Compounds of the formula (I) where: R1, R2 are each independently a) H b) -M1-A1-R5 c) a straight-chain or branched alkyl radical having from 1 to 16 carbon atoms or a straight-chain or branched alkenyl radical having from 2 to 16 carbon atoms, where c1) one or more nonadjacent and nonterminal CH2 groups may be replaced by —O—, —C(═O)O—, —O—C(═O)—, —O—C(═O)—O—, —C(═O)— or —Si(CH3)2—, and/or c2) one CH2 group may be replaced by —C≡C—, cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclohexane-1,4-diyl or phenylene-1,4-diyl, and/or c3) one or more hydrogen atoms may be replaced by F and/or Cl, p, q, r are each independently 0 or 1 M1—is —CO—O—, —O—CO—, —CH2—O—, —O—CH2—, —CF2—O—, —O—CF2—, —CH═CH—, —CF═CF—, —C≡C—, —CH2—CH2—CO—O—, —O—CO—CH2—CH2—, —CH2—CH2—, —CF2—CF2—, —(CH2)4—, —OC(═O)CF═CF— or a single bond, A1 is 1,4-phenylene where one or two hydrogen atoms may be replaced by F, Cl, CN and/or OCF3, or up to three hydrogen atoms may be replaced by fluorine, 1,4-cyclohexylene where one or two hydrogen atoms may be replaced by CH3 and/or F, 1-cyclohexene-1,4-diyl where one hydrogen atom may be replaced by CH3 or F, or 1,3-dioxane-2,5-diyl, R5 has the same possible definitions as R1 and R2 with the exception of -M1-A1-R5, with the provisos that: a) at least one of p, q, r is 1 b) R1 and R2 must not at the same time be H are used in liquid-crystal mixtures.