JPH0223540B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel organic compound, and more particularly to a novel liquid crystal compound that can be used as a component of a liquid crystal material. As is well known, liquid crystal materials are display elements that use nematic liquid crystals with twisted liquid crystal alignment (so-called TN).
In addition to display devices that utilize the guest-host effect of liquid crystal materials or liquid crystal mixtures containing appropriate dyes, DS type display devices that utilize the dynamic scattering effect of liquid crystals, and cholesteric-nematic phase transition. It is widely used in display devices that utilize this, and DAS display devices that utilize the field-controlled birefringence effect of liquid crystals. These liquid crystal materials cannot be used as a single compound in terms of their properties, such as liquid crystal temperature range, operating voltage, response performance, etc., and for practical purposes, it is necessary to mix several liquid crystal compounds to some extent. At present, we have obtained something that is usable. The present invention provides a compound useful as a component of such a stable liquid crystal composition with excellent practical performance. That is, the present invention is based on the general formula (In the above formula, R represents an alkyl group having 1 to 6 carbon atoms) 4'-(β-alkyloxyethyl-
4-cyanoterphenyl. The compound of formula (1) of the present invention is a novel liquid crystal compound with positive dielectric anisotropy, a wide liquid crystal temperature range, a high clearing point, and excellent stability. Since the compound of the present invention has a high melting point, it cannot be practically used alone, but it has excellent compatibility with other liquid crystal compounds, such as biphenyl, ester, azoxy, and phenyl cyclohexane carboxylates. It has the effect of raising the clearing point when mixed with one type or a mixture of several types of liquid crystals such as ester type, phenylcyclohexane type, and phenylpyrimidine type. The compound of the present invention can be synthesized as follows. First, the route is shown as a chemical formula. First, using P-phenylphenol () as a starting material, trans-4-phenylcyclohexanol () is obtained by nuclear hydrogenation reaction. As a catalyst, a platinum metal such as Pt, Rh, Pd, or Re or a Ni catalyst such as Raney nickel can be used, and as a solvent, an alcohol cyclohexane or the like can be used, but a polar solvent is preferable from the viewpoint of reaction rate. Reaction temperature is 100-200
℃ and hydrogen pressure of 10 to 100 Kg/cm ² . Compound () is acetylated by a conventional method to give trans-4-phenylcyclohexyl acetate (). Compound () was then nitrated in the presence of sulfuric acid to form trans-4-
(P-nitrophenyl)-cyclohexyl acetate () is obtained. When the compound () is reduced and the nitro group is changed to an amino group, trans-4-(P-aminophenyl)-cyclohexyl acetate () is obtained.
is obtained. Reduction of nitro groups can be carried out using normal nascent hydrogen (hydrochloric acid-iron system, hydrochloric acid-tin system, etc.) or by adding water under pressure or normal pressure using a normal hydrogenation catalyst such as platinum metal or Ni. An additive reaction may also be performed. Compound () is diazotized by a conventional method to form a diazonium salt of (), which is reacted with cuprous bromide in the presence of copper to form trans-4-(P-
Bromophenyl)-cyclohexyl acetate () is obtained. When this is hydrolyzed, trans-
4-(P-bromophenyl)-cyclohexanol () is obtained. Compound () is oxidized with an oxidizing agent such as chromic acid to give 4-(P-bromophenyl)-cyclohexanone (). Compound () is 4
-bromo-1-(β-alkyloxyethyl)-benzene () by Grignard reaction
-(β-alkyloxyethyl)-phenyl]-4
-(P-bromophenyl)-cyclohexene (XI)
get. Compound (XI) is subjected to a dehydrogenation reaction using sulfur or chloranil to obtain 4'-(β-alkyloxyethyl)-4-bromotarphenyl (XII). Compound (XII) is reacted with cuprous cyanide to obtain the target compound 4'-(β-alkyloxyethyl).
-4-cyanoterphenyl () is obtained. The compounds of the present invention will be explained in more detail below by showing production examples and usage examples thereof as examples. Example 1 [4'-(β-butyloxyethyl)-4
- Production of cyanoterphenyl] Step A Dissolve 1 kg (5.88 mol) of P-phenylphenol in 2 ethanol and charge it into an autoclave. Using 100 g of developed Raney nickel as a catalyst,
The hydrogenation reaction is carried out at a reaction temperature of 150 to 160°C and a hydrogen pressure of 30 to 40 Kg/cm ² . The reaction is stopped when 17.6 moles of hydrogen have been absorbed, and after cooling, the catalyst is separated, and then the ethanol is concentrated and the resulting residue is dissolved in toluene. The toluene solution is washed several times with 2N caustic soda and water, and after further washing with water, the toluene is concentrated and removed. The obtained crude crystals were recrystallized from ethanol to obtain 200 g of trans-4-phenylcyclohexanol (). The melting point of this thing is
The temperature was 118.4-119.2°C. Step B 352.5 g (2 mol) of trans-4-phenylcyclohexanol (2 mol), 791 g of pyridine, and 200 ml of toluene are mixed and dissolved, and 173 g (2.2 mol) of acetyl chloride is gradually added at a reaction temperature of 25°C. After the addition, the temperature is raised to 60°C and reacted for 1 hour, then cooled. Add 300 ml of toluene and 500 ml of water, mix and let stand, and dilute the upper toluene layer with 500 ml of 6N-hydrochloric acid.
twice, twice with 500ml of 2N caustic soda water, and then with water.
Wash 5 times with 500ml. After concentrating and removing toluene,
The residue was recrystallized from a mixed solvent of 300 ml of ethanol and 50 ml of water to obtain 380 g of trans-4-phenylcyclohexyl acetate (). The melting point of this product was 49.0-49.7°C. Step C Mix and dissolve 380 g (1.74 mol) of trans-4-phenylcyclohexyl acetate (), 380 ml of acetic acid, and 190 ml of acetic anhydride, and add 159.7 g (1.77 mol) of 70% nitric acid at such a rate that the internal temperature does not exceed 20°C. Add a mixed acid of 900g of concentrated sulfuric acid. After that, 300g of concentrated sulfuric acid
and react at 30°C for 4 hours. After finishing, add 1 part of toluene and 1 part of ice water while cooling in an ice bath, stir, wash the toluene layer with water (3 times), and add 2N-
Wash with caustic soda and water, and then wash with water until neutral. After concentrating and removing toluene, the remaining crude crystals were recrystallized with 500 ml of ethanol and trans-
267 g of 4-(P-nitrophenyl)-cyclohexyl acetate () was obtained. The melting point of this substance is 126.0
The temperature was ~127.5℃. Step D Trans-4-(P-nitrophenyl)-cyclohexyl acetate (267 g 1.01 mol) was dissolved in 1.2 g of ethyl acetate, 14 g of platinum/carbon powder supported at 5% was added as a catalyst, and the mixture was heated at 60°C under normal pressure. absorb hydrogen. When hydrogen absorption has stopped, separate the catalyst, concentrate and remove the solvent ethyl acetate,
The remaining crude crystals were recrystallized from 800 ml of ethanol to obtain 193 g of trans-4-(P-aminophenyl)-cyclohexyl acetate (). The melting point of this product was 132.3-134.2°C. Step E Dissolve 196 g (0.84 mol) of trans-4-(P-aminophenyl)-cyclohexyl acetate () in 390 ml of acetic acid, and add 361.3 g of 47% hydrobromic acid.
(2.10 mol) was added and cooled to below 5℃ in an ice bath, and 59.5 g (0.86 mol) of sodium nitrite was added to 78 ml of water.
Add the solution gradually so that the temperature does not exceed 10℃, and keep it under 10℃.
Stir for 20 minutes to obtain the diazonium salt of compound (). Anhydrous copper sulfate 33.4g (0.21mol), copper powder 16.5g
(0.26 mol), anhydrous sodium bromide 94.8 g (0.92 mol), concentrated sulfuric acid 23.2 g, and water 840 ml were mixed and heated.
Reflux for 3 hours. Under reflux, the solution of the diazonium salt prepared earlier is gradually added, and the mixture is further refluxed for 2 hours. After cooling, 1,000ml of toluene was added, and the toluene layer was diluted with 6N hydrochloric acid, then 2N caustic soda.
After washing with water and then with water until neutral, toluene is concentrated and removed, resulting in trans-4-(P-bromophenyl)-cyclohexyl acetate ().
166.5 g of a mixture of trans-4-(P-bromophenyl)-cyclohexanol () is obtained.
This mixture was used as it was in the next reaction, but the mixture was converted into acetate by a conventional acetylation method and purified with ethanol. The resulting compound () had a melting point of 77.8 to 78.3°C. Step F Dissolve 208.5 g of the mixture of compound () and compound () obtained in Step E in 460 ml of ethanol, add a solution of 28 g of caustic soda in 30 ml of water, and heat and reflux for 1 hour. After cooling, toluene
Add 500 ml and 500 ml of water, wash the toluene layer with 2N caustic soda water, and then wash with water until it becomes neutral. After concentrating and removing toluene, the obtained crude crystals were recrystallized with 130 ml of ethyl acetate to obtain trans-4-(P
-bromophenyl)-cyclohexanol ()
Obtained 130g. The melting point of this product was 109.5-111.0°C. Step G Dissolve 130 g (0.51 mol) of trans-4-(P-bromophenyl)-cyclohexanol () in 306 ml of acetone and add the oxidizing agent prepared in advance (a solution of 134 g of chromic anhydride, 217 g of concentrated sulfuric acid, and 250 ml of water). ) Gradually add 122ml while cooling so as not to exceed 20℃. After further reaction for 1 hour after addition,
Add 60 ml of isopropyl alcohol to reduce excess oxidant. After stirring 300ml of toluene, wash the toluene layer with water to make it neutral. After concentrating and removing toluene,
The residue is further distilled under reduced pressure to a boiling point of 135-145℃/2mmHg.
The fractions were collected and recrystallized with a mixed solvent of 70 ml of hexane and 5 ml of ethanol to give 4-(P-bromophenyl)-
71.8 g of cyclohexanone () was obtained. The melting point of this product was 59.4-61.4°C. Step H Put 6.9 g (0.28 mol) of metallic magnesium into a well-dried 1-3-necked flask, thoroughly dry the inside of the flask by blowing dry nitrogen gas, and add 50 ml of anhydrous tetrahydrofuran and a trace amount of iodine. While stirring, 4-bromo-1-(β-butyloxyethyl)-
A solution of 73 g (0.28 mol) of benzene in 146 ml of anhydrous tetrahydrofuran was gradually added while maintaining the reaction temperature at 30 to 35° C. After the addition, the reaction was further continued at the same temperature for 1.5 hours. Cool on ice to bring the internal temperature below 5℃, then proceed to step 4.
A solution of 72 g (0.28 mol) of -(P-bromophenyl)-cyclohexanone () in 146 ml of anhydrous tetrahydrofuran was added at such a rate that the internal temperature did not exceed 10°C. After reacting for 30 minutes at room temperature, add a small amount of 6N hydrochloric acid to make the contents weakly acidic, and add 200ml of toluene.
The aqueous layer is further extracted with 50 ml of toluene, the toluene layers are collected and washed with water, and the toluene is concentrated and removed. Add 200 ml of toluene and 10 g of potassium bisulfate to the residue, heat, and reflux at 110°C for 1 hour. After cooling, the toluene solution was washed with water to make it neutral, the toluene was concentrated and removed, and the resulting crude crystals were recrystallized with 200 ml of ethanol to obtain 1-[P-(β-butyloxyethyl)-phenyl]-4-(P 57.5 g of -bromophenyl)-cyclohexene (XI) was obtained. The melting point of this thing is 865-895
It was warm at ℃. Step I 1-[P-(β-Butyloxyethyl)-phenyl]-4-(P-bromophenyl)-cyclohexene (XI) 55 g (0.13 mol) and chloranil 78.4 g
(0.32 mol) and 624 ml of xylene are heated to 24
Reflux for an hour. After cooling, add 800ml of toluene,
After separately removing insoluble solids, toluene was concentrated and removed, and the resulting crude crystals were recrystallized with 50 ml of ethyl acetate to obtain 29 g of 4'-(β-butyloxyethyl)-4-bromoterphenyl (XII). Ta. The melting point of this thing is
The temperature was 225.7-227.0°C. Step J A mixture of 29 g (0.071 mol) of 4'-(β-butyloxyethyl)-4-bromotarphenyl (XII) and 70 ml of N-methyl-2-pyrrolidone and 7.6 g of cuprous cyanide was heated and refluxed for 4 hours. let After cooling to 60℃,
After adding 107 ml of a 7.8% aqueous solution of ferric chloride, cool to room temperature, add 150 ml of toluene, and stir. The toluene layer was treated with 6N-hydrochloric acid, then with 2N-P caustic soda water,
Further, the toluene layer is washed with water until it becomes neutral, and then the water in the toluene layer is removed by azeotropy, and then passed through an alumina-packed column to remove trace amounts of impurities by adsorption. Toluene was concentrated and removed, and the resulting crystal was recrystallized with ethyl acetate to obtain the target product, 4'-(β-butyloxyethyl).
13.4 g of -4-cyanoterphenyl () was obtained.
This substance is a nematic liquid crystal compound with a melting point (C-N
point) was 89.0°C, and clearing point (N-1 point) was 184.5°C. In addition, the elemental analysis values of this product were in good agreement with the calculated values as shown below. Analytical value Calculated value (as C ₂₅ H ₂₅ NO) C 84.1% 844.7% H 7.2% 70.9% N 3.8% 39.4% Examples 2 and 3 4-Bromo-1 in Step H in Example 1
-(β-Butyloxyethyl)-benzene can be replaced with 4-bromo-1-(β-ethyloxyethyl)benzene (Example 2) or 4-bromo-1-(β-
propyloxyethyl)-benzene (Example 3)
, and the rest was carried out in exactly the same manner as in Example 1.
4′-(β-ethyloxyethyl)-4′-cyanot-
Phenyl and 4'-(β-propyloxyethyl)-
4'-cyanoterphenyl was obtained. The physical property values are shown in Table 1 together with the results of Example 1.

[Table] Example 4 (Application example) The clearing point (N-1 point) of the liquid crystal composition consisting of is 62.5
℃, the dielectric constant anisotropy, ie, Δε, was 12.0, and the refractive index anisotropy, Δn, was 0.22. In this liquid crystal composition, the compounds were well fused with each other, and no crystal precipitation occurred even after 200 hours of heat cycle tests at -30° and +25°C. A TN cell (cell thickness: 10 μm) in which this liquid crystal composition was deposited with silicon oxide on a glass substrate with a transparent electrode and subjected to parallel alignment treatment by rubbing.
When encapsulated in a 2000 µm, the threshold voltage was 1.46V and the saturation voltage was 2.02V. A compound of the present invention from the above composition. The liquid crystal composition excluding NI point is 45.8℃, △ε11.7,
It can be seen that at Δn0.20, the clearing point is significantly increased by the compound of the present invention. In addition, when using the same TN cell as above, the threshold voltage is 1.31V,
The saturation voltage is 1.84V.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents an alkyl group having 1 to 6 carbon atoms) 4'-(β-alkyloxyethyl)-
4-cyanoterphenyl. 2 General formula (In the above formula, R represents an alkyl group having 1 to 6 carbon atoms) 4'-(β-alkyloxyethyl)-
A liquid crystal composition characterized by containing a small amount of 4-cyanoterphenyl as a co-component.