Patent ID: 7074462

Claim:
Liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, which comprises one or more compounds of the formula I in which R is H, an alkyl radical having from 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups in these radicals are optionally replaced, in each case independently of one another, by â€”Oâ€”, â€”Sâ€”, â€”COâ€”, â€”COâ€”Oâ€”, â€”Oâ€”COâ€”, â€”CHâ•CHâ€”, â€”Câ‰¡Câ€” or â€”Oâ€”COâ€”Oâ€” in such a way that O atoms are not linked directly to one another, A 1 and A 2 are each, independently of one another, (a) a trans-1,4-cyclohexylene radical, in which, in addition, one or more non-adjacent CH 2 groups are optionally replaced by â€”Oâ€” and/or â€”Sâ€”, (b) a 1,4-phenylene radical, in which, in addition, one or two CH groups are optionally replaced by N, (c) a 1,4-cyclohexenylene radical, or (d) a radical selected from the group consisting of 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, where the radicals (a) to (d) are optionally monosubstituted or polysubstituted by CN or fluorine, Z and Z 1 are each, independently of one another, â€”COOâ€”, â€”Oâ€”COâ€”, â€”CH 2 Oâ€”, â€”OCH 2 â€”, â€”C 2 H 4 â€”, â€”CHâ•CHâ€”, â€”CF 2 Oâ€”, â€”OCF 2 â€”, â€”Câ‰¡Câ€”, â€”CHâ•CHâ€”C 2 H 4 â€”, â€”C 2 F 4 â€” or a single bond, L 1 and L 2 are each, independently of one another, H or F, Y is F, Cl, CN, or an alkyl or alkoxy radical having from 1 to 6 carbon atoms which is substituted by one or more halogen atoms and in which, in addition, one or more CH 2 groups are optionally replaced by â€”Oâ€” or â€”CHâ•CHâ€” in such a way that O atoms are not linked directly to one another, m is 0 or 1, with the provisos that: a) when m=0 and A 2 = Z is not single bond and b) when m=0, A 2 = and Z=â€”COOâ€”, L 1 is F.