JP4030566B2 - Tolane derivative compound, liquid crystal composition, and liquid crystal electro-optical element - Google Patents

Description

  The present invention relates to a novel tolan derivative compound, a liquid crystal composition containing the compound, and a liquid crystal electro-optical element using the composition.

  Liquid crystal electro-optic elements are beginning to be used in various applications such as watches, calculators, measuring instruments, automotive instruments, photocopiers, cameras, display devices for office automation equipment, display devices for home appliances, and so on. Various performance requirements such as range, low operating voltage, high speed response, and chemical stability are made.

  However, at present, there is no material that satisfies all of these characteristics alone, and the required performance is satisfied as a liquid crystal composition in which a plurality of liquid crystal and non-liquid crystal compounds are mixed. For this reason, it is desired to develop a liquid crystal or non-liquid crystal compound excellent in one or more characteristics rather than all of the various characteristics.

In the field of electro-optic elements using liquid crystals, in the twisted nematic (TN) type cell, the refractive index of the liquid crystal material filled in the cell is used to prevent the occurrence of interference fringes on the cell surface, which causes the appearance of the cell to be impaired. It is necessary to set the product of the anisotropy value (Δn) and the cell thickness (d: μm) to a specific value. Since the value of Δnd is set to a constant value in this way, the value of d can be reduced by using a material having a large Δn value. If the value of d becomes small, the response time (τ) becomes small according to the well-known relational expression of τ∝d ² .

  Moreover, the response time can be reduced by using a compound having a low viscosity. Therefore, a compound having a large Δn value and a low viscosity is an excellent compound for producing a liquid crystal display cell having a high response speed and no interference fringes. Further, it is important that the liquid crystal compound is not only the physical properties but also has excellent compatibility with other liquid crystals or non-liquid crystals and is chemically stable.

In order to solve such problems, a tolan derivative compound represented by the following formula (2) has been proposed (Patent Document 1). In the formula (2), R ² represents a linear alkyl group having 1 to 10 carbon atoms, and X represents a chlorine atom or a fluorine atom.

JP-A-2-49746

  The compound represented by the above formula (2) is a compound having a large Δn value, a low viscosity, and a chemically stable compound, but is not sufficiently compatible with other liquid crystals or non-liquid crystals. There was a problem that the amount of addition of was limited.

  Thus, a compound satisfactory not only as a compound having a large Δn value, low viscosity and high chemical stability but also excellent compatibility with other liquid crystals or non-liquid crystals has not been obtained.

  The present invention provides a novel compound that solves the above-mentioned problems, that is, a tolan derivative compound represented by the following formula (1), a liquid crystal composition containing the compound, and liquid crystal electricity using the composition: An optical element is provided.

However, the symbol in Formula (1) shows the following meaning.
R ¹ : a C 1-6 aliphatic hydrocarbon group in which an etheric oxygen atom may be inserted between a hydrogen atom or a carbon-carbon single bond.
n: 0 or 1.
A: trans-1,4-cyclohexylene group, 1,4-phenylene group, or single bond.

  The novel tolan derivative compound (1) provided by the present invention is excellent in compatibility with other liquid crystals or non-liquid crystals, and is useful as a chemically stable compound for liquid crystals. In addition, the liquid crystal composition containing the tolan derivative compound (1) is low in viscosity, and a liquid crystal electro-optical element having the liquid crystal composition sandwiched between substrates with electrodes is an excellent element having a large Δn value. It is.

R ¹ in the tolan derivative compound (1) is a C 1-6 aliphatic hydrocarbon group in which an etheric oxygen atom (—O—) may be inserted between a hydrogen atom or a carbon-carbon single bond. Indicates.
Examples of the aliphatic hydrocarbon group in which an etheric oxygen atom is not inserted between carbon-carbon single bonds include an alkyl group, an alkenyl group, and an alkynyl group. The aliphatic hydrocarbon group preferably has a straight chain structure, and a trans alkenyl group is preferable in an alkenyl group in which a carbon-carbon double bond is present.

  Examples of the aliphatic hydrocarbon group in which an etheric oxygen atom (—O—) is inserted between carbon-carbon single bonds include an alkoxyalkyl group, an alkenyloxyalkyl group, an alkoxyalkenyl group, and an alkynyloxyalkyl group. And an alkyl group is preferable. These groups also preferably have a linear structure, and in the case of a group containing a carbon-carbon double bond, the bond is preferably a trans bond.

N in the tolan derivative compound (1) represents 0 or 1. When n is 0, it means that R ¹ and A are directly bonded. Further, when n is 0 and A is a single bond, it means that R ¹ and the 1,4-phenylene group which is an essential structural unit are directly bonded.
When n is 1, the R ¹ O— group is preferably an alkoxy group, an alkenyloxy group, an alkynyloxy group, and particularly preferably an alkoxy group.
Specific examples of R ¹ include those described in the examples.

Examples of the tolan derivative compound (1) of the present invention include compounds represented by the following formula (1a), the following formula (1b), and the following formula (1c), and in the formula (1a) or (1b) The compounds represented are preferred. Furthermore, the compound represented by the formula (1a) is preferably a case where n is 1 and R ¹ is a linear alkyl group. In the compound represented by the formula (1b), n is preferably 0 or 1, and R ¹ is a linear alkyl group, and particularly preferably n is 0.

The tolan derivative compound (1) of the present invention is a novel compound. The compound can be synthesized from a known compound according to the following method.
The symbols in the following formulas (3) and (4) have the same meaning as in the tolan derivative compound (1).

  That is, a phenylacetylene derivative (3) corresponding to the target compound and 2-fluoro-4-chloroiodobenzene (4) in the presence of a base such as diethylamine, a palladium catalyst such as dichlorobis (triphenylphosphine) palladium and By reacting with cuprous iodide as a catalyst, the desired tolan derivative compound (1) is obtained. In addition, the tolan derivative compound (1) of the present invention is not limited to the above synthesis method, and can be produced by various synthesis methods.

  The tolan derivative compound (1) of the present invention is a useful compound as a liquid crystal compound. The structure of the compound is characterized in that it has a fluorine atom at the 2-position of the benzene ring. The tolan derivative compound (1) of the present invention is a compound having a large Δn value and a low viscosity compound. In addition, it is chemically stable and particularly excellent in compatibility with other compounds such as other liquid crystals or non-liquid crystals. Therefore, by including the tolan derivative compound (1) of the present invention in another compound, the Δn value of the liquid crystal composition can be increased and the viscosity can be lowered.

  When a liquid crystal composition is used, usually one or more of the tolan derivative compounds (1) are included in other liquid crystal compounds or non-liquid crystal compounds. The amount of the tolan derivative compound (1) in the liquid crystal composition can be appropriately changed depending on the purpose of use, the purpose of use, the type of other compounds, etc., but in a normal case, 0.1% in 100 parts by weight of the composition. About 50 parts by weight is preferable, and 0.1 to 20 parts by weight is particularly preferable.

As other compounds in the case of a liquid crystal composition, it can be appropriately changed depending on the use and required performance, etc., but usually comprises a liquid crystal compound and a main component having a similar structure to the liquid crystal compound, and additional components as required. Those are preferred.
Specific examples of other compounds include components that improve dielectric anisotropy, components that exhibit liquid crystallinity at high temperatures, low viscosity components, components that adjust the refractive index anisotropy value, components that impart cholesteric properties, two colors Components exhibiting electrical properties, components imparting electrical conductivity, and the like.

Specific examples of other compounds in the case of a liquid crystal composition include the following compounds. R ³ and R ⁴ in the following formulas may be the same or different and each represents an alkyl group, an alkoxy group, a halogen atom, a cyano group or the like, and —Ph— represents a 1,4-phenylene group. -Cy- represents a trans-1,4-cyclohexylene group.

R ³ -Cy-Cy-R ⁴ ,
R ³ -Cy-Ph-R ⁴ ,
R ³ -Ph-Ph-R ⁴ ,
R ³ —Ph—C≡C—Ph—R ⁴ ,
^{R 3 -Cy-COO-Ph-} R 4,
R ³ -Ph-COO-Ph-R ⁴ ,
R ³ —Cy—CH═CH—Ph—R ⁴ ,
R ³ —Ph—CH═CH—Ph—R ⁴ ,
_{^{R 3 -Cy-CH 2 CH 2}} -Ph-R 4,
_{^{R 3 -Ph-CH 2 CH 2}} -Ph-R 4,
R ³ -Ph-N = N-Ph-R ⁴ ,
R ³ -Ph-NON-Ph-R ⁴ ,
R ³ -Cy-COS-Ph-R ⁴ ,
R ³ -Cy-Ph-Ph-R ⁴ ,
R ³ -Cy-Ph-C≡C-Ph-R ⁴ ,
R ³ -Cy-Ph-Ph-Cy-R ⁴ ,
R ³ -Ph-Ph-Ph-R ⁴ ,
R ³ -Cy-COO-Ph-Ph-R ⁴ ,
R ³ -Cy-Ph-COO-Ph-R ⁴ ,
^{R 3 -Cy-COO-Ph-} COO-Ph-R 4,
^{R 3 -Ph-COO-Ph-} COO-Ph-R 4,
^{R 3 -Ph-COO-Ph-} OCO-Ph-R 4.

  In the above compound, a hydrogen atom in the ring structure or terminal group may be substituted with a halogen atom, a cyano group, a methyl group, or the like. In addition, 1,4-phenylene group and trans-1,4-cyclohexylene group are divalent groups in which two hydrogen atoms of pyrimidine are bonds, and two hydrogen atoms of dioxane are bonds. The divalent group may be substituted with another 6-membered ring or a 5-membered ring such as a divalent group, and the divalent linking group between the rings may be changed to another divalent linking group. For these, various compounds may be selectively used according to the desired performance.

  Since the tolan derivative compound (1) of the present invention is a compound excellent in compatibility with other compounds, the concentration in the liquid crystal composition can be freely adjusted from a low concentration to a high concentration.

The liquid crystal composition containing the tolan derivative compound (1) of the present invention is introduced into a liquid crystal cell by a method such as injection and further sandwiched between substrates with electrodes to make a liquid crystal electro-optical element.
The liquid crystal electro-optical element can be used in various modes such as twisted nematic (TN), guest-host (GH), dynamic scattering, phase change, DAP, dual frequency drive, and ferroelectric liquid crystal display. Can be used.
As a typical liquid crystal electro-optical element, a TN liquid crystal electro-optical element can be cited. In addition, the liquid crystal electro-optical element here can be used for applications other than display applications, such as a dimming window, an optical shutter, and a polarization conversion element.

The liquid crystal electro-optical element is obtained by the following method. First, if necessary, an undercoat layer such as SiO ₂ or Al ₂ O ₃ or a color filter layer is formed on a substrate such as plastic or glass, and In ₂ O ₃ —SnO ₂ (ITO), SnO ₂ or the like is formed. After providing an electrode and patterning, if necessary, an overcoat layer of polyimide, polyamide, SiO ₂ , Al ₂ O ₃ or the like is formed and subjected to orientation treatment. A sealing material is printed on this, it arrange | positions so that an electrode surface may mutually oppose, a periphery is sealed, a sealing material is hardened, and an empty cell is formed.

  Further, a composition containing the compound of the present invention is injected into this empty cell, and the injection port is sealed with a sealant to constitute a liquid crystal cell. If necessary, this liquid crystal cell is laminated with a polarizing plate, a color polarizing plate, a light source, a color filter, a transflective plate, a reflective plate, a light guide plate, an ultraviolet cut filter, etc. Thus, a liquid crystal electro-optical element is obtained.

  The above description only shows the basic configuration and manufacturing method of the liquid crystal electro-optical element. For example, a substrate using a two-layer electrode, a two-layer liquid crystal cell having two liquid crystal layers, a TFT, and an MIM Various configurations such as an active matrix element using an active matrix substrate on which active elements such as the above are formed can be used.

  Further, the liquid crystal electro-optical element is in a mode other than the TN type, that is, a super twist nematic (STN) liquid crystal electro-optical element having a high twist angle, a GH liquid crystal electro-optical element using a polychromatic dye, It can also be used for dielectric liquid crystal electro-optic elements. Further, it can also be used for a device that writes data by heat rather than electrical.

  Examples of the present invention will be specifically described below. In the following examples, a group corresponding to an alkenyl group means a trans-alkenyl group, and a cyclohexyl group means a trans-cyclohexyl group.

[Example 1]
7.3 g (50 mmol) of 4-ethoxyphenylacetylene and 12.8 g (50 mmol) of 2-fluoro-4-chloroiodobenzene were dissolved in 40 ml of diethylamine, and 0.21 g (0.3 mmol) of dichlorobis (triphenylphosphine) palladium and After adding 0.19 g (1.0 mmol) of cuprous iodide, the mixture was stirred overnight at room temperature.

  Next, 300 ml of water is added to the reaction solution with stirring, extracted with toluene, washed with water, dried, purified by silica gel column chromatography, evaporated, and recrystallized twice with ethanol. 4.8 g (17 mmol) of -fluoro-4-chloro-4'-ethoxytolane was obtained. Melting point 73.3 ° C.

¹ H-NMR (CCl ₄ , TMS) δ (ppm): 1.37 (t, CH ₃ , 3H), 3.95 (q, CH ₂ , 2H), 6.7 to 7.35 (m, aromatic-H, 7H).
¹⁹ F-NMR (CCl ₄ , CFCl ₃ ) δ (ppm): -107.45 to -107.54 (m).
MS m / e 274 (M ^<+> ).

By using the corresponding 4-substituted (or unsubstituted) phenylacetylene instead of 4-ethoxyphenylacetylene in the same manner, the following compounds were obtained.
2-fluoro-4-chlorotolane,
2-fluoro-4-chloro-4'-methyltolane,
2-fluoro-4-chloro-4'-ethyltolane,

2-Fluoro-4-chloro-4'-n-propyltolane.
Melting point 42.5 ° C.
¹ H-NMR (CDCl ₃ , TMS) δ (ppm): 0.94 (t, CH ₃ , 3H), 1.58 to 1.72 (m, CH ₃ CH ₂ , 2H),
2.60 (t, C ₂ H ₅ CH ₂ , 2H), 7.10 to 7.47 (m, aromatic-H, 7H).
¹⁹ F-NMR (CDCl ₃ , CFCl ₃ ) δ (ppm): -107.90 to -108.02 (m).
MS m / e 272 (M ^<+> ).

2-fluoro-4-chloro-4'-n-butyltolane,
2-fluoro-4-chloro-4'-n-pentylsilane,
2-fluoro-4-chloro-4'-n-hexyltolane,

2-Fluoro-4-chloro-4'-methoxytolane.
Melting point: 85.4 ° C.
¹ H-NMR (CDCl ₃ , TMS) δ (ppm): 3.82 (s, CH ₃ O, 3H), 6.84 to 7.50 (m, aromatic-H, 7H).
¹⁹ F-NMR (CDCl ₃ , CFCl ₃ ) δ (ppm): -107.90 to -108.18 (m).
MS m / e 260 (M ⁺ ).

2-fluoro-4-chloro-4'-n-propoxytran,
2-fluoro-4-chloro-4'-n-butoxytran,
2-fluoro-4-chloro-4'-n-pentyloxytolane,
2-fluoro-4-chloro-4′-n-hexyloxytolan,
2-fluoro-4-chloro-4 '-(2-propenyl) tolane,
2-fluoro-4-chloro-4 '-(3-butenyl) tolane,

2-Fluoro-4-chloro-4 '-(3-pentenyl) tolane.
Melting point 57.0 ° C.
¹ H-NMR (CDCl ₃ , TMS) δ (ppm): 1.60 to 1.65 (m, CH ₃ , 3H), 2.22 to 2.31 (m, C ₃ H ₅ CH ₂ , 2H),
2.67 (t, C ₄ H ₇ CH ₂ , 2H), 5.34 to 5.51 (m, C ₂ H ₂ , 2H), 7.08 to 7.47 (m, aromatic-H, 7H).
¹⁹ F-NMR (CDCl ₃ , CFCl ₃ ) δ (ppm): -107.95 to -108.01 (m).
MS m / e 298 (M ^<+> ).

2-fluoro-4-chloro-4 '-(3-hexenyl) tolane,
2-fluoro-4-chloro-4 '-(5-hexenyl) tolane,
2-fluoro-4-chloro-4 '-(2-propenyloxy) tolane,
2-fluoro-4-chloro-4 '-(2-butenyloxy) tolane,
2-fluoro-4-chloro-4 '-(2-pentenyloxy) tolane,
2-fluoro-4-chloro-4 '-(3-pentenyloxy) tolane,
2-fluoro-4-chloro-4 '-(2-hexenyloxy) tolane,
2-fluoro-4-chloro-4 '-(4-hexenyloxy) tolane,

2-fluoro-4-chloro-4 ′-(1-propynyl) tolane,
Melting point 127.1 [deg.] C.
¹ H-NMR (CDCl ₃ , TMS) δ (ppm): 2.06 (s, CH ₃ , 3H), 7.10 to 7.46 (m, aromatic-H, 7H).
¹⁹ F-NMR (CDCl ₃ , CFCl ₃ ) δ (ppm): -107.60 to -107.75 (m).
MS m / e 268 (M ^<+> ).

2-fluoro-4-chloro-4 ′-(1-butynyl) tolane,
2-fluoro-4-chloro-4 '-(1-pentynyl) tolane,
2-fluoro-4-chloro-4 '-(1-hexynyl) tolane,
2-fluoro-4-chloro-4'-methoxymethyltolane,
2-fluoro-4-chloro-4'-ethoxymethyltolane,
2-Fluoro-4-chloro-4 '-(2-methoxyethoxy) tolane.

[Example 2]
11.3 g (50 mmol) of p- (4-n-propyl-cyclohexyl) phenylacetylene and 12.8 g (50 mmol) of 2-fluoro-4-chloroiodobenzene are dissolved in 100 ml of diethylamine, and dichlorobis (triphenylphosphine) palladium 21 g (0.3 mmol) and 0.19 g (1.0 mmol) cuprous iodide were added, followed by stirring overnight at room temperature.

  Next, 300 ml of water is added to this reaction solution with stirring, extracted with chloroform, washed with water, dried, purified by silica gel column chromatography, evaporated, and recrystallized twice with isopropyl alcohol-toluene mixed solvent. Thus, 14.4 g (41 mmol) of the intended 2-fluoro-4-chloro-4 ′-(4-n-propyl-cyclohexyl) tolane was obtained. Melting point (CN transition temperature) 116.1 [deg.] C. Clearing point (NI transition temperature) 201.2 ° C.

¹ H-NMR (CDCl ₃ , TMS) δ (ppm): 0.87 to 2.50 (m, aliphatic-H, 17H), 7.07 to 7.45 (m, aromatic-H, 7H).
¹⁹ F-NMR (CDCl ₃ , CFCl ₃ ) δ (ppm): -107.60 to -107.70 (m).
MS m / e 354 (M ^<+> ).

In the same manner, the following compounds were obtained by using the corresponding 4-substituted (or unsubstituted) phenylacetylene instead of p- (4-n-propyl-cyclohexyl) phenylacetylene.
2-fluoro-4-chloro-4 '-(cyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-methylcyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-ethylcyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-butylcyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-pentylcyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-hexylcyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-methoxycyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-ethoxycyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-propoxycyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-butoxycyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-pentyloxycyclohexyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-hexyloxycyclohexyl) tolane,

2-fluoro-4-chloro-4 '-[4- (2-propenyl) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (3-butenyl) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (3-pentenyl) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (3-hexenyl) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (5-hexenyl) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (2-propenyloxy) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (2-butenyloxy) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (2-pentenyloxy) cyclohexyl] tolane,
2-fluoro-4-chloro-4 '-[4- (3-pentenyloxy) cyclohexyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (2-hexenyloxy) cyclohexyl] tolane,
2-fluoro-4-chloro-4 '-[4- (4-hexenyloxy) cyclohexyl] tolane,
2-fluoro-4-chloro-4 '-[4-methoxymethylcyclohexyl] tolane,
2-fluoro-4-chloro-4 '-[4-ethoxymethylcyclohexyl] tolane,
2-fluoro-4-chloro-4 '-[4- (2-methoxyethoxy) cyclohexyl] tolane,

2-fluoro-4-chloro-4'-phenyltolane,
2-fluoro-4-chloro-4 '-(4-methylphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-ethylphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-propylphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-butylphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-pentylphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-hexylphenyl) tolane,

2-fluoro-4-chloro-4 '-(4-methoxyphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-ethoxyphenyl) tolane,
2-fluoro-4-chloro-4 ′-(4-n-propoxyphenyl) tolane, 2-fluoro-4-chloro-4 ′-(4-n-butoxyphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-pentyloxyphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-n-hexyloxyphenyl) tolane,

2-fluoro-4-chloro-4 '-[4- (2-propenyl) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (3-butenyl) phenyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (3-pentenyl) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (3-hexenyl) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (5-hexenyl) phenyl] tolane,

2-fluoro-4-chloro-4 '-[4- (2-propenyloxy) phenyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (2-butenyloxy) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (2-pentenyloxy) phenyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (3-pentenyloxy) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (2-hexenyloxy) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (4-hexenyloxy) phenyl] tolane,

2-fluoro-4-chloro-4 '-[4- (1-propynyl) phenyl] tolane,
2-fluoro-4-chloro-4 ′-[4- (1-butynyl) phenyl] tolane,
2-fluoro-4-chloro-4 '-[4- (1-hexynyl) phenyl] tolane,
2-fluoro-4-chloro-4 '-(4-methoxymethylphenyl) tolane,
2-fluoro-4-chloro-4 '-(4-ethoxymethylphenyl) tolane,
2-Fluoro-4-chloro-4 '-[4- (2-methoxyethoxy) phenyl] tolane.

[Example 3]
The clearing point (NI transition temperature) of the liquid crystal composition ZLI-1565 manufactured by Merck is 85.9 ° C., the viscosity at 25 ° C. is 14.4 cSt, and the Δn value is 0.125.
When 20 parts by weight of the compound of Example 1 (2-fluoro-4-chloro-4′-ethoxytolane) was added to 80 parts by weight of this composition, the clearing point (NI transition temperature) of the composition was 81. 1 ° C., the viscosity at 25 ° C. decreased to 13.7 cSt, and the Δn value increased significantly to 0.160. In addition, no crystal deposition was observed even when this composition was allowed to stand at 0 ° C. for 10 days.

[Comparative Example 1]
When 95 parts by weight of Merck's liquid crystal composition ZLI-1565 was added, 5 parts by weight of 4-chloro-4′-ethoxytolane, which is a known compound, and allowed to stand at 0 ° C. for 10 days, precipitation of crystals was observed. .

[Example 4]
When 10 parts by weight of the compound [2-fluoro-4-chloro-4 ′-(4-n-propylcyclohexyl) tolane] of Example 2 was added to 90 parts by weight of Merck liquid crystal composition ZLI-1565, The clearing point (NI transition temperature) of the composition rose to 95.7 ° C., the viscosity at 25 ° C. was 26.0 cSt, and the Δn value rose to 0.140. In addition, no crystal deposition was observed even when this composition was allowed to stand at 0 ° C. for 10 days.

Claims (6)

A tolan derivative compound represented by the following formula (1).

However, the symbol in Formula (1) shows the following meaning.
R ¹ : a C 1-6 aliphatic hydrocarbon group in which an etheric oxygen atom may be inserted between a hydrogen atom or a carbon-carbon single bond.
n: 0 or 1.
A: trans-1,4-cyclohexylene group, 1,4-phenylene group, or single bond.   The tolan derivative compound according to claim 1, wherein A is a single bond.   The tolan derivative compound according to claim 1, wherein A is a trans-1,4-cyclohexylene group.   A liquid crystal composition comprising the tolan derivative compound according to claim 1.   The liquid crystal composition according to claim 4, comprising 0.1 to 50 parts by weight of a tolan derivative compound in 100 parts by weight of the composition.   6. A liquid crystal electro-optical element obtained by sandwiching the liquid crystal composition of claim 4 or 5 between substrates with electrodes.