Phenyldioxanes

Details Phenyldioxanes Phenyldioxanes

1991-02-12

1993-10-19

Ivy, C. Warren

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

549374, 549375, 25229961, C07C31906

Patent

active

052546985

DESCRIPTION:

BRIEF SUMMARY
The invention relates to Phenyldioxanes of the formula I ##STR3## wherein R.sup.1 is an alkyl or alkenyl residue each with up to 16 C atoms, wherein one or two non-adjacent CH.sub.2 groups of these residues may be replaced by --O--, --S--, --CO--O-- or --O--CO--, ##STR4##
L.sup.1 and L.sup.2 are each independently F or H, and
Y is Cl, F, CN, CF.sub.3, OCF.sub.3 or OCF.sub.2 H,
m and n are 0 or 1 --OCF.sub.3 or OCF.sub.2 H or L.sup.1 and L.sup.2 are H and Y is Cl or F. ##STR5## one of L.sup.1 and L.sup.2 is F and Y is Cl, F, CF.sub.3, OCF.sub.3 or OCF.sub.2 H, and ##STR6## one of L.sup.1 and L.sup.2 is F or L.sup.1 and L.sup.2 are H and Y is Cl, --CF.sub.3, --OCF.sub.3 or --OCF.sub.2 H.
The compounds of the formula I can be used as components of liquid crystal media, in particular for displays which are based on the principle of the twisted nematic cell, including TN cells with a higher twist angle like STN, SBE, OMI etc., on the guest-host effect on the effect of deformation of orientated phases or on the effect of dynamic scattering.
Compounds similar to those of formula I are known from DE 29 44 905. These compounds comprising 2 rings but no terminal chlorine tend to reduce the mesophase range.
JP-57 064 689 describes ##STR7##
Compounds of the formula I with three rings and L=H or F are claimed in EP 0 087 679 and EP 0 154 840 via a very broad formula. There are, however, no specific examples for these compounds so that it may be stated that the surprisingly advantageous properties of these compounds have neither been realized nor used.
Similar phenyldioxanes with terminal OCF.sub.3 -group but without ethyllinhage are known from WO 89 02 884.
WO 87/06602 describes ##STR8## and
WO 90/01056 describes ##STR9##
Furthermore ethyl-linked phenyldioxanes with a negative or neutral value of the dielectricity are known: ##STR10##
EP-0 154 840.
The invention was based on the object of discovering new stable liquid crystalline or mesogenic compounds which are especially suitable for active matrix displays without exhibiting the shortcomings of the prior art compounds.
Surprisingly, it has been found that the compounds according to formula I meet these criteria to an outstanding degree and allow the realization of a very high resistivity and simultaneously favorable electro-optic characteristics. These compounds also show a surprisingly good solubility at -20.degree. C. in many LC base materials from other compound classes.
By providing the compounds of the formula I, the range of liquid crystal substances which are suitable, under various technological aspects for the preparation of nematic mixtures is also quite generally widened considerably.
The compounds of the formula I have a wide field of application and they are preferably added to liquid crystal base materials from other classes of compounds, for example in order to increase the clearing point while having little effect on other physical properties.
The compounds of the formula I are colourless in the pure state and form liquid crystal mesophases in a temperature range which is favorably placed for electrooptical use. They are sufficiently stable towards chemicals, heat and light.
The invention thus relates to the compounds of the formula I in particular to the compounds of the formula I1, ##STR11## wherein R.sup.1, Q.sup.2, L.sup.1 and Y have the meaning given and Y is Cl or in the case that one of L.sup.1 and L.sup.2 is F also F, in particular, wherein Q.sup.2 is 1,4-phenylene and n is 1 and Y is Cl, and furthermore to the compounds of the formula I2 ##STR12## wherein R.sup.1, L.sup.2 and Y have the meaning given o is 0 or 1, and ##STR13## with the proviso that in the case that o is O Y is different form CN and one of L.sup.1 and L.sup.2 is F.
Furthermore the invention relates to the use of these compounds as components of liquid crystal media. The invention furthermore relates to liquid crystal media containing at least one compound of the formula I and to liquid crystal display elements, in particular electrooptical display elements, which contain media

REFERENCES:
patent: 4621901 (1986-11-01), Petrzilka et al.
patent: 4846998 (1989-07-01), Pohl et al.
patent: 4871469 (1989-10-01), Reiffenrath et al.

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