JPS63280064A - Biphenylpyridine derivative - Google Patents

Abstract

NEW MATERIAL:A biphenylpyridine derivative shown by formula I (R is 1-12C alkyl; * is asymmetric carbon). EXAMPLE:4-(5-Nonylpyridin-2-yl)-4'-(2-chloro-3-methyl)pentanoyloxybiph enyl. USE:A stable, low-viscosity liquid crystal substance useful as a base component for a ferroelectric liquid crystal composition usable as an electro-optical switching element, showing chiral smectic C phase at in an extremely high- temperature and in a wide temperature range. PREPARATION:A compound shown by formula VII obtained from a compound shown by formula II through compounds shown by formula III-formula VII by fine processes is demethylated in acetic acid by the use of hydrobromic acid to give a compound shown by formula VIII. Then this compound is etherified with optically active 2-chloro-3-methylpentyltocylate in the presence of an alkali to give a compound shown by formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to novel ferroelectric liquid crystal materials, and more particularly to biphenyls which can constitute ferroelectric liquid crystal compositions used as electro-optic switching elements. Concerning pyridine derivatives.

[Conventional technology]

In recent years, ferroelectric liquid crystals are said to have extremely high-speed electro-optical switching characteristics and memory properties, and their practical application has been actively studied.

In general, the ferroelectricity of liquid crystals is expressed in a series of smectic phases that have optically active sites and have molecular alignment in which the long axes of the molecules are tilted from the perpendicular direction of the layers. Among them, chiral smectic C phase C (hereinafter abbreviated as SmO) has relatively low voltage operability and is advantageous in practice.

As conventional ferroelectric liquid crystals, for example, thick-type, azoxy-type, and ester-type compounds edited by Okano, Kobayashi, etc. [Liquid Crystal Basics Edition, P140゜, (1985)]
Also known are phenylpyrimidine compounds reported by Taro, Harada, Suenaga, etc. [Proceedings of the 11th Liquid Crystal Symposium, 2N18.2N19, (1985)].

[Problem that the invention seeks to solve]

However, these have the following drawbacks:
KJ, Schiff type and azoxy type have poor moisture resistance and light resistance. In addition, ester types are highly viscous and are not very desirable in terms of high-speed response, while phenylpyrimidine types have excellent stability and relatively low viscosity and can be said to be practical as basic components. SmC! Since the temperature at which * occurs tends to be near or below room temperature, it is insufficient to compensate for the practical temperature range.

Therefore, under these circumstances, there is a demand for a compound that has excellent stability and low viscosity and exhibits SmC* in a higher temperature range.

An object of the present invention is to provide a compound that is excellent in stability and low viscosity and exhibits SmC* in a high temperature range in order to meet such crab N.

[Means for solving problems]

That is, the present invention is a biphenylpigetine derivative represented by the following general formula [E].

(However, in the formula, R represents an alkyl group having 1 to 12 carbon atoms, and * represents an asymmetric carbon.) The compound represented by general formula (I) can be used in existing ferroelectric liquid crystals as illustrated in Examples. In comparison, it exhibits SmO* at extremely high temperatures and in a wide temperature range.

In addition, CI) has no instability factors against various environments such as heat, light, moisture, and electric fields, and has remarkable stability.
) has two large permanent dipoles formed by a chlorine bond directly connected to an asymmetric carbon and an adjacent carbonyl, so it has a large spontaneous polarization.

And (I) has excellent mutual solubility with other liquid crystal systems and can easily constitute a liquid crystal composition.

The compound represented by the general formula [I] can be separated, for example, according to the following reaction steps.

<Reaction Steps> Step 4> ↓ HBr/Ac0H (However, in the formula, R represents an alkyl group having 1 to 12 carbon atoms, and * represents an asymmetric carbon.) The outline of the steps will be explained below.

Step 1>4-Bromo-4'-hydroxybiphenyl (u) was etherified with iodomethane in the presence of potassium hydroxide in ethanol to obtain 4-bromo-4'-methoxybiphenyl.

Step 2> Compound (2) was subjected to an organolithium-halogen exchange reaction in dry benzene under a nitrogen stream to obtain 4-lithio-4'-methoxybiphenyl (IV).

Step 3-1> Compound (IV) is reacted with dry pyridine in dry diethyl ether under a nitrogen stream to obtain a compound intermediate.

Step 6-2> Under a nitrogen stream, tetrahydrofuran and 1-bromoalkane are added to the reaction solution of step 3-1 containing the compound intermediate (V), and reacted to obtain the compound (b).

Step 3-3> The reaction solution of step 3-2 containing compound (b) is hydrolyzed to obtain 4-(5-alkylpyridin-2-yl)-4'-methoxybipheni/I/(b).

Step 4> Compound (b) was demethylated using hydrobromic acid in acetic acid to give 4-(5-alkylpyridin-2-yl)-4'
-Hydroxybiphenyl(b) obtained.

Step 5> Compound (b) is etherified with optically active 2-chloro-3-methylpentyl tosylate in the presence of an alkali to give 4-(5-argylpyridin-2-yl)-4'-(2
-chloro-3-methylpentyl)biphenyl (I) is obtained.

〔Example〕

Next, a specific production example of the compound represented by the general formula (I) will be shown.

Step 1> 4-bromo 41-hydroxybiphenyl 60t, "J
Udomethane 68f! , 20g of potassium hydroxide! , 500m of ethanol was taken and 44e! After the reaction was heated under reflux for a while, the ethanol was distilled off, and the residue was extracted with chloroform A.
15 and washed with water three times. Chloroform was distilled off, the residue was recrystallized from a mixed solvent of acetone and chloroform, and 4-
Bromo 4'-methoxybiphenylsay was obtained.

Step 2> Under a nitrogen stream, 50 t of 4-bromo-4'-methoxybiphenyl was dissolved in 350 d of dry benzene, and while stirring, 100 d of a hexane solution containing 15% loop tillithium was dissolved.
was added dropwise over 30 minutes, and stirring was continued for 2 hours. After one reaction, the precipitated crystals were filtered under nitrogen pressure and dried under reduced pressure to give 4-
Lithio-4'-methoxybiphenyl was obtained.

Step 3-1> Under a nitrogen stream, 4-lithio-4'-methoxybiphenyl was dissolved in 230 d of dry diethyl ether, and 15 ml of dry pyridine was added dropwise over 30 minutes while stirring and cooling to below 5°C. Stirring was continued for 30 minutes.

Step 3-2> Under a nitrogen stream, the reaction solution from Step 5-1 was cooled to -5°C or lower, and 300 m of tetrahydro 7 run was added to this while stirring. Next, cooling and stirring were maintained, and 1-bromononane was added. o
A 200 d solution of t7 tetrahydrofuran was added dropwise over 50 minutes. Thereafter, the temperature was returned to room temperature and stirring was continued for 30 minutes.

<Step 3-3> After adding 400 d of water to the reaction solution of Step 3-2 and stirring for a while, the ether layer was separated and washed with water three times. The ether was distilled off, the residue was treated with chloroform on a silica gel column, and the separated product was recrystallized from athenne to give 4-(5-)ylpyridin-2-yl)-4'-methoxybiphenyl 58t. Obtained.

Step 4>4-(5-nonylpyridin-2-yl)-4'-methoxybiphenyl 189.48% hydrobromic acid 13d and acetic acid 40m were taken and heated under reflux for 40 hours. After the reaction, the mixture was heated. Pour into 500 d of water, extract with lyaCt form,
Washed twice with water. Chloroform was distilled off, and the residue was recrystallized from a mixed solvent of acetone and chloroform to give 4-(5-
Nonylpyridin-2-yl')-4'-hydroxybiphenyl 2-6f was obtained.

Step 5>4-(5-)Nylpyridin-2-yl)-4'-hydroxybiphenyl 12 is dissolved in pyridishif d, and while stirring, 2-chloro-3-methylpentanoyl chloride 0
．． Added 6f. The 8-reaction mixture was then heated at 70°C for 3 hours and poured into 252ml of salt and ice, followed by extraction with chloroform. After washing the chloroform layer once with 5% potassium hydroxide and three times with water, the chloroform was distilled off. The residue was treated with chloroform on a silica gel column,
The separated product was recrystallized from a mixed solvent of acetone and methanol to give 4-(5-nonylpyridin-2-yl)-4'-(2
-chloro-3-methyl)pentanoyloxybiphenyl (174 was obtained.

Phase transition temperature (K indicates crystalline phase, sm* indicates smectic human phase, and d indicates isotropic liquid phase, respectively). By treating in the same manner as in Example 1 using 1-bromoalkane having M 1 to 12 carbon atoms instead of 1-promononanno in step 3-2, the following series of compounds can be produced.

〔Effect of the invention〕

As exemplified above, the compound of the present invention exhibits an extremely wide range of 3 mO in the high temperature range. Therefore, by appropriately blending this with other ferroelectric liquid crystal systems, the liquid crystal temperature characteristics can be improved. Furthermore, the compound of the present invention has a permanent dipole formed by a chlorine bond directly connected to an asymmetric carbon, so it has a large spontaneous polarization and can realize high-speed response, which is the basic principle of a ferroelectric liquid crystal composition. Useful as an ingredient.

that's all

Claims (1)

[Scope of Claims] A biphenylpyridine derivative represented by the following general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (However, in the formula, R represents an alkyl group having 1 to 12 carbon atoms, and * represents an asymmetric carbon.)