JPH0825946B2 - Fluorine-substituted biphenyl derivative - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel liquid crystal compound and a liquid crystal composition containing at least one kind of these liquid crystal compounds. More specifically, the present invention relates to a ferroelectric liquid crystal, and a novel fluorine-substituted biphenyl derivative which is useful as a constituent component of a practical ferroelectric liquid crystal composition and is excellent in chemical stability, and these compounds. The present invention relates to a liquid crystal composition containing at least one novel fluorine-substituted biphenyl derivative.

[Background technology]

Liquid crystal display devices are widely used as display devices for watches, calculators, personal word processors, pocket televisions, and the like. This is a light receiving type, eyes are not tiring, power consumption is low,
It is because it has excellent features such as being thin,
On the other hand, there were limitations in application because of slow response speed and lack of memory. Twisted nematic (TN), which was conventionally used to expand the application area
A super twisted nematic (STN) type display system, which is an improved type display system, has also been found. However, these are not sufficient for large-screen display or graphic display, and various researches have been made on liquid crystal display elements that replace them.

One of them is a ferroelectric liquid crystal [RB Meyer et al .; Physique, 36
L-69 (1975)] display method [NAClark et al .; App
lied Phys.lett., 36,899 (1980)].

Since this method has excellent characteristics such as a 100 times faster response than the conventional method and a memory property, the application of the liquid crystal display device is expected to be expanded. Ferroelectric liquid crystal refers to a series of smectic liquid crystals in which the long axis of the liquid crystal molecule has an angle with the layer normal direction, but in practice a chiral smectic C (SmC ^* ) phase is used.

The actual material for a display device is (1) as a liquid crystal composition composed of various ferroelectric liquid crystal compounds, or (2) a liquid crystal composition composed of compounds having various smectic C (SmC) phases and an optically active compound. Used as. Recently, the method of using as the liquid crystal composition of (2) has become mainstream, but it has various characteristics required for practical use (operating temperature range, response speed, spontaneous polarization, spiral pitch, chemical stability). This is because (2) is considered advantageous because it is easy to adjust (2) and is cheap. However, there are still very few compounds that can be put to practical use, and it is desired to develop various novel compounds that can be useful components when preparing a ferroelectric liquid crystal composition.

From such a situation, the present inventors have a viewpoint on a compound having an SmC phase necessary for preparing a ferroelectric liquid crystal composition, and particularly for a compound known so far, the SmC phase temperature range is room temperature. There are few substances in the vicinity, and even if it exists near room temperature, there are many benzene rings in the substance structure and there are benzoic acid esters. From the standpoint that it is high and is disadvantageous for high-speed response, we have designed, synthesized and evaluated compounds with various novel structures, and as a result of intensive studies, they are chemically stable and the SmC phase temperature range near room temperature is We have succeeded in providing novel compounds that are broad and have low viscosity, and are considered to be advantageous for fast response.

[Disclosure of Invention]

The present invention has the general formula, (R ¹ and R ² are linear alkyl groups having 5 to 18 carbon atoms, one of which represents an alkyl group having 6 or more carbon atoms, Z is a single bond, O, COO or OCO. The present invention provides a non-optically active fluorine-substituted biphenyl derivative represented by the formula) and a liquid crystal composition containing at least one of them.

The novel liquid crystal compound according to the present invention is a compound having an SmC phase in a wide temperature range around room temperature by itself,
Also, if they are mixed in an appropriate ratio, a mixture having an SmC phase can be prepared in a wider temperature range, and since it is a fluorine-substituted biphenyl system, low viscosity can be expected, and therefore practical ferroelectricity It is a compound useful as a composition component when a liquid crystal composition is prepared.

Hereinafter, the present invention will be described in more detail with reference to synthetic routes, examples and the like.

The following synthetic route is one example, which does not limit the synthesis of the compounds according to the invention.

Synthetic pathway diagram In the case of 2-fluorobiphenyl derivative (synthetic pathway diagram) 2-Fluoro-4-bromobiphenyl is used as a starting material, which is acetylated by the Friedel-Crafts reaction, and is obtained by subjecting it to Baeyer-Villiger oxidation followed by hydrolysis 2 -Fluoro-4-brom-4'-
Etherification of hydroxybiphenyl with alkyl bromide gives 2-fluoro-4-bromo-4'-alkoxybiphenyl. This 2-fluoro-4-bromo-4 '
By reacting an alkoxy biphenyl with magnesium to prepare a Grignard reagent, which is reacted with boric acid tributyl ester and then subjected to an acid decomposition reaction to give 2
-Fluoro-4-hydroxy-4'-alkoxybiphenyl was also cyanated with cuprous cyanide and hydrolyzed to give 2-fluoro-4'-alkoxy-
4-Biphenylcarboxylic acid is obtained in each case. 2-Fluoro-4-hydroxy-4'-alkoxybiphenyl is etherified with alkyl bromide or esterified with alkylcarboxylic acid chloride, and 2-fluoro-4'-alkoxy-4-biphenylcarboxylic acid is alcoholized. By esterifying with, various 2-fluorobiphenyl derivatives according to the present invention can be obtained.

The abbreviations used in the examples have the following meanings.

GLC Gas chromatograph HPLC High performance liquid chromatograph IR Infrared absorption spectrum Mass Mass spectrometry mp Melting point bp Boiling point C Crystal S _X Smectic phase S _B Smectic B phase SmC, S _C Smectic C phase SmC ^* , S _C ^* chiral Smectic phase C S _A Smectic phase A Phase Ch Cholesteric phase I Isotropic liquid? Temperature unknown Example 1 113 g of anhydrous aluminum chloride and methylene chloride in the reactor
600 ml of acetyl chloride 1
13 g was dropped, and then a solution of 100 g of 2-fluoro-4-bromobiphenyl in 400 ml of methylene chloride was dropped, and the reaction was stirred for 7 hours while gradually returning to room temperature. The reaction solution was poured into ice and dilute hydrochloric acid, the methylene chloride layer was washed with water, washed with an aqueous sodium hydrogen carbonate solution, washed with water, dehydrated with sodium sulfate and the solvent was distilled off,
The residue was recrystallized from acetone to give 2-fluoro-4-bromo-4'-acetylbiphenyl.

Yield 96g (82.2%) GLC 100% 2-fluoro-4-bromo-obtained in (a) in a reactor
Charge 65 g of 4'-acetylbiphenyl and 300 ml of methylene chloride and stir at 10 ° C with 500 ml of 88% formic acid and 480 ml of acetic anhydride.
Was added dropwise, 1.5 ml of concentrated sulfuric acid was further added, 150 ml of 35% hydrogen peroxide was added dropwise over 3 hours, and after the addition, the temperature was gradually raised and the reaction was carried out with stirring at 45 to 50 ° C. for 30 hours. The reaction solution was poured into ice water, extracted with benzene, washed with an aqueous sodium hydrogen carbonate solution, washed with water and dehydrated with sodium sulfate, and the solvent was distilled off to obtain a residue. This residue and ethyl alcohol 2 were charged into another reactor, a 25% aqueous potassium hydroxide solution was added thereto, and the mixture was refluxed and stirred for 8 hours. The reaction mixture was poured into ice and dilute hydrochloric acid, extracted with benzene, washed with brine, dehydrated with sodium sulfate, the solvent was distilled off, and the residue was purified by silica gel chromatography (eluent benzene). Fluoro-4-brom-4'-idroxybiphenyl was obtained.

Yield 28.1g (47.5%) 2-fluoro-4-bromo-obtained in (b) in a reactor
4'-hydroxybiphenyl 5g, octyl bromide 8.
63 g, potassium carbonate 4 g and 2-butanone (MEK) 50 ml were charged, and after reacting for 8 hours under stirring and refluxing, the reaction solution was poured into diluted hydrochloric acid, extracted with benzene, washed with water, dehydrated with sodium sulfate, and the solvent was distilled off. The residue was recrystallized with a mixed solvent of acetone / methanol to obtain 6.45 g (90.8%) of 2-fluoro-4-bromo-4'-octyloxybiphenyl.

Yield 6.45g (90.8%) TLC mono spot A reactor was charged with 8.6 g of magnesium and a small amount of iodine, and a small amount of a solution of 135 g of 2-fluoro-4-bromo-4'-octyloxybiphenyl 135 g obtained in (c) in 200 ml of THF was added and heated. THF solution was added dropwise. After completion of dropping, the mixture was refluxed for 3 hours to prepare a Grignard reagent.
68 g of boric acid tributyl ester in another reactor was charged, and the Grignard reagent prepared above was added dropwise thereto at 40 ° C. with stirring, and after the addition, the mixture was stirred at the same temperature for 1 hour. After cooling, 10% aqueous sulfuric acid solution was added dropwise with stirring, and 500 ml of benzene was added to the reaction solution for extraction. This benzene extract was charged into another reactor, 72 ml of 20% hydrogen peroxide solution was added dropwise with stirring at 40 to 50 ° C., and the reaction was further stirred for 2 hours. Pour the reaction solution into water,
The benzene layer was treated with an aqueous sodium hydrogen sulfite solution, washed with water, dehydrated with sodium sulfate, the solvent was distilled off, and the residue was purified by silica gel chromatography (eluent hexane → benzene), and 2-fluoro-4- Hydroxy-4'-octyloxybiphenyl was obtained.

Yield 84.5g (75.5%) The reactor was charged with 5.0 g of 2-fluoro-4-hydroxy-4'-octyloxybiphenyl obtained in (d), 3.1 g of octyl bromide, 4.4 g of potassium carbonate and 35 ml of cyclohexanone, and the mixture was heated at 110 to 130 ° C for 5 hours. It was made to react. The reaction solution is filtered, the obtained solid is washed with benzene, the washing and the filtrate are combined, washed with water, dehydrated with sodium sulfate, the solvent is distilled off, and the residue is recrystallized with acetone to give 2- Fluoro-
4,4'-Dioctyloxybiphenyl was obtained.

Yield 6.46 g (95.5%) The purity of this product was 99% or more by HPLC. Also IR and
Mass analysis showed a molecular ion peak at 428,
In addition, it was confirmed that the obtained substance was the target product from the relation of the raw materials used.

This product was sandwiched between METTLER hot stage FP-82, and the phase change was observed under a polarizing microscope. The results are shown in Table-1.

Example 2 Example 1 (e) was replaced with 3.1 g of octyl bromide, 3.5 g of decyl bromide was used, and the other example 1 was used.
By operating in the same manner as in (e), 2-fluoro-4-
Decyloxy-4'-octyloxybiphenyl was obtained.

Yield 6.86 g (95.2%) The purity of this product was 99% or more by HPLC. Also IR and
Mass analysis showed a molecular ion peak at 456,
In addition, it was confirmed that the obtained substance was the target product from the relation of the raw materials used.

This product was sandwiched between METTLER hot stage FP-82, and the phase change was observed under a polarizing microscope. The results are shown in Table-1.

Example 3 3-fluoro-4 obtained in Example 1 (d) in a reactor
-Hydroxy-4'-octyloxybiphenyl 7.0 g,
20 ml of pyridine was charged, 4.3 g of octanoyl chloride was added dropwise with stirring at 0 to -5 ° C, and after the addition, the mixture was stirred at the same temperature for 10 hours. The reaction solution was poured into water, extracted with benzene, washed with dilute hydrochloric acid, washed with water, treated with diluted ammonia water, washed with water and dehydrated with sodium sulfate, benzene was distilled off, and the residue was recrystallized with a methanol / acetone mixed solvent, 2-Fluoro-4-octanoyloxy-4'-octyloxybiphenyl was obtained.

Yield 5.27 g (54.2%) The purity of this product was 99% or more by HPLC. Also IR and
Mass analysis showed a molecular ion peak at 442,
In addition, it was confirmed that the obtained substance was the target product from the relation of the raw materials used.

This product was sandwiched between METTLER hot stage FP-82, and the phase change was observed under a polarizing microscope. The results are shown in Table-1.

Example 4 In place of 4.3 g of octanoyl chloride in Example 3, 5.0 g of decanoyl chloride was used, and the same operation as in Example 4 was repeated except that 2-fluoro-4-decanoyloxy- was used.
4'-octyloxybiphenyl was obtained.

Yield 9.42 g (91.1%) The purity of this product was 99% or more by HPLC. Also IR and
Mass analysis showed a molecular ion peak at 470,
In addition, it was confirmed that the obtained substance was the target product from the relation of the raw materials used.

This product was sandwiched between METTLER hot stage FP-82, and the phase change was observed under a polarizing microscope. The results are shown in Table-1.

Example 5 An equal weight mixture of the following four kinds of compounds obtained in the present invention was prepared, and the mixture was sandwiched between METTLER HOTStage FP-82 and the phase change was observed under a polarizing microscope.

As a result, SmC phase from the crystal at 9.4 ℃ at temperature rise, Sm at 44.3 ℃
The C phase changed to the Ne phase, and at 62.0 ℃, the Ne phase changed to an isotropic liquid.

Thus, by mixing the compounds of the present invention, a mixture having an SmC phase in a wide temperature range including room temperature was obtained.

Example 6 A ferroelectric liquid crystal composition was prepared by adding 10% by weight of the following known ferroelectric liquid crystal to 90% by weight of the mixed liquid crystal prepared in Example 5.

The phase transition temperature of this liquid crystal composition rises from the crystal at a temperature rise of 13 ° C.
SmC ^* phase, changed from SmC ^* phase to Ch phase at 48 ° C, and changed from Ch phase to isotropic liquid at 67.5 ° C.

A liquid crystal cell with a cell thickness of 3 μm was prepared by coating the surface with polyvinyl alcohol (PVA) and rubbing the surface to perform parallel alignment treatment. A liquid crystal element was produced by enclosing the composition and gradually cooling it from an isotropic liquid to a SmC ^* phase. This liquid crystal element was sandwiched between two polarizing plates, a voltage was applied, and the response time was measured from the change in transmitted light intensity.

As a result, the response time was 1.2 msec at 200 Hz, ± 25 V square wave application, and 42.5 ° C.

Thus, the SmC liquid crystal composition comprising the SmC compound of the present invention can be used as a material for a ferroelectric liquid crystal display device.

Front Page Continuation (72) Inventor Kenji Suzuki 1-7-1 Inari, Soka City, Saitama Kanto Chemical Co., Ltd. Central Research Laboratory (72) Inventor Tsunenobu Fujii 1-7-1 Inari, Soka City, Saitama Kanto Chemical Co., Ltd. Central Research Laboratory of the Company (56) Reference JP-A 1-250335 (JP, A) JP-A 63-154637 (JP, A) JP-A 63-137983 (JP, A) JP-A 62-255446 (JP , A) JP-A-58-126823 (JP, A) JP-A-58-121225 (JP, A) JP-A 2-504520 (JP, A) Z. Natureforsch. , B: A norg. Chem. Org. Chem. 38B [10] (1983) P. 1221-1226

Claims (2)

[Claims] 1. A general formula (R ¹ and R ² are linear alkyl groups having 5 to 18 carbon atoms, one of which represents an alkyl group having 6 or more carbon atoms, Z is a single bond, O, COO or OCO. A non-optically active fluorine-substituted biphenyl derivative represented by 2. General formula (R ¹ and R ² are linear alkyl groups having 5 to 18 carbon atoms, one of which represents an alkyl group having 6 or more carbon atoms, Z is a single bond, O, COO or OCO. A liquid crystal composition comprising at least one non-optically active fluorine-substituted biphenyl derivative represented by