JPH0558958A - Fluorinated liquid crystal compound - Google Patents

Abstract

PURPOSE:To provide the subject compound exhibiting liquid crystal phase over a wide temperature range and capable of raising the N-I point and decreasing n of a liquid crystal composition without increasing the viscosity by the addition of a small amount of the compound to a liquid crystal composition. CONSTITUTION:The compound of formula I (X is F or Cl; (n) is 1 or 2; (m) is 1-10), e.g. 1,2-bis(4-fluorophenyloxycarbonyl-4-phenyloxy)tetrafluoroethane. The compound can be produced by reacting 2 times mol of 4-hydroxybenzoic acid methyl ester of formula II and an omega,omega'-diiodinated perfluoroalkylene of formula III with anhydrous potassium carbonate in DMF, hydrolyzing the obtained compound of formula IV in the presence of an acid catalyst, treating with thionyl chloride and reacting the resultant acid chloride of formula V with a phenol derivative of formula VI.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fluorine liquid crystal compound and a liquid crystal composition containing the compound.

[0002]

2. Description of the Related Art Display elements utilizing liquid crystals are widely used in watches, calculators, etc., but 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, of which the one using the nematic liquid crystal phase is most widely put into practical use.

They include a TN (twisted nematic) type corresponding to the electro-optical effect applied to liquid crystal displays.
There are display devices such as DS (dynamic scattering) type, guest-host type, and DAP type. It is desirable that the liquid crystal substance used for each has a liquid crystal phase in the widest temperature range in nature. At present, there is no single liquid crystal substance that fulfills such a condition, and several types of liquid crystal substances or non-liquid crystal substances are mixed for practical use. The properties of these substances, that is, the liquid crystal mixture and the liquid crystal composition, are stable against moisture, light, heat, air, etc.
It is desired to have a nematic liquid crystal temperature range from low temperature to high temperature.

[0004]

It is an object of the present invention to exhibit a liquid crystal phase in a wide temperature range, and to mix a small amount with another liquid crystal mixture or a mixture of a liquid crystal mixture and a non-liquid crystal substance to form an original liquid crystal mixture. It is to provide a novel liquid crystal compound and a liquid crystal composition containing the compound, which can extend the liquid crystal temperature range without increasing the viscosity of the compound.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, they succeeded in synthesizing a novel fluorine liquid crystal compound exhibiting a liquid crystal phase in a wide temperature range, and increased the NI point of the liquid crystal composition by adding a small amount of the compound to another liquid crystal composition. The present invention has been completed and the present invention has been completed. That is,

The fluorine liquid crystal compound of the present invention has the general formula

[Chemical 2] (In the formula (1), X is F or Cl, n
Represents 1 or 2 and m represents an integer of 1 to 10. ) Is a compound represented by.

The liquid crystal composition of the present invention is characterized by containing at least one kind of the compound.

The compound of the present invention can be produced, for example, by the reaction represented by the following reaction formula.

[Chemical 3]

[Chemical 4]

[Chemical 5]

[Chemical 6] (Here, X, n, and m in Chemical formula 3, Chemical formula 4, Chemical formula 5, and Chemical formula 6 are the same as above.)

That is, 2-molar 4-hydroxybenzoic acid methyl ester of the formula (b) and ω, ω'-of the formula (a) are used.
Diiodinated perfluoroalkylene is reacted with anhydrous potassium carbonate in N, N-dimethylformamide (hereinafter abbreviated as DMF) to give ω, ω′-bis (4-methyloxycarbonylphenyloxy) perfluoroalkylene of the formula (c). obtain. This was hydrolyzed with an acid catalyst to give a benzoic acid derivative of the formula (d). Then, with thionyl chloride, the acid chloride of the formula (e) is converted, and this is reacted with the phenol derivative of the formula (f) to obtain the desired compound of the formula (1).

The fluorine liquid crystal compound of the present invention can also be produced by the reaction represented by the following reaction formula.

[Chemical 7] (Here, X, n and m are the same as above)

That is, an ester derivative of 4-hydroxybenzoic acid 4-substituted phenol and ω, ω'-perfluoroalkylene diiodide are reacted with anhydrous potassium carbonate in DMF to give the desired compound of the formula (1). Can be manufactured.

The compound of the present invention exhibits a liquid crystal phase in a wide temperature range and has a high temperature at which the liquid crystal becomes a liquid. In addition, by adding a small amount to the liquid crystal composition,
There is an advantage that the liquid point (NI point) can be raised and the viscosity is not so high. Furthermore, the compound of the present invention has good compatibility with many liquid crystal compounds, that is, liquid crystal compounds of ester type, Schiff base type, biphenyl type, phenylcyclohexane type, heterocyclic type and the like.

The liquid crystal composition of the present invention is characterized by containing at least one component of the compound of the present invention represented by the above formula. Examples of the component other than the compound of the present invention which can be used as a component of the liquid crystal composition of the present invention include ester type compounds, Schiff base type compounds, biphenyl type compounds, phenylcyclohexane type compounds and heterocyclic type compounds.

The following compounds can be shown as specific examples of these compounds. Ester-based liquid crystal compounds include trans-4-alkylcyclohexanecarboxylic acid-4-alkylphenyl ester, trans-4-alkylcyclohexanecarboxylic acid-4-alkoxyphenyl ester, 4-alkoxybenzoic acid-4-alkylphenyl ester, 4-alkylbenzoic acid-4-cyanophenyl ester, 4- (trans-4-alkylcyclohexyl) benzoic acid-4-cyanophenyl ester, etc.,

Examples of the Schiff base type liquid crystal compound include 4-alkoxybenzylidene-4-alkanoyloxyaniline, 4-alkoxybenzylidene-4-aralkylaniline and 4-alkoxybenzylidene-4-cyanoaniline. 4'-alkyl-4-cyanobiphenyl, 4'-alkoxy-4-
Examples of phenylcyclohexane compounds such as cyanobiphenyl and 4'-alkoxy-4-alkylbiphenyl include trans-4-alkyl- (4-cyanophenyl)
Cyclohexane, trans-4-alkyl- (4-alkoxyphenyl) cyclohexane, etc.,

Examples of the heterocyclic liquid crystal compound include 5-alkyl-2- (4-cyanophenyl) -1,3-dioxane, 5-alkyl-2- (4-cyanophenyl) pyridine and 5-cyano-2- Examples thereof include (4-alkylphenyl) pyridine.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Production of 1,2-bis (4-fluorophenyloxycarbonyl-4-phenyloxy) tetrafluoroethane (in the formula (1), X = F,
Compound with n = 1 and m = 2) i) Preparation of 1,2-bis (4-hydroxycarbonylphenyloxy) tetrafluoroethane 4-hydroxybenzoic acid methyl ester 15 g (0.1
Mol), 21 g of 1,2-diiodinated tetrafluoroethane
20 (0.06 mol) with 50 g of anhydrous potassium carbonate
Heat stirring was carried out in 0 ml of DMF at 50 ° C. for 60 hours. After completion of the reaction, the reaction solution was poured into 2 liters of water, and the oily substance was extracted with 1.5 liters of toluene (divided into 3 times). The toluene layer was washed with 2N sodium hydroxide and then with water three times. Toluene was distilled off under reduced pressure, and the remaining oily substance was removed by 6
200 ml of N-sulfuric acid and 300 ml of acetic acid were added and the mixture was boiled under reflux for 5 hours. The reaction solution was poured into 2 liters of ice water, the precipitated crystals were filtered off, washed well with water, and then recrystallized with acetic acid. Yield 7g
(Yield 37%), CS point 209 ° C., SN point 253
C., NI point was 255.degree.

Ii) Esterification 3.7 g of 1,2-bis (4-hydroxycarbonylphenyloxy) tetrafluoroethane prepared in i) (0.
(01 mol) and thionyl chloride (20 ml) were refluxed in the flask for 10 hours. When thionyl chloride is distilled off under reduced pressure, a solid substance remains. This was dissolved in 100 ml of toluene, 3 g of 4-fluorophenol was dissolved in 50 ml of pyridine and 400 ml of toluene, and the mixture was stirred well.
After standing overnight, pour into 500 ml of water and add 10 toluene.
Extraction was performed by adding 0 ml. The toluene layer was washed with a 2N aqueous sodium hydroxide solution and then washed with water until it became neutral. Then, after drying over anhydrous sodium sulfate, toluene was distilled off under reduced pressure,
The remaining oily substance was chromatographed with a toluene solvent using a column of activated alumina. The eluted toluene solution is depressurized to distill off the toluene, and the remaining solid is recrystallized from ethanol to obtain the desired 1,2-bis (4-fluorophenyloxycarbonyl-4-phenyloxy) tetraphenylethane. Manufactured. Yield 2.2 g (yield 3
7%). Crystal-nematic phase transition temperature (CN): 130.3-
134.6 ° C, nematic phase-isotropic phase transition temperature (N-
I): 169.9 ° C

(Examples 2 and 3) In Example 1, 4-
Various ester compounds were prepared by using other phenol derivatives instead of fluorophenols. The results are shown in Table 1 together with the results of Example 1.

[0021]

[Table 1]

Reference Example (a). A liquid crystal mixture (A) having the following composition was prepared. Trans-4-Propyl- (4-cyanophenyl) cyclohexane 30% by weight trans-4-pentyl- (4-cyanophenyl) cyclohexane 40% by weight trans-4-heptyl- (4-cyanophenyl) cyclohexane 30% by weight This liquid crystal The NI point of mixture (A) is 52.3 ° C, 20 ° C.
The refractive index anisotropy Δn (= n _‖ −n _┴ , the difference between the refractive index in the direction parallel to the orientation vector and the refractive index in the direction perpendicular to the orientation vector) is 0.119, and the viscosity is 21.7 c.p. there were.

(B). As a liquid crystal cell, a substrate having a tin oxide transparent electrode coated with silicon oxide and subjected to a rubbing treatment was assembled so as to face an interelectrode distance of 9 μm. The liquid crystal mixture (A) is sealed in this liquid crystal cell,
When its characteristics were measured at ℃, the dielectric anisotropy Δε
(= Ε _∥ −ε _┴ , the difference between the permittivity parallel to the liquid crystal axis direction and the permittivity perpendicular to it) was +10.7, and the threshold voltage V _th was 1.60V.

(Embodiment 4) (Application 1) (a). 95% by weight of the liquid crystal mixture (A) of Reference Example (a)
In addition, the composition having 5 wt% of 1,2-bis (4-fluorophenoxycarbonyl-4-phenyloxy) tetrafluoroethane prepared in Example 1 dissolved therein had an NI point of 5
6.6 ℃, dielectric anisotropy (ε _∥- ε _┴ ), Δε is +9.
5, refractive index anisotropy (n _‖ −n _┴ ), Δn is 0.115,
The viscosity was 22.0 c.p. The threshold voltage V _th was 1.65V. As described above, although the NI point increased, the viscosity did not change so much, and Δn decreased a little.

[0025]

INDUSTRIAL APPLICABILITY The compound of the present invention exhibits a liquid crystal phase in a wide temperature range and also exhibits a liquid crystal phase up to a high temperature, and when added in a small amount to a liquid crystal composition, the N of the liquid crystal composition is not increased. The −I point can be increased and Δn can be reduced. Many liquid crystal compounds, such as ester type, Schiff base type, biphenyl type, phenylcyclohexane type,
It has good compatibility with heterocyclic systems and the like, and by adding a small amount of the compound of the present invention to the liquid crystal composition, Δn can be reduced without increasing the viscosity so much. These compounds can be advantageously applied to STN (Super Twisted Nematic) type display devices.

Claims (2)

[Claims] 1. A general formula: (In the formula (1), X is F or Cl, n
Represents 1 or 2 and m represents an integer of 1 to 10. ) A fluorine liquid crystal compound represented by 2. A liquid crystal composition comprising at least one kind of the fluorine liquid crystal compound according to claim 1.