JPH0331184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel liquid crystal material 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. Furthermore, 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, 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 fast. In order to achieve this, it is desirable that the viscosity be as low as possible.
In particular, recently there has been a demand for liquid crystal display elements that can be driven at low voltages. In order to meet this requirement, it is generally effective to use a substance with large dielectric anisotropy as a constituent component, but the compound of the present invention can be used as a constituent component even if the dielectric anisotropy is not so large. This is a compound that can reduce the driving voltage of liquid crystal by adding it. That is, the compound of the present invention has 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.) This is a liquid crystal composition containing.

The compounds of the present invention may or may not exhibit a liquid crystal phase, but in either case, their melting point or clearing point is relatively high.For example, 2-hexyl-6-( 4-chlorophenyl)
-1,1a,2,3,4,4a,5,8-octahydronaphthalene is a compound that exhibits a nematic phase between 62.7°C and 93.4°C, and these compounds can be used to create display elements that can be driven at low voltage. . Furthermore, the compound of the present invention has a small optical anisotropy value Δn, and can be applied to display cells that take advantage of this property.

Next, a method for producing the compound of the present invention is shown in which 2-substituted-decalin-6-one produced by a known method is reacted with 4-halogenophenylmagnesium bromide to produce 2-substituted-6-(4-halogenophenyl). )
Decalin-6-ol. This product was subjected to a dehydration reaction using potassium hydrogen sulfate as a catalyst, and 2-
Substituted-6-(4-halogenophenyl)-1,1a,
2,3,4,4a,5,8-octahydronaphthalene and 2-substituted-6-(4-halogenophenyl)
- A mixture of 1,1a,2,3,4,4a,7,8-octahydronaphthalene is obtained. This mixture was recrystallized to obtain each component.

If the above is expressed as a chemical formula, (R and X are the same as above) The present invention will be further explained below with reference to Examples.

Example 1 [2-propyl-6-(4-fluorophenyl)
-Production of 1,1a,2,3,4,4a,7,8-octahydronaphthalene] 2-propyldecalin produced by a known method -
4-fluorophenylmagnesium bromide prepared from 45.6 g of 4-fluorobromobenzene and 6.3 g of metallic magnesium was dissolved in 100 ml of tetrahydrofuran to dissolve 42 g of 2-one in 100 ml of tetrahydrofuran.
Drop while keeping at ℃. Next, add this reaction solution to 2
Reflux for an hour and then cool. Slowly add 200ml of 3N hydrochloric acid. Next, extract the oil layer with 200 ml of toluene, and then wash the toluene layer with water until the washing liquid becomes neutral. Toluene is distilled off from the toluene layer under reduced pressure, 7 g of potassium hydrogen sulfate is added to the remaining oil, and the mixture is heated at 150° C. for 2 hours in a nitrogen atmosphere to dehydrate. After the reaction is complete, add 200 ml of toluene, separate the insoluble matter, and wash the toluene layer with water. After neutralization, the toluene layer was distilled off under reduced pressure, and the remaining oil was recrystallized several times from a 1:1 acetone-ethanol solvent. NMR of the compound thus obtained
From the spectrum and IR spectrum, this substance is 2-propyl-6-(4-fluorophenyl)-
It was confirmed to be 1,1a,2,3,4,4a,5,8-octahydronaphthalene. Yield 42
g, and the melting point was 44.0-44.3°C.

Also, 2-propyl-6-(4-fluorophenyl)-1,1a,2,3,4,4a,7,8 from the mother liquor
- Octahydronaphthalene was obtained.

Examples 2 and 3 Similarly, in place of 2-propyldecalin-2-one in Example 1, the corresponding 2-
The following compound was prepared using an alkyldecalin-2-one and 4-chlorobromobenzene in place of 4-fluorobromobenzene.

2-propyl-6-(4-chlorophenyl)-
1,1a,2,3,4,4a,5,8-octahydronaphthalene melting point 83.0-83.7°C.

2-hexyl-6-(4-chlorophenyl)-
1,1a,2,3,4,4a,5,8-octahydronaphthalene C-N point 62.7-63.5℃, N-I point
93.4℃.

Example 4 (Usage example) Trans-4-propyl-(4'-cyanophenyl)cyclohexane 24% Trans-4-pentyl-(4'-cyanophenyl)cyclohexane 36% Trans-4-heptyl-(4'-cyanophenyl)cyclohexane The N-I point of a liquid crystal composition consisting of 25% trans-4-pentyl-(4″-cyanobihenyl)cyclohexane is 72°C and 20°C.
The viscosity is 28 cp, the threshold voltage is 1.7 V, and the saturation voltage is 1.7 V when sealed in a 10 μm thick TN cell.
It was 2.1V.

2-propyl-6-(4-fluorophenyl) prepared in Example 1 of the present invention was added to 90 parts of this liquid crystal composition.
-N-I of a liquid crystal composition containing 10 parts of 1,1a,2,3,4,4a,5,8-octahydronaphthalene
The temperature was 36.1°C, and the viscosity at 20°C was 51 cp, but the threshold voltage and saturation voltage of the cell sealed in the above cell could be reduced to 1.1V and 1.6V, respectively.

Claims (1)

[Claims] 1. General formula (In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents F or Cl.) 2-substituted-6-(4-halogenophenyl)octahydronaphthalene. 2 General formula (In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents F or Cl) 2-substituted-6-(4-halogenophenyl)-1,1a,2,3 , 4,4a,5,8-octahydronaphthalene. 3 General formula (In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents F or Cl.) )−1, 1a, 2,
The compound according to claim 1, which is 3,4,4a,7,8-octahydronaphthalene. 4 General formula (In the above formula, R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and X represents F or Cl.) Contains at least one type of 2-substituted-6-(4-halogenophenyl)octahydronaphthalene represented by A liquid crystal composition characterized by: