Patent ID: 7560147

Claim:
Liquid-crystalline medium based on a mixture of polar compounds, comprising at least one compound of the formula I in which R 11 and R 12 each, independently of one another, denote H, an alkyl or alkenyl radical having up to 15 C 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 may be replaced by —O—, —S—, —C≡C—, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another, A 1 and A 2 each, independently of one another, denote a) a 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH 2 groups may be replaced by —O— or —S—, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, c) a radical from the group consisting of piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, where the radicals a), b) and c) may be monosubstituted or polysubstituted by halogen atoms, Z 1 and Z 2 each, independently of one another, denote —CO—O—, —O—CO—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —CH 2 CH 2 —, —(CH 2 ) 4 —, —C 2 F 4 —, —CH 2 CF 2 —, —CF 2 CH 2 —, —CF═CF—, —CF═CH—, —CH═CH—, —C≡C— or a single bond, and m and n each, independently of one another, denote 0, 1 or 2.