Difluoromethylene compounds

A difluoromethylene compound of the formula I

• R.sup.1 --(A.sup.1 --Z.sup.1).sub.m --A.sup.2 --S--CF.sub.2 --R.sup.2
• in which
• R.sup.1 is alkyl or alkenyl of up to 15 C atoms, in each case optionally unsubstituted, monosubstituted by CN or CF.sub.3, or mono- or poly-substituted by halogen, or optionally having one or two CH.sub.2 groups, in each case independently of one another, replaced by --O--, ##STR41## --CO--, --CO--O--, --O--CO-- or --O--CO--O-- in a manner such that O atoms are not linked directly to one another,
• R.sup.2 is F, Cl or --CN,
• A.sup.1 and A.sup.2 independently of one another, are
• (a) trans-1,4-cyclohexylene in which, optionally one or two non-adjacent CH.sub.2 groups may be replaced by --O-- and/or --S--,
• (b) 1,4-phenylene, in which, optionally, one or two CH groups may be replaced by N, or
• (c) a radical which is 1,4-cyclohexenylene, 1,3-cyclobutylene, 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,
• where radicals (a) and (b) may be substituted by one CN or up to four fluorine,
• A.sup.1 can also be a single bond,
• Z.sup.1 is --CO--O--, --O--CO--, CH.sub.2 O--, --OCH.sub.2 --, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, --C.dbd.C-- or a single bond, and
• m is 1, 2 or 3.