are bonded to a dioxolane system, are suitable as components, in particular, of ferroelectric liquid-crystal mixtures.