JPH0219334A - Novel cyclohexylphenyl compound, liquid crystal composition and optical switching element containing the same - Google Patents

Abstract

NEW MATERIAL:A cyclohexylphenyl compound of formula I (R is alkyl; m and n are integers of >=1 and m<n). EXAMPLE:Trans-1-butyl-4-[4-(2-methylbutanoyl)phenyl]cyclohexane. USE:Useful as a liquid crystal composition. The compound exhibits excellent effects as a raw material for optoelectoronics-relating elements, such as the formation of a stable thermotropic liquid crystal state, a large spontaneous polarization and a ferroelectric liquid crystal having a high response rate. Therefore, the component of formula I is effectively utilized for the displays of liquid crystal televisions, etc., printer heads, optical Fourier transformation elements, etc. PREPARATION:A compound of formula II and a compound of formula III are subjected to a Friedel Crafts reaction to provide the compound of formula I. The compound of formula III is synthesized from a 2-alkyl-1-alkanol as a starting raw material.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention can take a stable thermotropic liquid crystal state, and can be used, for example, in displays such as liquid crystal televisions, optical printer heads, optical Fourier transform elements, light valves, etc. The present invention relates to a novel ester compound that can be used as a liquid crystal material that is useful as a material for optoelectronics-related devices that utilize liquid crystals and electrochemometry, as well as liquid crystal compositions and optical switching devices that contain this compound.

(Prior Art) Currently, liquid crystal compounds are used as display materials in various devices, and have been put to practical use in watches, calculators, small televisions, and the like.

These devices use a cell mainly composed of a nematic liquid crystal material, and employ a display system called a TN type or STN type.

The cell in this case operates based on the weak interaction (ΔεB''/2) between the dielectric anisotropy Δε of the liquid crystal compound and the electric field E, and the disadvantage is that the response speed to the electric field is slow at several seconds. Therefore, when used in televisions, an active matrix drive system in which a switching element is arranged and added to each pixel is mainly used as a drive system, which is one of the obstacles to achieving a larger screen.

However, in 1975, 4-(4n-decyloxybenzylideneamino) synthesized by R.B. Meyer et al.
Cinnamic acid-2-methylbutyl ester (DOBAMBC)
), the emergence of ferroelectric liquid crystals as a representative example, and the new display method using them proposed by N, A, C1ark et al.
pliedPhys, Lett, 1980.36.89
9), it has become possible to create a liquid crystal cell that has a high-speed response on the order of u sec and a property that the orientation of liquid crystal molecules does not change even when the electric field is turned off (memory property). By using display elements made of these materials, it becomes possible to create liquid crystal televisions using a simple matrix method using multiplex drive without using switching elements, and compared to active matrix devices, they are more efficient in terms of productivity, cost, reliability, and larger screens. It will be much more advantageous in terms of conversion etc.

For this reason, many ferroelectric liquid crystal materials have been synthesized and proposed to date. In order for these ferroelectric liquid crystal materials to be used as display materials, several physical properties are required, but among them, the basic ones are that they exhibit a smectic C phase in a wide temperature range near room temperature, and that they exhibit large It has spontaneous polarization and is chemically stable. However, early ferroelectric liquid crystals had a spontaneous polarization of 10 nC.
They were chemically unstable because they were small (less than 1/cm") and many had Schiff bases in their molecules.

Incidentally, the expression of large spontaneous polarization due to chemically stable ester compounds has recently been reported.

For example, the compound of the formula
The liquid crystal becomes a cholesteric phase in the temperature range of 0.8°C, but the spontaneous polarization of this liquid crystal at 83°C is 89nC.
/ cm” (Japanese Unexamined Patent Publication No. 1988-43).

On the other hand, two-ring compounds have been synthesized in order to lower the temperature at which chiral smectic C phase is exhibited.

For example, the biphenyl compound of the following formula becomes a smectic A phase liquid crystal in the temperature range of 57 to 38°C, and a chiral smectic C phase liquid crystal in the temperature range of 38 to 28.5°C. 7
2652).

Furthermore, phenylpyrimidine compounds that stably exhibit a chiral smectic phase near room temperature have been reported. For example, a compound of the following formula becomes a liquid crystal in a chiral smectic C phase in the temperature range of 40.7 to 82.8°C and a smectic A phase in a temperature range of 82.8 to 89.1°C (JP-A-61 -20097
Publication No. 3).

(Problem B to be Solved by the Invention) However, the above-mentioned ester compound has a drawback that the temperature range of the chiral smectic C phase is high.

In addition, the above biphenyl compound exhibits a chiral smectic C phase at a temperature close to room temperature, but the temperature range is approximately 10
°C is not wide enough. In addition, the above phenylpyrimidine compound has a response speed of 1500μsec at 43°C.
c, and the spontaneous polarization is estimated to be quite small.

In other words, liquid crystal materials for display devices that require high-speed response require physical properties such as having large spontaneous polarization, low viscosity, or exhibiting a chiral smectic C phase over a wide temperature range including near room temperature. is required, but
The reality is that to date, there is still no material that fully satisfies these physical properties.

In contrast, the present inventors have already found that compounds that have an asymmetric carbon at the α-position and a ketone group directly connected to a benzene ring in the molecule are stable against light, etc., and are enantiotropic and exhibit a liquid crystal state. If the temperature range is wide and the asymmetric carbon is given optical activity, the liquid crystal becomes chiral smectic C.
It has been discovered that a ferroelectric liquid crystal exhibits a phase with a large spontaneous polarization and a fast response speed (International Application No. JP 88).
100334).

Based on this knowledge, the present inventors conducted further intensive studies and succeeded in synthesizing a compound in which the benzene ring was substituted with cyclohexylphenyl, which is known to have the effect of lowering viscosity than before, and We have found that this compound is also effective as a liquid crystal composition.

The present invention was made based on such knowledge, and an object of the present invention is to provide a novel cyclohexylphenyl compound useful as a liquid crystal composition, and a liquid crystal composition containing the same.

Further, the present invention aims to provide a liquid crystal display element having high-speed response using such a novel cyclohexylphenyl compound or a liquid crystal composition containing the same.

(Means for Solving the Problems) The present invention provides the following general formula (I), (wherein R is an alkyl group, and n is an integer of 1 or more, and m
It consists of a novel cyclohexylphenyl compound represented by (an), a liquid crystal composition containing at least one of this compound, and an optical switching element containing at least one of this compound as a constituent element.

Although there is no particular upper limit for the number of carbon atoms in the alkyl group represented by R in the above formula (I) and the integer of n, from a practical manufacturing standpoint such as ease of obtaining raw materials, R is a carbon Number 1
Preferably, the number is up to 8, and the number of n is preferably up to 16.

In particular, in the above formula, if optical activity is imparted to the carbon to which CnHzn** is bonded, it becomes a ferroelectric liquid crystal either alone or in combination with other compounds, which is preferable.

Examples of typical compounds of the above formula and their physical and chemical properties are as follows.

One-through H-NMR (CDCj! 3.7MS standard, δ value p
pn+) Near, 89 (d, 21+), 7.2
9 (d, 2H), 3.38 (q, 18)2.
76~1.1 (27H) ■IR (Br, cm-'): 2900.167
5.1600. 1475°1215.965 ■ Mass: 300 (M”) ■ a = +1.133 (41! = 1,
neat) octanoyl phenyl cyclohexane (
34+1) ■IR (KBr, cm-1): 2910.167
5.1600.1445°1220.965.

■ Mass = 356 (M”) The number of carbon atoms in the alkyl group of OR in the compound represented by the above general formula (I) and the value of n depend on the physical properties such as the temperature range in which the compound can take a liquid crystal state, or the response It has an effect on properties such as speed, and can be selected as appropriate depending on the purpose.It goes without saying that this compound can be used alone or in combination with other liquid crystal materials. Not even.

The compound of formula (I) above can be obtained as follows.

■'H-NMR (CDC Ha, 7MS standard, δ value ppm
) Near, 8? (d, 2H), 7.28
(d, 2H), 3.45 (m, 18) 2.53
(t, IH), 1.95-1.6 (60), 1.
6-0.8 The compound (I) above can be obtained as follows.

(R″ is an alkyl group) The compound (I) above, which is R″ n-C4H9, is commercially available and may be used.

The compound (2) above can be easily obtained using 2-alkyl-1-alkanol as a starting material.

Specifically, 2-alkyl-1-alkanol is first oxidized with an oxidizing agent. As the oxidizing agent, in the synthesis of optically active compounds, an agent that can oxidize without causing racemization is selected, and potassium permanganate is the simplest and preferred. This oxidation reaction using potassium permanganate is preferably carried out under acidic conditions, and sulfuric acid is preferably used as the acid. The reaction operation is to add 2-alkyl-1-alkanol to a 2-50% aqueous sulfuric acid solution, and add 20-3 times the molar amount of potassium permanganate to the alcohol.
While maintaining the temperature at 30°C, slowly add and react. When the reaction mixture obtained as described above is added to an aqueous solution of sodium bisulfite, unreacted potassium permanganate and manganese dioxide are dissolved in water and can be extracted with an organic solvent such as ether. The 2-alkylalkanoic acid can be isolated and purified by repeating this extraction and separating by known means such as distillation and column chromatography.

The obtained 2-alkylalkanoic acid is reacted with an inorganic halide such as thionyl chloride, phosphorus pentachloride, phosphoryl trichloride, etc. to form an acid halide.

In this reaction operation, the above inorganic halide is
It is preferable to add the 2-alkyl alkanoic acid dropwise while stirring the mixture at a temperature of 50 to 90°C, and to react for 1 to 3 hours at a temperature of 50 to 90°C.

(Example) Next, the present invention will be specifically explained using examples.

3.14g (74+m) of sodium hydroxide in 500Id of water
mol) and 25.9 g of potassium permanganate (I64
m mol) was dissolved and maintained at a temperature of 38 to 42°C, while stirring, 10 g (I13+u+ol) of (-)-2-/l゛Tylbutyl Fluorine 2-JL was added from the dropping funnel to the solution maintained at a temperature of 38 to 42°C. The mixture was added dropwise over a period of minutes, and the mixture was further stirred and reacted for 20 minutes, followed by quenching with ice water.

Next, the obtained reaction mixture was washed with ether, made acidic by adding 3N hydrochloric acid, and then extracted with chloroform. After washing this extract with 10% sodium chloride,
After drying with magnesium sulfate and concentrating, vacuum distillation (boiling point 96-98°C/38 ms+Hg) L, 8.92
g of a colorless and transparent liquid was obtained. As a result of analysis, this compound was confirmed to be (+)-2-methylbutanoic acid,
The yield was 78% (87.3 mmol).

Next, 11.7 g of thionyl chloride (98.3 m mo
1) was maintained at a temperature of 36 to 38° C., and the (+)-2-methylbutanoic acid obtained above was added dropwise thereto over 7 minutes while stirring. After stirring and reacting at room temperature for 40 minutes, 8
The reaction mixture was stirred at a temperature of 0°C for 30 minutes. Then,
This was distilled to give 6.5 g (53.9 ta mol, yield 64) of colorless and transparent (+)-2-methylbutanoic acid chloride.
%) was obtained.

(+)-2-methylbutanoic acid chloride obtained above 2.0
2 g (I6, h mol) and dry methylene chloride 3 ru
While stirring under ice-water cooling, 2.42 g (I8,2+w mol) of anhydrous aluminum chloride was added, and the mixture was homogenized by stirring for 20 minutes in an ice-water bath and 20 minutes at room temperature, and then in an ice-water bath. Cooled.

Separately, 3.75 g (I7, 33 mmol) of commercially available trans-1-butyl-4-phenylcyclohexane and 3 d of dry methylene chloride were added, and the mixture was stirred while being cooled in an ice-water bath. To this was added the previously prepared methylene chloride solution of (+)-2-methylbutanoic acid chloride and anhydrous aluminum chloride over a period of 34 minutes while maintaining the liquid temperature at 3 to 5°C.

After continued stirring in an ice water bath for 1.5 hours, the reaction mixture was mixed with 20 d of melene chloride, 25 d of water, and 100 d of ice water.
and chloroform IO-. After separation of the two layers, the aqueous layer was extracted with chloroform, washed with water, and then dried over magnesium sulfate. Thereafter, magnesium sulfate was removed by filtration, and the filtrate was concentrated and dried under reduced pressure to obtain a slightly brown liquid. This liquid was separated by column chromatography and turned into a colorless and transparent liquid.3. Obtained OOg. Next, 36 ml of methanol was added to this, and the precipitated crystals were filtered out under cooling and dried under reduced pressure to obtain trans-1-butyl-4, a colorless and transparent liquid having the above-mentioned physical and chemical properties.
-(4-(2-methylbutanoyl)phenyl)cyclohexane 1.86 g (yield 37%) was obtained.

Armpit j 11 side 1i The above compound was injected into a 4μ-thick cell made of glass coated with polyimide and subjected to rubbing treatment, the temperature of the cell was controlled on a hot stage, and the inside of the cell was examined using a crossed Nicol polarizing microscope. The state of the compound was observed. When the temperature in the hot stage was changed at a rate of 2°C per minute and the change in the state of the compound was observed, it crystallized at 4°C during the cooling process and melted at 19°C during the heating process.

(-)-2-Methyloctatool 21.2g (I47m
mol) was added with an aqueous solution of 330 rnl of water and 46.4 g of concentrated sulfuric acid, and stirred to form an emulsion. To this, 63.4 g (401 n+ mol) of potassium permanganate was added over 7 hours. Next, 51.5 g of sodium bisulfite, 70 Id of ice water, and 20 Id of x-chill were added to this reaction solution.
0ml was used to transfer everything to ice water 270111. After separating the two layers, the reaction product was extracted from the aqueous layer with ether, then extracted with a 10% aqueous sodium hydroxide solution, ice was added, and then concentrated sulfuric acid was added to adjust the pH to 1 or less. This aqueous layer is extracted with chloroform, washed with water, dried over anhydrous magnesium sulfate, filtered, concentrated, and distilled under reduced pressure to obtain (+)-2-methyloctanoic acid 16, a colorless and transparent liquid. .5 g (yield 71%) was obtained.

Next, 2.38 g of thionyl chloride (I9, Oa+ mol
) was maintained at a temperature of 36-38°C and, with stirring, the (+)-2-methyloctanoic acid 2. obtained above was added to it.
51 g (I5.9 ta mol) was added dropwise over 7 minutes.

After stirring and reacting at room temperature for 40 minutes, at a temperature of 80°C
After stirring and reacting for 0 minutes, excess thionyl chloride was distilled off to obtain 2.81 g of colorless and transparent (+)-2-methyloctanoic acid chloride (I5.9 mmol, yield IOO%).
) was obtained.

(+)-2-Methyloctanoic acid chloride obtained above 1.
95g (I1,0m+mol) and 2d of dry methylene chloride
was added, and while stirring under ice-water cooling, 1.64 g (I2.3 mmol) of anhydrous aluminum chloride was further added, and the mixture was homogenized by stirring for 30 minutes under an ice-water bath, and then cooled in an ice-water bath.

On the other hand, 2.44 g (I1,3 ta mol) of commercially available trans-1-butyl-4-phenylcyclohexane and dry methylene chloride 2- were added, and the mixture was stirred while being cooled in an ice-water bath. To this was added the previously prepared methylene chloride solution of (+)-2-methyloctanoic acid chloride and anhydrous aluminum chloride over a period of 10 minutes while maintaining the liquid temperature at 3 to 5°C. After continued stirring for a subsequent 30 minutes in an ice-water bath and then for 25 minutes at room temperature, the reaction mixture was transferred to 100 d of ice water using 10 d of melene chloride 15-1 water and 15-chloroform. After separation of the two layers, the aqueous layer was extracted with chloroform, washed with water, and then dried over magnesium sulfate. Thereafter, magnesium sulfate was removed by filtration, and the filtrate was concentrated and dried under reduced pressure to obtain a slightly brown liquid. This liquid was separated by column chromatography to obtain a colorless and transparent liquid. Next, methanol 130i was added to this, cooled,
The precipitated crystals were filtered under cooling and dried under reduced pressure to obtain trans-1, a colorless and transparent liquid having the above-mentioned physical and chemical properties.
-Butyl-4-(4-(2-methyloctanoyl)phenyl)cyclohexane 0.89 g (yield 23%) was obtained.

When the above compound was observed using the method described in Example 1,
In the temperature-lowering process, crystallization occurred at -31.6°C, and in the temperature-raising process, the crystals melted at 10°C.

Preparation of decarbonized main liquid crystal composition (+)-trans-1-butyl- obtained in Example 1
4-(4-(2-methylbutanoyl)phenyl)cyclohexane and 4-octyloxyphenyl-4-octyloxybenzoic acid, which is a known compound and is not ferroelectric but is known to exhibit a smectic C phase. and ester in a ratio of 10 mol:90 mol to prepare a liquid crystal composition.

When the above liquid crystal composition was observed by the method described in Example 1, it turned into a cholesteric phase at 81.2°C during the cooling process, and 6
It became a smectic A phase at 5°C, a chiral smectic C phase at 60.2°C, and crystallized at 45.9°C. In this manner, a liquid crystal composition exhibiting a chiral smectic C phase was created by mixing.

Preparation of liquid crystal composition Trans-1-butyl-4 (4-(
2-Methyloctanoyl)phenyl)cyclohexane and 4-octyloxyphenyl-4-octyloxybenzoate described in Example 3 were mixed at a ratio of 10 mol:90 mol to prepare a liquid crystal composition.

When the above liquid crystal composition was observed using the method described in Example 1, it was found that during the cooling process, it changed to a cholesteric phase at 75.8°C.
It became a smectic A phase at 9.8°C, a chiral smectic C phase at 45°C, and crystallized at 43°C.

In this manner, a liquid crystal composition exhibiting a chiral smectic C phase was created by mixing.

Actual Example 3 The liquid crystal composition obtained in Example 3 was injected into a 3.6-μl-thick cell made of a glass plate with a transparent electrode coated with polyimide and subjected to a rubbing treatment, and the liquid crystal composition was gradually changed from an isotropic liquid state. The temperature was lowered and the cholesteric phase and smectic A phase were oriented. The orientation state was extremely good. When the temperature was further lowered to bring the cell into a chiral smectic C phase state and an electric field was applied to the cell while observing it with a crossed Nicol microscope, clear switching behavior was observed.

A 36v1 rectangular wave was applied to the above cell at 60°C, and the amount of transmitted light was measured with a photodiode to detect optical switching operation, and the response measurement was as fast as 374 μsec.

(Effects of the Invention) The compound of the present invention has extremely excellent effects as a material for optoelectronic devices, such as being able to take a stable thermotropic liquid crystal state and becoming a ferroelectric liquid crystal with large spontaneous polarization and fast response speed. It is something to play.

Therefore, the present invention can be said to be a liquid crystal material that is useful as a material for optoelectronic-related elements that utilize liquid crystals or electrochemistry, such as displays such as liquid crystal televisions, printer heads, optical Fourier transform elements, and light pulp.

Claims (1)

[Claims] 1. The following general formula (I), ▲Mathematical formula, chemical formula, table, etc.▼(I) (In the formula, R is an alkyl group, m and n are integers of 1 or more, and m
A novel cyclohexylphenyl compound represented by <n. 2. A liquid crystal composition containing at least one cyclohexylphenyl compound represented by the general formula (I) according to claim 1. 3. An optical switching device comprising at least one cyclohexylphenyl compound represented by the general formula (I) according to claim 1 as a constituent element.