JPH0239499B2 - 44 * TORANSUU4 *** TORANSUU4 *** ARUKIRUSHIKUROHEKISHIRU * SHIKUROHEKISHIRU * ANSOKUKOSAN44HAROGENNOFUENIRUESUTERU - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel liquid crystal material exhibiting a liquid crystal phase over a wide temperature range and having positive dielectric anisotropy, and a liquid crystal composition containing the same. Display elements using liquid crystals have come to be widely used in watches, calculators, etc. This liquid crystal display element utilizes the properties of optical anisotropy and dielectric anisotropy of liquid crystal materials, and there are three liquid crystal phases: nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase, among which nematic liquid crystal is used. The one that has been put into practical use is the most widely used. That is, they include TN (twisted nematic) type, DS (dynamic scattering type), guest-host type, DAP type, etc.
The properties required of the liquid crystal materials used for each type are different. However, in any case, it is desirable that the liquid crystal substances used in these display elements exhibit a liquid crystal phase over as wide a range as possible in nature, but there is currently no single substance that satisfies such conditions. Currently, materials that can be put to practical use are obtained by mixing several types of liquid crystal substances or non-liquid crystal substances. In addition, these materials must of course be stable against moisture, light, heat, air, etc., and the threshold voltage and saturation voltage necessary to drive the display element must be as low as possible, and the response speed must be as low as possible. In order to speed up the process, it is desirable that the viscosity be as low as possible. By the way, in order to widen the liquid crystal temperature range toward higher temperatures, it is necessary to use a liquid crystal substance with a high melting point as a component, but liquid crystal substances with a high melting point generally have a high viscosity, and therefore the liquid crystal composition containing it also has a high viscosity. As a result, the response speed of liquid crystal display elements that can be used at high temperatures, for example, up to about 80° C., particularly at low temperatures, has tended to become significantly slower. However, the present inventors found a liquid crystal material with a high liquid crystal temperature range and low viscosity, and arrived at the present invention. That is, the present invention is based on the general formula (In the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and X represents either F or Cl.)
(alkylcyclohexyl)cyclohexyl]benzoic acid 4-halogenophenyl ester and a liquid crystal composition containing the same. The compounds of the present invention have high clearing points, such as 4-[trans-4'-
(Trans-4″-propylcyclohexyl)cyclohexylbenzoic acid 4-fluorophenyl ester exhibits a nematic phase in a wide temperature range from 108.2 to 300°C or higher, and by adding it as a component of a liquid crystal composition, the liquid crystal composition can be modified. It is possible to raise the clearing point without increasing the viscosity of the composition. Also, although the dielectric anisotropy value of the compound of the present invention is about +3, it does not change the threshold voltage and saturation voltage of the composition so much. It also has good stability against heat, light, etc. Next, a method for producing the compound of the present invention will be described. First, phenylmagnesium bromide is produced from bromobenzene and metallic magnesium, and then it is converted into 4-(trans-4' -alkylcyclohexyl)cyclohexanone to form 4'-(trans-4''-alkylcyclohexyl)cyclohexane-1-ol-
Let it be benzene (). Next, this is dehydrated using potassium hydrogen sulfate as a catalyst to produce 4′-(trans-4″-
alkylcyclohexyl)cyclohexene-1′-
yl-benzene () is then hydrogenated using a Raney nickel catalyst to obtain trans-4′-(trans-4″-alkylcyclohexyl)cyclohexylbenzene (), which is ().
can also be obtained directly by hydrogenation using Raney nickel. Next, the compound () is halogenated with iodic acid or periodic acid to form 4-[trans-4'-trans-4''-alkylcyclohexyl)cyclohexyl]halogenobenzene (), which is converted into cyanated If cyanidated with copper, 4-[trans-4′-(trans-
4″-alkylcyclohexyl)cyclohexyl]
Benzonitrile () is obtained. Next, this compound () was hydrolyzed in an aqueous potassium hydroxide solution diethylene glycol system to obtain 4-[trans-
4′-(trans-4″-alkylcyclohexyl)
Manufactures cyclohexyl]benzoic acid. This benzoic acid derivative was converted into an acid chloride with thionyl chloride, and then 4-halogenophenol was reacted in pyridine to obtain the desired 4-[trans-4'-(trans-
4″-alkylcyclohexyl)cyclohexyl]
Benzoic acid 4-halogenophenyl ester () is obtained. If the above is expressed as a chemical formula, (In the above formula, R ₁ Example 1 [Production of 4-[trans-4′-(trans-4″-propylcyclohexyl)cyclohexyl]benzoic acid 4-fluorophenyl ester] 3.6 g (0.148 mol) of magnesium turnings was placed in a three-necked flask. , bromobenzene 23.2g
(0.148 mol) dissolved in tetrahydrofuran, the reaction temperature was kept at 30-35℃ in a _N2 atmosphere.
If you slowly drop it while stirring, it will react and 3
Over time, the magnesium dissolves and becomes homogeneous, producing phenylmagnesium bromide. 4-
26.2 g (0.118 mol) of [trans-4'-propylcyclohexyl)cyclohexanone was dissolved in tetrahydrofuran to make 50 ml, and the reaction temperature was adjusted.
Drop as quickly as possible while keeping the temperature below 10℃.
After dropping, the temperature was raised to 35℃, stirred for 30 minutes, and then
Add 100ml of 3N hydrochloric acid. The reaction solution was transferred to a separating funnel, extracted three times with 100 ml of n-heptane, and the combined n
- Wash the heptane layer with water until the washing liquid becomes neutral, and then distill off the n-heptane under reduced pressure. The remaining oil was [4'-(trans-4''-propylcyclohexyl)cyclohexane-1'-ol]benzene, and 19 g of potassium hydrogen sulfate was added to it.
Dehydrate for 2 hours at 170°C in a stream of _N2 . 200ml after cooling
After adding the n-heptane, remove the potassium hydrogen sulfate and wash the n-heptane layer with water using a separating funnel until the washing liquid becomes neutral. Next, n-heptane is distilled off under reduced pressure, and the remaining oil is recrystallized from n-heptane and acetone to obtain [4-(trans-4″-
Propylcyclohexyl)cyclohexene-1'-
benzene. Add 7.5g of this to ethanol
Dissolve in 500ml and add 3.2g of Raney nickel catalyst.
Catalytic reduction is carried out through hydrogen at 50°C and normal pressure. Both raw materials and products are tracked by gas chromatography,
The reduction reaction was terminated when the raw materials disappeared, that is, after 8 hours. The amount of hydrogen absorbed at this time was 800 ml. After separating the catalyst, the solvent was distilled off under reduced pressure, and the remaining crystals were recrystallized from ethanol [trans-
4′-(trans-4″-propylcyclohexyl)
cyclohexyl]benzene was obtained. This 1.4 g was dissolved in 50 ml of acetic acid, and a mixture of 0.9 ml of pure water, 1.0 ml of concentrated sulfuric acid, 0.20 g of iodic acid, 0.50 g of iodine, and 0.4 ml of carbon tetrachloride was refluxed at 80° C. for 5 hours. The reaction solution was cooled, the precipitated crystals were separated, and the crystals were recrystallized with n-heptane to obtain 4-[trans-
4′-(trans-4″-propylcyclohexyl)
cyclohexyl]iodobenzene ().
This item shows a liquid crystal state, and the C-Sm point is 119.0.
℃, the Sm-N point was 139.2℃, and the NI point was 189.2℃. This 1.2g was dissolved in 50ml of N,N'-dimethylformamide, 0.63g of cuprous cyanide was added, and the mixture was reacted at 130°C for 4 hours. n-heptane 100ml
was added, transferred to a separating funnel, separated with 30% aqueous ammonia, then washed with water, washed with 6N hydrochloric acid,
Further wash with water until the washing liquid becomes neutral. The solvent was distilled off under reduced pressure and the product obtained by recrystallizing with n-heptane was 4-[trans-4′-(trans-4″-propylcyclohexyl)cyclohexyl]benzonitrile. Yield: 0.4 g. is 45% for the cyanation reaction, and its C-Sm point is 73.1℃,
The Sm-N point was 81.1°C, and the N-I point was 242.5°C. 4-[trans-4′-] obtained as above
Add 5 g of (trans-4″-propylcyclohexyl)cyclohexyl]benzonitrile to 100 ml of diethylene glycol along with a solution of 5 g of potassium hydroxide dissolved in 10 ml of water, and heat in a flask at 200°C for 7 hours. After the reaction is complete, cool to room temperature. death,
Add 50ml of 6N HCl and 100ml of water. Filter the precipitated crystals and wash thoroughly with water. 1 g of 4-[trans-4′-(trans-4″-propylcyclohexyl)cyclohexyl]benzoic acid () obtained in this way was mixed with 0.1 ml of pyridine and 10 ml of thionyl chloride.
and heat to 80℃. The reaction solution became homogeneous in 2 hours, and the reaction was continued for an additional 1.5 hours. Excess thionyl chloride is distilled off under reduced pressure. The oil that remains is the acid chloride. On the other hand, 4-fluorophenol 0.5
g in 20 ml of pyridine, add the acid chloride, add 100 ml of toluene, and leave it overnight. Wash the toluene layer in a separatory funnel first with 6N hydrochloric acid, then with 2N caustic soda solution, and finally with water until neutral. After drying it over anhydrous sodium sulfate, the toluene layer was distilled off under reduced pressure. The precipitated crystals were recrystallized from ethanol and then from acetone to obtain the desired 4-[trans-4'-(trans-4''-propylcyclohexyl)cyclohexyl]benzoic acid 4-fluorophenyl ester. Yield: 0.3 g. , the yield is 23%, and the C-N point is
The temperature was 108.2°C, and the N-I point was over 300°C. Examples 2 to 4 4-[trans-4'-
(trans-4″-propylcyclohexyl)cyclohexane] with another alkyl group
- Using [trans-4′-(trans-4″-alkylcyclohexyl)cyclohexanone],
Furthermore, when X was Cl, the desired product was obtained in exactly the same manner using 4-chlorophenol instead of 4-fluorophenol. These results are shown in Table 1 together with the results of Example 1.

[Table] Example 6 (Usage example) Trans-4-propyl-(4'-cyanophenyl)cyclohexane 28% Trans-4-pentyl-(4'-cyanophenyl)cyclohexane 42% Trans-4-heptyl-(4'- The nematic liquid crystal temperature range of a liquid crystal composition having a composition of 30% (cyanophenyl)cyclohexane is -3 to 52°C. This liquid crystal composition has a cell thickness of
When sealed in a 10 μm TN cell (twisted nematic cell), the operating threshold voltage was 1.53V and the saturation voltage was 2.12V. The clay had a density of 23 cp at 20°C. 95 parts of this liquid crystal composition was added with the 4-
[Trans-4'-(trans-4''-propylcyclohexyl)cyclohexylbenzoic acid 4-fluorophenyl ester 5 parts nematic liquid crystal temperature range is -5~65℃.Threshold voltage is 1.55V, saturation voltage was 2.14 V.The viscosity was 25 cp at 20°C.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and X represents either F or Cl.)
4″-alkylcyclohexyl)cyclohexyl]
Benzoic acid 4-halogenophenyl ester. 2 General formula (In the above formula, R represents hydrogen or an alkyl group having 1 to 10 carbon atoms, and X represents either F or Cl.)
4″-alkylcyclohexyl)cyclohexyl]
A liquid crystal composition containing at least one type of benzoic acid 4-halogenophenyl ester.