JP2825990B2 - 4-alkylcyclohexenyl tolan compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel tolan compound, and more particularly, to a novel alkyl compound which is useful for increasing the refractive index anisotropy of a liquid crystal material when mixed with an STN type liquid crystal material. It relates to a cyclohexenyl tolan compound.

[0002]

2. Description of the Related Art
STN-type liquid crystal cells are being developed toward black-and-white and full-color rather than green or blue modes, and at the same time, studies are being made on high-speed response to moving images. Conventionally, ferroelectric liquid crystal has been studied as a high-speed response, but a high-speed response is expected by making the thickness of the STN-type liquid crystal cell thinner. In that case, it is necessary to increase the anisotropy (Δn) of the refractive index of the liquid crystal material filled in the cell, and various studies have been made.

For example, alkyl crotyl oxytran compounds (Japanese Patent Application Laid-Open No. 62-277333) and alkylcyclohexyl fluorotolan compounds (Japanese Patent Application Laid-Open No. 63-277333)
No. 287737) or an alkyl alkynyl oxytran compound (Japanese Patent Application Laid-Open No. 2-83346) has been disclosed but is still insufficient, and a compound exhibiting a higher Δn has been desired.

[0004]

In view of the above situation, the present inventors have conducted intensive studies to find a compound having a low viscosity and a high Δn. As a result, a novel compound represented by the following general formula 2 is obtained. By adding a 4-alkylcyclohexenyltolan compound to the liquid crystal composition, Δn of the liquid crystal composition is remarkably improved, the dielectric anisotropy (Δε) is increased, and the liquid crystal composition has a high NI point. And arrived at the present invention.

[0005]

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That is, the present invention provides a 4-alkylcyclohexenyltolan compound represented by the above general formula 2 (same as the chemical formula 1) and a liquid crystal composition containing at least one of the compounds.

Hereinafter, the present invention having the above gist will be described in detail.

The alkyl group represented by R in the compound represented by the above general formula 2 according to the present invention includes, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl , Undecyl, dodecyl and the like.

Further, in the 4-alkylcyclohexenyltolan compound represented by the above general formula 2, X and Y
Examples of the halogen atom represented by include a fluorine atom, a chlorine atom and a bromine atom.

The compound represented by the above general formula 2 according to the present invention can be easily produced, for example, according to the scheme shown in the following chemical formula 3.

[0011]

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The thus obtained 4-alkylcyclohexenyltolan compound of the present invention is mixed with an STN-type liquid crystal material to form a liquid crystal material composition having a refractive index anisotropy (Δ
It is useful not only for increasing n) but also for various synthetic intermediates due to its excellent reactivity.

The liquid crystal composition of the present invention contains the 4-alkylcyclohexenyltolan compound of the present invention.
Usually, it is prepared by mixing at least one kind of the compound with a mother liquid crystal. Examples of the compound constituting the mother liquid crystal include compounds as shown in the following chemical formula 4.

[0014]

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The mother liquid crystals are usually used by mixing several or more of the above compounds. The liquid crystal composition of the present invention is obtained by mixing 1 to 30 parts by weight of the compound of the present invention with respect to 100 parts by weight of the mother liquid crystals. Is preferred.

[0016]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited at all by the following examples.

Example 1 Synthesis of 4-fluoro-4'-propylcyclohexenyltolan

[0018]

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1- (4-bromophenyl) -4-n-
Synthesis of propylcyclohexene

[0020]

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141.5 g of p-dibromobenzene was dissolved in 190 ml of dry tetrahydrofuran (THF) and added dropwise to a flask previously containing 15.1 g of magnesium metal and 70 ml of THF. A solution in which 56.1 g of 4-n-propylcyclohexanone was dissolved in 42 ml of THF was slowly added dropwise to the Grignard reagent generated by the above operation. After stirring for 1 hour, 30 ml of a saturated aqueous ammonium chloride solution was added to hydrolyze. The supernatant organic layer was separated by celite filtration, dried and desolvated. After adding 40.9 g of potassium hydrogen sulfate to the remaining liquid and performing a dehydration reaction at 150 to 170 ° C. under an argon atmosphere,
200 ml of toluene was added and the mixture was filtered. Desolvate the filtrate,
A silica gel column treatment was carried out using n-hexane as a developing solvent, followed by recrystallization with ethanol to give a melting point of 67 ° C.
45.2 g of the desired product were obtained.

Synthesis of 4- (4-n-propylcyclohexenyl) phenyl-2-methyl-3-butyn-2-ol

[0023]

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1- (4-bromophenyl) obtained in
-3-n-propylcyclohexene 30.7 g, 2-methyl-3-butyn-2-ol 13.9 g, triphenylphosphine 0.58 g, bis (triphenylphosphine) palladium (II) chloride 0.23 g and iodide Dissolve 0.17 g of copper in 110 ml of triethylamine,
The mixture was refluxed for 3 hours under an argon atmosphere. Cool to room temperature,
After adding dilute hydrochloric acid, the product was extracted with ethyl ether,
Washed with water. The product is dried and desolvated, then ethyl acetate /
After silica gel column treatment using n-hexane (20/80) as a developing solvent, recrystallization was performed with n-hexane to obtain 24.1 g of the desired product having a melting point of 125 ° C.

Synthesis of 4- (4-n-propylcyclohexenyl) phenylacetylene

[0026]

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4- (4-n-propylcyclohexenyl) phenyl-2-methyl-3-butyne-2 obtained in
24.1 g of ol and 0.56 g of sodium hydride were dispersed in toluene, and the mixture was heated under an argon atmosphere to distill off generated acetone. The remaining liquid was cooled to room temperature, washed with dilute hydrochloric acid and water, dried and desolvated.
The residue was subjected to silica gel column treatment using n-hexane as a developing solvent to obtain 19.0 g of the desired product having a melting point of 44 ° C.

4.7 g of the acetylene compound obtained in the synthesis of 4-fluoro-4'-propylcyclohexenyl tolane, 3.5 g of 1-bromo-4-fluorobenzene
g, 105 mg of triphenylphosphine, 42 mg of bis (triphenylphosphine) palladium (II) chloride and 30 mg of copper iodide were dissolved in 35 ml of triethylamine and refluxed for 3 hours under an argon atmosphere. After cooling to room temperature and adding dilute hydrochloric acid, the product was extracted with toluene and washed with water. After drying and removing the solvent, the product was subjected to silica gel column treatment using n-hexane as a developing solvent, and then recrystallized with ethanol / ethyl acetate (75/25), and further recrystallized with n-hexane. Objective 4
3.7 g of -fluoro-4'-n-propylcyclohexenyltran were obtained. The obtained target product was C-Sm127
Each physical property value of C, Sm-N 141 C, and N-I 143 C was shown.

As a result of infrared spectroscopy, the obtained reaction product had the following characteristic absorption and was confirmed to be the desired product.

2950 cm ^-1 , 2920 cm ^-1 , 286
^{0cm -1, 2210cm -1, 1600cm -1} , 1510
cm ^-1 , 1460 cm ^-1 , 1230 cm ^-1 , 1150c
^{m -1, 1090cm -1, 830cm -1} , 810cm -1,
520 cm ^-1

Example 2 Synthesis of 3,4-difluoro-4'-n-propylcyclohexenyltolan (formula 9)

[0032]

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4.7 g of the acetylene compound obtained in Example 1, 3.9 g of 1-bromo-3,4-difluorobenzene, 105 mg of triphenylphosphine, bis (triphenylphosphine) palladium (II) chloride 4
2 mg and 30 mg of copper iodide were dissolved in 35 ml of triethylamine and refluxed for 3 hours under an argon atmosphere. After cooling to room temperature and adding dilute hydrochloric acid, the product was extracted with toluene and washed with water. After drying and removing the solvent, the product was subjected to silica gel column treatment using n-hexane as a developing solvent, and then recrystallized with ethanol / ethyl acetate (80/20).
Further, recrystallization was performed once again with n-hexane to obtain 3.5 g of the target product, 3,4-difluoro-4′-n-propylcyclohexenyltran. The obtained target is C-
Physical properties of Sm 109 ° C, Sm-N 130 ° C, and NI 154 ° C were shown.

As a result of infrared spectroscopy, the obtained reaction product had the following characteristic absorption and was confirmed to be the desired product.

2950 cm ^-1 , 2920 cm ^-1 , 286
^{0cm -1, 2210cm -1, 1610cm -1} , 1590
^{cm -1, 1520cm -1, 1420cm -1} , 1330c
^{m -1, 1270cm -1, 1200cm -1} , 1100cm
^-1 , 950 cm ^-1 , 870 cm ^-1 , 820 cm ^-1 , 77
0cm ^-1

Example 3 Synthesis of 4-cyano-4'-n-propylcyclohexenyltolan

[0037]

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4.7 g of the acetylene compound obtained in Example 1, 3.6 g of 4-bromobenzonitrile, 105 mg of triphenylphosphine, 42 mg of bis (triphenylphosphine) palladium (II) chloride and 30 mg of copper iodide were added to 35 ml of the mixture. It was dissolved in triethylamine and refluxed for 2 hours under an argon atmosphere. After cooling to room temperature and adding dilute hydrochloric acid, the product was extracted with toluene and washed with water.
After drying and removing the solvent, the product was treated with a silica gel column using ethyl acetate / n-hexane (10/90) as a developing solvent, and then recrystallized with ethanol / ethyl acetate (75/25). Hexane / methylene chloride (8
0/20) and recrystallized again to obtain the desired product, 4-cyano-4'-n-propylcyclohexenyltolan.
4 g were obtained. The obtained target substance is C-N 127 ° C, N-I
Each physical property value at 254 ° C was shown.

As a result of infrared spectroscopy, the obtained reaction product had the following characteristic absorption and was confirmed to be the desired product.

2950 cm ^-1 , 2910 cm ^-1 , 286
^{0cm -1, 2210cm -1, 1590cm -1} , 1510
^{cm -1, 1450cm -1, 1400cm -1} , 1270
^{cm -1, 1140cm -1, 840cm -1} , 810c
m ^-1 , 550cm ^-1

Example 4 The addition of a 4-alkylcyclohexenyltolan compound of the present invention to a liquid crystal gave a Δn, NI point and Δε of the liquid crystal.
In order to see that is improved, an existing 4-n-alkylcyclohexanecarboxylic acid alkoxyphenyl ester-based liquid crystal composition [4- (C3-5 alkyl) cyclohexanecarboxylic acid-4 ′-(C1-5 alkoxy) phenyl 84% by weight of an ester mixture and 16% by weight of a mixture of 4- (C3-5 alkyl) cyclohexanecarboxylic acid-4 '-(4 "-methylphenoxycarbonyl) phenyl ester] and 90 parts by weight of the 4-alkylcyclohexenyltrans of the present invention. 10 parts by weight of the compound were mixed, and the changes in the above physical properties were measured. The results are shown in Table 1 below.

[0042]

[Table 1]

As is clear from the above results, the 4-alkylcyclohexenyltolan compound of the present invention was found to have the effect of increasing the values of Δn, NI point, and Δε of the mother liquid crystals.

[0044]

The 4-alkylcyclohexenyltolan compound of the present invention, when added to a liquid crystal composition, significantly improves the Δn of the liquid crystal composition and increases the dielectric anisotropy (Δε). Moreover, it has a high NI point.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07C 25/24 C07C 255/50 C07C 255/51 C09K 19/30 C09K 19/42 CA (STN)

Claims (2)

(57) [Claims] 1. A 4-alkylcyclohexenyl tolan compound represented by the following general formula 1. Embedded image 2. A liquid crystal composition comprising at least one of the 4-alkylcyclohexenyltolan compounds according to claim 1.