JPH0822836B2 - Halogenoallylphenol derivative - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel ester compound and a liquid crystal composition containing the compound as an active ingredient.

[Prior Art and Its Problems] Display elements using liquid crystals are widely used in watches, calculators, and the like. These liquid crystal display elements utilize the optical anisotropy and dielectric anisotropy of liquid crystal substances. The liquid crystal phase includes a nematic liquid crystal phase, a smectic liquid crystal phase, and a cholesteric liquid crystal phase. Among them, a liquid crystal phase using a nematic liquid crystal is most widely used.

Corresponding to the electro-optic effect applied to liquid crystal displays, they are TN (twisted nematic) type, DS (dynamic scattering).
Type, guest-host type, DAP type display elements, etc., and it is desirable that the liquid crystal substances used for each display a liquid crystal phase in the widest temperature range in nature.

At present, there is no single liquid crystal substance that satisfies such conditions, and several types of liquid crystal substances or non-liquid crystal substances are mixed for practical use. These substances are water,
It is required to be stable against light, heat, air, etc.

In recent years, it has been desired to increase the size of the display element, and the display quality is inferior to the conventional TN type, so a new series of STN (Super Twist) type display methods are available: M. Shut, F. Leanfoot (Ap
It was developed by pl.Phys hett, 50,236 (1987), and the display quality is not inferior even if it is enlarged. The liquid crystal properties required for this method are large k ₃ / k ₁ , small K ₂ / K ₁ , and small Δε / ε⊥ (M.Schad
t, F.Leenhouts Society for Information Display Inte
rnational Symposium Digest of Technical Papars Vo
lX VIII New Orleans, Louisiana May 12-14, (1987)
372-375).

An object of the present invention is to provide a novel compound which has a large k ₃ / k _{1 and a} small Δn and is excellent in compatibility and which can be used in the above STN type display device and is useful as a liquid crystal composition. Is. Another object is to provide a liquid crystal composition containing the compound as an active ingredient.

[Means for Solving Problems] The present invention (second invention) is represented by the general formula (In the above formula, R is a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms, X is F or Cl,
l represents 0 or 1, and −− represents It is one selected from the group consisting of the following) and a liquid crystal composition containing the compound as an active ingredient.

Examples of the component other than the compound of the present invention that can be used as a component of the liquid crystal composition of the present invention include ester type, Schiff base type, biphenyl type, phenylcyclohexane type, and heterocyclic type liquid crystal compounds.

[Production Method of Compound] The production method of the compound of the present invention is shown, for example, by the following reaction scheme.

(In the above formula,-, l and X are the same as above.) That is, allyl bromide and 4-halogenophenol (l =
0) or 4-halogeno-4'-hydroxyphenyl (l
= 1) is reacted with potassium hydroxide in ethanol to give a phenylallyl ether, which is then refluxed in dimethylaniline and Claisen rearrangement to 2-allyl-4-halogenophenol (l = 0) or 3-allyl-4. -Hydroxy-4 '
-Halogenophenyl was obtained. This phenol derivative was reacted with carboxylic acid chloride corresponding to the final purpose in pyridine to obtain the target ester compound.

EFFECT OF THE INVENTION The compound of the present invention has good compatibility with many other liquid crystal compounds, that is, liquid crystal compounds such as ester type, Schiff base type, biphenyl type, phenylcyclohexane type, and heterocyclic type liquid crystal compounds. Can be added to the liquid crystal composition to reduce Δn and lower the threshold voltage. Also, k ₃ /
Since the value of k ₁ can be increased, the compound is suitable for a liquid crystal composition for STN type display devices.

[Examples] The compounds of the present invention will be described in more detail by the examples described below.

Example 1 Preparation of 2-allyl-4-fluorophenol: 11.2 g (0.01 mol) 4-fluorophenol in a flask
And dissolve in 100 ml of ethanol. Add 8.4 g (0.015 mol) of potassium hydroxide to this, and add what was dissolved in 10 ml of water. Allyl bromide while stirring and stirring this reaction solution with ice
18 g (0.015 mol) is added dropwise over 30 minutes. 2 hours at room temperature,
Refluxed on a water bath for 3 hours. The precipitated salt was filtered off, ethanol was distilled off under reduced pressure, water was added, and the oily matter was extracted with toluene. The toluene layer was extracted with 2N sodium hydroxide, the toluene layer was dried over anhydrous sodium sulfate, and the toluene was distilled off. The remaining oily matter was 4-allyloxyfluorobenzene. The yield was 12 g (74%).

12 g of this 4-allyloxyfluorobenzene was dissolved in 20 ml of NN-dimethylaniline, and the mixture was refluxed under a nitrogen atmosphere on a mantle heater for 5 hours. After the reaction, toluene 100 ml
In addition, it was extracted with 2N sodium hydroxide. When the aqueous sodium hydroxide solution layer was acidified with 6N hydrochloric acid, an oily substance was precipitated, and the mixture was extracted with toluene. After washing the toluene layer with water, the toluene was distilled off under reduced pressure, and the remaining oily substance was distilled to give 2-allyl-4-
Fluorophenol was obtained. Yield 10 g (83% yield) Boiling point 2
10 ° C. Similarly, use 4-chlorophenol instead of 4-fluorophenol for 2-allyl-4-chlorophenol, and 4-fluoro-4'-hydroxybiphenyl.
3-Allyl-4-hydroxy-4'-fluorobiphenyl was obtained.

Example 2 Preparation of trans-4- (trans-4-pentylcyclohexyl) cyclohexanecarboxylic acid 2-allyl-4-fluorophenyl ester: 1.6 g (0.01 mol) of 2-allyl-4-fluorophenol
Was dissolved in 10 ml of pyridine. While mixing well, transformer-
3.0 g (0.01 mol) of 4- (trans-4-pentylcyclohexyl) cyclohexanecarboxylic acid chloride was added.
Toluene (100 ml) was added and the mixture was allowed to stand overnight. The reaction product was poured into water (100 ml). The toluene layer was separated, washed with 6N hydrochloric acid, 2N sodium hydroxide solution and water, and then dried over anhydrous sodium sulfate. Toluene was distilled off from this toluene solution and the remaining oily substance was recrystallized from ethanol to give the desired trans-4- (trans-4-pentylcyclohexyl) cyclohexanecarboxylic acid 2-allyl-4-fluorophenyl ester. Obtained in 2.5 g (60% yield). This product had a CN point of 52.0 to 52.4 ° C and an NI point of 58.0 ° C.

Examples 3-11 Instead of 2-allyl-4-fluorophenol in Example 2, 2-allyl-4-chlorophenol, 3-allyl-
The desired compound was prepared by reacting 4-hydroxy-4'-fluorobiphenyl with various carboxylic acid chlorides instead of trans-4- (trans-4-pentylcyclohexyl) cyclohexanecarboxylic acid chloride. The results are shown in Table 1 together with the results of Example 2.

Example 11 (Application example) trans-4-propyl- (4-cyanophenyl) cyclohexane 30 wt% trans-4-pentyl- (4-cyanophenyl) cyclohexane 40 wt% trans-4-heptyl- (4-cyanophenyl ) The liquid crystal mixture (A) having a composition of 30% by weight of cyclohexane has an NI point of 52.1 ° C Δε
11.2, viscosity at 20 ℃ is 23.4, Δn is 0.119, k ₃ / k ₁
Is 1.82. As the liquid crystal cell, a substrate having a tin oxide transparent electrode coated with silicon oxide and rubbed was assembled so as to face each other, and an electrode distance between electrodes was 10 μm, and the above liquid crystal composition (A) was sealed therein. When its characteristics were measured at 20 ° C., the threshold voltage (hereinafter abbreviated as Vth) was 1.55V.

85% by weight of the liquid crystal composition (A) was added with 2-alkyl-4-trans-4- (trans-4-pentylcyclohexyl) cyclohexanecarboxylic acid prepared in Example 2 of the present invention.
The composition in which 15% by weight of fluorophenyl ester was dissolved had an NI point of 50.7 ° C., Δε of 9.3 Δn of 0.102, and Vth of 1.52V. Further, k ₃ / k ₁ is as large as 1.88, which is also suitable for STN.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C07C 69/757 C 9546-4H 69/76 A 9546-4H Z 9546-4H 69/92 69/94 C09K 19/20 9279-4H 19/30 9279-4H 19/32 9279-4H // G02F 1/13 500

Claims (2)

[Claims] 1. A general formula (In the above formula, R is a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms, X is F or Cl,
l represents 0 or 1, and −− represents Ester compound represented by one) selected from the group consisting of 2. General formula (In the above formula, R is a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms, X is F or Cl,
l represents 0 or 1, and −− represents A liquid crystal composition comprising an ester compound represented by the formula (1) selected from the group consisting of