Cyclohexane derivatives and liquid-crystalline medium

A cyclohexane compound of formula I

• wherien
• Y is alkyl or alkoxy having 1 to 10 carbon atoms which is optionally at least monosubstituted by halogen, is alkenyl or alkenyloxy having 2 to 10 carbon atoms which is optionally at least monosubstituted by —CN, —CF3 or —F, or is —CN, —F, —OCHF2, —OCF3, —OCHFCF3 or —OCF2CF3,
• one of X1 and
• X2 is CF3, CHF2, CH2F, OCHF2, OCF3, SF5 or an alkyl radical having 2 to 10 carbon atoms which is monosubstituted or polysubstituted by fluorine or chlorine, and one of X1 or X2 in each cyclohexane ring is H,
• R1 is H, alkyl or alkenyl having 1 to 12 carbon atoms which is optionally monosubstituted by CN or CF3 or at least monosubstituted by halogen, where one or more non-adjacent CH2 groups is optionally independently replaced by
• A1 and A2, are each independently
• a) a trans-1,4-cyclohexylene radical, in which at least one or more non-adjacent CH2 group is optionally independently replaced by —O— or —S—,
• b) a 1,4-phenylene radical, in which, one or two CH groups is optionally replaced by N,
• c) 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, or
• d) 1,4-cyclohexenylene,
• wherein a), b) and d) is optionally substituted by CN, Cl or F,
• Z1, Z2 are each independently, —CO—O—,
• and Z3—O—CO—, CH2O—, —O—, —O—CH2—, —CH2CH2—, —CH═CH—, —C≡C—, —CF2CF2——CF2O—, —OCF2— or a single bond,
• n and m, are each independently 0, 1, 2 or 3,
• and
• p is 0, 1, 2 or 3,
• where
• m+n+p is 1, 2, 3 or 4.