JP5007289B2 - Optically active compound, liquid crystal composition, and liquid crystal electro-optical element - Google Patents

Description

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

Liquid crystal electro-optic elements are used for various applications such as display devices for office automation equipment, measuring instruments, automotive instruments, display devices for home appliances, watches, calculators and the like.
In a liquid crystal electro-optical element, a pair of substrates having a transparent electrode, an intermediate protective film, and a liquid crystal alignment film formed on the surface of at least one substrate are arranged at a certain distance, and a liquid crystal material is sealed between the substrates. It has a structure, and functions as an optical switching element by applying a voltage from the electrode to the liquid crystal material and changing the alignment state of the liquid crystal material to change the optical properties.
In the twisted nematic (TN) type and super twisted nematic (STN) type liquid crystal electro-optical elements, a liquid crystal composition to which a small amount of an optically active compound (chiral agent) is added is used in order to achieve uniform twist alignment. Yes.
Examples of the optically active compound that is currently widely used include a compound represented by the following formula (CN), a compound represented by the following formula (CB-15), or the following formula (R-811). There are compounds.

The helical pitch length induced when an optically active compound is added to the liquid crystal composition is determined by the helical induction force inherent to the compound. An optically active compound having a smaller helical induction force has a longer induced helical pitch length, and the amount added must be increased in order to shorten the helical pitch length. In general, when the amount of the optically active compound added is increased, the performance as a liquid crystal material is reduced as compared to before addition, the viscosity is increased, the response speed is decreased, the driving voltage is increased, the isotropic phase transition temperature is decreased, Problems arise such as a reduction in the temperature range showing a specific phase such as a nematic phase or a cholesteric phase. Therefore, an optically active compound having a large helical induction force is required.
In order to solve such a problem, Japanese Patent Application Laid-Open No. 10-251185 proposes an optically active compound having a small viscosity and a large helical induction force.

  In recent years, a cholesteric liquid crystal composition obtained by adding a large amount (about 10 to 30% by weight) of an optically active compound to a nematic liquid crystal composition is used, and the cholesteric liquid crystal has a wavelength of a product of the average refractive index of the liquid crystal material and the helical pitch length. Reflective cholesteric liquid crystal elements utilizing the phenomenon of selectively reflecting light are attracting attention. Since this reflective cholesteric liquid crystal element does not require a polarizing plate and a color filter, the light utilization efficiency is high. In addition, since the display state is maintained (memory property), the voltage may be applied only at the time of switching (writing) the display, and it has a feature of low power consumption. However, since a large amount of the optically active compound is added, the viscosity of the cholesteric liquid crystal composition is large, which causes problems such as a slow response speed and a high driving voltage. In order to solve these problems, an optically active compound having a larger helical induction force than that of the optically active compound disclosed in the above-mentioned JP-A-10-251185 and capable of obtaining the desired helical pitch length even with a small amount of addition. Is required.

Furthermore, many practical liquid crystal compositions are prepared by mixing one or more compounds each having a nematic phase near room temperature and a compound having a nematic phase in a temperature region higher than room temperature. In recent years, with the diversification of application products of liquid crystal electro-optic elements, liquid crystal compounds whose operating temperature range has been expanded to the high temperature side are required. For this reason, the transition temperature from the liquid crystal phase to the isotropic phase [hereinafter transparent A liquid crystal composition having a high point (denoted as point (Tc)] is required.
Therefore, an optically active compound that does not lower the clearing point (Tc) of the liquid crystal composition when added to the liquid crystal composition is required.

The present invention provides a novel compound to solve the above-mentioned problems, and has the following formula (1)
R ¹ -A ¹ -C ^* HX-Y-A ² -Z ¹ -A ³ -Z ² -A ⁴ -R ² (1)
(However, the symbol in formula (1) is
C ^* : asymmetric carbon atom,
A ¹ : an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having 1 to 2 fluorine atoms ,
A ² , A ³ , A ⁴ : independently of each other, an unsubstituted 1,4-phenylene group, a 1,4-phenylene group having one or more halogen atoms, or an unsubstituted trans-1,4-cyclo Hexylene group,
R ¹ : hydrogen atom,
R ² : an alkyl group having 1 to 10 carbon atoms , an alkenyl group or an alkynyl group, a hydrogen atom, a halogen atom or a cyano group ,
X: - CH _3,
Y: —CH ₂ —,
Z ^1, Z ^2: independently of one _{another, -COO-, - CH 2 CH 2} - or a single bond, represents a.
Provided that A ² is an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having one or more halogen atoms, and A ³ and A ⁴ are both trans-1,4-cyclohexylene. a group, and, if Z ¹ is a single bond, Z ² is, -COO- or a single bond. ) (Wherein Ph—C ^* H (CH ₃ ) —CH ₂ —Ph—Cy—Cy—C ₃ H ₇₎ and Ph—C ^* H (CH ₃ ) —CH ₂ — A compound represented by Cy-Cy-Cy-C ₃ H ₇ (Ph represents an unsubstituted 1,4-phenylene group, Cy represents an unsubstituted trans-1,4-cyclohexylene group) , and A ⁴ is a 1,4-phenylene group having 1 to 2 fluorine atoms, and R ² is a cyano group or a fluorine atom .

Here, in the optically active compound, in formula (1), A1 is an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having 1 to 2 fluorine atoms, and X is —CH. ₃ and Y is —CH ₂ — .

Further, in the formula (1), A ² , A ³ and A ⁴ are independently of each other an unsubstituted 1,4-phenylene group, a 1,4-phenylene group having 1 to 2 fluorine atoms or a non- It is preferably a substituted trans-1,4-cyclohexylene group, and Z ¹ and Z ² are independently of each other —COO—, —CH ₂ CH ₂ — or a single bond.

In addition, in the formula (1), A ² is preferably a 1,4-phenylene group having 1 to 2 fluorine atoms.

  In addition, the present invention provides a liquid crystal composition containing at least one of the optically active compounds, and a liquid crystal electro-optical element formed by sandwiching the liquid crystal composition between substrates with electrodes.

The optically active compound of the present invention is a novel compound. Since the compound has a large helical induction force, a desired pitch length can be obtained with a small addition amount. Further, it is an optically active compound that does not lower the clearing point (Tc) of the liquid crystal composition when added to the liquid crystal composition.
A liquid crystal electro-optical element using the liquid crystal composition of the present invention containing such an optically active compound has a high response speed, a wide operating temperature range, and an excellent display quality.

The present invention will be described in detail below.
The optically active compound of the present invention is an optically active compound represented by the following formula (1) [hereinafter also referred to as optically active compound (1)].
R ¹ -A ¹ -C ^* HX-Y-A ² -Z ¹ -A ³ -Z ² -A ⁴ -R ² (1)
(However, the symbol in formula (1) is
C ^* : asymmetric carbon atom,
A ¹ : an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having 1 to 2 fluorine atoms ,
A ² , A ³ , A ⁴ : independently of each other, an unsubstituted 1,4-phenylene group, a 1,4-phenylene group having one or more halogen atoms, or an unsubstituted trans-1,4-cyclo Hexylene group,
R ¹ : hydrogen atom,
R ² : an alkyl group having 1 to 10 carbon atoms , an alkenyl group or an alkynyl group, a hydrogen atom, a halogen atom or a cyano group ,
X: - CH _3,
Y: —CH ₂ —,
Z ^1, Z ^2: independently of one _{another, -COO-, - CH 2 CH 2} - or a single bond, represents a.
Provided that A ² is an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having one or more halogen atoms, and A ³ and A ⁴ are both trans-1,4-cyclohexylene. a group, and, if Z ¹ is a single bond, Z ² is, -COO- or a single bond. )

The optically active compound (1) of the present invention has a tetracyclic structure, and further, the asymmetric carbon atom C ^* and the cyclic group A ¹ are directly bonded to each other, but the clearing point (Tc) is very high. It has excellent characteristics such as viscosity and large helical induction force. In addition, the optically active compound (1) is chemically stable and has excellent compatibility with other liquid crystal or non-liquid crystal compounds.

Specifically, the optically active compound (1) of the present invention is preferably a compound as shown below. The carbon atom with the symbol ^{* in} the formula represents an asymmetric carbon atom, and the absolute configuration may be R or S. R ¹ , R ² , X, Y, Z ¹ and Z ² represent the same meaning as in formula (1). The configuration of the 1,4-cyclohexylene group in the formula is trans. The symbol (Hal) in the formula indicates that it is unsubstituted or substituted by one or more halogen atoms, and when two or more halogen atoms are substituted, May be different. In order to represent the substitution position when one or more halogen atoms are substituted, the substitution position is defined as shown below for convenience.

Preferred examples of the compound include the following.

  Each of these optically active compounds of the present invention has a large helical induction force, and at the same time, has a very high clearing point (Tc) and a low viscosity. In addition, it is chemically stable and excellent in compatibility with other compounds such as other liquid crystalline or non-liquid crystalline compounds.

In order to lower the driving voltage of the liquid crystal electro-optical element, a compound having a large dielectric anisotropy is used particularly when a liquid crystal composition having a large positive dielectric anisotropy is produced. Such a purpose is that R ² is a halogen atom or a cyano group and / or at least one of A ¹ , A ² , A ³ , A ⁴ has 1 or 2 halogen atoms. -Achievable by using a phenylene group. In this case, when R ² is a halogen atom or a cyano group, at least one of A ¹ , A ² , A ³ , A ⁴ has a halogen atom at the 3-position and / or 5-position, A 4-phenylene group is preferred.

A compound having negative dielectric anisotropy is used for a liquid crystal composition used for a liquid crystal electro-optical element driven by applying an electric field parallel to the molecular long axis direction of the liquid crystal compound. In the compound having negative dielectric anisotropy, at least one of A ¹ , A ² , A ³ and A ⁴ introduces a 1,4-phenylene group having a halogen atom at the 2-position and / or 3-position thereof This can be achieved.

In the liquid crystal composition used for the liquid crystal electro-optical element, several kinds of liquid crystalline or non-liquid crystalline compounds are mixed and used. Therefore, the optically active compound is required to have good compatibility with other liquid crystalline or non-liquid crystalline compounds. The optically active compound (1) of the present invention is excellent in compatibility with other liquid crystal or non-liquid crystal compounds, but at least one of A ¹ , A ² , A ³ and A ⁴ is halogenated. By using a 1,4-phenylene group having an atom, the compatibility can be further improved.

The helical pitch length induced when an optically active compound is added to the liquid crystal composition is determined by the helical induction force inherent to the compound. As described above, the addition of a large amount of an optically active compound degrades the performance of the liquid crystal material. Therefore, the optically active compound is required to have a large helical induction force in order to reduce the amount of addition.
The optically active compound (1) of the present invention has a large helical inductive force. However, when A ¹ and / or A ² is a 1,4-phenylene group having one or more halogen atoms, further helical induction is achieved. The power can be increased. At this time, A ¹ is preferably a 1,4-phenylene group having a halogen atom at the 3-position and / or 5-position, and A ² is a 1,4-phenylene group having a halogen atom at the 2-position and / or 6-position. A phenylene group is preferred.

When each of A ¹ , A ² , A ³ , and A ⁴ has one or more halogen atoms, the halogen atom is preferably a chlorine atom and / or a fluorine atom, and particularly has 1 to 3 fluorine atoms. preferable.
When R ² is a halogen atom, a chlorine atom, a bromine atom or a fluorine atom is preferable, and a chlorine atom or a fluorine atom is particularly preferable.

R ¹ is a hydrogen atom.
R ² is preferably a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms having one or more halogen atoms.
The aliphatic hydrocarbon group having 1 to 10 carbon atoms of R ² may have a linear structure or a branched structure. As the aliphatic hydrocarbon group, an alkyl group, an alkenyl group or an alkynyl group is preferable. Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, isobutyl group, 1-methyl-to Examples include a butyl group. As the alkenyl group having 1 to 10 carbon atoms, the carbon-carbon double bond in the group is preferably a trans bond, and a 3-butenyl group or a 3-trans-pentenyl group is particularly preferable.
Moreover, as a C1-C10 aliphatic hydrocarbon group which has a 1 or more halogen atom, the group by which one or more of the hydrogen atoms in the said aliphatic hydrocarbon group was substituted by the halogen atom is mentioned. As a halogen atom, a chlorine atom and / or a fluorine atom are preferable, and a fluorine atom is particularly preferable.

When R ² is a C 1-10 aliphatic hydrocarbon group or a C 1-10 aliphatic hydrocarbon group having one or more halogen atoms, the carbon-carbon bond in the group And / or an etheric oxygen atom (—O—) and / or an ester bond (—COO— and / or —OCO—) is inserted between the carbon-carbon bond connecting the group and the ring. Also good. Examples of the group having an etheric oxygen atom and / or ester bond inserted include an alkoxy group, an alkoxyalkyl group, an alkoxyalkoxy group, a fluoroalkoxy group, a fluoroalkoxyalkyl group, a perfluoroalkoxyalkyl group, an alkoxycarbonyl group, or an alkylcarbonyloxy group. Groups and the like.

Examples of alkoxy groups include methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, isobutoxy and 1-methyl-heptyloxy Is mentioned.
Examples of the alkoxyalkyl group include 2-methoxyethyl group, 2-ethoxyethyl group, 2-propoxyethyl group, 2-butoxyethyl group, 2-pentyloxyethyl group, 2-isobutoxyethyl group, 2- (1-methyl -Heptyloxy) ethyl group, 4-methoxybutyl group, 4-ethoxybutyl group, 4-propoxybutyl group, 4-butoxybutyl group, 4-pentyloxybutyl group and the like.
Examples of alkoxyalkoxy groups include 2-methoxyethoxy group, 2-ethoxyethoxy group, 2-propoxyethoxy group, 2-butoxyethoxy group, 2-pentyloxyethoxy group, 2-isobutoxyethoxy group, 2- (1-methyl -Heptyloxy) ethoxy group, 4-methoxybutoxy group, 4-ethoxybutoxy group, 4-propoxybutoxy group, 4-butoxybutoxy group, 4-pentyloxybutoxy group and the like.

  Moreover, when a C1-C10 aliphatic hydrocarbon group or a C1-C10 aliphatic hydrocarbon group having one or more halogen atoms has a branched structure, an asymmetric carbon atom is contained in these groups. It is preferable that a fluorine atom, a chlorine atom, a methyl group, a trifluoromethyl group or the like is bonded to the asymmetric carbon atom.

Also, X is - preferably - preferably because CH ₃ is easy to synthesize, Y is -CH ₂ especially a large helical twisting power are obtained.
Furthermore, Z ^1, Z ^2, independently of one _{another, -COO-, - CH 2 CH 2} - or a single bond.

Among these optically active compounds (1), (a) A ¹ is an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having 1 to 2 fluorine atoms, and X is − An optically active compound which is CH ₃ and Y is —CH ₂ — is one of particularly preferred embodiments because it has a particularly low viscosity and a large helical induction force.

In addition to (a), (b) A ² , A ³ and A ⁴ are independently of each other an unsubstituted 1,4-phenylene group and 1,4-fluorine having 1 or 2 fluorine atoms. An optical activity which is a phenylene group or an unsubstituted trans-1,4-cyclohexylene group, and Z ¹ and Z ² are independently of each other —COO—, —CH ₂ CH ₂ — or a single bond. The compound is one of the particularly preferred embodiments because of its low viscosity and high helical induction force.

Alternatively, in addition to (a) and (b), an optically active compound in which A ² is a 1,4-phenylene group having 1 to 2 fluorine atoms has a particularly high helical inductive force, and thus has a particularly preferred embodiment. One.

However, in the optically active compound (1) of the present invention, A ¹ and A ² are unsubstituted 1,4-phenylene groups, and A ³ and A ⁴ are unsubstituted trans-1,4-cyclohexylene. A group, Z ¹ and Z ² are single bonds, X is CH ₃ , Y is —CH ₂ —, R ¹ is a hydrogen atom, and R ² is the number of carbon atoms. 1 to 10 alkyl group, alkoxy group or alkenyl group, or hydrogen atom, or A ¹ is an unsubstituted 1,4-phenylene group, and A ² , A ³ , A ⁴ are unsubstituted A trans-1,4-cyclohexylene group, Z ¹ and Z ² are single bonds, X is —CH ₃ , Y is —CH ₂ —, R ¹ , R If ² is an alkyl group, an alkoxy group or alkenyl group or a hydrogen atom having 1 to 10 carbon atoms, Contact In addition, when A ⁴ is a 1,4-phenylene group having 1 to 2 fluorine atoms and R ² is a cyano group or a fluorine atom, it is preferably excluded.

  Since such an optically active compound (1) is chemically stable and excellent in compatibility with other liquid crystal or non-liquid crystal compounds, it can be mixed with these compounds to form a liquid crystal composition. The clearing point (Tc) can be further increased without increasing the viscosity of the liquid crystal composition. Therefore, the liquid crystal composition is an excellent composition for producing a liquid crystal electro-optical element having a high response speed and a wide operating temperature range.

  When the liquid crystal composition is used, usually at least one of the optically active compounds (1) of the present invention is used as another liquid crystal compound and / or a non-liquid crystal compound [hereinafter, other liquid crystal compounds and a non-liquid crystal compound. Are collectively referred to as other compounds]. The amount of the optically active 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, and the like. 1-50 mass parts is preferable, and 0.1-20 mass parts is especially 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 a liquid crystal compound and a main component having a similar structure to the liquid crystal compound, and additional components as necessary Those consisting of are preferred.
In the liquid crystal composition containing the optically active compound (1), examples of other compounds included in the composition include the following. In the following formula, Ph represents a 1,4-phenylene group, Cy represents a trans-1,4-cyclohexylene group, and PhF ₂ CN represents a 3,5-difluoro-4-cyanophenyl group. , R ³ and R ⁴ represent groups such as an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, a halogen atom and a cyano group. R ³ and R ⁴ may be the same or different from each other.

R ³ -Cy-Cy-R ⁴
R ³ -Cy-Ph-R ⁴
R ³ -Cy-PhF ₂ CN
R ³ -Ph-Ph-R ⁴
R ³ -Ph-C≡C-Ph-R ⁴
R ³ -Cy-COO-Ph-R ⁴
R ³ -Cy-COO-PhF ₂ CN
R ³ -Ph-COO-Ph-R ⁴
R ³ -Ph-COO-PhF ₂ CN
R ³ —Cy—CH═CH—Ph—R ⁴
R ³ -Ph-CH = CH-Ph-R ⁴
R ³ -Ph-CF = CF-Ph-R ⁴
R ³ -Cy-CF = CF-Ph-R ⁴
R ³ -Cy-CF = CF-Cy-R ⁴
R ³ -Cy-Ph-CF = CF-Ph-R ⁴
R ³ —Cy—Ph—CF═CF—Cy—R ⁴
R ³ —Ph—Cy—CF═CF—Cy—R ⁴
R ³ -Cy-Cy-CF = CF-Ph-R ⁴
R ³ -Ph-Ph-CF = CF-Ph-R ⁴
R ³ —Cy—CH ₂ CH ₂ —Ph—R ⁴
R ³ -Cy-Ph-CH ₂ CH ₂ -Ph-R ⁴
R ³ -Cy-Ph-CH ₂ CH ₂ -Cy-R ⁴
R ³ -Cy-Cy-CH ₂ CH ₂ -Ph-R ⁴
R ³ —Ph—CH ₂ CH ₂ —Ph—R ⁴
R ³ -Ph-Ph-CH ₂ CH ₂ -Ph-R ⁴
R ³ -Ph-Ph-CH ₂ CH ₂ -Cy-R ⁴
R ³ -Cy-Ph-Ph-R ⁴
R ³ -Cy-Ph-PhF ₂ CN
R ³ -Cy-Ph-C≡C-Ph-R ⁴
R ³ -Cy-Ph-C≡C-PhF ₂ CN
R ³ -Cy-Ph-C≡C-Ph-Cy-R ⁴
R ³ —Cy—CH ₂ CH ₂ —Ph—C≡C—Ph—R ⁴
R ³ —Cy—CH ₂ CH ₂ —Ph—C≡C—Ph—Cy—R ⁴
R ³ -Cy-Ph-Ph-Cy-R ⁴
R ³ -Ph-Ph-Ph-R ⁴
R ³ -Ph-Ph-C≡C-Ph-R ⁴
R ³ —Ph—CH ₂ CH ₂ —Ph—C≡C—Ph—R ⁴
R ³ —Ph—CH ₂ CH ₂ —Ph—C≡C—Ph—Cy—Ry
R ³ -Cy-COO-Ph-Ph-R ⁴
R ³ -Cy-COO-Ph-PhF ₂ CN
R ³ -Cy-Ph-COO-Ph-R ⁴
R ³ -Cy-Ph-COO-PhF ₂ CN
R ³ -Cy-COO-Ph-COO-Ph-R ⁴
R ³ -Cy-COO-Ph-COO-PhF ₂ CN
R ³ -Ph-COO-Ph-COO-Ph-R ⁴
R ³ -Ph-COO-Ph-OCO-Ph-R ⁴
R ³ —Cy—CH ₂ CH ₂ —PhF ₂ CN
R ³ —Ph—CH ₂ CH ₂ —PhF ₂ CN
R ³ —Ph—Cy—CH ₂ CH ₂ —PhF ₂ CN
R ³ -Cy-Ph-CH ₂ CH ₂ -PhF ₂ CN
R ³ -Cy-Cy-CH ₂ CH ₂ -PhF ₂ CN
R ³ —Ph—C ^* HX—CH ₂ —Ph—R ⁴
R ³ —Ph—C ^* HX—CH ₂ —Cy—R ⁴
R ³ —Ph—C ^* HX—CH ₂ —Ph—Cy—R ⁴
R ³ -Ph-C ^* HX-CH ₂ -Cy-Ph-R ⁴
R ³ -Ph-C ^* HX-CH ₂ -Ph-Ph-R ⁴

These compounds are merely examples, and a hydrogen atom present in the ring structure or the terminal groups R ³ and R ⁴ in the compound may be substituted with a halogen atom, a cyano group, a methyl group, or the like. Further, the trans-1,4-cyclohexylene group or 1,4-phenylene group may be substituted with another 6-membered ring or a 5-membered ring such as a pyrimidine ring or a dioxane ring, These linking groups may be substituted with other divalent linking groups or the like, and various compounds may be selectively used according to the desired performance. Further, since the optically active compound (1) is excellent in compatibility with other compounds, the concentration of the optically active compound (1) in the liquid crystal composition can be freely adjusted from a low concentration to a high concentration.

  Such a liquid crystal composition of the present invention is injected between liquid crystal cells and sandwiched between substrates with electrodes, twisted nematic method, guest / host method, dynamic scattering method, phase change method, DAP method. It can be used as a liquid crystal electro-optical element of various modes such as a dual frequency drive system, a ferroelectric liquid crystal display system, or a reflective cholesteric liquid crystal display system.

As a method for producing a liquid crystal electro-optical element, basically, the following methods are exemplified. That is, 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 as necessary, and In ₂ O ₃ —SnO ₂ (ITO), SnO ₂ or the like is formed. After providing the electrode and patterning, if necessary, an overcoat layer of polyimide, polyamide, SiO ₂ , Al ₂ O ₃ or the like is formed, oriented, a sealing material is printed on this, and the electrode surfaces face each other Thus, the periphery is sealed and the sealing material is cured to form an empty cell.
The liquid crystal composition of the present invention is injected into this empty cell, and the injection port is sealed with a sealant to form a liquid crystal cell. This liquid crystal cell is laminated with a polarizing plate, a color polarizing plate, a light source, a color filter, a transflective plate, a reflecting plate, a light guide plate, an ultraviolet cut filter, etc., printed with characters, figures, etc., and non-glare processed. Thus, a liquid crystal electro-optical element is manufactured.

Since the optically active compound (1) of the present invention has a large helical induction force, when added to a liquid crystal composition, a liquid crystal composition having a desired helical pitch can be obtained with a smaller amount of addition than conventional optically active compounds.
Therefore, when the liquid crystal composition is used as a TN type or STN type liquid crystal electro-optical element, uniform twist alignment can be achieved, and when a reflective cholesteric type liquid crystal electro-optical element is used, the target reflection wavelength is can get.
The liquid crystal composition containing the optically active compound (1) of the present invention can be used in various systems such as active matrix elements, polymer dispersed liquid crystal elements, GH type liquid crystal elements using polychromatic dyes, and ferroelectric liquid crystal elements. It can also be used as a liquid crystal electro-optical element. Moreover, it can be used for purposes other than display applications such as a light control element, a light control window, an optical shutter, a polarization exchange element, a variable focus lens, an optical color filter, a colored film, an optical recording element, and a temperature indicator.

The optically active compound (1) of the present invention can be easily produced industrially according to the following method. In each formula, C ^* , A ¹ , A ² , A ³ , A ⁴ , R ¹ , R ² , Z ¹ , Z ² , X, and Y have the above-mentioned meanings.

[Method 1] Y is -CH ₂ -, when Z ¹ and Z ² are not each -COO- a

The desired compound (1) is obtained by reducing the ketone compound (9) with a reducing agent such as triethylsilane in the presence of trifluoroacetic acid. The optical purity of the optically active compound in the formula is retained. In the formula (9), k and l are each 0, 1 or 2, and k + l is 2 or less.

[Method 2] When Z ¹ is —COO—

[Method 3] When Z ² is —COO—

[Method 6] When A ² is an unsubstituted trans-1,4-cyclohexylene group
Grignard reagent (7) is reacted with cyclohexanone derivative (22) and dehydrated by refluxing in hydrochloric acid to obtain cyclohexene compound (23). Then, hydrogenation reaction is performed in the presence of a palladium carbon catalyst. Compound (1) is obtained. Here, Ch represents a 1,4-cyclohexenylene group, and O═C ₆ H ₉ — represents a 4-oxocyclohexyl group. In each reaction, the optical purity of the optically active compound in the formula is retained.

  Any of the above methods is a method capable of maintaining the absolute configuration of the raw material, and therefore the raw material compound may be appropriately changed depending on the absolute configuration of the target optically active compound (1). These production methods are merely examples, and various production methods can be used.

Hereinafter, the present invention will be described specifically by way of examples.
[Example 1]
Synthesis of (R) -1- [4- [4- (trans-4-propylcyclohexyl) phenyl] phenyl] -2-phenylpropane

  While adding 70 ml of tetrahydrofuran to 25.3 g (1.04 mol) of magnesium, 9.45 g (0.087 mol) of ethyl bromide and 200 g of (R) -2-phenyl-1- (4-chlorophenyl) propane were added while stirring. 867 mol) in 250 ml of tetrahydrofuran was added dropwise at room temperature over 30 minutes, and the mixture was stirred for 6 hours under reflux. After cooling to room temperature, 650 ml of tetrahydrofuran was added. 112 g (0.44 mol) of trimethoxyborane was added dropwise to a 300 ml solution of tetrahydrofuran over 1 hour at −20 ° C., and the mixture was stirred for 1 hour. The temperature was raised to 0 ° C., 700 ml of 3M hydrochloric acid was added dropwise, and the mixture was stirred at the same temperature for 1 hour. The reaction solution was extracted with toluene, washed with water and dried to remove the solvent. 19.5 g (16.9 mmol) of tetrakistriphenylphosphine palladium was added to a solution of 238 g (0.845 mol) of 1-bromo-4- (trans-4-propylcyclohexyl) benzene and 800 ml of 1,2-dimethoxyethane. A solution of 260 g (2.45 mol) of sodium carbonate in 1160 ml of water was added and stirred for 3 hours under reflux. After cooling to room temperature, the organic layer separated by adding toluene was washed with water, dried, evaporated, recrystallized and purified by silica gel column chromatography to obtain the desired (R) -1- [4- [4- (trans- 240 g of 4-propylcyclohexyl) phenyl] phenyl] -2-phenylpropane were obtained. Melting point: 93.8 ° C., TSI: 130.8 ° C., MS m / e: 396 (M +)

Example 3
Synthesis of (S) -1- [2,6-difluoro-4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyl] -2-phenylpropane

  1- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -3,5-difluorobenzene 10 g (0.031 mol) in tetrahydrofuran 50 ml solution in n-butyllithium / hexane solution (1.6 M, 0.041 mol) ) Was added dropwise at -60 ° C over 1 hour and stirred at the same temperature for 2 hours. Subsequently, a solution of 5.5 g (0.041 mol) of zinc chloride in 30 ml of tetrahydrofuran was added dropwise at −60 ° C. over 2 hours, followed by stirring at room temperature for 1 hour. After adding 0.72 g (0.62 mmol) of tetrakis (triphenylphosphine) palladium, a solution of 4.7 g (0.041 mol) of (R) -2-phenylpropionyl chloride in 10 ml of tetrahydrofuran was added dropwise at room temperature over 1 hour. And stirred at room temperature overnight. To the reaction solution, 43 ml of 1M hydrochloric acid was added dropwise at room temperature, followed by stirring at the same temperature for 1 hour. This solution was extracted with toluene, washed with water, dried, evaporated, and recrystallized (R) -1- [2,6-difluoro-4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl]. 4.1 g of phenyl] -2-phenyl-1-propanone was obtained.

Subsequently, 4.1 g (9.1 mmol) of (R) -1- [2,6-difluoro-4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyl] -2-phenyl-1-propanone. ) In 1,2-dichloroethane (8 ml) was added 5 ml of trifluoroacetic acid and 2.6 g (23 mmol) of triethylsilane at room temperature, and the mixture was stirred at 60 ° C. for 10 hours. The reaction solution was poured into 200 ml of 5% sodium hydroxide solution, extracted with toluene, washed with water, dried, evaporated, recrystallized and purified by silica gel column chromatography to obtain the desired (S) -1- [2,6- 2.5 g of difluoro-4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyl] -2-phenylpropane was obtained. Melting point: 93.7 ° C., MS m / e: 438 (M +)
The following compounds were obtained in the same manner.

Example 4
(S) -1- [2,6-difluoro-4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyl]-with respect to 95 parts by mass of liquid crystal composition ZLI-1565 manufactured by Merck & Co., Inc. The liquid crystal composition obtained by adding 5 parts by mass of 2-phenylpropane was measured for clearing point (Tc, unit: ° C) and kinematic viscosity (η, 25 ° C, unit: cst). Moreover, (S) -1- [2,6-difluoro-4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] phenyl with respect to 100 parts by mass of the liquid crystal composition ZLI-1565 manufactured by Merck & Co., Inc. The helical pitch length (P, 25 ° C., unit: μm) of the liquid crystal composition obtained by adding 1 part by mass of 2-phenylpropane was measured. Similarly, Tc, η, and P were also measured for (R) -1- [4- [4- (trans-4-propylcyclohexyl) phenyl] phenyl] -2-phenylpropane. The results are shown in Table 1. Here, Tc of the liquid crystal composition ZLI-1565 manufactured by Merck & Co. was 86.0 ° C. and η was 15.7 cst. As a comparative example, the results of R-811 are shown in Table 1.

Claims (5)

Optically active compounds represented by the following formula (1) (where Ph—C ^* H (CH ₃ ) —CH ₂ —Ph—Cy—Cy—C ₃ H ₇ and Ph—C ^* H (CH ₃ )) compounds represented by _{-CH 2 -Cy-Cy-Cy-} C 3 H 7, and a 1,4-phenylene group having a a ⁴ is 1-2 fluorine atoms, and, R ² is a cyano group or Excluding compounds that are fluorine atoms ).
R ¹ -A ¹ -C ^* HX-Y-A ² -Z ¹ -A ³ -Z ² -A ⁴ -R ² (1)
(However, the symbol in formula (1) is
C ^* : asymmetric carbon atom,
A ¹ : an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having 1 to 2 fluorine atoms ,
A ² , A ³ , A ⁴ : independently of each other, an unsubstituted 1,4-phenylene group, a 1,4-phenylene group having one or more halogen atoms, or an unsubstituted trans-1,4-cyclo Hexylene group,
R ¹ : hydrogen atom,
R ² : an alkyl group having 1 to 10 carbon atoms , an alkenyl group or an alkynyl group, a hydrogen atom, a halogen atom or a cyano group ,
X: - CH _3,
Y: —CH ₂ —,
Z ¹ and Z ² : each independently represents —COO— , —CH ₂ CH ₂ — or a single bond.
Provided that A ² is an unsubstituted 1,4-phenylene group or a 1,4-phenylene group having one or more halogen atoms, and A ³ and A ⁴ are both trans-1,4-cyclohexylene. a group, and, if Z ¹ is a single bond, Z ² is, -COO-, or a single bond.
In the proviso, Ph represents an unsubstituted 1,4-phenylene group, and Cy represents an unsubstituted trans-1,4-cyclohexylene group. ) In Formula (1), A ² , A ^Three , A ^Four Are independently of each other an unsubstituted 1,4-phenylene group, a 1,4-phenylene group having 1 to 2 fluorine atoms or an unsubstituted trans-1,4-cyclohexylene group, and , Z ¹ , Z ²  Are independently of each other, —COO—, —CH ₂  CH ₂ The optically active compound according to claim 1, which is-or a single bond. In Formula (1), A ² The optically active compound according to claim 1, wherein is a 1,4-phenylene group having 1 to 2 fluorine atoms. A liquid crystal composition containing at least one of the optically active compounds according to claim 1. A liquid crystal electro-optical element obtained by sandwiching the liquid crystal composition according to claim 4 between substrates with electrodes.