JP2001316346A - Benzene derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a benzene derivative as a liquid crystal material capable of lowering threshold voltage without significantly deteriorating its liquid crystal characteristics including current value and response, and to provide a liquid crystal composition containing the above material as a constitutive material. SOLUTION: This benzene derivative as a liquid crystal material is shown by general formula I (for example, a compound of formula II, formula III or formula IV). The other objective liquid crystal composition contains the above material as a constitutive element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal compound useful as an electro-optical liquid crystal display material, a nematic liquid crystal composition using the same, and a liquid crystal display device.

[0002]

2. Description of the Related Art Since liquid crystal displays (LCDs) have appeared as calculator displays, they have progressed from computer development to TN-LCDs (twisted nematic liquid crystal displays) to STN-LCDs. It has responded to the expansion of capacity. STN-L
CDs include Scheffer and others [SID '85 Digest, 120
(1985)] or Kinukawa et al. [SID '86 Digest, 122
Page (1986)], a word processor,
It has begun to spread widely to displays for high information processing such as personal computers. Recently, an active addressing drive method has been proposed for the purpose of improving the response characteristics of an STN-LCD. (Proc. 12th International Display Res
earch Conference p.503 1992)
(Personal Digital Assistance) requires good display characteristics in a wider temperature range. Such a liquid crystal material is required to have a low viscosity, a low driving voltage and a constant value over a wide temperature range, or a driving voltage that does not fluctuate in a frequency range corresponding to various time divisions. I have. However, the response speed and contrast when incorporated into a display element cannot be said to be sufficient, and new liquid crystal compounds or liquid crystal compositions have been proposed at present.

[0003] In recent years, the demand for portable notebook computers has increased, and there has been an increasing demand for a wide operating temperature range that allows outdoor use and low power consumption that enables long-time battery operation. For low power consumption, a liquid crystal composition with a low threshold voltage that can be driven at a low voltage is required. In order to lower the threshold voltage, a material that increases the dielectric anisotropy Δε is necessary. However, in a system having a large dielectric anisotropy, the viscosity is increased and the response is deteriorated. There has been a problem that it is difficult to maintain high resistance because it is susceptible to surrounding contamination.
For this reason, liquid crystal compositions for liquid crystal display devices such as TN, STN, and AM-LCD include (1) a wide liquid crystal temperature range that can be used outdoors (2) stability that can be used even at high temperatures (3) low threshold voltage Voltage (4) High voltage holding ratio (5) There is a need for a Δn that can be adjusted in order to prevent coloring and obtain optimal contrast with a wide viewing angle.

The conventional liquid crystal compositions cannot always meet these demands, and a decrease in contrast due to a decrease in voltage holding ratio at a high temperature, a crystal precipitation at a low temperature, and the appearance of a smectic phase have been observed. In addition, when left outdoors at high temperatures or under exposure to UV light or sunlight, the retention rate decreased and display defects were observed. That is, a low threshold voltage capable of driving at a low voltage,
There has been no liquid crystal composition or liquid crystal display device which simultaneously satisfies a high nematic-isotropic transition temperature, a low crystal (or smectic) transition temperature, a low viscosity enabling high-speed response, and a high retention at a high temperature.

[0005]

As described above, TN-LCD and
One of the important characteristics improvement issues of STN-LCD is to improve the contrast. With the rapid expansion of applications of LCDs, LCDs are not only used indoors, but are also used outdoors where temperature conditions are severe, such as displays for computer portable terminals, in-vehicle instruments, and outdoor measuring instruments. Has increased. For this reason, there has been a problem that the display contrast is lowered due to a change in the temperature of the environment in which the LCD is placed, and the display quality is deteriorated due to the lowered response speed at low temperatures. In addition, high reliability has been required for outdoor use.

There are various causes for the deterioration of LCD display quality due to a change in ambient temperature. The change is caused by a temperature change in the elastic constant and dielectric constant of the nematic liquid crystal and a temperature change in the specific pitch of the added chiral substance. Threshold voltage Vth
A proposal to improve the temperature dependence of the threshold voltage by controlling the temperature change of the specific pitch of the chiral substance (Japanese Patent Laid-Open No. 55-38869) has already been known. Depending on the combination of chiral substances, the effect changes, and by increasing the amount of chiral,
There has been a problem that display characteristics such as response are adversely affected.

However, since the current value increases due to the temperature change of the mobility of the ionic substance contained in the liquid crystal, the effective value voltage applied to the liquid crystal is consumed by the ions, thereby lowering the contrast and reliability. No remedy is known. From this viewpoint, it is necessary to reduce the amount of a compound having an ester bond, which has been widely used in the past, but the resulting increase in threshold voltage has been a problem.

An object of the present invention is to provide a liquid crystal material capable of reducing a threshold voltage without greatly deteriorating various liquid crystal characteristics such as a current value and a response. Providing a composition; and
An object of the present invention is to provide a liquid crystal display device using the liquid crystal composition.

[0009]

In order to solve the above-mentioned problems, the present invention has found the following liquid crystal compound, a liquid crystal composition using the same, and a liquid crystal display device constituted by this composition.

That is, the general formula (I)

[0011]

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(Wherein ring A ′ is a trans-1,4-cyclohexylene group and a terminal is a cyclohexyl group (one CH ₂ group present in this group or two or more non-adjacent groups) the CH ₂ group -O- and or -S- to be replaced) or 1,4-phenylene group, one CH ₂ group in the terminal present in the phenyl group (in this group or adjacent Two or more CH ₂ groups that are not substituted may be replaced by -N-),
Or may be substituted with halogen, and when a plurality of rings A ′ are present, they may be the same or different, and k is 1 to
3 represents an integer, L is -CH ₂ CH _2- , -CH (CH ₃ ) CH _2- , -CH ₂ CH (C
H ₃ )-, -CH ₂ O-, -OCH _2- , -CF ₂ O-, -OCF _2- , -COO-, -OCO
-, - CH = CH -, - CF = CF -, - C≡C -, - O (CH 2) 3 -, - (CH 2) 3 O
-,-(CH ₂ ) ₄ -or a single bond, X and X ′ each independently represent F, Cl or H, Y represents -F, -Cl, -CF ₃ , -O
CF ₃ , -OCHF ₂ , -OCH ₂ F, -COOH, -CN or R ¹ represents R
¹ represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and this group is unsubstituted or has at least one halogen as a substituent,
And one or more CH ₂ present in these groups
The groups may each independently be replaced by -O-, -S-, -CO-, -COO-, -OCO-, -OCO-O-, provided that the O atoms are not directly bonded to each other. ) And a liquid crystal composition containing at least one compound represented by the general formula (I).

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described below.

In the compound of the present invention, ring A 'may be a substituted trans-1,4-cyclohexylene group, and at the terminal, a cyclohexyl group or 1,4-phenylene group; Represents a phenyl group, but trans-1,4
A cyclohexylene group, a cyclohexyl group at the end or an unsubstituted or F-substituted 1,4-phenylene group,
At the terminal, a phenyl group is preferred. k represents an integer of 1 to 3, preferably 1 to 2, and more preferably 1. L is -CH ₂
CH _2- , -CH (CH ₃ ) CH _2- , -CH ₂ CH (CH ₃ )-, -CH ₂ O-, -OCH _2- ,
-CF ₂ O-, -OCF _2- , -COO-, -OCO-, -CH = CH-, -CF = CF-, -C
≡C-, -O (CH ₂ ) ₃ -,-(CH ₂ ) ₃ O-,-(CH ₂ ) ₄ -or a single bond, but -CH ₂ CH _2- , -COO-, -C≡ C- or a single bond is preferred, and a single bond is more preferred. X and X ′ each independently represent F, Cl or H, but X represents F or Cl, and X ′
Preferably represents F, Cl or H, X represents F,
More preferably, X ′ represents F or H. Y is-
Represents F, -Cl, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, -COOH, -CN or R ¹ , but F, -CF ₃ , -OCF ₃ , -OCHF ₂ , -CN Is preferable, and F and —CN are more preferable.

Among them, the following general formulas (Ia) to (Ia)
d) is particularly preferred, among which the general formulas (Ia) and (Ib)
Is more preferred.

[0016]

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[0017]

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[0018]

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[0019]

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The general formula (I) is the same as the general formula (IV)

[0021]

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(Wherein A ′, k and L have the same meanings as in the general formula (I), and Z represents a halogen such as a bromine atom or an iodine atom) in the presence of a transition metal catalyst such as Pd. (V)

[0023]

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Wherein X, X ′ and Y have the same meanings as in the general formula (I), and M is MgX (X represents a chlorine atom, bromine atom or iodine atom) or a metal atom such as Li, B (OH) ₂ , which represents SiF (CH ₃ ) ₂ ).
In the case of a directly connected compound, the compound represented by the general formula (VI)

[0025]

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(Wherein A ', k and L have the same meanings as in the general formula (I)). The compound of the general formula (V) is also reacted with a compound of the general formula (V) in the presence of a transition metal catalyst such as Pd. can do. General formula (VII)

[0027]

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(Wherein A ′, k and L have the same meanings as in the general formula (I)), and after reacting the compound of the general formula (V), the hydroxyl group is dehydrated to obtain a compound of the general formula (VIII) )

[0029]

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Wherein A ′, k, L, X, X ′ and Y have the same meaning as in the general formula (I). By reducing this compound, a compound in which ring A of the general formula (I) has a cyclohexane ring can be obtained.

After the hydrogen at the α-position of the halogen of the compound of the formula (I) of Y = H which can be produced by the above-mentioned method is extracted using a base such as alkyllithium, carbon dioxide is reacted to produce a compound of the formula (IX) )

[0032]

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Wherein A ′, k, L, X and X ′ have the same meaning as in the general formula (I). This is converted into an acid halide, reacted with ammonia, and then dehydrated with phosphorus oxychloride or the like, whereby a compound of the general formula (I), Y = CN can be produced. The liquid crystal composition of the present invention contains at least one compound selected from the general formula (I), and preferably one or two compounds.

As another embodiment of the liquid crystal composition of the present invention, one or more compounds selected from the general formula (I) are contained as the first component, and the general formulas (II) and ( III)

[0035]

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(Where R^Two, R^Three, R^FourAre independent
Optionally substituted with 1 to 16 carbon atoms
Group or alkoxyl group, alkenyl having 2 to 16 carbon atoms
Alkenyloxy group having 3 to 16 carbon atoms, or
Carbon source substituted with an alkoxyl group having 1 to 10 carbon atoms
Represents an alkyl group having 1 to 12 children, and includes ring A, ring B, ring C, ring D and
And ring E is each independently substituted by a fluorine atom
1,4-phenylene, 2-methyl-1,4-phenylene
Group, 3-methyl-1,4-phenylene group, naphthalene-2,6-di
Yl group, phenanthrene-2,7-diyl group, fluorene-2,
7-diyl group, trans-1,4-cyclohexylene group, 1,2,
3,4-tetrahydronaphthalene-2,6-diyl group, decahydr
Ronaphthalene-2,6-diyl group, trans-1,3-dioxane
-2,5-diyl group, pyridine-2,5-diyl group, pyrimidine-
2,5-diyl group, pyrazine-2,5-diyl group or pyridazi
Represents a 2,5-diyl group, l and m are each independently 0, 1
Or 2 and Z¹, Z^Two, Z^Three, Z^FourAre each independently
Single bond, -CH_TwoCH_Two-,-(CH_Two)_Four-, -OCH_Two-, -CH _TwoO- or -C≡C
-Represents X^TwoIs a cyano group, a fluorine atom, a chlorine atom,
Fluoromethoxy group, trifluoromethyl group, difluoro
Romethoxy group, hydrogen atom, 3,3,3-trifluoroethoxy
Represents a group, R ′ or —OR ′, wherein R ′ is a straight chain having 1 to 12 carbon atoms.
Represents a linear alkyl group or 2 to 12 linear alkenyl groups.
Then X¹, X^ThreeRepresents a hydrogen, fluorine or chlorine atom
You. ) Contains one or more compounds selected from
The refractive index anisotropy (Δn) is in the range of 0.07 to 0.24.
And a liquid crystal composition characterized by the following, and as the first component
Contains at least one compound selected from the general formula (I)
However, one or two are preferred. In addition, with the second component
One or more compounds selected from the general formulas (II) and (III)
Contains two or more, preferably three or more, three to 20
Species are more preferred, 5 to 15 are particularly preferred,
Contains at least two compounds of the general formula (II)
Is more preferred. Δn is in the range of 0.07 to 0.24
It is characterized in that it is 0.08 to 0.22. R^Two, R^Three,
R^FourAre each independently a fluorine-substituted carbon
C1-16 alkyl or alkoxyl group, carbon
Alkenyl group having 2 to 16 atoms, alke having 3 to 16 carbon atoms
Nyloxy group or alkoxyl having 1 to 10 carbon atoms
Represents an alkyl group having 1 to 12 carbon atoms substituted with a group
Is an alkyl group having 1 to 16 carbon atoms,
Alkenyl groups are preferred, alkyl having 1 to 8 carbon atoms
Group, an alkenyl group having 2 to 8 carbon atoms is more preferable.
As an alkyl or alkenyl group having 1 to 5 elementary atoms
Formulas (a) to (e)

[0037]

Embedded image (It is assumed that the structural formula is connected to the ring at the right end).

Each of ring A, ring B, ring C, ring D and ring E is
1,4-phenyl optionally substituted by a fluorine atom
Nylene group, 2-methyl-1,4-phenylene group, 3-methyl-1,4-
Phenylene group, naphthalene-2,6-diyl group, phenanthate
Len-2,7-diyl group, fluorene-2,7-diyl group, tran
1,4-cyclohexylene group, 1,2,3,4-tetrahydrona
Phthalene-2,6-diyl group, decahydronaphthalene-2,6-di
Yl group, trans-1,3 dioxane-2,5-diyl group, pyri
Gin-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine
Represents a 2,5-diyl group or a pyridazine-2,5-diyl group
Is a 1,4-phenylene group, trans-1,4-cyclohexyl
In ring A, ring B, ring D, and ring E,
-1,4-cyclohexylene group is more preferable, and the ring C
In this case, a 1,4-phenylene group is more preferred. l and m are respectively
Independently represents 0, 1 or 2, preferably 0 or 1
No. Z¹, Z^Two, Z^Three, Z^FourAre each independently a single bond, -CH_TwoCH
_Two-,-(CH _Two)_Four-, -OCH_Two-, -CH_TwoO- or -C≡C-, but Z¹, Z
^TwoIs a single bond or -CH_TwoCH_Two-Is preferred, single tie
Is more preferred. Z^Three, Z^FourIs a single bond or -C
≡C- is preferred, and a single bond is more preferred. X^TwoIs cyano
Group, fluorine atom, chlorine atom, trifluoromethoxy group,
Trifluoromethyl group, difluoromethoxy group, hydrogen atom
, A 3,3,3-trifluoroethoxy group, R 'or -OR'
R ′ is a linear alkyl group having 1 to 12 carbon atoms or 2
Represents a linear alkenyl group of ~ 12, but a cyano group, fluorine
Atom, trifluoromethoxy group, difluoromethoxy group
Are preferably a fluorine atom, a trifluoromethoxy group,
A fluoromethoxy group is more preferable, and a fluorine atom is particularly preferable.
preferable. X¹, X^ThreeIs hydrogen atom, fluorine atom or chlorine atom
Represents a hydrogen atom, preferably a hydrogen atom or a fluorine atom,
Atoms are particularly preferred.

As another embodiment of the liquid crystal composition of the present invention, when the content of the compound of the general formula (I) is in the range of 5 to 40% by mass and the compound of the general formula (II) or the general formula (III) is Contains one or more selected from among, characterized in that the content of each of the selected compounds is in the range of 5 to 95% by mass,
The content of the general formula (I) is 5 to 40% by mass, but 5 to 25% by mass.
Is preferably 5 to 20% by mass, and the content of the general formula (II) or the general formula (III) is 5 to 95% by mass.
It is preferably from 85 to 85% by mass, particularly preferably from 25 to 85% by mass.

In another embodiment of the liquid crystal composition of the present invention, as a compound of the general formula (II), ring A and ring B are trans-1,4
-A general formula in which Z ¹ and Z ² are single bonds, each being a cyclohexylene group
(II-a)

[0041]

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(Wherein, R ⁵ and R ⁶ have the same meanings as R ² and R ³ , ring F represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and n represents 0 or 1 represents one or more compounds selected from the group consisting of one or more compounds of the general formula (I), the content of which is 5 to 40 mass% And the general formula (I
The compound of the formula (Ia) contains one or more kinds and the content thereof is in the range of 5 to 95% by mass, but the compound of the general formula (I) contains one or two kinds and the content is 5 to 95% by mass. 25 mass% is preferable, 5 to 20 mass% is particularly preferable, the content of the compound of the general formula (II-a) is preferably 5 to 95 mass%, and more preferably 15 to 85 mass%. Is preferable, and 25 to 85% by mass is particularly preferable.

In another embodiment of the liquid crystal composition of the present invention, as the compound of the general formula (III), ring D is a trans-1,4-cyclohexylene group, Z ³ and Z ⁴ are single bonds, General formula (III-a) where m = 1

[0044]

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(In the formula, R ⁷ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and ring G represents 1,4-phenylene group or trans-1,4-cyclohexylene group. X ⁵ represents a cyano group, a fluorine atom, a trifluoromethoxy group or a difluoromethoxy group, and X ⁴ and X ⁶ each independently represent a hydrogen atom or a fluorine atom.) Characterized in that it contains one or more compounds of the general formula (I), the content of which is in the range of 5 to 40% by mass, and as a second component, the compound of the general formula (III) -a) contains one or more compounds, the content of which is in the range of 5 to 95% by mass, but contains one or two compounds of the general formula (I) and the content is Five
~ 25 mass% is preferred, 5 ~ 15 mass% is particularly preferred, containing two or more compounds of the general formula (III-a), the content is 5 ~ 9
It is preferably 5% by mass, more preferably 15 to 85% by mass, and particularly preferably 25 to 85% by mass.

As another embodiment of the liquid crystal composition of the present invention, the content of the general formula (I) is in the range of 5 to 40% by mass, and one or more compounds of the general formula (III-a) are used. The content is in the range of 5 to 95% by mass, containing one or more compounds of the general formula (I), the content of 5 to 40% by mass Within the range and the general formula (II-b)

[0047]

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(In the formula, R ⁸ and R ⁹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) The content is preferably from 5 to 25% by mass, and further represented by the general formula (II-c)

[0049]

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(In the formula, R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) It contains the compound and its content is preferably 5 to 50% by mass, and 5 to 40% by mass.
It is more preferable that the content is mass%.

As another embodiment of the liquid crystal composition of the present invention, one or more compounds of the general formula (I) are contained, the content of which is in the range of 5 to 40% by mass, and the compound of the general formula (I) II-b) contains one or more compounds selected from the group, the content is in the range of 5 to 40% by mass, one or more compounds selected from the general formula (II-c) Although containing a compound and its content is in the range of 5 to 60% by mass, the compound of the general formula (I)
It is preferable that the content of the species or two is contained in the range of 5 to 20% by mass, the content of the general formula (III-a) is in the range of 5 to 35% by mass, and 5 to 25% by mass. Is more preferably in the range of the general formula (II-b) or the general formula (II-b).
The content of (II-c) is preferably in the range of 5 to 55% by mass, and more preferably in the range of 5 to 45% by mass. In the formula
R ⁸ , R ⁹ , R ¹⁰ , and R ¹¹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, but an alkyl group or alkenyl having 1 to 5 carbon atoms. Formulas (a) to (e) as groups

[0052]

Embedded image (It is assumed that the structural formula is connected to the ring at the right end).

As another form of the liquid crystal composition of the present invention, one or more compounds of the general formula (I) are contained, the content of which is in the range of 5 to 40% by mass, and the compound of the general formula (I) III-a)
Contains one or more compounds, and the content is
In the range of 5 to 40% by mass, and containing one or more compounds of the general formula (II-b) or the general formula (II-c), the content is in the range of 5 to 60% by mass. However, it is preferable that one or two compounds of the general formula (I) are contained and the content thereof is in the range of 5 to 20% by mass, and the general formula (II-b) and the general formula (I
The compound of Ic) contains at least one compound and the content is 5 to
It is preferably in the range of 20% by mass, and preferably contains two or more compounds of the general formula (III-a) and the content thereof is in the range of 5 to 25% by mass.

In another embodiment of the liquid crystal composition of the present invention, the compound represented by the general formula (III-b) may be represented by the general formula (III) or (III-a):

[0055]

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Wherein R ¹² represents one or more compounds selected from the group consisting of an alkyl group having 1 to 16 carbon atoms and an alkenyl group having 2 to 8 carbon atoms. Rate is in the range of 5 to 40% by mass, containing 1 to 10 compounds of the general formula (III-b), the content of which is 5 to 3
The content is preferably in the range of 5% by mass, more preferably 1 to 5 kinds, and the content is more preferably in the range of 5 to 30% by mass. In the formula, R ¹² represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, wherein the alkyl group or alkenyl group having 1 to 5 carbon atoms has the formula (a) to (e). Particularly preferred.

As another embodiment of the liquid crystal composition of the present invention, a compound represented by the general formula (III-c) represented by the general formula (III) or (III-a)

[0058]

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(Wherein R ¹² represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), and contains at least one compound selected from the group consisting of Is in the range of 5 to 40% by mass, preferably contains 1 to 10 compounds of the general formula (III-c) and the content thereof is in the range of 5 to 35% by mass, and 1 to 5 Contains 5-30
More preferably, it is in the range of mass%. In the formula, R ¹² represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, wherein the alkyl group or alkenyl group having 1 to 5 carbon atoms has the formula (a) to (e). Particularly preferred.

The present invention is useful for a liquid crystal display device using the above liquid crystal composition, but has a twist angle of 220 ° to 270 °, a super twisted nematic (STN) liquid crystal display device, an active matrix. (AM) Liquid crystal display element, in-
Although a plane switching (IPS) liquid crystal display element is preferable, it is particularly useful for an AM-LCD and can be used for a transmissive or reflective liquid crystal display element. The liquid crystal composition of the present invention may contain a normal nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal, and the like, in addition to the above compounds.

[0061]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Further, “%” in the compositions of the following Examples and Comparative Examples means “% by mass”.

The characteristics measured in the examples are as follows. TN-I: Nematic phase-isotropic liquid phase transition temperature (° C.) T → N: Solid phase or smectic phase-nematic phase transition temperature (° C.) Vth: Threshold when a TN-LCD having a cell thickness of 6 μm is constructed. Value voltage (V) Δε: dielectric anisotropy Δn: birefringence τr = τd: response speed (msec)

Example 1 Synthesis of 4-cyclohexyl-2,6-difluorobenzonitrile (Ib-1)

[0064]

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(A) Synthesis of 1-cyclohexyl-3,5-difluorobenzene Magnesium (6.7 g) was suspended in THF (15 mL), and a THF (160 mL) solution of 1-bromo-3,5-difluorobenzene (51.6 g) was refluxed at a speed at which THF was gently refluxed. The solution was dropped over about 30 minutes. After further stirring for 1 hour, a solution of 25 g of cyclohexanone in 75 mL of THF was added dropwise over 30 minutes. After further stirring for 2 hours, 80 mL of 10% hydrochloric acid was added.
Toluene was added, the organic layer was separated, the aqueous layer was extracted with toluene and the organic layers were combined. The extract was washed with water, saturated aqueous sodium hydrogen carbonate and saturated saline, and dried over anhydrous sodium sulfate. Distill off the solvent,
200 mL of toluene and 2.5 g of p-toluenesulfonic acid monohydrate were added, and the mixture was heated under reflux for 1 hour while separating and removing the distilled water. After the water distills out, return to room temperature and add 150 mL of water.
Was added and the organic layer was separated. Organic layer is saturated aqueous sodium bicarbonate, water,
The extract was washed with saturated saline and dried over anhydrous sodium sulfate.
The solvent was distilled off, the whole amount was dissolved in 180 mL of ethyl acetate, 8.5 g of 5% palladium / carbon (containing water) was added, and the mixture was stirred in an autoclave under a hydrogen pressure of 500 kPa. After stirring at room temperature for 4 hours, the catalyst was removed by filtration through Celite, and the solvent was distilled off to obtain 43.4 g of a crude product of 1-cyclohexyl-3,5-difluorobenzene.

(B) Synthesis of 4-cyclohexyl-2,6-difluorobenzonitrile 43.4 Crude of 1-cyclohexyl-3,5-difluorobenzene
g was dissolved in 210 ml of tetrahydrofuran and cooled to -70 ° C. n-butyllithium n-hexane solution (1.5mol / l) 187
ml was added dropwise at a rate to maintain the liquid temperature at -60 ° C or lower. Plus 30
After stirring for 2 minutes, carbon dioxide was introduced into the system at a rate to maintain the liquid temperature at -60 ° C or lower. After fever subsides, return to room temperature, 10%
100 ml of hydrochloric acid was added, and the mixture was extracted with 250 ml of ethyl acetate. The organic layer was washed with water and saturated saline, and dried over anhydrous sodium sulfate. The solvent was distilled off to obtain 61.9 g of a crude product of 4-cyclohexyl-2,6-difluorobenzoic acid. 180 mL of thionyl chloride was added to the whole amount, and the mixture was heated under reflux for 8 hours. After cooling to room temperature, excess thionyl chloride was distilled off under reduced pressure, 300 ml of dichloromethane was added, and the mixture was cooled to 10 ° C or lower. Under stirring,
Ammonia was introduced into the solution at a rate that kept it below 20 ° C.
After the exotherm subsided, the solvent was distilled off under reduced pressure, N, N-dimethylformamide (300 ml) was added, and the mixture was cooled to 10 ° C or lower. 50.8 g of phosphorus oxychloride was added dropwise at such a rate that the liquid temperature was kept at 10 ° C. or lower. After returning to room temperature, the solution was poured into crushed ice, and the precipitated crystals were filtered. The obtained crystals were washed with water and dried under reduced pressure. Purification by silica gel column chromatography (solvent: toluene) gave 4-cyclohexyl-2,6-difluorobenzonitrile. Purification by distillation and further recrystallization from ethanol gave 22.8 g of a purified product. The melting point of this compound was 58 ° C. MS: m / e = 221 (M +)

Example 2 Synthesis of 2,6-difluoro- (4-propylphenyl) benzonitrile (Ib-10)

[0068]

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In a THF solution of iodobenzene, tetrakis was added.
(Triphenylphosphine) palladium (0) was added and the mixture was stirred at room temperature, and reacted with a Grignard reagent prepared from 3,5-difluorobromobenzene and magnesium. After stirring at room temperature for 2 hours, the mixture was cooled to room temperature, water was added, and the mixture was extracted with toluene. The organic layer was washed with water and saturated saline in this order, and dried over anhydrous sodium sulfate and dried. The crude product obtained by evaporating the solvent was purified by silica gel column chromatography (hexane) to obtain 3,5-difluorobiphenyl. 3,5-difluorobiphenyl using the same method as in Example 1 (b) 2,6-difluoro- (4-propylphenyl)
Benzonitrile was produced.

(Example 3, Comparative Example 1) General-purpose p-type host liquid crystal composition (H)

[0071]

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This (H) shows a nematic phase at 116.7 ° C. or lower, and its melting point is 11.0 ° C. (H) TN with a cell thickness of 6.0 μm
The liquid crystal element was prepared by filling the cell, and the electro-optical characteristics at 20 ° C. were as follows. Threshold voltage (Vth) 2.14 V Dielectric constant anisotropy (Δε) 4.8 Refractive index anisotropy (Δn) 0.090 Next, 80% by mass of this (H) and the compound (Ia) of the present invention obtained in Example 2 (Ia -10) to prepare a liquid crystal composition (H-1) consisting of 20% by mass, filling a TN cell having a cell thickness of 6.0 μm to form a liquid crystal element, and measuring its electro-optical properties at 20 ° C. It was as follows. Threshold voltage (Vth) 0.99V Dielectric anisotropy (Δε) 6.0 Refractive index anisotropy (Δn) 0.064 From these results, it can be seen that the compound (Ia-10) has an extremely large effect of reducing the threshold voltage. Next, as a comparative example
80% by mass of (H) and (R)

[0073]

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A liquid crystal composition (R-1) consisting of 20% by mass was prepared, filled in a TN cell having a cell thickness of 6.0 μm to prepare a liquid crystal element, and its electro-optical characteristics were measured at 20 ° C. It was as follows. Threshold voltage (Vth) 1.39V Dielectric anisotropy (Δε) 8.6 Refractive index anisotropy (Δn) 0.104 From these results, (R) is the compound (Ia-1)
It turns out that it does not reach 0).

Example 4 Preparation of Liquid Crystal Composition Host liquid crystal composition (H ′) having the following composition

[0076]

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Was prepared. Here, the physical property values of (H ′) are as follows. Nematic phase upper limit temperature (TN-I): 75.0 ° C Solid phase or smectic phase-nematic phase transition temperature (T →
N): -70 ° C. Threshold voltage (Vth): 1.49 V Dielectric anisotropy (Δε): 10.3 Refractive index anisotropy (Δn): 0.142 90% of the base liquid crystal (H ′) obtained in Example 1 (Ia-10) 10%
A liquid crystal composition (M-2) was prepared. The physical properties of this composition are as follows. Nematic phase upper limit temperature (TN-I): 55.7 ° C Solid phase or smectic phase-nematic phase transition temperature (T →
N): -70 ° C Threshold voltage (Vth): 1.32 V Dielectric anisotropy (Δε): 10.4 Refractive index anisotropy (Δn): 0.110

(Example 5, Comparative Example 2) Preparation of Liquid Crystal Composition A liquid crystal composition (M-3) containing the compound (Ia-10) and having the following composition was prepared.

[0079]

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As a comparative example, a liquid crystal composition (R-3) having the following composition and containing no compound of the general formula (I) was prepared.

[0081]

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A liquid crystal display device was prepared using this liquid crystal composition, and the characteristics were measured. The results are shown in Table 1 below.

[0083]

[Table 1]

As shown in Table 1, the liquid crystal composition of Example 5 has an extremely low threshold voltage as compared with the composition of Comparative Example, and has the effect of greatly reducing the anisotropy of the refractive index. I understand.

[0085]

According to the liquid crystal material of the present invention, a liquid crystal composition having an extremely low threshold voltage was obtained. In addition, an excellent liquid crystal display device could be manufactured using this composition. This liquid crystal material is very practical as STN and AM-LCD.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C07C 43/225 C07C 43/225 C (72) Inventor Haruyoshi Takatsu 3-6-27 Nakahara, Higashiyamato-shi, Tokyo F-term ( Reference) 4H006 AA01 AB64 EA22 EA33 EA35 EA36 GP03 4H027 BA01 BD05 BD07 BD08 BD09 BE04 BE05 CB01 CC04 CD04 CD05 CL01 CL04 CM01 CM04 CM05 CN01 CN04 CP04 CQ01 CQ04 CQ05 CR04 CS04 CT01 CT04 CT05 CW01 DE04

Claims (22)

[Claims] 1. A compound of the general formula (I) (In the formula, ring A ′ is a trans-1,4-cyclohexylene group, and a terminal is a cyclohexyl group (one CH present in this group is present)
_Two or two or more non-adjacent CH ₂ groups may be replaced by -O- and / or -S-) or 1,4-phenylene group, and a phenyl group at the terminal (in this group, One CH ₂ group or two or more non-adjacent CH ₂ groups are-
May be substituted with N-), may be substituted with -CN or halogen, may be the same or different when a plurality of rings A 'are present, and k is an integer of 1 to 3. L represents -CH ₂ CH _2- , -CH (CH ₃ ) CH _2- , -CH ₂ CH (CH ₃ )-, -CH ₂ O
-, -OCH _2- , -CF ₂ O-, -OCF _2- , -COO-, -OCO-, -CH = CH-,
-CF = CF-, -C≡C-, -O (CH ₂ ) ₃ -,-(CH ₂ ) ₃ O-,-(CH ₂ ) ₄ -or a single bond, and X and X 'are each independent Represents F, Cl or H, and Y represents -F, -Cl, -CF ₃ , -OCF ₃ , -OCHF ₂ ,
Represents -OCH ₂ F, -COOH, -CN or R ¹ , wherein R ¹ has 1 carbon atom
Represents an alkyl group having up to 15 or an alkenyl group having 2 to 15 carbon atoms, wherein the group is unsubstituted or has at least one halogen as a substituent, and 1 Or two or more CH ₂ groups are each independently O atoms not directly bonded to each other.
-, -S-, -CO-, -COO-, -OCO-, -OCO-O- may be substituted. ). 2. The method according to claim 1, wherein ring A ′ represents a trans-1,4-cyclohexylene group, a cyclohexyl group or 1,4-phenylene group at the terminal, and a phenyl group at the terminal. The compound according to 1. 3. The compound according to claim 1, wherein L represents a single bond. 4. The compound according to claim 1, wherein k represents 1. 5. The compound according to claim 1, wherein at least one of X or X ′ represents F. 6. k represents 1, L represents a single bond, X and X ′
The compound of claims 1 to 5, wherein represents F and Y represents -CN. 7. A liquid crystal composition containing at least one compound represented by the general formula (I) according to claim 1. 8. The first component is selected from the general formula (I)
Contains one or more compounds, as a second component
Formulas (II) and (III)(Where R^Two, R^Three, R^FourAre each independently fluorine substituted
An alkyl group having 1 to 16 carbon atoms which may be
Coxyl group, alkenyl group having 2 to 16 carbon atoms, carbon source
An alkenyloxy group having 3 to 16 children or 1 to carbon atoms
A group having 1 to 12 carbon atoms substituted with 10 alkoxyl groups
A ring group, ring A, ring B, ring C, ring D and ring E are each
1,4-, which may be independently substituted by a fluorine atom
Phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-
1,4-phenylene group, naphthalene-2,6-diyl group, phena
Nthrene-2,7-diyl group, fluorene-2,7-diyl group,
Lance-1,4-cyclohexylene group, 1,2,3,4-tetrahydride
Ronaphthalene-2,6-diyl group, decahydronaphthalene-2,
6-diyl group, trans-1,3-dioxane-2,5-diyl group,
Pyridine-2,5-diyl group, pyrimidine-2,5-diyl group,
A azine-2,5-diyl group or a pyridazine-2,5-diyl group
Represents, l and m each independently represent 0, 1 or 2, Z
¹, Z^Two, Z^Three, Z^FourAre each independently a single bond, -CH_TwoCH_Two-,-
(CH_Two)_Four-, -OCH_Two-, -CH _TwoO- or -C≡C-, X^TwoIs sheer
Group, fluorine atom, chlorine atom, trifluoromethoxy
Group, trifluoromethyl group, difluoromethoxy group, water
Elemental atom, 3,3,3-trifluoroethoxy group, R 'or -OR'
Represents a linear alkyl group having 1 to 12 carbon atoms or
Represents a linear alkenyl group of 2 to 12, X¹, X^ThreeIs hydrogen
Represents an atom, a fluorine atom or a chlorine atom. )
Contains one or more compounds, and has an anisotropic refractive index.
Characteristic (Δn) is in the range of 0.07 to 0.24.
8. The liquid crystal composition according to claim 7. 9. The compound of the general formula (I) has a content of 5 to 40% by mass.
%, Further contains one or more selected from compounds of the general formula (II) or the general formula (III), the content of the selected compound is in the range of 5 to 95% by mass, respectively. 9. The liquid crystal composition according to claim 7, wherein: 10. The compound of the general formula (II), wherein ring A and ring B are trans-1,4-cyclohexylene, Z ¹ ,
General formula (II-a) in which Z ² is a single bond (Wherein R ⁵ and R ⁶ represent the same meaning as R ² and R ³ , ring F represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and n represents 0 or 1. 8.) comprising one or more compounds selected from the group consisting of:
10. The liquid crystal composition according to any one of items 9 to 9. 11. The compound of the general formula (II-a) as a second component having a content of the general formula (I) in the range of 5 to 40% by mass.
11. The liquid crystal composition according to claim 7, wherein the liquid crystal composition contains one or more kinds and has a content of 5 to 95% by mass. 12. A compound of the general formula (III-a) wherein ring D is a trans-1,4-cyclohexylene group, Z ³ and Z ⁴ are single bonds, and m = 1. ) (Wherein, R ⁷ is an alkyl group having 1 to 8 carbon atoms or 2 to 8
X represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, X ⁵ represents a cyano group, a fluorine atom, a trifluoromethoxy group, a difluoromethoxy group, and X ⁴ , X ⁶ each independently represent a hydrogen atom or a fluorine atom. One or two selected from)
Claims 7 to 1 containing at least one compound
The liquid crystal composition according to 1. 13. A compound of the general formula (III-a) having a content of the general formula (I) in the range of 5 to 40% by mass and one or more compounds of the general formula (III-a)
13. The liquid crystal composition according to claim 12, wherein the liquid crystal composition contains at least one species and has a content of 5 to 95% by mass. 14. A compound of the general formula (II-b) containing at least one compound of the general formula (I) in a content of 5 to 40% by mass. (In the formula, R ⁸ and R ⁹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.)
One or two or more compounds selected from the group consisting of a compound represented by the general formula (II-c): (Wherein, R ¹⁰ and R ¹¹ each independently represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) 14. The liquid crystal composition according to claim 7, wherein the content thereof is in a range of 5 to 60% by mass. 15. A compound of the general formula (I) containing one or more compounds, the content of which is in the range of 5 to 40% by mass, and the compound of the general formula (III-a) is one or more. Contains two or more, the content of which is in the range of 5 to 40% by mass, and one or two compounds of the general formula (II-b) or the general formula (II-c)
15. The liquid crystal composition according to claim 7, wherein the liquid crystal composition contains at least one species and has a content of 5 to 60% by mass. 16. A compound of the general formula (I) containing one or more compounds, the content of which is in the range of 5 to 40% by mass, and one or more compounds of the general formula (III-a) Contains two or more, the content is in the range of 5 to 40% by mass, and contains one or more compounds of the general formula (II-b) and the general formula (II-c), 16. The liquid crystal composition according to claim 7, wherein the content is in a range of 5 to 40% by mass. 17. A compound of the general formula (III-b) represented by the general formula (III) or (III-a): (In the formula, R ¹² represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) 17. The liquid crystal composition according to claim 7, wherein the content is in a range of from about 40% by mass to about 40% by mass. 18. A compound represented by the general formula (III-c) represented by the general formula (III) or (III-a): (In the formula, R ¹² represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) The compound contains one or more compounds selected from the group having a content of 5 to 40 mass
17. The liquid crystal composition according to claim 7, wherein the content is in the range of%. 19. A liquid crystal display device using the liquid crystal composition according to claim 7. 20. A super twisted nematic (STN) liquid crystal display device using the liquid crystal composition according to claim 7 and having a twist angle of 220 ° to 270 °. 21. An active matrix (AM) liquid crystal display device using the liquid crystal composition according to claim 7. 22. An in-plane switching (IPS) liquid crystal display device using the liquid crystal composition according to claim 7.