JPH045249A - Fluorine-containing tolan compounds - Google Patents

Abstract

NEW MATERIAL:The alkenyltolan compound of formula I (R is 3-6C alkenyl). EXAMPLE:4-(4'-Fluorophenyl)-4'-allyltolan. USE:An electrooptical display material. Especially useful for increasing the anistropy of refractive index of a liquid crystal material by mixing to a nematic- type liquid crystal material. PREPARATION:The objective compound of formula I can be produced by reacting dibromobenzene with magnesium, reacting the obtained Grignard reagent with an alkenyl bromide to obtain 4-bromoalkenylbenzene of formula II, reacting the compound with methylbutynol of formula III, decomposing the resultant 4-(4-alkenylphenyl)-2-methyl-3-butyn-2-ol of formula IV in the presence of a catalyst such as sodium hydride and reacting the produced 4- alkenylphenylacetone of formula V with the compound of formula VI.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a tolan compound useful as an electro-optical display material, and more specifically, it is capable of changing the refractive index of a liquid crystal material by mixing it with a nematic liquid crystal material. This invention relates to alkenyltolan compounds useful for increasing polarity.

[Prior art and problems] Currently, STN type liquid crystal cells are being developed from green or blue mode to black and white and full color, and at the same time, studies are being carried out to increase the speed of response to support video. There is. As for high-speed response, ferroelectric liquid crystals have been studied so far, but high-speed response is expected by making the layer thickness of the STN liquid crystal cell thinner. In that case,
It became necessary to use a liquid crystal material with a large refractive index anisotropy (Δn) to fill the cell. As a representative example, various tolan compounds that exhibit low viscosity and high Δn are disclosed in Japanese Patent Application Laid-Open No. 1983-1989.
-155142, JP-A-60-204734, JP-A-6
1-260031, JP-A-63-287737, etc., but these are still insufficient, and a compound exhibiting an even higher Δn has been desired.

[Means for solving problems]

In view of the above-mentioned current situation, the inventors of the present invention have developed a method that has a low viscosity and a high Δn.
As a result of intensive studies to find a compound that exhibits
It has been found that the nematic isotropic liquid transition point (Ni point) can be significantly improved.

(In the formula, R represents an alkenyl group having 3 to 6 carbon atoms.) In the compound represented by the above general formula (I) in the present invention, the alkenyl group having 3 to 6 carbon atoms representing R is 1-
Propenyl group, allyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 1-pentenyl! , 2-pen-fr-nyl group, 3-pentenyl group,
4-pentenyl group, 3-methyl-2-butenyl group, 3-
Examples include methyl-3-butenyl group.

Specific examples of the alkenyltolan compound represented by the above general formula (I) used in the present invention include, for example, 4-
(4"-fluorophenyl)-4"-(I-propenyl)tran, 4-(4"-fluorophenyl)-4'-
Allyltran, 4-(4“fluorophenyl)-4'
-(I-butenyl)tolan, 4- (4'-fluorophenyl)-4''-(2-butenyl)tolan, 4- (4
'-fluorophenyl)-4'-(3-butenyl)tolan,4-(4"-fluorophenyl)-4'-(Ipentenyl)tolan, 4- (4"-fluorophenyl)-4"-(2 -pentenyl)tolan, 4-(4°-fluorophenyl)-4'-(3-pentenyl)tolan, 4-(4°-fluorophenyl)-4'-(4-
pentenyl)tolan, 4-(4”-fluorophenyl)
-4'-(3-methyl-2-butenyl)toran, 4-
(4”-fluorophenyl)-4°-(3-methyl-
3-butenyl)tolan and the like.

The compound represented by the above general formula (I) in the present invention is:
It can be manufactured according to the following manufacturing method.

(I) A Grignard reagent produced by the reaction of dibromobenzene and magnesium is reacted with alkenyl bromide to obtain 4-furomoalkenylbenzene of formula (II).

(2) Compound (II) is reacted with methylbutynol of formula (III) using a catalyst such as bis(triphenylphosphine)palladium(II) chloride,
rV) 4-(4-alkenylphenyl)2-methyl-
3-butyn-2-ol is obtained.

(3) The compound of formula (IV) is decomposed in the presence of a catalyst such as sodium hydride to obtain 4-alkenylphenylacetylene of formula (V).

(4) Bis(triphenylphosphine)palladium(II) in 4-alkenylphenylacetylene of formula (V)
A compound of formula (I) is prepared by reacting a compound of formula (Vl) obtained from 4-fluorobiphenyl and iodine using a catalyst such as chloride.

The alkenyltolan compound of the present invention thus obtained is not only useful for increasing the anisotropy of the refractive index of a nematic liquid crystal material by being mixed with it, but also has excellent reactivity, so it can be used as a variety of synthetic intermediates. Useful.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 (I) Synthesis of 4-promoallylhenzene 41.5 g of p-dibromobenzene was added to dry tetrahydrofuran (T
HF), dissolved in 230 ml of magnesium metal in advance.
It was dropped into a flask containing 6.0 g and THFloom. A solution of 87.1 g of allyl bromide dissolved in THFloom was added dropwise to this Grignard reagent, and the mixture was allowed to stand overnight. Next, 120 m of a saturated ammonium chloride aqueous solution was added for hydrolysis, and the supernatant organic layer was separated by decantation, dried, and the solvent was removed, followed by vacuum distillation.
- 63.0 g of promoallylhenzen was obtained.

(2) 4-(4-allylphenyl)-2-methyl3-
63.0 g of 4-promoallylhenzene obtained in synthesis (I) of butyn-2-ol, 40.4 g of methylbutynol, 1 g of triphenylphosphine
．． 7 g, bis(triphenylphosphine) valadium (II) chloride 0.67 g and iodized steel 0.24 g were dissolved in 320 ml of triethylamine and heated under reflux.
Time reacted.

After cooling to room temperature and removing the salt, the solvent was removed, extracted with diethyl ether, and washed with dilute hydrochloric acid and distilled water. After drying and removing the solvent, the desired 4- (4-
24.1 g of allyl phenyl 3-butyn-2-ol was obtained.

(3) Synthesis of 4-allylphenylacetylene 24.1 g of 4-(4-allylphenyl)-2methyl-3-butyn-2-ol obtained in (2) and 0.4 g of sodium hydride
3 g was dispersed in 220 ml of dry toluene and reacted under an argon atmosphere at a maximum temperature of 110°C, and the acetone produced was distilled off. After cooling, it was washed with 5% hydrochloric acid and then further washed with water. After drying and removing the solvent, the resulting reaction product was distilled under reduced pressure to obtain 4-allylphenylacetylene 14.
9g was obtained.

(4) Synthesis of 4-fluoro-4'-iodobiphenyl 8.6 g of 4-fluorobiphenyl, iodine! Dissolve 5.1g of iodic acid and 2.0g of iodic acid in 22ml of acetic acid, and then add 1ml of concentrated sulfuric acid.
1 dissolved in 4 ml of water and 2 ml of carbon tetrachloride were added thereto, and the mixture was reacted at 85° C. for 2 hours. After cooling to room temperature, a saturated aqueous sodium thiosulfate solution was added to remove free iodine, extracted with methylene chloride, and washed with water. drying,
After removing the solvent, the obtained reaction product was subjected to silica gel column treatment using n-hexane as a developing solvent. Next, recrystallization was performed with ethanol to obtain 6.7 g of 4-fluoro-4°-iodobiphenyl.

(5) Synthesis of 4-(4'-fluorophenyl)-4'allyltran 4-fluoro-4'-iodobiphenyl 1.2g, bis(triphenylphosphine)palladium(I[)chloride 0.009g, iodized steel 0.008 g and diethylamine 1.23 g N,N dimethylformamide 3.0
In ml? I understand. A solution of 0.6 g of 4-allylphenylacetylene dissolved in N,N-dimethylformamide was added dropwise to this at room temperature, and the reaction was stirred for 6 hours. Extracted with diethyl ether and washed with dilute hydrochloric acid and water. After drying and removing the solvent, the reaction product was treated with a silica gel column using n-hexane as a developing solvent. Next, recrystallization was performed with ethanol to obtain net 4-(4°-fluorophenyl-allyltran. [Melting point 16
8°C] As a result of infrared spectroscopic analysis, the obtained product had the following characteristic absorption, and was confirmed to be the desired product.

3040cm-', 2200cm-'
, 1640cm-1590cm-',
1510cm-' 1410cm1240c
+w-'1190cm-' 116
0cm-'1100cm-', 990cm-
'910cm-'810cm-' Example 2 In order to show that the Δn and N-I points of liquid crystals are improved by adding the novel allyltolan compound of the present invention to liquid crystals, existing alkoxyphenyl alkylcyclohexanecarboxylate A 10% tolan compound was mixed into an ester-based liquid crystal composition, and changes in physical property values were measured, and the results are shown below.

〔Effect of the invention〕

As is clear from the above results, the novel allyltolan compound of the present invention increases the Δn value of the mother liquid crystal, and
The effect of increasing the N-1 point can be seen.

Claims (1)

[Claims] An alkenyltolan compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R represents an alkenyl group having 3 to 6 carbon atoms.)