| abstract |
Derivatives of 2,3-difluorohydroquinone have the formula (I), in which R1 and R2 represent, independently of one another, an alkyl having between 1 and 15 C atoms or an alkenyl having between 3 and 15 C atoms, not substituted or monosubstituted by cyanogen or at least monosubstituted by fluorine or chlorine, a CH2 group can also be substituted in these residues by -O-, -CO-, -CO-O-, -O-CO-, or - O-CO-O-; A1, A2 and A3 represent independently of each other: (a) trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups can also be substituted by -O- and / or -S-; (b) 1,4-phenylene, in which one or two CH groups may also be substituted by N; (c) a residue from the group consisting of piperidin-1,4-diyl, 1,4-bicyclo (2,2,2) octylene, 1,3,4-thiadiazol-2,5-diyl, naphthalin-2,6 -diyl, decahydronaphthalin-2,6-diyl and 1,2,3,4-tetrahydronaphthalin-2,6-diyl, the residues (a) and (b) possibly being substituted one or more times by F, Cl, CH3 or CN; Z1 represents -CO-O-, -O-CO, -CH2-CH2-, -OCH2-, -CH2O-, -C = C- or single bond, Q1 and Q2 represent independently of each other - CO- or -CH2-; m and n are equal to 0, 1 or 2, and (m + n) is equal to 0, 1 or 2. These derivatives are useful as components of liquid crystal phases. |