JPH06135924A - Tolan derivative, liquid crystal composition comprising the same and liquid crystal display element using the same - Google Patents

Abstract

PURPOSE:To obtain a new tolan derivative, good in compatibility with other liquid crystal compounds, having effects on extension of the practical temperature range and increase in the DELTAn and effectively usable as a basic component of liquid crystal compositions for super-twisted nematic (STN) type display. CONSTITUTION:This tolan derivative of formula 1 (R is 1-10C straight-chain alkyl), e.g. 4-cyano-2-fluoro-4'-propyltolan. The compound of formula 1 is obtained by reacting a compound of formula 2 with 3-methyl-1-butyn-3-ol, providing a compound of formula 3, then reacting the resultant compound of formula 3 with sodium hydride, affording a compound of formula 4, subsequently reacting the obtained compound of formula 4 with a compound of formula 5, providing a compound of formula 6 and finally reacting the prepared compound of formula 6 with copper cyanide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel tolan derivative used as an electro-optical display material, a liquid crystal composition containing the same, and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A liquid crystal display device utilizes the electro-optical effect of liquid crystal, and a liquid crystal phase used for the liquid crystal display device includes a nematic phase, a cholesteric phase and a smectic phase. The most widely used display method at present is a twisted nematic (hereinafter referred to as TN) type that utilizes a nematic phase or a super twisted nematic (hereinafter referred to as STN) type that further increases the twist angle.

The liquid crystal display device is small and can be made thin.

2. Low driving voltage and low power consumption.

3. Since it is a light receiving element, eyes do not get tired even if it is used for a long time.

Since it has advantages such as the above, it has been conventionally applied to watches, calculators, audio equipment, various measuring instruments, automobile dashboards, and the like. In particular, it has recently been applied to displays with a large number of pixels such as displays of personal computers and word processors, as well as color televisions, and has been attracting attention as a display device replacing CRT. As described above, the liquid crystal display device is applied in various fields, and its application field is expected to further expand in the future. The characteristics required for liquid crystal materials are expected to change along with this, but the characteristics shown below are basic and indispensable.

1. No coloration and stable to heat, light, electrical and chemical.

2. Wide operating temperature range.

3. The electro-optical response speed is fast.

4. The driving voltage is low.

5. The voltage-light transmittance characteristic has a steep rise and the threshold voltage (hereinafter referred to as Vth) has a small temperature dependency.

6. Wide viewing angle range.

[0013]

However, many liquid crystals satisfying one of these characteristics are known, but no liquid crystal compound satisfying the characteristics of 2 or less with a single component is known. Therefore, in order to obtain these characteristics, a liquid crystal composition in which several kinds of nematic liquid crystal compounds or non-liquid crystal compounds are mixed is used. In order to satisfy the three characteristics among these, there is the following relational expression between the response speed (hereinafter referred to as τ), the viscosity coefficient (hereinafter referred to as η), and the cell gap (hereinafter referred to as d). In order to increase the speed, it is necessary to reduce d by a small τ∝ηd ² . By the way, in a practically used cell, the value of Δn · d (Δn is a refractive index anisotropy, the same applies hereinafter) is constant in order to prevent the generation of interference fringes on the cell surface, which causes the cell appearance to be impaired. Since the value is set, the value of d can be reduced by using a material having a large Δn, and as a result, the response speed can be increased.

Therefore, the present invention responds to the demands in such an actual situation, and its purpose is to have a good compatibility with several kinds of nematic liquid crystal compounds or non-liquid crystal compounds, and by mixing them, a liquid crystal composition having a large Δn value. A novel liquid crystal compound capable of obtaining

[0015]

The present invention has the general formula

[0016]

[Chemical 4]

(Wherein R represents a linear alkyl group having 1 to 10 carbon atoms), a tolan derivative, a liquid crystal composition containing the same, and a liquid crystal display using the same. It is an element. The compound (1) of the present invention can be obtained by the following production method.

[0018]

[Table 1]

Step 1) Compound (2) was added to bis (triphenylphosphine) palladium (I
I) Compound (3) is obtained by reacting with 3-methyl-1-butyn-3-ol in the presence of chloride, triphenylphosphine and copper (I) iodide.

Step 2) The compound (3) is reacted with sodium hydride in toluene to obtain the compound (4).

Step 3) Compound (4) is added to bis (triphenylphosphine) palladium (II) in diethylamine.
Compound (6) is obtained by reacting with compound (5) in the presence of chloride and copper (I) iodide.

Step 4) Compound (6) is reacted with copper (I) cyanide in N-methylpyrrolidone (hereinafter referred to as NMP) to obtain compound (1).

The components of the liquid crystal composition which becomes the base when the tolan derivative of the present invention is mixed include the compounds shown below, but not limited thereto, all conventional liquid crystal compounds or analogues thereof. It has good compatibility with the compound, and the obtained liquid crystal composition is characterized by having a large Δn.

[0024]

[Table 2]

(Wherein R and R'represent an alkyl group, an alkoxy group, an alkoxymethylene group, a nitrile group or a fluoro group, the phenylene group may have a halogen substituent at the 2- or 3-position, and a cyclohexane ring. The liquid crystal composition can be mixed with the compound of the present invention in an amount of 1 to 50% by weight, but 1 to 30 in consideration of crystal precipitation in a low temperature region.
A weight percent range is particularly preferred.

The liquid crystal display device using the liquid crystal composition containing at least one kind of the compound of the present invention is suitable for the liquid crystal display device using the time division driving method, and particularly TN type and S type.
High time-division driving is possible in a TN type liquid crystal display element.

[0027]

The present invention will be described in more detail with reference to the following examples.

(Example 1) [Synthesis of compound (1)] Production of 4-cyano-2-fluoro-4'-propyltolan Step 1) 60 g of 1-bromo-4-propylbenzene, 3-methyl in a nitrogen atmosphere 38 g of -1-butyn-3-ol, 1.3 g of triphenylphosphine, 0.7 g of bis (triphenylphosphine) palladium (II) chloride were dissolved in 260 ml of triethylamine, and copper (I) iodide was added therein.
0.2 g was added. After stirring at room temperature for 1 hour, the mixture was stirred at 90 ° C. for 5 hours. The precipitated crystals were filtered, triethylamine was distilled off, and the crystals were extracted with chloroform. After washing twice with 10% hydrochloric acid and twice with water, chloroform was distilled off. The residue was purified by silica gel-chloroform column chromatography to give 3-methyl-1- (4'-propylphenyl) -1-butyne-
37 g of 3-ol was obtained.

Step 2) 3-methyl-1-in a nitrogen atmosphere
(4'-Propylphenyl) -1-butyn-3-ol
33 g was dissolved in 320 ml toluene, and 2 g of sodium hydride (60% in paraffin liquid) was added thereto. The mixture was stirred at 60 ° C for 6 hours. The reaction solution was poured into 300 ml of water, extracted with chloroform, and washed with water three times. After distilling off toluene and chloroform, vacuum distillation (bp60-63 ℃ / 4mmHg) was performed to
16 g of propylphenylacetylene was obtained.

Step 3) 33 g of 4-bromo-2-fluoro-1-iodobenzene in 37 ml of diethylamine in a nitrogen atmosphere.
Was dissolved in 0.1 g of bis (triphenylphosphine) palladium (II) chloride and 0.1 g of copper (I) iodide, and the mixture was stirred. The flask was cooled to 5 ° C. or lower, and 16 g of 4-propylphenylacetylene was added dropwise. After stirring at room temperature for 5 hours, the reaction mixture was concentrated with hydrochloric acid (23 ml) and ice (150 ml).
Pour into the mixing of g. After extraction with chloroform and washing with water twice, the chloroform was distilled off. Vacuum distillation of the residue (bp19
After performing 0 to 200 ° C./4 mmHg), recrystallization from a mixed solvent of acetone and methanol was performed to obtain 23 g of 4-bromo-2-fluoro-4′-propyltolan.

Step 4) 4-Bromo-2-fluoro-4 '
-Propyl tolan 5.5g and copper (I) cyanide 1.7g NM
P20 ml and refluxed for 2 hours. The reaction solution is iron (II) chloride
Poured into a mixture of 6.5 g, concentrated hydrochloric acid 2.2 ml, and water 8 ml. The precipitated crystals were filtered and washed with water. The obtained crystals were dissolved in chloroform, washed with water three times, and then chloroform was distilled off. Vacuum distillation of the residue (bp 180-190 ℃ / 5mmHg)
Then, recrystallization is performed from a mixed solvent of acetone and methanol to 4-cyano-2-fluoro-4′-propyltolan.2.
1 g was obtained. The crystal phase-isotropic liquid transition point (hereinafter referred to as CI point) of this compound was 81.4 ° C, and the nematic liquid crystal phase-isotropic liquid transition point (hereinafter referred to as NI point) was 77.3.
It was ℃.

The following compounds were synthesized by the same method.

Production of 4-Cyano-2-Fluoro-4′-Methyl Tolan Production of 4-Cyano-2-Fluoro-4′-Ethyl Tolan Production of 4-Cyano-2-Fluoro-4′-Butyl Tolan CI Point 74.1 ° C. NI point 63.6 ° C. Production of 4-cyano-2-fluoro-4′-pentyltran 4 Production of 4-cyano-2-fluoro-4′-hexyltran 4-Cyano-2-fluoro-4′-heptyl Manufacture of Tolan Manufacture of 4-cyano-2-fluoro-4′-octyltran Manufacture of 4-Cyano-2-fluoro-4′-nonyltran Manufacture of 4-cyano-2-fluoro-4′-decyltran (Example 2 ) [Liquid crystal composition] Commercially available mixed liquid crystal ZLI-1565 (product of Merck & Co., NI point 89.3)
A liquid crystal composition having 90% by weight of C) and 10% by weight of 4-cyano-2-fluoro-4′-propyltolan of Example 1 which is a compound of the present invention was prepared. When the NI point and Δn of this composition were measured, the NI point was 85.6.
C. and Δn was 0.146.

(Embodiment 3) [Liquid crystal display element] As shown in FIG. 1, an electrode 3 made of a transparent electrode film (for example, an ITO film) is formed on glass substrates 1 and 2 and made of polyimide or the like. Apply the alignment film. Next, rubbing is performed to form the orientation control layer 4, and the glass substrates 1 and 2 are further formed.
Were opposed to each other with a sealant 6 in between, the liquid crystal composition prepared in Example 2 was injected between the glass substrates, and a polarizing plate was attached to the outer surfaces of the substrates 1 and 2 to prepare a TN type liquid crystal display cell.
The cell gap was 8 μm.

The liquid crystal display cell thus prepared was subjected to AC static drive to measure the viewing angle dependence (hereinafter referred to as α), steepness (hereinafter referred to as β) and Vth of voltage-light transmittance at 25 ° C. Note that α, β, and Vth are defined by the following equations.

[0036]

[Equation 1]

As a result of the measurement, α is 1.192, β is 1.274, and Vth is
It was 1.957 (V).

Although the TN type liquid crystal display cell is used in the above embodiment, the same effect can be obtained when the STN type display cell is used.

[0039]

As described above, the compound of the present invention has good compatibility with other liquid crystal compounds, and when mixed with a general liquid crystal mixture, it has the effect of widening the practical temperature range and increasing Δn. is there. In these respects, the present invention is extremely effective as a basic component of a liquid crystal composition for STN type display, which is currently the mainstream of display devices.

[Brief description of drawings]

FIG. 1 is a diagram showing a liquid crystal display cell created in an example of the present invention.

[Explanation of symbols]

 1.2. Glass substrate 3. Transparent electrode 4. Orientation control layer 5. Polarizing plate 6. Sealant

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Miko Nakayama 3-3-5 Yamato, Suwa City, Nagano Seiko Epson Corporation

Claims (3)

[Claims] 1. A general formula: (In the above formula, R represents a linear alkyl group having 1 to 10 carbon atoms). 2. A general formula: (In the above formula, R represents a linear alkyl group having 1 to 10 carbon atoms) and at least one kind of tolan derivative represented by the formula is contained in the liquid crystal composition containing the tolan derivative. 3. A general formula: (Wherein R represents a linear alkyl group having 1 to 10 carbon atoms), and a liquid crystal composition containing at least one kind of tolan derivative is used. A liquid crystal display device using a liquid crystal composition containing a tolan derivative.