JPH045021B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel liquid crystal material and a liquid crystal composition containing the same. The display methods of liquid crystal display elements that utilize the optical anisotropy and dielectric anisotropy of liquid crystal materials include TN type,
DS type, guest-host type, dual frequency method type, DAP
There are various methods such as type, White-Taylor type, etc., and each method requires different properties of the liquid crystal material used. For example, depending on the type of display element, a liquid crystal material with positive or negative dielectric anisotropy may be required, or a material with an intermediate value may be suitable. The liquid crystal material used must exhibit a liquid crystal phase over as wide a temperature range as possible and be stable against moisture, heat, air, light, etc. At present, there is no single compound that satisfies all of these conditions, and several types of liquid crystal compounds and non-liquid crystal compounds are mixed and put into practical use. Recently, there has been an increasing demand for liquid crystal display elements that operate over a wide temperature range, ie, from low temperatures to high temperatures. Furthermore, there is a need for a liquid crystal composition that can lower the threshold voltage and saturation voltage necessary to drive a display element. An object of the present invention is to provide a compound useful as a component of a liquid crystal composition that satisfies such requirements. That is, the present invention is based on the general formula (In the formula (I), R or R' represents an alkyl group or an alkoxy group having 1 to 15 carbon atoms, and X is

【formula】

【formula】

【formula】

【formula】

[expression] or

[Formula] is shown. ) 2-(β-substituted ethyl)-5-substituted pyridine and a liquid crystal composition containing the same. The compound of the present invention in which X in formula () is two rings has a liquid crystal phase. The compound of the present invention has excellent compatibility with other liquid crystal compounds, such as ester-based, Schiff base-based, biphenyl-based, phenylcyclohexane-based, and heterocyclic-based liquid crystal compounds, and can be used in compositions mixed with other liquid crystal compounds. It is possible to lower the driving voltage of a liquid crystal display element using Next, a method for producing the compound of the present invention will be described. Adding 3-substituted-6-methylpyridine () to a solution of lithium diisopropylamide in tetrahydrofuran produces 4-substituted benzaldehyde ().
or react with trans-4-substituted cyclohexylaldehyde () to produce 2-{β-(4-substituted phenyl)-β-hydroxyethyl}-5-substituted pyridine () or 2-{β-(trans-4-substituted cyclohexyl)-β-hydroxyethyl}-5
-substituted pyridine () is obtained. This compound was then dehydrated with potassium hydrogen sulfate and then treated with palladium-
By catalytic reduction using carbon, the desired 2-{β-(4-substituted phenyl)ethyl}-5-
Substituted pyridine () or 2-{β-(trans-4-substituted cyclohexyl)ethyl}-5-substituted pyridine () is obtained. This is shown in the chemical formula as follows. The present invention will be explained in more detail below using Examples. Example 1 2-{β-(4-propoxyphenyl)ethyl}
-5-pentyloxypyridine 3-pentyloxy-6-methylpyridine 4.0
g (0.02 mol) in 40 ml of a solution of lithium diisopropylamide (0.03 mol) in tetrahydrofuran,
Add while maintaining the temperature at -70°C, then add 3.7 g (0.02 mol) of 4-propoxybenzaldehyde dropwise.
Stirring was continued at this temperature for 1 hour thereafter. After further stirring at room temperature for 2 hours, 50ml of water was added and toluene was added.
Extract with 100ml. Separate this toluene layer and 2N
- Washing with hydrochloric acid, then washing with an aqueous sodium carbonate solution, and then washing with water until the washing water became neutral.
Next, the toluene layer was distilled off under reduced pressure, and the remaining solid was recrystallized with methanol to give 2-{β-(4-propoxyphenyl)-β-hydroxyethyl}-5-
Obtained 1.0 g of pentyloxypyridine (melting point 128
℃). Next, 0.3 g of potassium hydrogen sulfate was added to this compound, and the mixture was stirred at 180°C for 2 hours. After the reaction is complete, water
After adding 50 ml and 50 ml of chloroform and extracting with chloroform, the extract was washed with water until the washing water became neutral. This chloroform layer was distilled off under reduced pressure to obtain 2-
{β-(4-propoxyphenyl)vinyl}-5-
0.6 g of pentyloxypyridine was obtained. This compound was dissolved in 50 ml of toluene, 0.2 g of palladium-carbon was added, and catalytic reduction was carried out at room temperature and normal pressure.
After the reaction is complete, the catalyst is filtered off, the solvent is distilled off under reduced pressure, and then recrystallized from ethanol to obtain the target product, 2-
{β-(4-propyloxyphenyl)ethyl}-
5-pentyloxypyridine was obtained. Yield 0.4g,
The melting point was 48.0°C. Examples 2 to 7 The following compounds were synthesized by a method similar to Example 1. 2-{β-(4″-pentylbiphenyl-4′)ethyl}-5-pentyloxypyridine 2-{p-(trans-4′-propylcyclohexyl)phenethyl}-5-pentyloxypyridine 2-{β -(4″-pentylbiphenyl-4′)ethyl}-5-ethylpyridine 2-{p-(trans-4′-pentylcyclohexyl)phenethyl}-5-ethylpyridine 2-{β-(4″-ethyl Biphenyl-4′)ethyl}-5-propylpyridine 2-{β-(4″-propylbiphenyl-4′)ethyl}-5-propylpyridine The physical properties of these compounds are shown together with the results of Example 1. Shown in Table 1.

【table】

[Table] In the table, C, S, N, and I represent crystal, smectic phase, nematic phase, and isotropic liquid phase, respectively, and the * mark indicates the presence of the phase in the column above it, and -
The mark indicates that the phase above it does not exist, and the number indicates the phase transition temperature (℃) between the marked phases.
shows. Example 8 (Application example) Trans-4-propyl-(4'-cyanophenyl)
Cyclohexane 24% trans-4-pentyl-(4'-cyanophenyl)
Cyclohexane 36% trans-4-heptyl-(4'-cyanophenyl)
The nematic clearing point of a liquid crystal mixture with the following composition is cyclohexane 25% and 4-cyano-4'-(trans-4-pentylcyclohexyl)biphenyl 15%.
72.0℃, viscosity is 28cp at 20℃, dielectric anisotropy value (hereinafter abbreviated as △ε) is +11.6, optical anisotropy value (hereinafter abbreviated as △n)
) is 0.140. This is made into a cell with a thickness of 10 μm.
The threshold voltage of a liquid crystal cell sealed in a TN cell is
The voltage was 1.75V, and the saturation voltage was 2.40V. this mixture
The nematic clearing point of the liquid crystal composition consisting of 90 parts by weight and 10 parts by weight of 2-{β-(4-propyloxyphenyl)ethyl}-5-pentyloxypyridine of Example 1 of the present invention was 59.6°C; Viscosity at 20℃
29cp, Δε was +10.2, Δn was 0.131, threshold voltage was 1.54V, and saturation voltage was 2.16V. As described above, by applying the present invention, it was possible to lower the threshold voltage and saturation voltage of a liquid crystal display element.

Claims (1)

[Claims] 1. General formula (In the formula, R or R' represents an alkyl group or an alkoxy group having 1 to 15 carbon atoms, and X represents [formula] [formula] [formula] [formula] [formula] or [formula].) 2-(β-substituted ethyl)-5-substituted pyridine. 2 General formula (In the formula, R or R' represents an alkyl group or an alkoxy group having 1 to 15 carbon atoms, and X represents [formula] [formula] [formula] [formula] [formula] or [formula].) A liquid crystal composition containing 2-(β-substituted ethyl)-5-substituted pyridine.