Pyrimidinecyclohexane derivatives, process for their preparation

Details Pyrimidinecyclohexane derivatives, process for their preparation Pyrimidinecyclohexane derivatives, process for their preparation

1992-09-03

1994-12-06

Stoll, Robert L.

Compositions

Liquid crystal compositions

Containing nonsteryl liquid crystalline compound of...

25229901, 544295, 544296, 544298, C09K 1934, C09K 1952, C07D23902

Patent

active

053708237

DESCRIPTION:

BRIEF SUMMARY
The unusual combination of anisotropic and fluid behavior of the liquid crystals has resulted in their use in electro-optical switching and display devices, where their electrical, magnetic, elastic and/or thermal properties can be utilized to cause changes in alignment. Optical effects can be achieved, for example, with the aid of birefringence, inclusion of dichroically absorbent dye molecules ("guest-host mode") or light scattering.
In order to satisfy the ever increasing demands of practice in the various areas of application, there is a constant demand for novel improved liquid crystal mixtures and thus also for a large number of mesogenic compounds of various structure. This applies both to the areas in which nematic LC phases (for example TN="twisted nematic", STN="supertwisted nematic", SBE="supertwisted birefringence effect", ECB .sup.= "electrically controlled birefringence") are used, and to those having smectic LC phases (for example ferroelectric and electroclinic).
Many of the compounds which are suitable for LC mixtures can be described by a structure principle [see, for example, J. Am. Chem. Soc. 108, 4736 (1986), Structure I; Science 231, 350 (1986), FIG. 1 A; J. Am. Chem. Soc. 108, 5210 (1986), FIG. 3], in which the rings from cyclic compounds - aromatic compounds, heteroaromatic compounds, but also saturated ring systems - are linked to straight-chain alkyl side chains or to alkyl side chains which are substituted in the chain by small groups (for example methyl or chlorine) and are thus branched. The object of the present invention is to provide novel mesogenic bispyrimidinylcyclohexane compounds which can be combined with other components to give novel LC mixtures which have particularly advantageous properties for practical use. The liquid-crystalline bispyrimidinylcyclohexane compounds of the formula (I) defined below achieve this object, ##STR2## where R.sup.1 and R.sup.2 are identical or different straight-chain or branched (with or without an asymmetric carbon atom) alkyl or alkenyl having 1 to 16 carbon atoms, it also being possible for one or two non-adjacent --CH.sub.2 -- groups to be replaced by --O--, --S-, --CO--, --CO--O--, --O--CO-- or --O--CO--O, and it also being possible for one or more H to be replaced by F, or are one of the following radicals: OCF.sub.3, OCHF.sub.2, ##STR3## X.sup.1 and X.sup.2 are identical or different H, F, C1, CN, preferably H or F, straight-chain or branched alkyl having 1 to 16 carbon atoms or alkenyl having 2-16 carbon atoms, in which, in addition, one --CH.sub.2 -- group may be replaced by --O--, --CO--O-- or --O--CO--, or R.sup.3 and R.sup.4 or R.sup.5 and R.sup.6 together are cyclic alkyl having 3-8 carbon atoms, R.sup.7, R.sup.8 and R.sup.9 are identical or different straight-chain or branched alkyl having 1 to 16 carbon atoms or alkenyl having 2 to 16 carbon atoms, in which, in addition, one or two non-adjacent --CH.sub.2 -- groups may be replaced by --O--, --CO--O-- or --O--CO--, with the proviso that silicon is only bonded to one or more carbon atoms which have H and/or C as neighboring atoms, or are cyclic alkyl having 3 to 8 carbon atoms, or, together with the Si atom, are alternatively ##STR4## G is straight-chain or branched alkylene having 1 to 16 carbon atoms or alkenylene having 2 to 16 carbon atoms, in which, in addition, one or two non-adjacent --CH.sub.2 -- groups may be replaced by --O--, --S--, --O--CO--, --CO--O--, --S--CO-- or --CO--S--, with the proviso that Si is only bonded to a carbon atom which has H and/or C atoms as neighboring atoms,
Preference is given to compounds in which R.sup.1 and R.sup.2 are both linear or branched alkyl having 1 to 16 carbon atoms or alkoxy having 1 to 15 carbon atoms or alkyldimethylsilylalkyl(oxy) of the formula R.sup.7 --Si(CH.sub.3).sub.2 --G. Preference is furthermore given to compounds in which R.sup.1 is linear or branched alkyl or alkoxy, and R.sup.2 is one of the abovementioned optically active substituents. Preference is also given to compounds of the formula (I) in which R.sup.1

REFERENCES:
patent: 4609485 (1986-09-01), Kitano et al.
patent: 4640796 (1987-02-01), Yoshida et al.

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