Compositions – Liquid crystal compositions
Patent
1994-05-04
1997-09-09
Wu, Shean C.
Compositions
Liquid crystal compositions
25229961, 25229963, 25229964, 25229965, 25229966, 25229967, 544242, 544336, 546 1, 548136, 560 55, 560 76, 570124, 570127, 570129, C09K 1952, C07D23902, C07C 6976, C07C 2513
Patent
active
056652704
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/JP92/00646 filed May 20, 1992.
FIELD OF THE ART
This invention relates to an optically active trifluorolactic acid derivative and a liquid crystal composition. More particularly it relates to a novel optically active compound derived from trifluorolactic acid and useful as a component of ferroelectric liquid crystal compositions. Further, it relates to a novel optically active intermediate derivable from optically active trifluorolactic acid in the preparation of the above optically active compounds.
BACKGROUND OF THE ART
At present, TN (twisted nematic) type display mode has been most broadly used. This TN display has many advantages such as low driving voltage, low power consumption, etc. However, it is far inferior in the aspect of response speed to emissive display elements such as cathode ray tube, electroluminescence, plasma display, etc. A new type TN display element having a twist angle increased up to 180.degree. to 270.degree. has also been developed, but it is still yet inferior in the aspect of response speed. Efforts for various improvements have been made as described above, and nevertheless, development of TN display element having a high response speed has not yet been realized.
However, as to a new display mode using a ferroelectric liquid crystal which has now been extensively researched, a notable improvement in the response speed has been anticipated (Clark et al, Applied Phys. lett., 36, 899 (1980)). This display mode utilizes chiral smectic phases exhibiting ferroelectricity such as chiral smectic C phase (hereinafter abbreviated to Sc* phase), etc.
A number of specific features have been required for ferroelectric liquid crystal materials having been used for ferroelectric liquid crystal display elements practically used. Representative items of the above specific features are spontaneous polarization (Ps), tilt angle (.theta.), viscosity (.eta.), liquid crystal phase sequence, etc.
The molecule in the ferroelectric liquid crystals can move only on a cone, and it can form two states wherein the parallel direction of the molecule is perpendicular to the electric field corresponding to a direction of the electric field. The angle made between the two states is referred as cone angle and the half of the cone angle is referred to as tilt angle (.theta.).
The ferroelectric liquid crystal display mode currently includes mainly two modes i.e. a mode referred to as a birefringence mode wherein two upper and lower polarizers are used, and a mode referred to as guest-host mode (G.H.) wherein one polarizer is used and a dichroic dyestuff is added. In order that the ratio of brightness of the bright and dark states (contrast ratio) is the best, a tilt angle of 22.5.degree. is required for the birefringence mode, while a tilt angle of 45.degree. is required for the G.H. mode.
Further, since a relationship of .tau..infin..eta./Ps is existent among the responce time (.tau.), Ps and .eta., a material having a larger Ps and a lower .eta. is required for making the response speed higher. A number of specific features are required for ferroelectric liquid crystal materials used for ferroelectric liquid crystal display elements practically used, as described above, but any single compound cannot satisfy the requirements in the current state. Hence the ferroelectric liquid crystal compositions have been provided in the form of a mixture of a numer of materials. The compositions may be composed of even either liquid crystal compounds or non-liquid crystalline compounds. Ferroelectric liquid crystal compositions can be prepared by composing only of ferroelectric liquid crystal compounds, or by a method of mixing as a basic substance, a compound or a composition exhibiting tilted smectic phases of achiral smectic C, F, G, H, I, etc. (hereinafter abbreviated to Sc phase etc.), with one member or more of ferroelectric liquid crystal compounds or non-liquid crystalline, optically active compounds to thereby form a composition exhibiting a ferroelectric liquid crystalline
REFERENCES:
patent: 5204020 (1993-04-01), Suzuki et al.
Caplus :431747 Abstract, 1989.
Caplus :101130 Abstract, 1991.
Haydock et al, "Analogues of clofibrate and clobuzarit containing floorine in the side chains" in Eur. J. Med. Chem.-Chem. Ther., 1984-19. pp. 205-214.
Journal of Organic chemistry, vol. 55, No. 13, perfrancesco Bravo et al "Synthesis of SC-.beta., .beta., .beta.-Trifluorolactic acid and (S)-.alpha.-methoxy-.alpha.-trifluoromethyl-phenylacetic acid from (R)-methyl-p-Tolylsulfoxide", pp. 4216-4218. (1990).
Ponomarenko et al., "Nature Of Catalytic Centers In Polymerization Of Trifluoropropylene Oxide In The Presence Of Ferric Chloride", Chemical Abstracts, vol. 70, 1969, Abstract 97245q.
Fukushima Masatoshi
Saito Shin-ichi
Chisso Corporation
Wu Shean C.
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