Chlorobenzene derivatives

Details Chlorobenzene derivatives Chlorobenzene derivatives

1990-06-22

1995-02-14

Wu, Shean

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

25229901, 359103, 570182, C09K 1930, C07C 2606, G02F 113

Patent

active

053892941

DESCRIPTION:

BRIEF SUMMARY
SUMMARY OF THE INVENTION

The invention relates to chlorobenzene derivatives of formula I ##STR2## wherein R.sup.1 denotes an alkyl residue with up to 12
carbon atoms wherein one or two non-adjacent CH.sub.2 -groups may also be replaced by --O--, --O--CO--, --CO--O-- and/or --CH.dbd.CH--, compounds, characterized in that at least one compound is a chlorobenzene derivative according to formula I.
The invention was based on the object of discovering new stable liquid crystal or mesogenic compounds which are suitable as components of liquid crystalline media and, in particular, have advantageous values for optical and dielectric anisotropy combined with low viscosity and high nematogenity.
Trans,trans-4-(2-p-chlorophenylethyl)-4'-alkyl-bicyclohexyls and 4-(trans-4-alkylcyclohexyl)-chlorobenzenes are described as liquid crystals in European patents 0 125 563 and 0 074 608, respectively.
It has now been found that chlorobenzene derivatives of formula I are highly suitable as components of liquid crystalline media. In particular, they have especially advantageous values of elastic properties, optical and dielectric anisotropy. It is also possible to obtain stable liquid crystal phases (temperature and UV) with a broad nematic mesophase range including a good deep temperature behavior and a comparatively low viscosity with the aid of these compounds.
The compounds of the formula I can be used as the base materials from which liquid crystal media are predominantly composed; however, it is also possible for compounds of the formula I to be added to liquid crystal base materials of other classes of compounds, for example in order to influence the elastic properties and/or the dielectric and/or optical anisotropy and/or the viscosity and/or the nematic mesophase range of such a dielectric.
The compounds of the formula I are colorless in the pure state and are liquid crystalline in a temperature range which is favorably placed for electrooptical use. They are very stable towards chemicals, heat and light.
The invention thus relates to the chlorobenzene derivatives of the formula I, to liquid crystalline media with at least two liquid crystalline components, wherein at least one component is a compound of the formula I and to liquid crystal display devices containing such media.
Above and below, R.sup.1 has the meaning given unless expressly indicated otherwise.
R.sup.1 is preferably alkyl, alkoxy, oxaalkyl, alkanoyloxy or alkenyl and can exhibit a straight-chain or branched structure.
Alkyl or alkoxy preferably are straight-chain and have 2, 3, 4, 5, 6 or 7 C atoms. Accordingly they are preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, also methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy.
Oxaalkyl is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxybutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4- 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7-or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8-, or 9-oxadecyl.
Alkenyl is preferably straight-chain and has 2 or 10 C atoms. It is accordingly, in particular, vinyl, prop-1- or prop-2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5- -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl or dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.
Compounds of the formula I containing a branched terminal group can occasionally be of importance because of an improved solubility in the customary liquid crystal base materials, but in particular as chiral doping substances if they are optically active.
Branched groups of this type as a rule contain not more than one chain branching. Preferred branched radicals are isopropyl, 2-butyl (=1-methylpropyl), isobutyl (=2-methylpropyl, 2-methylbutyl, isopentyl, (=3-met

REFERENCES:
patent: 4455443 (1984-06-01), Takatsu et al.
patent: 4659502 (1987-04-01), Fearon et al.
patent: 4871470 (1989-10-01), Wachtler et al.

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