JPS6013032B2 - 4↓-alkyl↓-4′↓-(4″↓-cyanobenzoyloxy)↓-3′↓-cyanobiphenyl - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compound represented by the general formula [wherein R represents a direct mirror alkyl group having 1 to 8 carbon atoms].

One of the display principles that utilizes the electro-optic effect of liquid crystals is a dual-frequency display element.

This takes advantage of the fact that liquid crystals that exhibit positive dielectric anisotropy in the low frequency range exhibit negative dielectric anisotropy in the high frequency range above a certain value. Anisotropy is highly positive in the low frequency region;
Furthermore, in the high frequency region, the larger the negative absolute value, the lower the driving voltage, which is advantageous in terms of power consumption. Many compounds have been known to have positive dielectric anisotropy or negative dielectric anisotropy, but a single compound can give a large amount of positive dielectric anisotropy in the low frequency region, while giving a large amount of positive dielectric anisotropy in the high frequency region. No compound is known that provides a large absolute value of negative dielectric anisotropy. Although such a compound is preferably present as a liquid crystal compound, in reality, even a compound that does not exhibit a liquid crystal phase can be used by mixing a compound having the above-mentioned characteristics with a liquid crystal composition. An object of the present invention is to provide a compound that can be added to a dual-frequency liquid crystal composition to impart large positive dielectric anisotropy in the low frequency region and dielectric anisotropy with a large negative absolute value in the high frequency region. It is something. The compound of the present invention is represented by the general formula [wherein R represents a Dokyo alkyl group having 1 to 8 carbon atoms].

4-alkyl-4'-(4''-cyanobenzoyloxy)-gorcyanobiphenyls.

The reaction system for this compound is shown below, and the method for producing it will be briefly explained. Reaction System 1 [In the formula, R'CO1 represents a Dokyo alkanoyl group having 1 to 7 carbon atoms, and becomes R by reduction.

R represents a straight chain alkyl group having 1 to 8 carbon atoms. 〕first,
Brominated 4-phenylphenol to form 2-bromo-4-
Obtain phenylphenol.

This is 1. Reaction with dimethyl sulfate in an alkaline solution gives 3-furomo-4-methoxybiphenyl. This is subjected to a Friedel-Crafts acylation reaction with an alkanoyl chloride in dry methylene chloride using aluminum chloride as a catalyst to obtain 4-alkanoyl-4'-methoxy-13'-bromobiphenyl. This is subjected to a Wolf-Kishner reduction reaction in diethylene glycol in the presence of hydrazine hydrate and potassium hydroxide to obtain 4-alkyl-4'-methoxy-3'-bromobiphenyl. This is further demethylated with hydrobromic acid in glacial acetic acid to give 4-alkyl-4'-hydroxy-3-bromobiphenyl. Reaction system 2P-cyanobenzoic acid and thionyl chloride are reacted to obtain P-cyanobenzoyl chloride.

Reaction system 3 4-alkyl-4'-hydroxy-3-bromobiphenyl in reaction system 1 and P-cyanobenzoyl chloride in reaction system 2 are esterified in the presence of pyridine to form 4-alkyl-4'-(4''-cyanobenzoyloxy)-3'-promopyphenyl was obtained.

This is further cyanated with cuprous cyanide in N-dimethylformamide to produce the related 4-alkyl-4'-(4''-cyanobenzoyloxy)-3'-cyanobiphenyl. In the formula, R' represents an alkanoyl group having 1 to 7 carbon atoms, becomes R by a reduction reaction, and R represents a straight chain alkyl group having 1 to 8 carbon atoms] The following examples show examples of the production of related compounds. Example 1 Example 1-1 Commercially available 4-phenylphenol (0.294 mol) was dissolved in 350 ml of glacial acetic acid by gentle heating.
Add 48 moles (0.6 mol) of bromine at 80 °C
After the reaction, the solvent was removed by distillation, and the product was recrystallized from ligroin.
-bromo-phenylphenol 53 was obtained.

Next, add this 53 moles (0.213 mol) to 1. Dissolved in 500 ml of aqueous soda solution of the mark and 53 ml of dimethyl sulfate (0.
．． 42 mol) was added and the temperature was kept below 6,000 to perform coagulation, and after precipitation of white crystals, after coagulation for 30 minutes, the crystals were collected in a furnace, recrystallized from ethanol, and the melting point was 74.5q○.
2-bromo-4-methoxybiphenyl was obtained.

Next, this 30 mm (0.114 mol) was dissolved in 90% of dehydrated tyrene chloride, and after cooling to 0 to 5°C, 18 mm (0.1 mol) of anhydrous aluminum chloride, which had been sublimated and purified, was added. Furthermore, heptanoyl chloride 18.69 (0.1
14 mol) was gradually added dropwise, the mixture was cooled for a while, heated at room temperature for 1 hour, further heated to 40 qo, and heated for 4 hours to complete the reaction. Next, the reaction mixture was cooled again to 0 to 5°C, 60% of well-cooled concentrated hydrochloric acid was added thereto, and the mixture was stirred for 30 minutes to decompose the salt. The separated organic layer was washed with water three times, and the solvent was removed by distillation, and the product was recrystallized with ethanol to obtain 27.52 4-heptanoyl-4'-methoxy-3'-bromobifenyl having a melting point of 7 to 0. Next, this 27.5 mm (0.071 mol) was heated and dissolved in diethylene glycol 220, and 7.5 mm (0.15 mol) of hydrazine hydrate in diethylene glycol 50 was added. The reaction mixture was heated under reflux at 120 to 130°C for 1 hour, and then the reaction temperature was raised to 180 to 200°C while distilling off produced water and the like, and then heated under reflux for 5 hours. After the reaction, the mixture was cooled to room temperature, and an appropriate amount of hydrochloric acid was added to make an acidic solution. The precipitated crystals were removed by filtration, and ether was added to the filtration solution for extraction. After removing the ether by distillation, the product was recrystallized using a hexane filter to obtain 12.4 g of 4-octyl-4'-methoxy-3'-promobiphenyl having a melting point of 60. Next, this 12.4 evening (0.
033 mol) was dissolved in 200 molar glacial acetic acid, 47% hydrobromic acid was added, and after heating under reflux for 8 hours, 250 molar of glacial acetic acid was dissolved.
After cooling sufficiently, the precipitated crystals were collected by a furnace.
4-octyl-4'-oxy-3- with melting point 36.5oo
Promobiphenyl 11 units were obtained.

Example 1-2 10 moles (0.0 mol) of commercially available P-cyanobenzoic acid and 10.5 moles (0.088 mol) of thionyl chloride were tested and heated under reflux for 1 hour.

After the reaction, excess thionyl chloride was removed by distillation, and the residue was recrystallized from hexane to obtain 8.5 ml of P-cyanobenzoic acid chloride having a melting point of about 100°C. Examples 1-3 4-octyl-4'-oxine-3-bromopifenyl 5 (0.014 mol) in Examples 1-1 and P-cyanobenzoic acid chloride 2. in Examples 1-2.
After dissolving 300g (0.014 mol) in 160ml of pyridine, the solution was added to ice-cooled concentrated hydrochloric acid.

The precipitated crystals were recrystallized with ethanol and 4-octyl-4'-(4''-promobenzoyloxy)-3
5.6 ml of '-cyanobiphenyl was obtained. The melting point of this compound was 73qo. Example 1-4 4-octyl-4'-(4''-bromobenzoyloxy)-3'-cyanobiphenyl 4.92 (0.01 mol)
and 1.8 moles (0.02 mol) of cyanide in 50 [
of N-dimethylformamide and heated under reflux for 1 hour.

After refluxing, the reaction mixture was dissolved in a solution of ferric chloride in hydrochloric acid (FeC1
3. Mother L0 6 evening, HC12 [30 water screams] added 60
After maintaining the temperature at 0 and stirring for 30 minutes, the mixture was heated to 100
Pour into water to precipitate solid matter. After dissolving this solid in chloroform and washing with 5% sanitary soda solution, the chloroform was removed by distillation, and the product was purified with ethanol to form the 4-octyl-4'-(4''-cya/penzoyloxy)-3'- 2.5% of cyanobiphenyl was obtained. The melting point of this compound was 98°C. The infrared absorption spectrum of this compound is shown in Figure 1. Example 2 The compounds obtained by the present invention are shown in Table 1. The dielectric anisotropy was investigated by adding it to the liquid crystal composition shown below.

Table 1 shows the base liquid crystal composition, the compositional formula of the liquid crystal mixture containing the compounds shown in Table 2, the mixing ratio of each component, and the physical properties of each composition.・ Ship■ The average in the table shows the crossing frequency when the dielectric anisotropy of each liquid crystal composition changes from positive to negative, and △L shows the dielectric anisotropy in the low frequency region, and A Shows dielectric anisotropy in the high frequency region.

From this result, when the compound provided by the present invention is mixed into a liquid crystal material for a two-frequency method or a liquid crystal composition, the terminal -C3N of the compound itself is mainly used in the low frequency region. In the high frequency region above a certain value, -C=N of the side chain mainly acts to impart a large negative dielectric anisotropy.

In this way, increasing the absolute value of yield anisotropy lowers the driving voltage and helps reduce power consumption, and the compound provided by the present invention can be used as a material for dual-frequency display elements. It is valid.

[Brief explanation of the drawing]

FIG. 1 shows a 4-octyl 4'-(4''
FIG. 2 is an infrared absorption spectrum diagram of 1-3-cyanobiphenyl (cya/penzoyloxy).

Claims (1)

[Claims] 1 The general formula is 4-alkyl-4'-(, which is represented by a mathematical formula, a chemical formula, a table, etc.) [where R represents a straight-chain alkyl group having 1 to 8 carbon atoms] 4″-cyanobenzoyloxy)-3′-cyanobiphenyl.