JPH0730007B2 - Difluorocyano compound and liquid crystal composition containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a difluorocyano derivative compound used in a liquid crystal electric and / or thermo-optical element and a liquid crystal composition containing the same.

[Prior Art] In the field of display elements, low power consumption, high-speed response electric and / or thermo-optical elements are desired. The liquid crystal display element is one that optically utilizes changes in the nematic phase, smectic phase, and cholesteric phase of liquid crystal due to electricity and / or heat, and is drawing attention as meeting such requirements.

The liquid crystal material used for the liquid crystal display device cannot stand alone in terms of operating temperature range, operating voltage, response performance, etc., and several kinds of liquid crystal materials are currently mixed and used.

[Problems to be Solved by the Present Invention] A liquid crystal display device using a conventionally used liquid crystal composition has a drawback that the operating voltage is high because the dielectric anisotropy is small.

[Means for Solving the Problem] The present invention has been made to solve the above-mentioned problems, and has the general formula (In the formula, ring X and ring Y represent a trans-1,4-di-substituted dichlorohexane ring or 1,4-di-substituted phenylene, R represents an alkyl group having 1 to 8 carbon atoms, and n represents 0 or 1). Show.
However, the ring X and the ring Y are not trans-1,4-di-substituted cyclohexane rings at the same time. And a difluorocyano compound represented by the formula (1) and at least one kind of the compound are mixed in the composition in an amount of 1 to 50% by weight.

The general name of the compound represented by the general formula (I) is 4- (trans-4-'substituted ethyl) -2,5-difluorobenzonitrile.

In the compound represented by the general formula (I), R has 1 carbon atom.
Although an alkyl group of 8 to 8 is shown, when the carbon number is large, the viscosity is generally high, and when the carbon number is small, the clearing point of the liquid crystal composition to which the compound is added is low, so that the carbon number is preferably 2 to 6. Further, when R is an alkyl group having a branched chain, the clearing point of the liquid crystal composition to which the compound is added is generally low, so that R is preferably a linear alkyl group.

The first characteristic of the liquid crystal composition containing the compound of the present invention is that its dielectric anisotropy is large, but the second characteristic is that its viscosity is low and its response speed as a display element is fast. .

Since the difluorocyano compound of the present invention does not exhibit a sufficiently wide operating temperature range by itself, one kind or a mixture of one or more kinds is used as a liquid crystal composition having a desired liquid crystal temperature range. In that case, the compound of the present invention is used in the mixture in an amount of 1 to 50 wt%, more preferably 3 to 40 wt%. Other liquid crystal compounds, depending on the application, required performance, etc., consists of a component exhibiting liquid crystallinity and an additive component added as necessary, a component exhibiting liquid crystallinity at high temperature, a low viscosity component for low temperature, Other components that improve the dielectric anisotropy, components that impart cholesteric properties, 2
A component having a color property, a component imparting conductivity, and other various additives may be appropriately mixed and used.

Specifically, there are the following compounds.

R and R'in the following formulas are different from R in the present invention and represent groups such as an alkyl group, an alkoxy group, a halogen atom and a cyano group.

Note that these compounds are merely examples, substitution of a hydrogen atom with a halogen atom, a cyano group, a methyl group, etc., substitution of a cyclohexane ring, a benzene ring with another 6-membered ring, a 5-membered ring, etc. Various materials are selected and used, such as the change of the bonding group between them.

The composition of the present invention is used by being injected into a liquid crystal cell.

As a typical electro-optical liquid crystal cell, there is a twist nematic (TN) type liquid crystal cell in which a transparent electrode such as Tn ₂ O ₃ —SnO ₂ is formed in a desired pattern on the inner surface of a transparent substrate such as glass or plastic. Then, if necessary, overcoating of SiO ₂ , polyimide, etc., the substrates on which the lateral alignment layers are formed are made to face each other, the periphery is sealed, and the liquid crystal is injected to seal the injection port. It is used by laminating a polarizing plate on the outer surface. In addition to these, a phase transition type, a guest-host type, a dynamic scattering type, or a combination thereof may be used, or a type in which writing is performed by heat instead of electrically.

Furthermore, as the structure of the cell, between the transparent substrate and the transparent electrode,
An undercoat layer of SiO ₂ , Al ₂ O ₃ or the like is provided, a reflective electrode is used, a two-layer electrode is used, a color polarizing plate is used,
Various applications such as a color filter, a semiconductor substrate and a two-layer element are possible, and various applications such as a clock, a calculator, a measuring instrument, a measuring instrument for an automobile, a game, and a computer terminal device are possible.

The compound of general formula (I) is synthesized, for example, through the steps shown below.

That is, a compound of formula (II) is reacted with a chlorinating agent such as thionyl chloride to give an acid chloride (III), and Grignard reagents (IV) and (III) prepared from 3,5-difluorobromobenzene and magnesium To (V),
(VI) is reduced to (VI) by lithium aluminum hydride and aluminum chloride complex, and (VI) is n-
After lithiation with a lithiating agent such as butyllithium, the carboxylic acid compound (VI
I), (VII) is reacted with a chlorinating agent such as thionyl chloride to give an acid chloride (VIII), (VIII) is reacted with ammonia to give (IX), and (IX) is paratoluenesulfonic acid. The desired compound (I) is obtained by reacting with a dehydrating agent such as chloride.

EXAMPLES Next, the present invention will be specifically described with reference to examples.

Example 1 Formula A mixture of 38.1 g (0.207 mol) of the compound of Example 1, 70 ml of thionyl chloride and 70 ml of carbon tetrachloride was heated under reflux for 6 hours, and then the solvent and excess thionyl chloride were distilled off to give a compound of the formula Was obtained. Aside, the formula Compound of 40g (0.207mol) and scraped magnesium 5.28g
In 300 ml of tetrahydrofuran, the formula The Grignard reagent of was prepared.

The formula synthesized earlier Of tetrahydrofuran, 100 g of tetrahydrofuran, and 3.3 g of iron (III) acetylacetonate were stirred at a temperature of -55 ° C while stirring, Tetrahydrofuran solution was added dropwise at −55 ° C. over 1 hour, then gradually returned to room temperature, treated with water and dilute hydrochloric acid, toluene was added, the organic layer was separated, and the organic layer was washed with water,
After drying, vacuum distillation 44.3 g of the compound of Yield 76.4%, melting point 41.9%
Met.

formula 18.0 g (0.064 mol) of the compound of Example 1 was dissolved in 50 ml of chloroform to prepare a solution of lithium aluminum hydride 14.97.
g, aluminum chloride 68.3 g, and ether 200 ml were gradually added at room temperature and heated under reflux for 48 hours. After cooling to room temperature, water is added to decompose excess reagents, toluene is added to separate the organic layer, and the organic layer is washed with water, dried, and distilled under reduced pressure to give a formula. 11.9 g of the compound of Yield 70%.

formula 3.53g (0.013mol) of the compound of 10m in tetrahydrofuran
l, the dissolved solution was cooled to −55 ° C., and a solution of 1.28 g (0.020 mol) of n-butyllithium in 12 ml of n-hexane and 10 ml of tetrahydrofuran was added dropwise at −55 ° C. over 30 minutes, and After stirring at this temperature for 30 minutes, carbon dioxide gas-
After blowing at 55 ° C., the temperature was gradually returned to room temperature, diluted hydrochloric acid was added, and toluene was further added to separate the organic layer, which was washed with water and dried, and then the solvent was distilled off. The residue obtained is converted from hexane to 2
Recrystallized twice to give a white crystal with a melting point of 173.7 ° C. 2.6 g of the compound of Yield 64.5%.

formula By heating 2.6 g (0.0084 mol) of the compound of Example 1 with excess thionyl chloride under reflux, Was dissolved in 10 ml of toluene, and this solution was added dropwise to 100 ml of concentrated aqueous ammonia cooled to 0 ° C. to obtain a white bond precipitated. 2.4 g of the compound of Yield 92%.

formula 2.4 g (0.0077 mol) of the compound of formula 2.2 g of the compound of Example 1, pyridine 1.8 g, and benzene 25 ml were mixed, and 1
Heated under reflux for 0 hours. After the reaction mixture was returned to room temperature and allowed to pass, the solution was chromatographed on alumina-n-hexane,
Recrystallized twice from hexane to give a white crystalline formula 1.3 g of 4- (trans-4'-n-propylcyclohexylethyl) -2,5-difluorobenzonitrile which can be represented by the above formula was obtained. Yield 58%. The infrared spectrum of this compound (KBr plate smeared) is shown in FIG.

The ¹ H NMR spectrum of this compound was as follows. ¹ HNMR (CDCl ₃ solvent, TMS internal standard) δ (ppm) 0.6 to 2.0 (complex m. 19H) 2.72 (triplet J = 7Hz 2H) 6.93 (d J = 7Hz 2H) Example 2 In 100 ml of dry tetrahydrofuran, Lithium aluminum hydride 15.3g was added and dissolved in tetrahydrofuran 500ml with vigorous stirring. 100 g (0.384 mol) of the compound of was added dropwise over 1 hour,
Then, it stirred at room temperature overnight. With 600 ml of dilute hydrochloric acid,
After decomposing excess lithium aluminum hydride, toluene was added to the product to separate the organic layer, the organic layer was washed with water, dried, and the solvent was distilled off, followed by recrystallization with hexane, 86.1 g of the compound of Yield 91%.

The obtained formula A solution of the compound 39.7 g (0.161 mol) in 200 ml of acetonitrile was added to a solution of triphenylphosphine dibromide prepared from 100 ml of acetonitrile, 43.2 g (0.165 mol) of triphenylphosphine and 25.8 g (0.162 mol) of bromine, The solution was added dropwise over 15 minutes and then stirred overnight at room temperature. N-Hexane was added to the product to separate the organic layer, and the organic layer was washed with water and dried, and then the solvent was distilled off and subjected to alumina-hexane column chromatography. After distilling the solvent, recrystallization was carried out with ethyl alcohol. ,formula 41.8 g of the compound of Yield 84%.

The obtained formula Compound of 41.8g (0.135mol) and shaving-like magnesium 3.61
Formula prepared from g in 150 ml of tetrahydrofuran The Grignard reagent of the formula Compound of 21.7g (0.113mol), tetrahydrofuran 80m
l, bis (1,2-diphenylphosphino) ethanenickel (II) chloride 4.16 g (7.88 mmol) while stirring, added dropwise at room temperature over 30 minutes and stirred at room temperature overnight Then, 240 ml of diluted hydrochloric acid was added, the organic layer was separated, and the aqueous layer was extracted with toluene. The organic layers were combined and washed with water, the solvent was distilled off, the residue was distilled under reduced pressure, and recrystallized from ethyl alcohol to give the compound of the formula 13.5 g of the compound of Boiling point 197-198 ° C / 2mmHg. Yield 35
%.

The obtained formula 10.3 g (0.003 mol) of the compound of
After dissolving in ml and cooling to -50 ° C, a mixed solution of 2.50 g (0.039 mol) of n-butyllithium in 25 ml of n-hexane and 30 ml of tetrahydrofuran was added dropwise at -50 ° C over 20 minutes. Further, the mixture is stirred for 1 hour at this temperature to remove carbon dioxide gas.
After blowing at 50 ° C, the temperature was gradually returned to room temperature, diluted hydrochloric acid was added, and toluene was further added to separate the organic layer, which was washed with water and dried, and then the solvent was distilled off, followed by recrystallization with a toluene-hexane mixed solvent. Done, expression 8.9 g of the compound of Melting point 225 ° C. Yield 77%.

The obtained formula By heating 8.8 g (0.023 mol) of the compound of Example 1 with excess thionyl chloride under reflux, Was dissolved in 120 ml of toluene, and the solution was cooled to 0 ° C. 80 ml of toluene and 30 ml of concentrated aqueous ammonia.
Was added dropwise to the solution of 8.8 g of the compound of Yield 100%.

This formula 8.8 g (0.023 mol) of the compound of 1 was mixed with 50 ml of toluene and 10 ml of thionyl chloride and heated under reflux for 10 hours. After cooling, water was added, extraction with toluene was performed, the extract was washed with water, dried over anhydrous magnesium sulfate, subjected to alumina-toluene column chromatography, the solvent was distilled off, and recrystallized twice with ethyl alcohol. Target expression 4.3 g of the compound of Yield 52%. Melting point 78.6 ° C. Estimated clearing point 23.3 ° C. Refractive index anisotropy (Δn) 0.100. Dielectric anisotropy (Δε) 36.4.

The infrared spectrum (KBr tablet) of this compound is shown in FIG.

The ¹ H NMR spectrum of this compound was as follows. ¹ HNMR (CDCl ₃ solvent, TMS internal standard) (ppm) 0.8~2.6 (complex m , aliphatic, 17H) 2.95 (s, CH 2 CH 2, 4H) 6.75~7.3 (complex m, aromatic, 6H) Example 3 -16 The following compounds can be synthesized in the same manner as in Example 1.

4- (trans-4'-ethylcyclohexylethyl)
-2,5-Difluorobenzonitrile 4- (trans-4'-n-butylcyclohexylethyl) -2,5-difluorobenzonitrile 4- (trans-4'-n-pentylcyclohexylethyl) -2,5-difluoro Benzonitrile 4- (trans-4'-n-hexylcyclohexylethyl) -2,5-difluorobenzonitrile 4 {(trans-4 ', 4 "-ethylphenylcyclohexyl) ethyl} -2,5-difluorobenzonitrile 4 -{(Trans-4 ', 4 "-n-propylphenylcyclohexyl) ethyl} -2,5-difluorobenzonitrile 4-{(trans-4', 4" -n-butylphenylcyclohexyl) ethyl} -2, 5-difluorobenzonitrile 4-{(trans-4 ', 4 "-n-pentylphenylcyclohexyl) ethyl} -2,5-diph Orobenzonitrile 4-{(trans-4 ', 4 "-n-hexylphenylcyclohexyl) ethyl} -2,5-difluorobenzonitrile 4-{(4'-trans-4" -ethylcyclohexylphenyl) ethyl}- 2,5-Difluorobenzonitrile 4-{(4'-trans-4 "-n-propylcyclohexylphenyl) ethyl} -2,5-difluorobenzonitrile 4-{(4'-trans-4" -n-butyl Cyclohexylphenyl) ethyl} -2,5-difluorobenzonitrile 4-{(4'-trans-4 "-n-pentylcyclohexylphenyl) ethyl} -2,5-difluorobenzonitrile 4-{(4'-trans- 4 ″ -n-hexylcyclohexylphenyl) ethyl} -2,5-difluorobenzonitrile Example-17 Formula Compound of formula Compound and formula An equal weight mixture of compounds of the above formula (referred to as host liquid crystal A) exhibits a dielectric anisotropy of -1.52 at 0 ° C. The liquid crystal composition obtained by adding 10 wt% of the above compound to the base liquid crystal A is 0.
It showed a dielectric anisotropy of +3.15 at ℃. On the other hand, a formula that is a known compound The liquid crystal composition obtained by adding 10 wt% of the above compound to the base liquid crystal A is 0.
It only showed a dielectric anisotropy of +0.62 at ° C.

Thus, it can be seen that the compound of the present invention is useful for increasing the dielectric anisotropy.

EFFECTS OF THE INVENTION As described above, the present invention provides a compound of the general formula (Wherein ring X and ring Y represent a trans-1,4-di-substituted cyclohexane ring or 1,4-di-substituted phenylene, R represents an alkyl group having 1 to 8 carbon atoms, and n represents 0 or 1) .
However, the ring X and the ring Y are not trans-1,4-di-substituted cyclohexane rings at the same time. By providing the difluorocyano compound represented by the formula (1), the liquid crystal composition of the present invention is excellent in producing an effect such that a liquid crystal composition having a large dielectric anisotropy can be formed. It is widely used for displaying instrument panels, computer terminals, high-density dot matrix, etc.

[Brief description of drawings]

FIG. 1 and FIG. 2 are infrared spectrum diagrams of the compounds of Examples 1 and 2.

Claims (3)

[Claims] 1. A general formula (Wherein ring X and ring Y represent a trans-1,4-di-substituted cyclohexane ring or 1,4-di-substituted phenylene, R represents an alkyl group having 1 to 8 carbon atoms, and n represents 0 or 1) .
However, the ring X and the ring Y are not trans-1,4-di-substituted cyclohexane rings at the same time. ) The difluoro cyano compound represented by these. 2. The difluorocyano compound according to claim 1, wherein R in the formula (I) is a linear alkyl group having 2 to 6 carbon atoms. 3. General formula (Wherein ring X and ring Y represent a trans-1,4-di-substituted cyclohexane ring or 1,4-di-substituted phenylene, R represents an alkyl group having 1 to 8 carbon atoms, and n represents 0 or 1) .
However, the ring X and the ring Y are not trans-1,4-di-substituted cyclohexane rings at the same time. ) In the composition at least one difluorocyano compound represented by
A liquid crystal composition characterized by being mixed in wt%.