JPH04321639A - Optically active fluoroalkyl derivative and liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a new optically active fluoroalkyl derivative capable of preparing a ferroelectric liquid crystal composition causing no lowering of upper limit temperature of ferroelectric liquid crystal phase and capable of responding at high speed when added to SmC-Host. CONSTITUTION:An optically active fluoroalkyl derivative [e.g. (R)-2-fluoro-4-(2- fluorooctyl)oxy-4'-octyloxybiphenyl] expressed by formula I (R<1> and R<2> are 1-14C alkyl; n is 1-6; Z is single bond, O, COO or OCO; A is formula II or formula II). The compound expressed by formula I wherein A is formula II is obtained by etherification of a compound expressed by formula V (Ts is tosyl) and compound expressed by formula VI. The compound expressed by formula I has molecular skeleton which introduced a fluoroalkoxy group at molecular ends as an element for inducing large spontaneous polarization and introduced a fluorine atom at lateral position as an element for enhancing chiral SmC property or liquid crystallinity.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a novel optically active compound and a liquid crystal composition containing at least one of the optically active compounds. More specifically, the present invention relates to ferroelectric liquid crystals, and the present invention relates to novel optically active fluoroalkyl derivatives that are useful as composition components and have excellent chemical stability when preparing practical ferroelectric liquid crystal compositions, as well as novel optically active fluoroalkyl derivatives having excellent chemical stability. The present invention relates to a liquid crystal composition containing at least one active fluoroalkyl derivative.

0002

BACKGROUND ART Liquid crystal display elements are widely used as display elements for watches, calculators, personal word processors, pocket televisions, and the like. These have excellent features such as light-receiving type that does not cause eye strain, low power consumption, and thinness. There were restrictions on. In order to expand the range of applications, super twisted nematic (STN) display systems, which are improved versions of the conventionally used twisted nematic (TN) display systems, have also been provided. However, these are not sufficient for large screen display or graphic display, and various studies are being conducted on liquid crystal display elements to replace them. One of them is ferroelectric liquid crystal [R. B. Meyer et al; Physique,
36 L-69 (1975)]
N. A. Clark et al.; Applied Phys.
let. , 36, 899 (1980)].

[0003] This method has excellent features such as a response time 1000 times faster than conventional methods and memory performance, so it is expected that the applications of liquid crystal display elements will expand. There is. Ferroelectric liquid crystals are a series of smectic liquid crystals in which the long axes of liquid crystal molecules form a certain angle with the layer normal direction. is used.

In practical terms, as in the case of manufacturing nematic liquid crystal display elements, various characteristics required in practical terms,
That is, in order to satisfy the operating temperature range, response speed, helical pitch, chemical stability, etc., multiple components are mixed and used as a ferroelectric liquid crystal composition. Ferroelectric liquid crystal compositions can be prepared using a compound having a chiral SmC phase as a main component, or by adding an optically active compound (Chiral SmC) to a mixture having a smectic C (SmC) phase (SmC-Host).
Currently, the latter method is becoming the mainstream of research.

However, in the latter method, when an optically active compound that does not itself exhibit a chiral SmC phase or a liquid crystal phase is added to the SmC-Host, the upper limit temperature of the ferroelectric liquid crystal phase often decreases. It is desired to develop a compound that does not lower the upper limit temperature, and further a compound that increases the upper limit temperature.

Up to now, various optically active compounds that induce large spontaneous polarization have been announced for the purpose of enabling high-speed response, but these do not exhibit a chiral SmC phase or exhibit a liquid crystal phase. However, many of them do not have the above-mentioned problems, and they are not necessarily satisfactory.

[0007]

DISCLOSURE OF THE INVENTION The present inventors have obtained a novel optically active compound that does not lower the upper limit temperature of the ferroelectric liquid crystal phase when added to SmC-Host and allows the creation of a ferroelectric liquid crystal composition with high-speed response. As a result of intensive research with the aim of Design new optically active compounds,
As a result of synthesis and evaluation, we have discovered a new optically active liquid crystal compound that does not lower the upper limit temperature of the ferroelectric liquid crystal phase when added and can create a ferroelectric liquid crystal composition that exhibits high-speed response.

That is, the present invention provides general formula (I)

[C5
] (In the formula, R1 and R2 each independently have a carbon atom number of 1
~14 alkyl group, n represents an integer from 1 to 6, Z represents a single bond, -O-, -COO- or -OCO-,

The present invention provides a liquid crystal composition containing a novel optically active fluoroalkyl derivative represented by the following formula and at least one compound thereof.

[0009] The methods for synthesizing these compounds will be outlined below as Synthetic Routes 1 and 2, and will be explained in more detail by presenting examples of the present invention.

[0010] It should be understood that the physical property values of the compounds and compositions in each example are affected by differences in the equipment and methods used to measure them, so that the numerical values may vary to some extent.

[0011]

[C7]

According to the method described in JP-A No. 62-93248, using a compound obtained by addition reaction of hydrogen fluoride to an optically active 1,2-epoxyalkane as a starting material, the above synthetic route 1 is carried out. Accordingly, n=1 to 6

[
Chemical formula 8] can be synthesized.

That is, regarding a compound where m=1,

Obtained by chlorinating [Chemical 9] with thionyl chloride and then cyanating with sodium cyanide.

If [Chemical 10] is hydrolyzed with alkali and then esterified with alcohol/sulfuric acid,

[Chemical formula 11] is obtained.

[0014] By reducing this ester compound with lithium aluminum hydride, it has one more carbon atom than the starting material.

[Chemical formula 12] is obtained.

Obtained

[Chemical formula 13] using the same route as the starting material

[Chemical formula 14] can be synthesized.

[0016] Thus, n=m+1=2 to 6.

[Chemical formula 15] of

It can be synthesized sequentially using [Image Omitted] as a raw material. synthesized in this way

[Chemical formula 17] is reacted with tosylic acid chloride, which is the raw material for the next step of etherification,

[Chemical formula 18] can be obtained.

[0017]

[Chemical formula 19]

Target substance 1 can be obtained by [synthetic route 1]

[
It can be synthesized by an etherification reaction with

Target substance 2 can be obtained by [synthetic route 1]

[
Obtained by etherification reaction with

[C22] with Bayer-Villiger oxidation.

It can be obtained by synthesizing [Image Omitted] and etherifying it with an alkyl bromide.

[0020]

[Chemical formula 24] are respectively disclosed in Japanese Patent Application Laid-open No. 2-165937 and Japanese Patent Application No. 1-1999.
Synthesized according to the method described in No. 336366.

[0021] Details will be explained below with reference to examples, and the abbreviations described in this specification, including the examples, have the following meanings: C Crystalline SmC, SC Smectic C phase SA
Smectic A phase Ch
Cholesteric phase Ne Nematic phase I Isotropic liquid

0
Example 1

embedded image Into the reactor, (2R)-2-fluorooctanol 10.
0 g and 25 ml of pyridine were added, 13.0 g of tosyl chloride was added under stirring at 0 to -5°C, and after reaction for 6 hours, it was poured into water and extracted with 100 ml of benzene. The resulting benzene solution was mixed with water, NaHCO3 After washing with an aqueous solution and water in that order, drying with Glauber's salt, and then distilling off the solvent to remove the residue [
Crude (2R)-2-fluorooctyl tosylate]19.
0 g (yield 92.6%) was obtained. GLC90.8%.

[0023]

embedded image 2.0 g of (2R)-2-fluorooctyl tosylate obtained in (a) and 2-fluoro-4-hydroxy-
Charge 2.1 g of 4'-octyloxybiphenyl, 1.8 g of potassium carbonate and 20 ml of cyclohexanone,
The mixture was heated and stirred at 40°C for 6 hours. The reaction solution was poured into diluted hydrochloric acid, extracted with ether, washed with water, and dried over sodium sulfate. The solvent was distilled off, and the residue was decolorized by refluxing with alumina/hexane for 1 hour. Alumina was removed by filtration, hexane was distilled off, and the residue was recrystallized from acetone to yield 2.0 g of (R)-2-fluoro-4-(2-fluorooctyl)oxy-4'-octyloxybiphenyl. 67.7%).

[0024] The purity of this product was 99.5% by HPLC, and a molecular ion peak was observed at 446 by IR and Mass analysis, and based on the raw materials used,
It was confirmed that the obtained substance was the desired substance.

[0025] This item was installed on the Mettler Hot Stage FP-8.
The results of observing the phase change under a polarizing microscope equipped with 2 are shown below.

[0026]

Example 2

embedded image 3.4 g of (R)-2-fluorooctyl tosylate obtained in Example 1(a) and 3,3′-difluoro-4-hydroxy-4″-acetyl-p-terphenyl were placed in a reactor. 3.3 g of potassium carbonate, 2.8 g of potassium carbonate, and 40 ml of cyclohexanone were charged, and heated and stirred at 140°C for 9 hours.The reaction solution was poured into dilute hydrochloric acid, extracted with ether, washed with water, dried with Glauber's salt, and the solvent was distilled off. The residue was recrystallized from acetone to give (S)-3,3'-difluoro-4-(2-fluorooctyl)oxy-4''-acetyl-p-terphenyl 3.26 g (yield 70.4 %) was obtained. GLC99.
0%.

[0028]

embedded image Into the reactor, (S)-3,3′-difluoro- obtained in (a)
3.26 g of 4-(2-fluorooctyl)oxy-4″-acetyl-p-terphenyl in methylene chloride solution 32
12 g of 88% formic acid under stirring at below 0°C.
5.1 g of acetic anhydride, 0.2 ml of concentrated sulfuric acid, and then 9.0 g of 35% hydrogen peroxide were sequentially added dropwise, and after the dropwise addition, the mixture was heated under reflux at 40° C. for 48 hours. The reaction solution was poured into water, extracted with methylene chloride, washed with water until the washing solution became neutral, dried with Glauber's salt, the solvent was distilled off, the residue was charged into another reactor, and 90 ml of methanol and 15 % KOH aqueous solution was added thereto, and the mixture was stirred at 70°C for 3 hours.

After pouring the reaction solution into water and making it acidic with hydrochloric acid,
It was extracted with ether, washed with water, dried with Glauber's salt, and then the solvent was distilled off. The residue was purified by silica gel column chromatography (eluent: benzene/methylene chloride = 1:1) to obtain (S)-3,3'-difluoro-4-(2-fluorooctyl)oxy-4''-hydroxy-p-terphenyl 1.84 g (yield (60.4%)) was obtained. TLC
1 spot.

[0030]

embedded image Into the reactor, (S)-3,3′-difluoro- obtained in (b)
4-(2-fluorooctyl)oxy-4″-hydroxy-p-terphenyl 1.8 g, octyl bromide 0
．． 9g, potassium carbonate 1.2g and cyclohexanone 2
0 ml was charged, and the mixture was heated and stirred at 140°C for 7 hours. The reaction solution was poured into diluted hydrochloric acid, extracted with ether, washed with water, and dried over sodium sulfate.The solvent was distilled off, and the residue was subjected to silica gel column chromatography (eluent: benzene/hexane = 2:1).
) and further recrystallized with acetone to obtain S)-3,3'
-difluoro-4-(2-fluorooctyl)oxy-
2.0 g (yield: 86.1%) of 4''-octyloxy-p-terphenyl was obtained.

The purity of this product was 99.9% by HPLC. Furthermore, it was confirmed that the obtained substance was the target substance based on the fact that a molecular ion peak was observed at 540 in IR and Mass analysis, and on the basis of the raw materials used.

[0032] This item was installed on the Mettler Hot Stage FP-8.
The results of observing the phase change under a polarizing microscope equipped with 2 are shown below.

[0033]

Example 3 The following four pyrimidine compounds and SmC-
Adjusted the host liquid crystal.

[0035]

embedded image The phase transition temperature of the present pyrimidine-based SmC-Host liquid crystal upon cooling is shown below.

A ferroelectric liquid crystal composition was prepared by adding 10 wt % of the following compound obtained in Example 1 to the SmC-Host.

[0037]

[Chemical formula 31]

The phase transition temperature of this ferroelectric liquid crystal composition upon cooling is , and the upper limit temperature of the chiral SmC phase is SmC-Hos
It is the same as the SmC phase upper limit temperature of the t-liquid crystal, and has not decreased.

[0039] This ferroelectric liquid crystal composition was applied to the surface of a cell with a thickness of 3 and had a transparent electrode, which was subjected to parallel alignment treatment by coating polyvinyl alcohol (PVA) on the surface and rubbing the surface.
Chiral Sm from an isotropic liquid is sealed in a μm liquid crystal cell.
A liquid crystal device was produced by slowly cooling to the C phase.

[0040] This liquid crystal element was sandwiched between two polarizing plates, and
When a 5V, 200Hz square wave was applied and the response time was determined from the change in transmitted light intensity, it was 263μsec at 25℃.
Met. In addition, when the spontaneous polarization was measured using the Sawyer-Tower method, it was 8.3 nC/cm2 at the same temperature, and the tilt angle measured from the shift angle of the extinction position when the polarity of the applied voltage was reversed was 26.2°. there were.

Example 4 A ferroelectric liquid crystal composition was prepared by adding 10 wt % of the following compound obtained in Example 2 to the SmC-Host prepared in Example 3.

[0042]

[C32]

The phase transition temperature of this ferroelectric liquid crystal composition upon cooling is , and the upper limit temperature of the chiral SmC phase is SmC-Ho
It is higher than the SmC phase upper limit temperature of the st liquid crystal, and is increased by the addition of the compound according to the present invention.

The response time, spontaneous polarization, and tilt angle of this ferroelectric liquid crystal composition were measured by the method described in Example 3. As a result, the response time at 25° C. was 279 μsec, the spontaneous polarization was 5.2 nC/cm2, and The tilt angle was 25.8°.

As described above, the optically active compound according to the present invention has extremely excellent properties as a liquid crystal component when producing a ferroelectric liquid crystal display element, and is a useful substance with high practical value. be.

Claims (6)

[Claims] Claim 1: General formula (I) [Formula 1] (wherein R1 and R2 each independently have a carbon atom number of 1
-14 alkyl group, n represents an integer from 1 to 6, Z represents a single bond, -O-, -COO- or -OCO-, and is an optically active fluoroalkyl derivative represented by the following formula. 2. The optically active fluoroalkyl derivative according to claim 1, wherein n in the general formula (I) is 1. 3. The optically active fluoroalkyl derivative according to claim 2, wherein Z in the general formula (I) is O. Claim 4: General formula (I) [Formula 3] (wherein, R1 and R2 each independently have a carbon atom number of 1
~14 alkyl group, n represents an integer from 1 to 6, Z represents a single bond, -O-, -COO-, or -OCO-, and at least an optically active fluoroalkyl derivative represented by A liquid crystal composition characterized by containing one type. 5. A liquid crystal composition containing at least one optically active fluoroalkyl derivative according to claim 4, wherein n is 1 in the general formula (I). 6. In the general formula (I), Z is -O-
A liquid crystal composition containing at least one optically active fluoroalkyl derivative according to claim 4.