JPH03133943A - Fluorine-substituted 1-(4-alkylbenzyloxy)-4-alkylbenzene - Google Patents

Abstract

NEW MATERIAL:The compound of formula I (R<1> and R<2> are 1-18C alkyl; X and Y are H or F provided that at least one of them is F). EXAMPLE:1-(4-Octylbenzyloxy)-2-fluoro-4-octylbenzene. USE:A material for a ferroelectric liquid crystal display having excellent response and memory property. PREPARATION:The compound of formula I can be easily produced by reacting a compound of formula II (Z is eliminable group such as Cl, Br or p- toluenesulfonyl group) with a compound of formula III in the presence of a base. The compound can effectively lower the viscosity of an SC matrix liquid crystal or SC* liquid crystal composition with little lowering of the upper limit temperature of the liquid crystal. The phase transition can be adjusted by the substitution position of F. The compound can be easily produced on an industrial scale. It is colorless, has excellent chemical stability against water, light, heat, etc., and realizes a response of as quick as <=87musec.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a novel fluorine-substituted 1-(4-alkylbenzyloxy)-4-alkylbenzene useful as an electro-optical display material and a liquid crystal material containing the same. More specifically, the present invention relates to a ferroelectric liquid crystal display material with excellent responsiveness and memory properties.

[Conventional technology]

Liquid crystal display elements are currently widely used due to their excellent features (low voltage operation, low power consumption, thin display capability, and can be used in bright places without straining the eyes). However, in the most common TN type display system, CR
Compared to light-emitting display systems such as T, the response is extremely slow and there is no memorization of the display (memory effect) when the applied electric field is turned off. There are many restrictions on the application to moving images such as those on televisions, etc., which require high resolution, and it could not be said to be suitable.

Recently, Mayer et al. reported a display method using ferroelectric liquid crystal, which has a high-speed response 100 to 1000 times faster than the TN type and a memory effect, so it is expected to be the next generation of liquid crystal display elements, and currently, Research and development is actively underway.

The liquid crystal phase of ferroelectric liquid crystal belongs to the tilted chiral smectic phase, but in practical terms, the chiral smectic C (hereinafter abbreviated as "SC") phase is the one with the lowest viscosity. Most desirable.

There are already many liquid crystal compounds (synthesized,
However, the conditions for using it as a ferroelectric display element are (a) exhibiting the SC phase over a wide temperature range including room temperature; and (b) maintaining the SCI phase in order to obtain good orientation. It is preferable that it has an appropriate phase series on the high temperature side and a large helical pitch, (c) it has an appropriate chilled angle, (d) it has low viscosity, and (e) it has a somewhat large spontaneous polarization. but,
Nothing that satisfies these requirements alone is known.

For this reason, a liquid crystal composition exhibiting an SC'' phase (hereinafter referred to as an S01 liquid crystal composition) is used.

The method for preparing the SC'' liquid crystal composition mainly includes (I)
(2) A method of mixing a liquid crystal compound exhibiting an "SC" phase (hereinafter referred to as an "SC2 compound");
Examples include a method of adding an optically active compound or composition as a chiral dopant to a liquid crystal compound (hereinafter referred to as SC compound) or liquid crystal composition (hereinafter referred to as SC base liquid crystal) that exhibits a phase. The S01 liquid crystal composition obtained by the latter method has a lower viscosity than that obtained by the former method, so it is suitable for high-speed response and is suitable for boat fishing.

Many SC compounds are already known and generally have lower viscosity than SC2 compounds.

[Problem to be solved by the invention]

However, known SC compounds have never shown a sufficiently low viscosity to be used as a material for preparing faster-responsive SC'' liquid crystal compositions.

The problem to be solved by the present invention is to
By adding C" to the liquid crystal composition, SC phase or S
SC without almost lowering the upper limit temperature of 01 phase.
The object of the present invention is to provide a compound that can effectively reduce the viscosity of a host liquid crystal or an S01 liquid crystal composition, and to provide a ferroelectric liquid crystal composition with high-speed response that contains the compound.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides the general formula (I) of the present invention, wherein one of the general formulas (I) represents a fluorine atom, preferably one represents a hydrogen atom and the other represents a fluorine atom.
The compound can be produced, for example, as follows.

That is, a compound represented by the general formula (II) (wherein R1 represents an alkyl group having 1 to 18 carbon atoms, and Z represents a leaving group such as chlorine, bromine, or valatoluenesulfonyl group) and general Formula (III) (wherein R1 and R2 each independently represent an alkyl group having 1 to 18 carbon atoms, preferably a linear alkyl group having 5 to 12 carbon atoms.

X and Y each independently represent a hydrogen atom or
2 represents an alkyl group having 1 to 18 carbon atoms, and X and Y each independently represent a hydrogen atom or a fluorine atom,
At least one of X and Y represents a fluorine atom.

) can be easily produced by reacting with a phenol derivative represented by: in the presence of a base.

Here, the compound of form (II) is obtained by reducing 4-alkylbenzoic acid, its ester, or its acid chloride to produce 4-alkylbenzyl alcohol, which is then chlorinated, brominated, or para-toluene. It can be easily obtained by sulfonylation.

Moreover, the phenol derivative of the -format (II[) is the following -
After acylation of the anisole derivative of form (IV), the carbonyl group may be reduced or alternatively - form (V)
It can also be obtained by reacting the 4-cyanophenol derivative with an excess Grignard compound, treating it with an acid, and then reducing it in the same manner.

(DI) where - X and Y in forms (IV) and (V) represent the same meanings as in general formula (I), and R3 is CHJ
The s form has the same meaning as R1.

The compound of the general formula (I) of the present invention is obtained as described above, and the melting point, phase transition temperature, infrared absorption spectrum (IR), nuclear magnetic resonance spectrum (NMR) of each specific compound belonging to these are ), etc.).

Examples of representative compounds are listed in Table 1.

(I[[) Table 1 The compound of the general formula (RI) of the present invention hardly exhibits liquid crystallinity when used alone, so it is used by adding it to other liquid crystal compositions. Ferroelectric liquid crystal As a liquid crystal composition other than the compound of general formula (I) when used as a composition, a composition containing an SC compound or an SC host liquid crystal and a chiral dopant is preferable.
The compounds are also useful as viscosity-lowering agents for nematic liquid crystal compositions.

Examples of the compound used for the SC matrix liquid crystal include -Formula (A) R'' + COO+Rh... (A) (wherein R1 and R'' each independently represent a linear or branched alkyl group,
It represents an alkoxyl group, an alkoxycarbonyl group, an alkanoyloxy group or an alkoxycarbonyloxy group. ) and -
A pyrimidine compound represented by the formula (B) (wherein R''' and Rh have the same meanings as in the general formula (A)) and -form (C)R''
() Z1◇XR' ... (C) (In the formula, R" and R1' represent the same meanings as in the general formula (A), Ha-
Coo OCOCHzo-OCHz CH
zCJ CE Represents C- or a single bond. ) (excluding compounds represented by -format (I)). Furthermore, for the purpose of increasing the upper limit temperature of the SC phase of the SC matrix liquid crystal, -form (D) ... (D) (wherein R'' and Rb are the same as in the case of i-form (A),
Z''' and zb each independently have the same meaning as 21 in general formula (C).) Three prototype compounds represented by the following can be used.

These compounds used in the SC matrix liquid crystal only need to exhibit an SC phase as a composition, and the individual compounds do not necessarily need to exhibit an SC phase.

By adding the compound represented by the general formula (I) of the present invention and a chiral dopant to the SC base liquid crystal prepared in this way, a ferroelectric liquid crystal composition exhibiting an SC phase in a wide temperature range including room temperature is obtained. be able to.

A ferroelectric liquid crystal composition containing the compound of general formula (I) of the present invention can be used as a display cell by being sealed as a thin film of about 1 to 20 μm between two transparent glass electrodes. In order to obtain good contrast, uniformly oriented monodomains are required. For this purpose, many methods have been tried, but the liquid crystal materials include isotropic liquid phase (I), chiral nematic phase (N''), smectic A phase (SA), and chiral smectic C phase ( S00
), and the helical pitch in the N1 phase and the SC "phase, especially the N" phase is thicker (
It is known to exhibit good orientation. The helical pitch depends primarily on the chiral dopant used, whereas the phase sequence of the liquid crystal depends on the compounding order used. (I) of the present invention
The compound has a strong tendency to expand the nematic phase when X=F and Y=H, and has a strong tendency to expand the smectic A phase when X=H and Y=F. Therefore, it is possible to maintain a desired phase series by using other SC host liquid crystal compounds or chiral dopants in accordance with their properties.

Now, as mentioned above, the compound of formula (I) of the present invention is characterized in that when added to an SC0 liquid crystal composition, it can reduce the viscosity and improve the responsiveness.

As shown in the examples below, as an SC compound, 2
A chiral dopant (hereinafter referred to as chiral dopant (a)) consisting of 80% by weight of a pyrimidine compound matrix liquid crystal with a ring pyrimidine and the following composition: 20
The SC9 liquid crystal composition consisting of % by weight of chiral dopant (a) CI exhibits a response of 87 μsec at room temperature (25° C.).

27% by weight S09 liquid crystal composition in which 68% by weight of the above SC base liquid crystal was combined, 12% by weight of compounds No. and 2 listed in Table 1 were added, and 20% by weight of chiral dopant (a) was added as well. showed a high-speed response of 73 μsec at 25°C. The values of spontaneous polarization for both sets of paraboloids are almost equal (approximately 2
1 nC7cm2), it can be seen that the viscosity of the composition was greatly reduced by adding the compound (I) of the present invention.

〔Example〕

The present invention will be specifically explained with reference to Examples below.
Of course, the gist and scope of the present invention are not limited by these examples.

The structure of the compound can be determined by nuclear magnetic resonance spectrum (NMR).
), and confirmed by infrared absorption spectrum (IR) and mass spectrum (MS). The phase transition temperature was measured using a polarizing microscope equipped with a temperature control stage and a differential scanning calorimeter (D
SC) was used in combination. (KBr) in IR is
By tabletting, (neat) the liquid film measurement,
(Nujol) represents the measurement in suspension in liquid paraffin.

In NMR, (CDCf 3) represents a solvent, S represents a singlet, d represents a doublet, t represents a triplet, q represents a quartet, m represents a multiplet, broad represents broad absorption, and J represents a Represents a coupling constant. Moreover, temperature represents °C.

All "%" in the composition represents "% by weight".

Example 1 [1-(4-octylbenzyloxy)-2-fluoro-4-octylbenzene (synthesis of compound Nα1 in Table 1)] 2-fluoro-4-octylphenol (this compound was synthesized by combining 2-fluoroanisole with (Obtained by reacting with octanoyl chloride and anhydrous aluminum chloride in dichloromethane to obtain 2-fluoro-4-octanoylanisole, and then reacting with potassium hydroxide and hydrazine monohydrate in diethylene glycol with heating.) 0
．． Dissolve 32g in 10ml of dimethylformamide,
0.33 g of t-butoxypotassium was added to this solution and stirred. After 30 minutes, 0.43 g of 1-bromomethyl-4-octylbenzene was added, and the mixture was reacted at room temperature for 10 hours. Then, 100 ml of water was added, the mixture was made weakly acidic with dilute hydrochloric acid, and extracted with ethyl acetate.

The organic layer was washed with water and saturated brine, and dehydrated by adding anhydrous sodium sulfate. The oil obtained by removing the solvent was subjected to silica gel column chromatography (developing solvent: n-
Purification using hexane:ethyl acetate=5:1) gave 0.34 g of the title compound. (Yield 56%) The structure was confirmed by IR and NMR.

NMR (CDCf3): 0.83-0.92 (m
, 6H).

1.18-1.37 (m, 20H), 1.50-1.
65 (m, 4H).

2.52(t, J=8.5Hz, 2H), 2.60(
t, J=8Hz, 2H).

5.06 (s, 2H), 6.79-6.82 (m, I
H).

6.88-6.92 (m, 2H), 7.18 (d, J
=8Hz, 2H).

7.34 (d, J=8Hz, 2H) IR (Nujol): 1590.1525.12B
0.1225.1135°1020, 8?5.810(
cm-') Furthermore, the melting point of the compound obtained by recrystallization from ethanol was measured and found to be 29°C.

Example 2 (I-(4-octylbenzyloxy)-3-fluoro-4-octylbenzene (N of Table 1).

Synthesis of Compound 2)] In Example 1, 3-fluoro-4-octylphenol (3-fluoro-4-octylphenol) was used instead of 2-fluoro-4-octylphenol.
This compound was produced by reacting 3-fluoro-4-cyanophenol with excess beptylmagnesium bromide in benzene, followed by acid treatment to form 3-fluoro-4-octanoylphenol. Obtained by heating with potassium hydroxide and hydrazine monohydrate in diethylene glycol. ) was used in the same manner as in Example 1 to obtain the title compound.

NMR (CDCNz): 0.80-0.94 (m
, 6H).

1.18-1.38 (o+, 20H), 1.48-1
．． 67 (+n, 411).

2.55 (t, J=8Hz, 2H), 2.60 (t,
J=8Hz, 2H).

4.97 (s, 2H), 6.63-6.70 (m, 2
H).

7.03-7.07 (m, IH), 7.19 (d, J
=8Hz, 28).

7.33 (d, J=8Hz, 28) IR (Nujol): 1630.1590.151
5.1285.1270゜1160, 1125.102
0.975.835 (cm-') Melting point 27.7° Example 3 (Synthesis of I-(4-hexylbenzyloxy)-3-fluoro-4-heptylbenzene (compound Nα3 in Table 1)) In the same manner as in Example 2, an oily compound was obtained.

NMR and IR of this compound showed absorption patterns similar to those of the compound of Example 2.

This compound did not crystallize even when left at low temperatures for a long time, and its melting point was unknown.

Example 4 (Preparation of SC' liquid crystal composition and display element) An SC' liquid crystal composition having the following composition was prepared.

Compound of Nα2 in Table 1 12.0% of the above-mentioned thiral dopant) 20.0% of this S
The C"liquid crystal composition has an SC" phase below 53.5°C.
Shows SA phase up to 4°C, N1 phase up to 65.5°C,
At higher temperatures, it becomes an isotropic liquid phase.

This S09 liquid crystal composition was filled into a cell having a thickness of approximately 2 μm and consisting of two glass transparent electrode plates subjected to alignment treatment (polyimide coating and rubbing). The phase (2) was gradually cooled to room temperature to uniformly orient the sc1 phase. When a rectangular wave of 501 (z) with an electric field strength of 1 o vp-P/μm was applied to this and the electro-optic response speed was measured, it was found that 25°
It showed a high-speed response of 73 H seconds at C. The tilt angle at that time was 27.4°, and the contrast was also good.

Further, the spontaneous polarization at this time was 20.7 nC/0m''.

Comparative Example In Example 4, an SC'' liquid crystal composition having the following composition was prepared without using the compound Nα2 in Table 1.

When the electro-optic response speed of this S01 liquid crystal composition was measured in the same manner as in Example 4, it was 87 μsec at 25°C. The tilt angle at this time was 27.2°, and the spontaneous polarization was 21.1 nC/0 m'', which was not much different from Example 4.

Example 5 In Example 4, instead of the compound Nα2 in Table 1,
An SC0 liquid crystal composition was prepared in the same manner as in Example 4, except that the compound NcLl shown in Table 1 was used.

This SC* liquid crystal composition maintains the SC0 phase at 55°C up to 54°C.
．． It showed an SA phase up to 5°C and an N''' phase up to 62°C, and turned into a ■ phase at higher temperatures.Compared to the composition of Example 4, the temperature range of the N9 phase was expanded, and SA It can be seen that the temperature range of the phase is narrower.

〔Effect of the invention〕

Although the compound represented by the general formula (I) of the present invention does not exhibit a liquid crystal phase, it has a very low viscosity and can be used as a so-called viscosity-reducing liquid crystal in other SC''' liquid crystal compositions or SC matrix liquid crystals. By this, the viscosity of the composition can be greatly reduced.As a result, especially in the S01 liquid crystal composition, high-speed response can be made possible.Furthermore, in the compound represented by the formula (I), fluorine It is also possible to adjust the phase change of the composition by selecting the substitution position of
It is easy to produce industrially, is colorless, and has excellent chemical stability against water, light, heat, etc., making it practical.

Furthermore, the liquid crystal material made of the chiral smectic liquid crystal compound or composition of the present invention can achieve a high-speed response of 87 μsec or less, and is extremely useful as an optical switching element for display.

Claims (1)

[Claims] 1. General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1 and R^2 each independently represent the number of carbon atoms of 1
- represents an alkyl group of 18. X and Y each independently represent a hydrogen atom or a fluorine atom, and at least one of X and Y represents a fluorine atom. ) Compound 2 represented by: A liquid crystal composition containing the compound according to claim 1. 3. The liquid crystal composition according to claim 2, which exhibits a ferroelectric chiral smectic phase. 4. A liquid crystal display element comprising the liquid crystal composition according to claim 2 or 3 as a constituent element.