JPH0216745B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel cyanocyclohexane derivatives. More specifically, the dielectric anisotropy is negative and
It relates to a liquid crystal compound whose absolute value is large. Liquid crystals with negative dielectric anisotropy can be used for DSM display that utilizes the dynamic scattering effect, guest-host (GH) display that uses dichroic dyes, and multicolor display that utilizes the birefringence of liquid crystal molecules. It is well known that it is useful for applications such as (ECB method). In order to be able to drive with a low threshold voltage, there is a demand for liquid crystals that have particularly negative dielectric anisotropy and a large absolute value. For such purposes, we have already (Unexamined Japanese Patent Publication No. 52-118450), (Japanese Unexamined Patent Publication No. 55-43016) is known. but,
In the compound (), the cyano group extends in the direction of about 60°C with respect to the long axis of the molecule, so the induced anisotropy does not show a very large value (Δε-4).
In addition, the compound () has two cyano groups and therefore exhibits large negative dielectric anisotropy (Δε-22).
Since it is an ester of phenol with a strong electron-withdrawing group (cyano group) in the ortho position, it is easily hydrolyzed and requires special care when mixing with other liquid crystals and sealing cells. Compounds provided by the present invention () (In the formula, R is an aliphatic alkyl group having 1 to 10 carbon atoms, and Z is

【formula】

【formula】

【formula】

【formula】

【formula】

[expression] or

[Formula], where R' is hydrogen, an aliphatic alkyl group having 1 to 10 carbon atoms, an aliphatic alkoxy group having 1 to 10 carbon atoms, a cyano group, or a halogen atom) may not exhibit liquid crystal properties. As is clear from its molecular structure, the cyano groups extend almost perpendicularly to the long axis of the molecule, so even one cyano group can increase the dielectric anisotropy (△ε) of the fabric, which has a sufficiently large absolute value. −20). Further, although the compound () has an ester group, since it is an ester of an aliphatic alcohol, it is quite stable against hydrolysis (there are no problems in normal handling). Further, since the compound () is colorless and has very good compatibility with other liquid crystals, it is particularly useful for guest-host type displays. Furthermore, by mixing it with Np liquid crystal such as cyanobiphenyl, it is possible to make its voltage-transmittance characteristics steep. In the general formula (), R is methyl, ethyl,
n-propyl, n-butyl, n-pentyl, n-
aliphatic alkyl groups having 1 to 10 carbon atoms such as hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl and their various isomers; R' is hydrogen; methyl, ethyl, n-decyl; -propyl,
n-butyl, n-pentyl, n-hexyl, n-
heptyl, n-octyl, n-nonyl, and n
C1-10 aliphatic alkyl groups such as -decyl and their various isomers; methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n -octyloxy, n-nonyloxy,
and aliphatic alkoxy groups having 1 to 10 carbon atoms such as n-decyloxy and various isomers thereof;
Indicates a cyano group or a halogen atom such as fluorine or chlorine. Further, R and the ester group are substituted in the 1st and 4th positions of the cyclohexane ring in a trans relationship with each other. Examples of the cyanocyclohexane derivative of general formula () include the following compounds. 1-cyano-4-ethylcyclohexyl p-
Methoxybenzoate, 1-cyano-4-ethylcyclohexyl p-ethoxybenzoate, 1
-Cyano-4-ethylcyclohexyl p-butoxybenzoate, 1-cyano-4-ethylcyclohexyl p-fluorobenzoate, 1-cyano-4-pentylcyclohexyl p-ethoxybenzoate, 1-cyano-4- Hexylcyclohexyl p-chlorobenzoate, 1-cyano-4-pentylcyclohexyl p-pentyloxybenzoate, 1-cyano-4-decylcyclohexyl p-methoxybenzoate, 1-cyano-4-nonylcyclohexyl p -chlorobenzoate, 1-cyano-4-ethylcyclohexyl p-(trans-4-propylcyclohexyl)benzoate, 1-cyano-4-ethylcyclohexyl p-(trans-heptylcyclohexyl)benzoate, 1-cyano -4-propylcyclohexyl p-(trans-4-pentylcyclohexyl)benzoate, 1-cyano-4-pentylcyclohexyl p-(trans-4-propylcyclohexyl)benzoate,
1-cyano-4-pentylcyclohexyl p-
(trans-4-pentylcyclohexyl)benzoate, 1-cyano-4-pentylcyclohexyl p-(trans-4-heptylcyclohexyl)benzoate, 1-cyano-4-heptylcyclohexyl p-(trans-4-butyl cyclohexyl)benzoate, 1-cyano-4-
Pentylcyclohexyl p-(p-propylphenyl)benzoate, 1-cyano-4-pentylcyclohexyl p-(p-heptylphenyl)
Benzoate, 1-cyano-4-pentylcyclohexyl trans-4-(trans-4-pentylcyclohexyl)cyclohexanecarboxylate, 1-cyano-4-pentylcyclohexyl p-(trans-5-heptyl-1,3- dioxan-2-yl)benzoate, 1-cyano-4-hexylcyclohexyl p-(trans-5-propyl-1,3-dioxan-2-yl)benzoate, 1-cyano-4-ethylcyclohexyl p -(p-methoxybenzoyloxy)benzoate, 1-cyano-4-ethylcyclohexyl p-(p-ethoxybenzoyloxy)benzoate, 1-cyano-4-butylcyclohexyl p-(p-propylbenzoyloxy) Benzoate, 1-cyano-4-heptylcyclohexyl p-(p-butoxybenzoyloxy)benzoate, 1-cyano-4-ethylcyclohexyl trans-4-propylcyclohexanecarboxylate, 1-cyano-1-ethylcyclohexyl = trans-4-pentylcyclohexanecarboxylate, 1-cyano-4-
Ethylcyclohexyl trans-4-hexylcyclohexanecarboxylate, 1-cyano-
4-ethylcyclohexyl trans-4-heptylcyclohexanecarboxylate, 1-cyano-1-propylcyclohexyl trans-4
-pentylcyclohexanecarboxylate, 1
-cyano-1-butylcyclohexyl = trans-4-heptylcyclohexanecarboxylate, 1-cyano-1-pentylcyclohexyl =
trans-4-propylcyclohexanecarboxylate, 1-cyano-1-pentylcyclohexyl trans-4-pentylcyclohexanecarboxylate, 1-cyano-1-pentylcyclohexyl trans-4-heptylcyclohexanecarboxylate, 1-cyano-4 -Hexylcyclohexyl=trans-4-pentylcyclohexanecarboxylate, 1-cyano-1-
Hexylcyclohexyl trans-4-heptylcyclohexanecarboxylate, 1-cyano-1-heptylcyclohexyl trans-4-
Propylcyclohexanecarboxylate, 1-
Cyano-1-heptylcyclohexyl = trans-4-pentylcyclohexanecarboxylate, 1-cyano-1-heptylcyclohexyl =
trans-4-heptylcyclohexanecarboxylate, 1-cyano-4-octylcyclohexyl trans-4-pentylcyclohexanecarboxylate, 1-cyano-4-nonylcyclohexyl trans-4-pentylcyclohexanecarboxylate. These compounds can be produced, for example, by the method shown below. (In the formula, R, Z, and R' have the same meanings as above.) It can be obtained by reacting 4-alkylcyclohexanone with hydrocyanic acid to form cyanohydrin, and then reacting with a carboxylic acid chloride. The present invention will be explained in more detail below using Examples. Example 1 Preparation of 1-cyano-4-n-pentylcyclohexyl p-(trans-4-n-propylcyclohexyl)benzoate 4-n-pentylcyclohexanone (contains about 5% 4-n-pentylcyclohexanol) )
A solution of 13.1 g of potassium cyanide in water (25 ml) was added to a mixture of 16.45 g of acetic anhydride and 21 g of acetic anhydride while cooling with ice water. After stirring at room temperature for 4 hours, the mixture was made alkaline by adding a saturated aqueous sodium carbonate solution and extracted with benzene (50 ml x 3). Wash the extract with 30% aqueous sodium bisulfite solution (10 ml x 3 times),
It was dried with anhydrous sodium sulfate. After filtration, it was concentrated under reduced pressure to obtain 19.05 g of cyanohydrin as an orange liquid. After heating 3.58 g of p-(trans-4-n-propylcyclohexyl)benzoic acid with 35 ml of thionyl chloride under reflux for 1 hour, excess thionyl chloride was distilled off under reduced pressure. 2.84 g of the cyanohydrin obtained above was added to the obtained acid chloride and heated at a bath temperature of 150° C. for 1.5 hours. After cooling, 50 ml of benzene was added, washed with water, and dried over anhydrous magnesium sulfate. After that,
The residue obtained by distilling off the solvent under reduced pressure was subjected to silica gel column chromatography. Benzene-
Developing with n-hexane gives white crystals of 1-cyano-4-pentylcyclohexyl p-(trans-4-n-propylcyclohexyl)benzoate.
3.57g (58%) was obtained. When recrystallized from n-hexane, the melting point was 80.5-81.0°C and the N-I point was 55.5°C (monotropic liquid crystal). The IR spectrum is shown in Figure 1, and the NMR spectrum is shown in Figure 2. 10 parts of 1-cyano-4-pentylcyclohexyl p-(trans-4-n-propylcyclohexyl) benzoate was dissolved in 90 parts of commercially available liquid crystal ZLI1565 (the value of Δε at 20°C is +6.0). The material is sealed in a cell with a rubbed transparent electrode, a distance between the electrodes of approximately 20 μm, and an electrode area of 2.0 cm ² , and a 1K
The capacitance was measured using a sine wave of Hz, and the dielectric constant was determined from the following formula, where ε=C/Co (Co: capacity of empty cell) +3.37 was obtained. From this result, by extrapolation, 1-cyano-4-pentylcyclohexyl=p-(trans-4-n-propylcyclohexyl)benzoate [R=n・C ₅ H ₁₁ in (1),

【formula】

[Formula] R′=n− C ₃ H ₇ ] itself is determined to have Δε of approximately −20. Examples 2 to 20 Other cyanocyclohexane derivatives were synthesized in the same manner as in Example 1. Typical examples are shown in Table 1 (the derivative obtained in Example 1 is also shown).

【table】

[Table] Usage example 1 p-(trans-4-n-propylcyclohexyl)benzonitrile 24%, p-(trans-4
-n-pentylcyclohexyl)benzonitrile
36%, p-(trans-4-n-heptylcyclohexyl)benzonitrile 25%, 4-cyano-
A mixture consisting of 15% 4'-(trans-4-n-pentylcyclohexyl)benzonitrile has a clearing point of 71.5°C. When this was sealed in a TN cell with a thickness of 8 μm (30°C), the threshold voltage was 1.71V and the saturation voltage was 2.40V. The clearing point of a liquid composition containing 13.0% of the compound 1-cyano-4-n-pentylcyclohexyl p-(trans-4-n-propylcyclohexyl)benzoate of the present invention in 86.4% of this liquid crystal composition was 64.5°C. The threshold voltage is 1.61J when sealed in a TN cell with a thickness of 8μm (30℃).
The saturation voltage was 2.08V, and the steepness was improved.

[Brief explanation of drawings]

Figure 1 shows the infrared absorption spectrum (KBr method) of 1-cyano-4-pentylcyclohexyl p-(trans-4-n-propylcyclohexyl)benzoate obtained in Example 1 of the present invention, and the second
The figure shows the nuclear magnetic resonance absorption spectrum (CDCl ₃ solution, 200MHz) of the same compound, and Figure 3 shows the 1-cyano-4-pentylcyclohexyl p-(trans-4-n - Infrared absorption spectrum (liquid film method) of heptylcyclohexanecarboxylate.

Claims (1)

[Claims] 1. General formula (In the formula, R represents an aliphatic alkyl group having 1 to 10 carbon atoms, Z represents [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] or [Formula], and R' represents Hydrogen, aliphatic alkyl group having 1 to 10 carbon atoms, 1 carbon number
A cyanocyclohexane derivative represented by ~10 aliphatic alkoxy groups, cyano groups, or halogen atoms. 2 In the formula (1), R represents an aliphatic alkyl group having 1 to 10 carbon atoms, Z represents a 1,4-phenylene group, and R' is hydrogen, an aliphatic alkyl group having 1 to 10 carbon atoms, or The compound according to claim 1, which is an alkoxy group, a cyano group, or a fluoro atom having a number of 1 to 10. 3 In formula (1), R represents an aliphatic alkyl group having 1 to 10 carbon atoms, Z represents [Formula] [Formula] [Formula] [Formula] or [Formula], and R' represents an aliphatic alkyl group having 1 to 10 carbon atoms. A compound according to claim 1 which is an aliphatic alkyl group of -10. 4 In the formula (1), R represents an aliphatic alkyl group having 1 to 10 carbon atoms, Z represents [formula], and R' is an aliphatic alkoxy group having 1 to 5 carbon atoms, A compound according to scope 1. 5 General formula (In the formula, R represents an aliphatic alkyl group having 1 to 10 carbon atoms, Z represents [formula] [formula] [formula] [formula] [formula] [formula] [formula] or [formula], and R' represents hydrogen , aliphatic alkyl group having 1 to 10 carbon atoms, 1 carbon number
1. A liquid crystal composition comprising at least one cyanocyclohexane derivative represented by 1 to 10 aliphatic alkoxy groups, cyano groups, or halogen atoms.