| CORP. SALE | NC-(Ethyne)-C6H3F-C6H4-Me |
| PATENT ASSIGNEE'S COUNTRY | Japan |
| UPDATE | 01.00 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 25.01.00 |
| PATENT TITLE |
Propiolonitrile derivatives and liquid crystal compositions comprising the same |
| PATENT ABSTRACT |
A propiolonitrile derivative of formula (I) ##STR1## wherein n1 and n2 each independently stand for 0 or 1; A1, A2 and A3 each independently represent a 1,4-phenylene, a 1,4-phenylene substituted by one or more fluorine atoms, a trans-1,4-cyclohexylene, a 1,3-dioxane-2,5-diyl or a 1,3-pyrimidine-2,5-diyl; Z1, Z2 and Z3 each independently represent a single bond, ethylene, ethenylene, ethynylene, carbonyloxy, oxycarbonyl, methyleneoxy, oxymethylene, 1,4-butylene or 1,4-butenylene; R represents a saturated, aliphatic hydrocarbyl radical of 1-10 carbons, an unsaturated, aliphatic hydrocarbyl radical of 2-10 carbons, a saturated or unsaturated, aliphatic hydrocarbyl radical of 1-10 carbons containing one or more ether linkages (--O--) in the chain and a saturated or unsaturated, fluoro-substituted aliphatic hydrocarbyl radical of 1-10 carbons containing one or more fluorine atoms in the chain; X1 and X2 each independently represent H, F or Cl; provided that at least one of X1 and X2 is F or Cl, when both n1 and n2 are 0, Z1 represents a single bond, ethylene, carbonyloxy or oxycarbonyl and R represents alkyl or alkoxy; or when n1 is 1, n2 is 1 or 0, Z1 and Z2 each independently represent a single bond or ethylene, Z3 represents ethylene and R represents alkyl or alkoxy. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 13.06.97 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A propiolonitrile derivative of formula (I) ##STR493## wherein n1 and n2 each independently stand for 0 or 1; A1, A2 and A3 each independently represent a 1,4-phenylene, a 1,4-phenylene substituted by one or more fluorine atoms, a trans-1,4-cyclohexylene, a 1,3-dioxane-2,5-diyl or a 1,3-pyrimidine-2,5-diyl; Z1, Z2 and Z3 each independently represent a single bond, ethylene, ethenylene, ethynylene, carbonyloxy, oxycarbonyl, methyleneoxy, oxymethylene, 1,4-butylene or 1,4-butenylene; R represents a saturated, aliphatic hydrocarbyl radical of 1-10 carbons, an unsaturated, aliphatic hydrocarbyl radical of 2-10 carbons, a saturated or unsaturated, aliphatic hydrocarbyl radical of 1-10 carbons containing one or more ether linkages (--O--) in the chain and a saturated or unsaturated, fluoro-substituted aliphatic hydrocarbyl radical of 1-10 carbons containing one or more fluorine atoms in the chain; X1 and X2 each independently represent H, F or Cl; provided that at least one of X1 and X2 is F or Cl, when both n1 and n2 are 0 or when n1 is 0 and n2 is 1, Z1 represents a single bond, ethylene, carbonyloxy or oxycarbonyl and R represents alkyl or alkoxy; or when n1 is 1, n2 is 1 or 0, Z1 and Z2 each independently represent a single bond or ethylene, Z3 represents ethylene and R represents alkyl or alkoxy. 2. The derivative of claim 1 wherein n1 and n2 are 0. 3. The derivative of claim 1 wherein n1 is 1 and n2 is 0. 4. The derivative of claim 1 wherein n1 and n2 are 1. 5. The derivative of claim 1 wherein R is alkenyl of 2-10 carbons. 6. The derivative of claim 1 wherein R is alkenyl of 2-10 carbons, both X1 and X2 are hydrogen. 7. The derivative of claim 1 wherein n1 and n2 are 0 and R is alkenyl of 2-10 carbons. 8. The derivative of claim 1 wherein n1 is 1, n2 is 0 and R is alkenyl of 2-10 carbons. 9. The derivative of claim 1 wherein n1 and n2 are 0, Z1 is a single bond and R is alkenyl of 2-10 carbons. 10. The derivative of claim 1 wherein n1 is 1, n2 is 0, Z1 is a single bond and R is alkenyl of 2-10 carbons. 11. The derivative of claim 1 wherein one or both of X1 and X2 represent F or Cl and R is alkyl of 1-10 carbons. 12. The derivative of claim 1 wherein one of Z1, Z2 and Z3 is ethylene, 1,4-butylene, oxymethylene or methyleneoxy, and the other is a single bond or ethylene. 13. The derivative of claim 1 wherein n1 and n2 are 0 and Z1 is ethylene, 1,4-butylene, oxyethylene or methyleneoxy. 14. The derivative of claim 1 wherein n1 is 1, n2 is 0 and one of Z1 and Z2 is ethylene, 1,4-butylene, oxymethylene or methyleneoxy, and the other is a single bond or ethylene. 15. The derivative of claim 1 wherein n1 and n2 are 1, and one of Z1, Z2 and Z3 is ethenylene, 1,4-butenylene or ethynylene, and the other is a single bond or ethylene. 16. The derivative of claim 1 wherein n1 and n2 are 0, and Z1 is ethenylene, 1,4-butenylene or ethynylene. 17. The derivative of claim 1 wherein n1 is 1, n2 is 0 and one of Z1 and Z2 is ethenylene, 1,4-butenylene or ethynylene, and the other is a single bond or ethylene. 18. The derivative of claim 1 wherein n1 and n2 are 1, one of Z1, Z2 and Z3 is carbonyloxy or hydroxycarbonyl, and the other is a single bond or ethylene. 19. The derivative of claim 1 wherein n1 and n2 are 1, one of Z1, Z2 and Z3 is carbonyloxy or oxycarbonyl, and the other is a single bond or ethylene and one or both of X1 and X2 represent F. 20. The derivative of claim 1 wherein n1 and n2 are 0 and Z1 is carbonyloxy or hydroxycarbonyl. 21. The derivative of claim 1 wherein n1 and n2 are 0 and Z1 is carbonyloxy or hydroxycarbonyl, and one or both of X1 and X2 represent F. 22. The derivative of claim 1 wherein n1 is 1, n2 is 0 and one of Z1 and Z2 is carbonyloxy or oxycarbonyl, and the other is a single bond or ethylene. 23. The derivative of claim 1 wherein n1 is 1, n2 is 0, one of Z1 and Z2 is carbonyloxy or oxycarbonyl, and the other is a single bond or ethylene and one or both of X1 and X2 represent F. 24. The derivative of claim 1 wherein n1 and n2 are 0, and A1 is 1,4-cyclohexylene. 25. The derivative of claim 1 wherein n1 and n2 are 0, and A1 is 1,4-phenylene which may be substituted by one or more fluorine atoms. 26. The derivative of claim 1 wherein n1 is 1, n2 is 0 and one or both of A1 and A2 represent trans-1,4-cyclohexylene. 27. The derivative of claim 1 wherein n1 is 1, n2 is 0 and one or both of A1 and A2 represent 1,4-phenylene. 28. A liquid crystal composition comprising at least two ingredients containing at least one of the propiolonitrile derivatives of claim 1. 29. A liquid crystal composition comprising as a first ingredient, at least one of the propiolonitrile derivatives of claim 1 and as a second ingredient, at least one of a compound of formula (2) ##STR494## wherein a is 1 or 2; b is O or 1; A4 represents a trans-1,4-cyclohexylene or a 1,4-phenylene which may be substituted by one or more fluorine atoms; Z4 and Z5 each independently represent a single bond, ethylene or ethenylene; R.sub.1 respresents an alkyl group of 1-10 carbons and X5 represents F, CF.sub.3, OCF.sub.3, OCF.sub.2 H or Cl; and (F) stands for the case which the phenyl ring may be substituted by F. 30. A liquid crystal composition comprising as a first ingredient, at least one of the propiolonitrile derivatives of claim 1 and as a second ingredient, at least one of a compound of formula (3) R.sub.2 --(--A5--Z6--).sub.c --(--A6--Z7--).sub.d --(--A7--Z8--).sub.e --A8--(--COO--).sub.f --R.sub.3 ( 3) wherein c, d, e and f each independently stand for 0 or 1; A5, A6 and A7 each independently represent a trans-1,4-cyclohexylene, a 1,4-phenylene which may be substituted by one or more fluorine atoms, a trans-1,4-cyclohexylene, a 1,3-dioxane-2,5-diyl and a 1,3-pyrimidine-2,5-diyl; A8 represents a trans-1,4-cyclohexylene or 1,4-phenylene which may be substituted by one or two fluorine atoms; Z6, Z7 and Z8 each independently represent a single bond, ethylene, ethenylene, ethynylene, 1-butene-3-ynylene or carbonyloxy; R.sub.2 represents a saturated or unsaturated aliphatic hydrocarbyl radical of 1-10 carbons optionally having one or more ether linkages (--O--) in the chain and R.sub.3 represents --CN, --F, --OCF.sub.3, --0CF.sub.2 H, --CF.sub.3, --CF.sub.2 H, --CFH.sub.2 or a saturated or unsaturated aliphatic hydrocarbyl radical of 1 to 10 carbons optionally containing one or more ether linkages (--O--) in the chain. 31. A liquid crystal display element composed of the liquid crystal composition as defined in any one of claims 28-30. 32. The liquid crystal composition of claim 30, further comprising at least one compound of a formula (2) ##STR495## wherein a is 1 or 2; b is 0 or 1; A4 represents a trans-1,4-cyclohexylene or a 1,4-phenylene which may be substituted by one or more fluorine atoms; Z4 and Z5 each independently represent a single bond, ethylene or ethenylene; R,, represents an alkyl group of 1-10 carbons and X5 represents F, CF.sub.3, OCF.sub.3, OCF.sub.2 H or Cl; and (F) stands for the case in which the phenyl ring may be substituted by F. 33. A liquid crystal display element composed of the liquid crystal composition as defined in claim 32. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION This invention relates to a liquid crystalline compound consisting of new propiolonitrile derivatives, a liquid crystal composition comprising the same and a liquid crystal display element using said composition. BACKGROUND OF THE INVENTION A display element utilizing the characteristics of liquid crystal materials such as optical anisotropy and dielectric anisotropy has been extensively used in the applications including watch, calculator or the like. Liquid crystal phase includes a nematic phase, a smectic phase and a cholesteric phase. In practical use, the nematic phase is most conventional. The display modes in this case can include a twisted nematic (TN) mode, a dynamic scattering (DS) mode, a guest/host mode, a DAP (deformation of aligned phases) mode or the like. A large number of the liquid crystalline compounds used for the display modes have been developed, but there is no commercial example for a display element in which a single compound is encapsulated. It is required that liquid crystal materials for display element exhibit a liquid crystal phase over a broad temperature range centering in room temperature, have a good stability towards moisture, light, heat, air, electric fields and electromagnetic radiation under the environment in which a display element is used, and have sufficient characteristics to drive a display element. The physical values such as optical anisotropy, dielectric anisotropy and electrical conductivity required for liquid crystal materials are dependent on mode of the display and configuration of the element. In particular, the liquid crystal materials for the STN mode which have been recently applied to the liquid crystal display of high quality level should have high elastic constant ratio (k3/k1) and dielectric anisotropy, and low viscosity to obtain good display having high steepness and quick response rate. However, a single compound satisfying these requirements at the same time is not known yet and the liquid crystal materials used in the current display are the composition comprising a mixture of liquid crystalline compounds having each of the characteristics. If a single compound having different characteristics is mixed each other, frequency and temperature dependences are higher, which makes it difficult to obtain uniform display under each use environment. Thus, a compound having high elastic constant ratio, high dielectric anisotropy, optical anisotropy close to the predetermined constants, broad liquid crystal temperature range, high compatibility with other liquid crystals, good stability and low viscosity not injuring a response rate is an important key to obtain a display of the STN mode having very reduced frequency and temperature dependences and good characteristics. As the liquid crystalline compounds having high elastic constant ratio, high dielectric anisotropy and relatively low viscosity, alkenyl compounds of the following formula (A) are generally known in Japanese Patent Kokai 59-176221. Those compounds are comparatively narrow in the nematic liquid crystal temperature range and so require a combined use with the compounds having high clearing points to compensate the narrow temperature range, where they are used as an ingredient of the liquid crystal composition. In general, however, the compound having high clearing point exhibits high viscosity. Therefore, an addition of the above-mentioned alkenyl compounds results in an increase in the viscosity of the total composition. Cinnamonitrile derivatives of the following formula (B) wherein R is alkyl of 1-8 carbons are also known as a liquid crystalline compound in Japanese Patent Kokai 55-9012, but they may have poor stability towards light. Further, propiolonitrile derivatives of the following formula (C) wherein R is a straight-chain alkyl of 1-9 carbons or a straight-chain alkoxy of 1-9 carbons are known in Japanese Patent Kokai 58-110527, which have broad liquid crystal range, relatively high dielectric anisotropy and elastic constant ratio, but further improvement may be desired. ##STR2## SUMMARY OF THE INVENTION An object of the present invention is to provide a new liquid crystalline compound having excellent properties as an ingredient of a liquid crystal composition such as broad liquid crystal temperature range, high dielectric anisotropy and good compatibility with other liquid crystalline compounds, while keeping the properties of the composition such as low viscosity and being capable of providing high elastic constant ratio. Another object of the invention is to provide a liquid crystal composition comprising the liquid crystalline compound and a liquid crystal display element using said liquid crystal composition. We have found that a group of the compounds exhibit unique liquid crystal characteristics, by varying a combination of the six-membered rings and bridges therebetween, the substituents on the six-membered rings and the position of the substituents in the propiolonitrile derivatives of the above formula (C). DETAILED DESCRIPTION OF THE INVENTION The present invention provides propiolonitrile derivatives of formula (1) ##STR3## wherein n1 and n2 each independently stand for 0 or 1; A1, A2 and A3 each independently represent a 1,4-phenylene, 1,4-phenylene substituted by one or more fluorine atoms, a trans-1,4-cyclohexylene, a 1,3-dioxane-2,5-diyl or a 1,3-pyrimidine-2,5-diyl; Z1, Z2 and Z3 each independently represent a single bond, ethylene, ethenylene, ethynylene, carbonyloxy, oxycarbonyl, methyleneoxy, oxymethylene, 1,4-butylene or 1,4-butenylene; R represents a saturated, aliphatic hydrocarbyl radical of 1-10 carbons, an unsaturated, aliphatic hydrocarbyl radical of 2-10 carbons, a saturated or unsaturated, aliphatic hydrocarbyl radical of 1-10 carbons containing one or more ether linkages (--O--) in the chain and a saturated or unsaturated, fluoro-substituted aliphatic hydrocarbyl radical of 1-10 carbons containing one or more fluorine atoms in the chain; X1 and X2 each independently represent H, F or Cl; provided that at least one of X1 and X2 is F or Cl, when both n1 and n2 are 0, Z1 represents a single bond, ethylene, carbonyloxy or oxycarbonyl and R represents alkyl or alkoxy; or when n1 is 1, n2 is 1 or 0, Z1 and Z2 each independently represent a single bond or ethylene, Z3 represents ethylene and R represents alkyl or alkoxy. The present invention also provides liquid crystal compositions comprising at least two ingredients containing at least one of the propiolonitrile derivatives of formula (1), more specifically liquid crystal compositions comprising as a first ingredient, at least one of the propiolonitrile derivatives of formula (1) and as a second ingredient, at least one of a compound of formula (2) and/or at least one of a compound of formula (3). Further, the invention provides liquid crystal display elements composed of said liquid crystal compositions. ##STR4## in which a is 1 or 2; b is 0 or 1; A4 represents a trans-1,4-cyclohexylene or a 1,4-phenylene which may be substituted by one or more fluorine atoms; Z4 and Z5 each independently represent a single bond, ethylene or ethenylene; R.sub.1 respresents an alkyl group of 1-10 carbons and X5 represents F, CF.sub.3, OCF.sub.3, OCF.sub.2 H or Cl; and (F) stands for the case where the phenyl ring may be substituted by F. R.sub.2 --(--A5--Z6--).sub.c --(--A6--Z7--).sub.d --(--A7--Z8--).sub.e --A8--(--COO--).sub.f --R.sub.3 (3) in which c, d, e and f each independently is 0 or 1; A5, A6 and A7 each independently represent a trans-1,4-cyclohexylene, a 1,4-phenylene which may be substituted by one or more fluorine atoms, a 1,3-dioxane-2,5-diyl or a 1,3-pyrimidine-2,5-diyl; A8 represents a trans-1,4-cyclohexylene or 1,4-phenylene which may be substituted by one or more fluorine atoms; Z6, Z7 and Z8 each independently represent a single bond, ethylene, ethenylene, ethynylene, 1-butene-3-ynylene or carbonyloxy; R.sub.2 represents a saturated or unsaturated hydrocarbyl radical of 1 to 10 carbons optionally having one or more ether linkages (--O--) in the chain; and R.sub.3 represents --CN, --F, --OCF.sub.3, --OCF.sub.2 H, --CF.sub.3, --CF.sub.2 H, --CFH.sub.2 or a saturated or unsaturated aliphatic hydrocarbyl radical of 1 to 10 carbons optionally having one or more ether linkages in the chain. The propiolonitrile derivatives of the present invention have excellent properties as the ingredient of a liquid crystal composition, e.g. broad liquid crystal temperature range, high dielectric anisotropy and good compatibility with other liquid crystalline compounds, while keeping the properties of the composition such as low viscosity and being capable of providing high elastic constant ratio. In the propiolonitrile derivatives of formula (1), the terminal group R represents a saturated, aliphatic hydrocarbyl radical of 1-10 carbons; an unsaturated, aliphatic hydrocarbyl radical of 2-10 carbons; a saturated or unsaturated, aliphatic hydrocarbyl radical of 1-10 carbons containing one or more ether linkages (--O--) in the chain; and a saturated or unsaturated, fluoro-substituted aliphatic hydrocarbyl radical of 1-10 carbons containing one or more fluorine atoms in the chain. The term "saturatred aliphatic hydrocarbyl radical" includes a straight or branched-chain alkyl group of 1-10 carbons, specific examples of which can include ethyl, methyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, pentyl, 2-methylbutyl, hexyl, 2-methylpentyl, 3-methylpentyl, heptyl, 2-methylhexyl, octyl, 2-ethylhexyl, 3-methylheptyl, nonyl, decyl or the like. The term "unsaturated aliphatic hydrocarbyl radical" includes an alkynyl and alkenyl group of 1-10 carbons containing one unsaturated moiety in the straight- or branched-chain and an alkadienyl group of 1-10 carbons containing two unsaturated moieties in the chain, specific examples of which can include vinyl, allyl, 1-butenyl, 3-butenyl, 3-methyl-1-butenyl, 1-pentenyl, 3-pentenyl, 4-methyl-3-pentenyl, 3-nonenyl, ethynyl, propynyl, 1-butynyl, butadienyl, 1,5-hexadienyl or the like. The term "saturated aliphatic hydrocarbyl radical containing one or more ether linkages (--O--) in the chain" includes a straight- or branched-chain alkoxy, alkoxyalkyl and alkoxyalkoxy groups in which the alkyl moiety has 1-10 carbons, specific examples of which can include methoxy, ethoxy, isopropoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, methoxymethyl, methoxyethyl, ethoxymethyl, propoxymethyl, propoxypropyl, ethoxymethoxy, propoxyethoxy or the like. The term "unsaturated aliphatic hydrocarbyl radical containing one or more ether linkages (--O--) in the chain" includes a straight- or branched-chain alkenyloxy, alkynyloxy and alkenyloxyalkyl groups of 1-10 carbons, specific examples of which can include allyloxy, 2-butenyloxy, pentenyloxy, propynyloxy, allyloxymethyl or the like. The term "saturated or unsaturated, fluoro-substituted aliphatic hydrocarbyl radical" includes fluoroalkyl, fluoroalkenyl, fluoroalkoxy, fluoroalkoxyalkyl and fluoroalkenyloxy groups in which the alkyl moiety has 1-10 carbons, specific examples of which can include fluoromethyl, difluoromethyl, trifluoromethyl, fluoroethyl, difluoroethyl, trifluoroethyl, perfluoroethyl, 2,2-difluorovinyl, 4-fluoro-3-butenyl, 4,4-difluoro-3-butenyl, fluoromethoxy, difluoromethoxy, trifluoromethoxy, trifluoromethoxymethyl, 3-fluoro-1-propenyloxy or the like. The propiolonitrile derivatives of formula (1) can be classified into a two ring system of formula (1a) wherein both n1 and n2 are 0, a three ring system of formula (1b) wherein n1 is 1 and n2 is 0 and a four ring system of formula (1c) wherein both n1 and n2 are 1. ##STR5## In the above formulas, A1, A2, A3, Z1, Z2, Z3, R, X1 and X2 have the same meaning as defined above. The two ring system compounds of formula (1a) have a liquid crystal temperature range at approximately room temperature and a lower viscosity, and also are excellent materials which are not easy to precipitate a crystal when used as an ingredient for the liquid crystal composition. The liquid crystal display using the two ring system compounds can conduct a display at more quick response rate than the case of using other cyclic compounds of larger number of six membered rings. More specific examples of the two ring system compounds are represented by the following formulas (1a-1) to (1a-28) wherein R has the same meaning as defined above, Alkyl stands for alkyl of 1-10 carbons, Alkenyl stands for alkenyl of 2-10 carbons and (F) stands for the case where the phenyl ring may be substituted by F. ##STR6## The three ring system compounds of formula (1b) have higher clearing points, good compatibility with other liquid crystalline compounds and higher elastic constant ratio required for obtaining good steepness of the liquid crystal composition. More specific examples of the three ring system compounds are represented by the following formulas (1b-1) to (1b-81) wherein R, Alkyl, Alkenyl and (F) have the same meaning as defined above. ##STR7## The four ring system compounds of formula (1c) have very high clearing points, higher elastic constant ratio and relatively higher optical anisotropy, and so they are very important as the ingredient constituting the liquid crystal composition. More specific examples of the four ring system compounds are represented by the following formulas (1c-1) to (1c-33) wherein A1, A2, A3, Alkyl, Alkenyl, R and (F) have the same meaning as defined above. ##STR8## The physical properties of the propiolonitrile derivatives can be adjusted to a desired level by choice and combination of rings A1, A2 and A3, choice and combination of bridges Z1, Z2 and Z3 between the rings and choice of a terminal group R and the substituents X1 and X2 on the ring in the molecular structure of formula (1), and thus the propiolonitrile derivatives of the present invention can be advantageously used as the ingredient of the liquid crystal composition having good characteristics. The compounds of formula (1) wherein the terminal group R is alkyl or alkenyl, i.e. those of formulas (1a-1) to (1a-5), (1a-15) to (1a-19), (1b-1) to (1b-5), (1b-16) to (1b-20) and (1b-31) to (1b-34) as well as (1c-1) to (1c-13) have higher clearing points, higher elastic constant ratio, higher dielectric anisotropy and higher optical anisotropy, which are very suitable for the ingredients of the liquid crystal materials. In particular, the compounds of formulas (1a-3) to (1a-5), (1a-17) to (1a-19), (1b-3) to (1b-5), (1b-18) to (1b-20), (1b-33) and (1b-34) as well as (1c-3, -4, -7, -8, -11 and -12) have higher elastic constant ratio and lower viscosity, which are useful as a display material of the STN mode. The compounds of formula (1) wherein any one of Z1, Z2 and Z3 is ethylene, 1,4-butylene or 1,4-butenylene, i.e. those of formulas (1a-7,-11, -12, -21, -25 and -26), (1b-6, -10, -11, -21, -25, -26, -36, -40, -41, -47, -53, -54, -56, -60, -61, 65, -71, -72, 74, -78 and -79) as well as (1c-15, -19, -20, -26, -32 and -33) have higher compatibility and suitable broader nematic liquid crystal phase for the application of a liquid crystal display, thus being useful. The compounds of formula (1) having a highly conjugated partial structure, i.e. those of formulas (1a-6, -8, -15 to -20, -22 and -26), (1b-5, -7, -16 to -20, -22, -26, -30, -31 to -43, -45, -46, -48, -55, -57, -64, -66 and -73 to -81) as well as (1c-5 to -12, -14, -16, -25 and -27) have broad liquid crystal temperature range and particularly higher optical anisotropy, which are useful as the liquid crystal materials for display having a thinner cell thickness. In particular, the compounds of formulas (1a-20 and -22 as well as 1b-20, -22, -35, -37, -55, -73 and -75) have beyond comparison high optical anisotropy, which are useful as the materials used in polymer dispersion type liquid crystal display elements. The compounds of formula (1) wherein any one of Z1, Z2 and Z3 is oxycarbonyl or carbonyloxy or any one of A1, A2 and A3 is 1,3-dioxane-2,5-diyl or 1,3-pyrimidine-2,5-diyl, i.e. the ester, pyrimidine and dioxane derivatives represented by formulas (1a-13, -14, -27 and -28), (1b-12, -13, -14, -15, -27, -28, -29, -30, -42, -43, -44, -45, -51, -52, -58, -59, -62, -63, -69, -70, -76, -77, -80 and -81) as well as (1c-12, -13, -21, -22, -23 and -24) have especially high dielectric anisotropy, which are very suitable for the liquid crystal material for a low voltage driving display. The compounds of formulas (1a-i) to (1a-14), (1b-1) to (1b-30) and (1b-46) to (1b-72) as well as (1c-1) to (1c-13) containing a cyclohexane ring in the backbone structure have broader liquid crystal temperature range and good compatibility with other liquid crystalline compounds. In the propiolonitrile derivatives of formula (1), one or more hydrogens adjacent to a propiolonitrile group on the phenyl ring attached to the propiolonitrile may be substituted by a fluorine atom. Such F-containing compounds have higher dielectric anisotropy, which are useful as the ingredients of the liquid crystal composition for the STN with a view to setting the driving voltage lower. The compounds wherein the phenyl ring is not substituted by F can provide the liquid crystal composition with higher clearing points than the fluorine containing compounds. The propiolonitrile derivatives of formula (1) according to the present invention can be synthesized by any of the following processes A to C. A-1. Synthesis of the compounds of formula (1) wherein none of bridges Z1, Z2 and Z3 are ester linkage (carbonyloxy or oxycarbonyl) The propiolonitrile derivatives of formula (1) wherein Z1, Z2 and Z3 each independently represent a single bond, ethylene, ethenylene, ethynylene, methyleneoxy, oxymethylene, 1,4-butylene or 1,4-butenylene and n1, n2, R, A1, A2, A3, X1 and X2 have the same meaning as defined above are prepared by cyanation of ethynylene halides of the following formula (4) wherein X3 is Cl, Br or I, n1, n2, R, A1, A2, A3, Z1, Z2, Z3, X1 and X2 have the same meaning as defined above, with the agents for cyanation. ##STR9## This reaction is generally carried out in an aprotic, polar solvent using as the cyanating agent, metal cyanides, preferably sodium cyanide, copper cyanide, potassium cyanide or the like. The amount of metal cyanides used ranges from one equivalent to a large excess based on the substrate, preferably 1-3 equivalents considering after-treatment. The preferred aprotic, polar solvents include tetrahydrofuran, dimethylformamide, acetonitrile, acetone, dioxane, N-methylpyrrolidone or the like. Especially preferable are tetrahydrofuran, acetonitrile, dimethylformamide and N-methylpyrrolidone, since they give good yield. The reaction temperature is selected from the ranges between room temperature and the boiling points of the chosen solvents, but the temperature in the neiborhood of boiling point of the solvent is preferable for prompt progress of the reaction. For the purpose of securing prompt progress of the reaction and increasing the yield, the additives may be added. As the additives are preferable the salts such as lithium bromide, lithium chloride, sodium bromide, sodium iodide or the like. The amount of additives added is selected from the range of 1-200 mole % based on the reaction substrate. The halogenated ethynylenes of formula (4) which are starting materials in the reaction can be readily synthesized from the aldehyde compounds of formula (5) using the process disclosed in DE 4027458 or the process shown in the following reaction scheme in which Z1, Z2, Z3, n1, n2, R, A1, A2, A3, X1 and X2 have the same meaning as defined above. ##STR10## A-2. Synthesis of the compounds of formula (1) wherein any one of Z1, Z2 and Z3 is an ester linkage (carbonyloxy or oxycarbonyl) The propiolonitrile derivatives of formula (1) wherein any one of Z1, Z2 and Z3 is carbonyloxy or oxycarbonyl and the other independently is a single bond, ethylene, ethenylene, ethynylene, methyleneoxy, oxymethylene, 1,4-butylene or 1,4-butenylene are prepared by an esterification reaction of a carboxylic acid compound of the following formula (6) with an alcohol compound of the following formula (7) or by an esterification reaction of an alcohol compound of the following formula (8) with a carboxylic acid compound of the following formula (9). In formulas (6) to (9), n'1, n"1, n'2 and n"2 are 0 or 1, and n'1+n"1=1, n'2+n"2=1, and R, A1, A2, A3, X1 and X2 have the same meaning as defined above. As this esterification reaction can be employed most conventional process in which the reaction is carried out in a solvent inert to the reaction per se, such as toluene, xylene or the like and in the presence of an acid catalyst, while dehydrating azeotropically, a process in which the reaction is performed in an aprotic, polar solvent and in the presence of a base using a dehydrating agent for condensation such as DCC, and other processes. Suitable processes for the substrate can be employed. ##STR11## Alternatively, the propiolonitrile derivatives of the present invention can be synthesized by reacting the carboxylic acid compound of formula (6) or the carboxylic acid compound of formula (9) with a halogenation agent such as thionyl halide in an inert solvent to form the corresponding acid halide of formula (10) or (11) wherein X4 represents Cl, Br or I and n'1, n"1, n'2, n"2, R, A1, A2, A3, Z1, Z2, Z3, X1 and X2 have the same meaning as defined above, followed by esterification with the alcohol compound of formula (7) or (8), and finally subjecting to dehydrohalogenation treatment in an inert solvent and in the presence of a base with no catalyst. ##STR12## The alcohol compounds of formulas (7) and (9) which are starting materials in the present reaction are readily prepared by application of the later-mentioned process C or the methods known per se. The carboxylic acid compounds of formulas (6) and (8) are prepared for example by the methods disclosed in Japanese Patent Kokai 4-501275, 4-503523 or 59-122440. B. Synthesis of the compounds of formula (1) not containing other unsaturated bond than the propiolonitrile group in the molecule The propiolonitrile derivatives of formula (1) wherein Z1, Z2 and Z3 each independently represents a single bond, ethylene, carbonyloxy, oxycarbonyl, methyleneoxy or 1,4-butylene and R represents a saturated hydrocarbyl can be prepared by reacting a cinnamonitrile derivative of the following formula (12) with bromine to form a dibromo compound of the following formula (13) and subjecting the dibromo compound to dehydrobromination with a base. In formulas (12) and (13), n1, n2, A1, A2, A3, X1 and X2 have the same meaning as defined above. The bromination of the cinnamonitrile derivative of formula (12) to the bibromo compound of formula (13) is carried out by adding one or more equivalents bromine based on the cinnamonitrile derivative at ordinary temperatures in an inert solvent such as chloroform, carbon tetrachloride, dichloroethylene, dichloromethane or the like. The dibromo compound of formula (13) can be reacted with one or more equivalents base, e.g. diazabicycloundecene, potassium butoxide, sodium hydride, in a solvent inert to the reaction such as tetrahydrofuran, dioxane, toluene, benzene, to provide the propiolonitrile derivative of formula (1). The cinnamonitrile derivative of formula (12) is prepared by reacting the aldehyde compound of formula (5) with diethylcyanomethyl phosphonate and sodium hydride in an aprotic, polar solvent, as shown in the following reaction scheme (14). ##STR13## C. Synthesis of the compounds of formula (1) not containing a thermally unstable partial structure in the molecule The propiolonitrile derivative of formula (1) can be prepared by reacting an acid halide of the following formula (15) with cyanomethylenetriphenylphosphorane in a solvent inert to the reaction, e.g. benzene, toluene, monochlorobenzene, nitrobenzene, to provide a phosphorane derivative of the following formula (16) and heating the derivative under reduced pressure, e.g. at 200-300.degree. C. for thermal decomposition. In formulas (15) and (16), n1, n2, A1, A2, A3, Z1, Z2, Z3, R, X1 and X2 have the same meaning as defined for the formula (1). The acid halide of formula (15) which is a starting material for this reaction can be prepared by reacting the carboxylic acid derivative prepared by oxidation of the aldehyde derivative of formula (5), with a halogenating agent such as thionyl halide. ##STR14## Specific examples of the propiolonitrile derivatives according to the present invention are shown in the following tables. |
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