| 摘要 |
New 3,4-difluoro pyridine derivatives of formula (I) R<1>(-M<1>)a(A<1>)b(-M<2>)c(-A<2>)d(-M3)e-B(-M4)f(-A<4>)g- (-M<5>)h(-A<4>)i(M<6>)k-R<2> (I). B= gp. (II); R<1>, R<2> = H, CN, F, Cl, -CF3, -CHF2, -CH2F, -OCF3, -OCHF2, -OCH2F; or 1-20C alkyl with one or more CH2 groups replaced by -O-, -S-, -CO-, -CS-, -CH=CH-, -C?=C-, 1,2-cyclopropanylene, Si(CH3)2-, 1,4-phenylene, trans-1,4-cyclohexylene or 1,3-cyclopentylene, with the proviso that oxygen and sulphur atoms are not bonded to one another, and/or where the hydrogen atoms of the alkyl group can be replaced by one or more F, Cl, Br, OR<3>, -SCN, -OCN or -N3 groups; or can be one of the following groups e.g.(III)-(V) (optically active or racemic), R<4>-CH(Cl)COO-, R<4> CH(F)-COO-, R<4>-CH(Cl)-CH2-O-, R<4>-CH(F)-CH2-O-, R<4>-CH(N)COO-, R<4>-CH(CN)-CH2-O-, R<4>-O-CH(CH3)-COO-, R<4>-O-CH(CH3)-CH2-O-, R<3>-R<7> = 1-16C alkyl with one or more asymmetric C atom, with one or more CH2 group opt. substd. by -O- and/or -CH=CH-, with the proviso that oxygen atoms can not be bonded to one another; and/or one or more H atoms of the alkyl group can be replaced by F or Cl, and R<4> and R<5> can together be -(CH2)4 or -(CH2)5 and bonded into an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system; A<1>, A<2>, A<3>, A<4> = 1,4-phenylene, pyrazine-2,5-diyl, pyridazene-3,6-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl, all opt. substd. with F, Cl and/or CN groups, trans-1,4-cyclohexylene opt. substd. with CN and/or CH3, (1,3,4)-thiadiazol-2,5-diyl, 1,3-dioxan-2,5-diyl, 1,3-dithione-2,5-diyl, 1,3-thiazole-2,4-diyl, opt. substd. with F, Cl and/or CN, thiophene-2,4-diyl, opt. substd. with F, Cl and/or CN, thiophene-2,5-diyl opt. substd. with F, Cl and/or CN piperazine-2,5-diyl, naphthalene-2,5-diyl opt. substd. with F, Cl and/or CN, bicyclo(2,2,2)-octane-1,4-diyl opt. substd. with F, Cl and/or CN, or 1,3-dioxaborinane-2,5-diyl, or the group B. Also claimed are: the use of these compounds as components of liquid crystal mixtures; liquid crystal mixture containing these compounds; and switching and/or display apparatus containing these compounds as a liquid crystal medium.
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