JPH0224815B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal compound having positive dielectric anisotropy. Liquid crystal materials exhibiting positive dielectric anisotropy are used in display devices that use nematic liquid crystals (so-called TN cells) that have a twisted liquid crystal alignment by utilizing their chemical and dielectric anisotropy, and color displays that apply the guest-host effect. There are uses for devices, etc. These liquid crystal materials cannot be used as a single compound in terms of their performance, such as liquid crystal temperature range, threshold voltage, response speed, stability, etc., and for practical purposes, several types of liquid crystal compounds or Mixtures of non-liquid crystal compounds have been used.

The present invention provides a compound that has excellent practical properties and is useful as a component of a liquid crystal composition with positive dielectric anisotropy.

That is, the compound of the present invention is trans-4-alkyloxymethyl- represented by the following general formula ().
1-(4″-cyano-4′-biphenylyl)cyclohexane.

(In the above formula, R represents an alkyl group having 1 to 5 carbon atoms) The compound of the formula () of the present invention has positive dielectric anisotropy, a wide liquid crystal temperature range, a high clearing point, and stability. This is a new liquid crystal compound with excellent properties.

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. When used in combination with one type or a mixture of several types of liquid crystal compounds such as ester, phenylcyclohexane, phenylpyrimidine, and phenylmetadioxane, it has the effect of raising the clearing point.

The compound of formula (1) can be produced by the following steps.

That is, first, the known substance methyl trans-4-phenylcyclohexanecarboxylate (W, S,
Jyonson et al. JACS 67 , 1045 (1945) () is used as a starting material and () is reduced with aluminum hydride (LiAlH ₄ ) or the like to obtain trans-4-phenylcyclohexylmethanol (). (1st
step). This is then reacted with P-toluenesulfonyl chloride in dry pyridine to obtain trans-4-phenylcyclohexylmethyl P-toluenesulfonate (2nd stage). Trans-4-alkyloxymethyl-1-phenylcyclohexane () is obtained by reaction of this () with an alkoxide (third stage).

Compound () is heated with iodine and iodic acid in a solvent to form trans-4-alkyloxymethyl-1-(4'-iodophenyl)cyclohexane () (4th step), and the iodine is converted to n-
The trans-4-alkyloxymethyl-1-
(4'-cyclohexenyl phenyl)cyclohexane () is obtained (5th stage). Trans-4-alkyloxymethyl-1-
(4'-biphenylyl)cyclohexane () is obtained (6th stage). Compound () is converted into trans-transformer by heating with iodine and iodic acid in a solvent.
4-alkyloxymethyl-1-(4″-iodo-
4'-biphenylyl)cyclohexane () (7th stage), and reacting (2) with a cyanating agent such as cuprous cyanide yields the desired compound of formula (2) (8th stage).

By using sodium methoxide, sodium ethoxide, sodium propoxide, sodium butoxide, sodium pentoxide, sodium hexyl oxide, sodium heptyl oxide, and sodium octyl oxide as the alkoxides to be reacted with the compound () in the third step, respectively. , trans-4-methyloxymethyl-1-(4″-
Cyano-4'-biphenylyl)cyclohexanetrans-4-ethyloxymethyl-1-(4''-
Cyano-4'-biphenylyl)cyclohexane trans-4-propyloxymethyl-1-
(4″-cyano-4′-biphenylyl)cyclohexanetrans-4-butyloxymethyl-1-(4″-
Cyano-4'-biphenylyl)cyclohexanetrans-4-pentyloxymethyl-1-
(4″-cyano-4′-biphenylyl)cyclohexanetrans-4-hexyloxymethyl-1-
(4″-cyano-4-biphenylyl)cyclohexanetrans-4-heptyloxymethyl-1-
(4″-cyano-4-biphenylyl)cyclohexane trans-4-octyloxymethyl-1-
(4″-cyano-4-biphenylyl)cyclohexane is obtained.

The details of the production method and properties of the compound of the present invention as well as its use as a liquid crystal material will be explained below using Examples.

Example 1 [trans-4-methyloxymethyl-1-
(Production of (4″-cyano-4′-biphenylyl)cyclohexane) [First step] Lithium aluminum hydride (11.1 g (0.293 mol)) and dried tetrahydrofuran (THF) 420
ml of trans-4 and stirred vigorously.
- A solution of 64.0 g (0.293 mol) of methyl phenylcyclohexanecarboxylate dissolved in 70 ml of THF is added dropwise while keeping the reaction temperature below 20°C. After completion of the dropwise addition, the mixture was heated to 55°C, reacted for 2 hours, and cooled. Next, add 12 ml of ethyl acetate and 100 ml of water, then add 350 ml of 18% sulfuric acid to separate into two layers: a tetrahydrofuran layer and an aqueous layer. Add 200 ml of n-heptane, transfer to a separating funnel, wash with 500 ml of water, then wash with 500 ml of a 2% aqueous sodium carbonate solution, and then wash with water until the aqueous layer becomes neutral. Heptane and THF are completely distilled off from the solvent layer, and the solid remaining in the pot is recrystallized with 20 ml of heptane, separated, and the crystals are dried to obtain 51.4 g of 4-phenylcyclohexylmethanol (). Melting point 47.3
~48.5℃.

[Second stage] Compound () obtained in the first stage 50g (0.268
mol) was dissolved in 110 c.c. of dry pyridine and cooled to below 5°C. A solution of 50.1 g (0.2628 mol) of P-toluenesulfonic acid chloride dissolved in 70 ml of dry toluene was added through a dropping funnel until the reaction temperature was 10°C. Add a small amount at a time, making sure not to exceed the amount. When the addition is complete, remove the cooling and stir at room temperature for 4 hours, then add 100% water.
ml and 300ml of toluene and stir. Transfer to a separating funnel and wash the toluene layer twice with 100 ml of 6N hydrochloric acid, then once with 200 ml of water, and then 2 N-NaOH aqueous solution.
Wash twice with 100ml, then four times with 200ml of water,
Toluene is distilled off under reduced pressure and the resulting crystals are extracted with toluene.
Recrystallization from 90 ml, separation, and drying of the crystals yields 77 g of trans-4-phenylcyclohexylmethyl P-toluenesulfonate (). Melting point 108.0-108.7℃.

[Step 3] Stir 250ml of methyl alcohol at room temperature,
To this, add 17.4 g (0.755 mol) of finely chopped sodium metal little by little to make sodium methoxide. After the metallic sodium pieces are gone, a solution of 200 g (0.581 mol) of the compound (2) obtained in the second step dissolved in 600 ml of dry toluene is gradually added to the dropping funnel while keeping the internal temperature within the range of 50 to 60°C. Add. After completion of the dropwise addition, the mixture was refluxed for 4 hours, then cooled, 20 ml of water was added, the mixture was transferred to a separatory funnel, and the toluene layer was washed with water until the aqueous layer became neutral. After distilling off the toluene in the toluene layer under reduced pressure, distill it under reduced pressure and collect the fraction with a boiling point of 105-108℃/1.5mmHg to obtain 100.0g of trans-4-methyloxymethyl-1-phenylcyclohexane (). .

[Fourth step] Into the three-necked flask in step 1, add 100 g (0.489 mol) of the compound () obtained in step 3, 344 ml of acetic acid, and 91 ml of water.
ml, iodic acid 20.6g (0.117mol), iodine 54.5g
(0.215 mol), 40 ml of carbon tetrachloride, and 14 ml of concentrated sulfuric acid were added, stirred and mixed, then heated with a mantle heater and refluxed for 3 hours. After the reaction is complete, cool to room temperature and add 15 ml of 10% sodium thiosulfate water to eliminate the color of excess iodine. n-heptane 200
ml was added and transferred to a separatory funnel, the n-heptane layer was washed with water until the aqueous layer became neutral, the n-heptane was distilled off under reduced pressure, and the residue was dissolved in 50 ml of n-hexane from -10 to - After standing at 20°C for 12 hours, the resulting crystals were separated and dried to obtain 81.3 g of trans-4-methyloxymethyl-1-(4'-iodophenyl)cyclohexane (). Melting point 40.3-42.3℃.

[Step 5] 30 g (0.091 mol) of the compound obtained in step 4 in a 500 ml three-necked flask under a dry nitrogen atmosphere.
Add 60ml of dry toluene and stir at 20℃ to dissolve. To this, 68.9 ml (0.921 mol) of a 1.67N hexane solution of 2-butyllithium was added dropwise over about 10 minutes while maintaining the liquid temperature at 20 to 25°C. At 25℃ after completion of dripping
After keeping it for 30 minutes, cool it to 5℃, and add 10.3g (0.105mol) of cyclohexanone for 20 minutes while keeping it at 5~10℃.
Dropped in minutes. After dropping for 30 minutes at 45°,
Add ml of water dropwise and add 6N while keeping the temperature below 30℃.
60 ml of hydrochloric acid was added dropwise. Separate this, discard the lower aqueous layer, and add 3g of acidic potassium sulfate (KHSO ₄ ) to the organic layer.
is added, the solvent is distilled off by heating, and the solution is concentrated until the temperature reaches 110°C. During this time, the dehydration reaction proceeds.
After the reaction was cooled, transferred to a separatory funnel and washed twice with water, the solvent was distilled off and the purified trans-4-methyloxymethyl-1-(4'-cyclohexenylph) was recrystallized from 10 ml of ethyl alcohol. enil)
7.8 g of cyclohexane () was obtained. The melting point of this product was 74.8-75.5°C.

[Step 6] In a 300ml three-neck flask, add 7.8 g (0.027 mol) of the compound obtained in step 5 and 15.5 g of chloranil.
(0.063 mol) and 130 ml of xylene were heated and refluxed for 24 hours. After cooling, insoluble solids were separately removed, toluene was concentrated and removed, and the resulting crude crystals were recrystallized from 5 ml of ethyl alcohol to give trans-
4-Methyloxymethyl-1-(4'-biphenyl)
2.9 g of cyclohexane () was added. The melting point of this product was 67.3-69.5°C.

[Step 7] In a 100 ml three-necked flask, add 2.9 g (0.011 mol) of the compound obtained in step 6, 8 ml of acetic acid, and 2 ml of water.
ml, iodic acid 0.44g (0.002mol), iodine 1.2g
(0.004 mol), 1 ml of carbon tetrachloride, and 0.8 ml of concentrated sulfuric acid were added, and the mixture was heated and refluxed for 3 hours. After the reaction is complete, add about 2 c.c. of 10% sodium thiosulfate water while still warm to eliminate the color of excess iodine. After cooling and separating the formed crystals, the crystals were recrystallized from 10 c.c. of ethyl acetate to give trans-4-methyloxymethyl-1-(4″-
2.8 g of iodo-4'-biphenylyl)cyclohexane () was obtained. This substance is also a liquid crystal, and its melting point (C-N point) is 156.2℃, and its clearing point (N-I point) is
It was 158.0℃.

[Step 8] In a 100ml three-necked flask, put 2.8 g (0.007 mol) of the compound obtained in Step 7 and cuprous cyanide.
Add 0.72 g (0.008 mol) and 15 c.c. of N,N-dimethylformamide (DMF), heat and stir under reflux for 6 hours, cool, and add aqueous ammonia (28%).
2.2 ml was added, followed by 30 ml of toluene. The organic layer was washed with dilute hydrochloric acid, then with dilute caustic soda water, and then with water. After removing a small amount of solid matter by filtration, the solvent was distilled off under reduced pressure and the residue was dissolved in 50 ml of dry toluene. After passing through a column chromatography layer packed with alumina, the toluene was concentrated, and the target compound trans-4 was purified by recrystallization.
-Methyloxymethyl-1-(4″-cyano-4′-
1.1 g of biphenylyl)cyclohexane () was obtained. The melting point (C-N point) of this product was 156.7°C, the clearing point (N-I point) was 226.8°C, and the elemental analysis values agreed well with the calculated values as shown below.

Actual value (%) Calculated value (%) (as C ₂₁ H ₂₃ NO) C 82.5 82.59 H 7.5 7.59 N 4.5 4.58 Examples 2 and 3 Ethyl alcohol in place of methyl alcohol in the third step in Example 1, respectively The following compound was obtained in the same manner as in Example 1, except that the alkoxide was prepared using propyl alcohol.
trans-4-ethyloxymethyl-1-(4″-
Cyano-4'-biphenylyl)cyclohexane, C
-N point 106.6℃, N-I point 194.4℃ trans-4-propyloxymethyl-1-
(4″-cyano-4′-biphenylyl)cyclohexane, C-N point 92.9°C, N-I point 180.0°C Example 4 (Usage example 1) The nematic liquid crystal temperature range (MR) of the liquid crystal composition consisting of is -3 to 52.6℃, and the viscosity η ₂₀ at 20℃ is
23cp, dielectric anisotropy △ε is 11.3 (ε ₁₁ = 16.2, ε ₁ =
4.9), when this was sealed in a TN cell with a cell thickness of 10 μm, the threshold value was 1.5V and the saturation voltage was 2.2V.

Example 3, which is one of the compounds of the present invention, was added to this liquid crystal composition. The MR of the liquid crystal composition to which ₁₀ parts of
11.4 (ε ₁₁ = 16.1, ε = 4.7), which is the same as above.
The threshold voltage of the TN cell sealed was 1.6V and the saturation voltage was 2.3V.

Example 5 (Usage example 2) The nematic liquid crystal temperature range (MR) of the liquid crystal composition consisting of is -9.6 to 62.5℃, and the viscosity η ₂₀ at 20℃ is
27.6cp, dielectric anisotropy △ε is -0.9 (ε ₁₁ = 3.7, ε ₁
= 4.6) and this is sealed in a TN cell with a cell thickness of 10 μm, which cannot operate normally as a TN cell because Δε is negative.

The compound of the present invention is added to this liquid crystal composition. (Example 2) 5 parts, (Example 3) 5 parts and The MR of the liquid crystal composition to which 5 parts was added is -8.4 to 74.0°C, which spreads toward the higher side, η ₂₀ is 31 cp, and Δε is 2.2 (ε ₁₁ =
7.1, ε ₁ = 4.9), and the threshold voltage of the same TN cell as above is 2.9V; the saturation voltage is
It operated normally as a TN cell at 3.9V.

Claims (1)

[Claims] 1. General formula Trans-4-alkyloxymethyl-1-(4″-cyano-4′-biphenylyl)cyclohexane represented by (in the above formula, R represents a straight-chain alkyl group having 1 to 5 carbon atoms). 2 General formula (In the above formula, R represents a straight-chain alkyl group having 1 to 5 carbon atoms.) A liquid crystal composition comprising: