3-fluoropyridines, method of preparing them and their use in liquid-crystal mixtures

摘要

A 3-fluoropyridine of the formula (I) in which the symbols have the following meanings: R<1> and R<2>, independently of one another, are, for example, H or straight-chain or branched alkyl, A<1>, A<2>, A<3> and A<4> are identical or different and are, for example, 1,4-phenylene, pyrazine-2,5-diyl or trans-1,4-cyclohexylene, M<1>, M<2>, M<3> and M<4> are identical or different and are, for example, -O- or -CO-O-, R<3>, R<4>, R<6> and R<7>, independently of one another, are, for example, H or straight-chain or branched alkyl, M<5> is, for example, -O-CO- or a single bond, k, l, m, n, o, p, q and r are zero or one, with the proviso that the sum of k+m+p+r is less than 4 and is greater than zero, can advantageously be employed as a component of ferroelectric liquid-crystal mixtures.