JPH06256339A - Chroman derivative - Google Patents

Abstract

PURPOSE:To obtain a new chroman derivative having chemical stability and excellent compatibility with nematic liquid crystals widely in use at present and extremely useful as a constituent material for light-switching element for display. CONSTITUTION:The compound of formula I [R<1> is 1-18C alkyl or alkenyl both of which may have substituent; rings A and B are 1,4-cyclohexylene, 1,4- phenylene (which may be substituted with F), pyrimidin-2,5-diyl, pyridin-2,5-diyl, pyrazin-2,5-diyl or 1,3-dioxan-2,5-diyl; (m) is 0 or 1; R<2> is 1-12C alkyl], e.g. 2- butyl-6-(trans-4-propylcyclohexyl)carbonyloxychroman. The compound of formula I can be produced e.g. by reacting a 2-alkyl-6-hydroxychroman of formula II with a carboxylic acid derivative of formula III in the presence of a condensation agent. The compound of formula I is useful also as a constituent component for SC matrix liquid crystal of a ferroelectric liquid crystal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel compound which is a chroman derivative useful as an electro-optical liquid crystal display material and a liquid crystal composition containing the same.

[0002]

2. Description of the Related Art Liquid crystal display devices have come to be used in watches, calculators, various measuring instruments, automobile panels, word processors, electronic notebooks, printers, computers, televisions and the like. Typical liquid crystal display methods are TN (twisted nematic) type, STN (super twisted nematic) type, DS (dynamic light scattering) type, GH (guest host) type, and FLC (ferroelectric liquid crystal). ) Etc. Also, as the drive system, the conventional static drive has become more common, and the multiplex drive has become more common, and the simple matrix system and recently the active matrix system have been put into practical use.

The liquid crystal materials used for these are required to have various characteristics in accordance with the above-mentioned display system and driving system, and further the application thereof, and compounds which satisfy these various properties alone are known. Not not. Therefore, it is the actual situation that a large number of compounds are mixed and used as a liquid crystal composition, but in order to obtain a composition excellent in various characteristics, it is necessary to mix as many kinds of liquid crystal compounds each having characteristics as possible. is there.

Generally, liquid crystal compounds have a central skeleton (core).
And a side chain (terminal group), and the central skeleton is composed of a ring structure and, if necessary, a linking group. As the ring structure, in addition to monocycles such as a benzene ring, a cyclohexane ring, a pyrimidine ring, a pyridine ring, and a dioxane ring, a large number are known so far, including a condensed ring such as a naphthalene ring, a decalin ring, and a benzoxazole ring. Has been.

[0005]

Among the above-mentioned various liquid crystal display systems, the TN type and ST type are predominant at present.
It is N type. The liquid crystal material used in this method is required to have a wide temperature range of the nematic phase and a low threshold voltage, which are important characteristics in common, depending on the application. Further, in order to obtain a wide visual range, it is necessary that the refractive index anisotropy (Δn) is not so large. However, in this TN type or STN type display, there is a limit in the number of scanning lines used due to the so-called crosstalk phenomenon, and high-definition display above a certain level is impossible.

On the other hand, by using the active matrix driving method, it is possible to improve the display quality and display with high definition, but this method is very expensive and it is difficult to increase the area. It has drawbacks. Therefore, the ferroelectric liquid crystal display has been attracting attention as a display method capable of large-area and high-definition display by an inexpensive simple matrix driving method.

In this display system, unlike a nematic liquid crystal, a chiral smectic (usually a chiral smectic C)
Although a liquid crystal composition is used, high-speed response is important in such a display system. As a liquid crystal material of a chiral smectic C liquid crystal composition (hereinafter, abbreviated as SC ^* liquid crystal composition), an achiral smectic C liquid crystal is generally used as a host liquid crystal, and an optically active liquid crystal compound is added as a chiral dopant. However, it is particularly important that the host liquid crystal has a wide temperature range of the smectic C phase and low viscosity.

The problem to be solved by the present invention is TN
As a liquid crystal material used for the STN type and STN type display systems, it is an object to provide a compound capable of effectively lowering the threshold voltage and lowering Δn without lowering the liquid crystal phase transition temperature of the composition.

Further, as a constituent material of the ferroelectric liquid crystal, a liquid crystal compound having a low viscosity and a wide temperature range of the smectic C phase, or the addition of which does not narrow the temperature range of the smectic C phase of the composition. To provide.

[0010]

In order to solve the above-mentioned problems, the present invention has the general formula (I)

[0011]

[Chemical 2]

(In the formula, R ¹ represents an optionally substituted linear or branched alkyl group or alkenyl group having 1 to 18 carbon atoms, which is a linear alkyl group having 1 to 12 carbon atoms. A group or an alkenyl group is preferable, and the number of carbon atoms is 1 to
12 straight chain alkyl groups are particularly preferred. X represents a single bond or -O-, and m represents 0 or 1. Ring A and Ring B are each independently a 1,4-cyclohexylene group,
1,4-phenylene group optionally substituted by 1 or 2 fluorine atoms, pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, pyrazine-2,5-
It represents a diyl group or a 1,3-dioxane-2,5-diyl group, and both ring A and ring B may be substituted with a 1,4-cyclohexylene group or 1 or 2 fluorine atoms. , 4-phenylene group is preferred. Further, when the ring A is a 1,4-cyclohexylene group, X is preferably a single bond. R ² represents an alkyl group having 1 to 12 carbon atoms, which has 1 to 8 carbon atoms.
The linear alkyl group of is preferred. )

Further, particularly as a nematic liquid crystal material,
In the general formula (I), R ¹ is a linear alkyl group having 1 to 7 carbon atoms, and both ring A and ring B are 1,4-
Cyclohexylene group or R ² has 1 carbon atom
It is preferable that any one of a straight chain alkyl group having 5 to 5 carbon atoms is satisfied. As the ferroelectric liquid crystal material, in the general formula (I), R ¹ is a straight chain alkyl group having 5 to 12 carbon atoms. Is preferred.

The compound of the general formula (I) of the present invention is, for example, a compound of the general formula (II)

[0015]

[Chemical 3]

(In the formula, R ² has the same meaning as in formula (I)) and 2-alkyl-6-hydroxychroman represented by formula (III)

[0017]

[Chemical 4]

By reacting a carboxylic acid derivative represented by the formula (wherein R ¹ , X, ring A, ring B and m have the same meanings as in formula (I)) in the presence of a condensing agent. Obtainable.

Alternatively, the carboxylic acid derivative of the general formula (III) is treated with a chlorinating agent such as thionyl chloride to give the general formula (I).
V)

[0020]

[Chemical 5]

(Wherein R ¹ , X, ring A, ring B and m have the same meanings as in general formula (I)), and an acid chloride represented by the general formula (II) Can also be obtained by reacting with the presence of a basic substance such as pyridine.

The general formula (II
The carboxylic acid derivative of I) is a commonly used compound, some of which are commercially available, and the other compounds can be easily produced from commercially available compounds by a known method.

The other compound of the general formula (II) is a novel compound, and the present invention also provides this compound. The compound of the general formula (II) is produced, for example, as follows. can do.

[0024]

[Chemical 6]

(In the formula, R ² has the same meaning as in formula (I).) 2,5-dimethoxybenzaldehyde (commercially available) represented by formula (V) is dithioacetalized with propanedithiol. The obtained dithiane derivative of the general formula (VI) is converted to an anion with a strong base to give the general formula (VI)
I) with an oxirane derivative of the general formula (VII)
A (2-hydroxyalkyl) dithiane derivative of I) is obtained.

[0026]

[Chemical 7]

(In the formula, R ² has the same meaning as in the general formula (I).) Next, the compound of the general formula (VIII) is reductively desulfurized with Raney nickel to give the alcohol of the general formula (IX). Further, demethylation with aluminum chloride-dimethyl sulfide or the like gives the triol of the general formula (X).

[0028]

[Chemical 8]

(In the formula, R ² has the same meaning as in formula (I).) The compound of formula (X) is cyclized in the presence of an acid catalyst to give a chroman derivative of formula (II). Can be obtained.

Representative examples of the compounds represented by the general formula (I) thus produced are shown in Table 1.

[0031]

[Table 1]

(In the table, Cr represents a crystalline phase, SC represents a smectic C phase, SA represents a smectic A phase, N represents a nematic phase, and I represents an isotropic liquid phase.) It is apparent that the compound represented by the general formula (I) exhibits a liquid crystal phase in a wide temperature range and further exhibits a nematic phase.

When the compound of the general formula (I) of the present invention is produced by the above-mentioned method, it is usually obtained as a racemic compound. The compound of the general formula (I) is used as a racemic compound in various liquid crystal compositions. It can be used by adding.

The compound (No. 1) in Table 1 is suitable as a constituent component of, for example, a TN type or STN type display nematic liquid crystal composition. For example, a matrix liquid crystal (A) currently widely used as a nematic liquid crystal material.

[0035]

[Chemical 9]

(Wherein the cyclohexane ring represents the trans configuration and "%" represents "% by weight") is 50.5.
It exhibits a nematic phase at a temperature of not higher than 0 ° C., a dielectric anisotropy (Δε) of 12.0, and a refractive index anisotropy (Δn) of 0.117.
Threshold voltage (V _th ) of TN cell manufactured using this
Was 1.50V.

75% by weight of the base liquid crystal (A) and (N
o. A liquid crystal composition (M-
1) was prepared. The upper limit temperature of the nematic phase of (M-1) is 49 ° C, Δn is 0.099, and Δε is 9.
It became as small as 7. When a cell was similarly prepared using this composition, V _th was 1.38 V, which was about 10% lower than that of the base liquid crystal (A), although Δε was about 20% smaller.

Generally, the threshold voltage (V _th ) in a TN type liquid crystal display is expressed by the equation (1).

[0039]

[Equation 1]

(In the formula, k represents a proportional constant and K represents an elastic constant.) From this formula, (N
o. The elastic constant of the compound of 1) is considered to be quite small. As described above, by adding the compound of (No. 1), the threshold voltage can be effectively lowered without substantially lowering the upper limit temperature of the nematic phase of the host liquid crystal, and Δn is also small. can do.

On the other hand, each of the compounds (No. 2) to (No. 4) can be used, for example, as a constituent material of a ferroelectric liquid crystal, and more specifically, a base liquid crystal showing a smectic C phase (hereinafter, It is suitable as a constituent material of the SC host liquid crystal).

Currently, the most commonly used phenylpyrimidine-based SC host liquid crystal (B)

[0043]

[Chemical 10]

(In the above, "%" represents "% by weight") has a melting point of 12.5 ° C and SC up to 55.5 ° C.
Phase, SA phase up to 64.5 ° C., N phase up to 70 ° C., and isotropic liquid (I) phase at higher temperatures. 90% by weight of this SC matrix liquid crystal (B) and (No.
Liquid crystal compositions (M-2) to (M-4) each containing 10% by weight of each compound of Nos. 2) to (No. 4) were prepared. The phase transition temperature of each liquid crystal composition was as follows.

(M-2): 60.5 (SC-SA), 6
7 (SA-N), 79.5 (N-I) (M-3): 53 (SC-SA), 55.5 (SA-).
N), 65.5 (N-I) (M-4): 45 (SC-SA), 58 (SA-N),
66 (N-I)

Since the compound of (No. 2) itself shows the SC phase up to a high temperature, the addition of (No. 2) produces a SC phase as shown in (M-2).
The liquid crystal phase maximum temperature of the composition can be expanded to a high temperature range. Moreover, the phase series in the high temperature range is hardly changed.

The compound (No. 3) does not show the SC phase, but when added in the same manner, the temperature range of the SC phase is hardly narrowed. Moreover, since it has a relatively low viscosity, when a liquid crystal composition showing a chiral smectic C phase (hereinafter abbreviated as SC ^* liquid crystal composition) is prepared by adding a chiral dopant, it is possible to improve the response. is there.

The compound (No. 4) also showed no SC phase,
The maximum temperature of the SA phase is also higher than that of the compound (No. 3). However, since it has a very low viscosity, the viscosity of the composition can be lowered and the responsiveness can be improved by the addition thereof.

Generally, many liquid crystal compounds having a viscosity reducing effect tend to widen the temperature range of the SA phase and narrow the temperature range of the N phase and SC phase of the composition. Since the compound (4.) has an N phase in a wide temperature range, the addition does not narrow the temperature range of the N phase of the composition.

Further, in the current alignment technology, as a liquid crystal phase of a ferroelectric liquid crystal material, a chiral nematic (N ^* ) phase and an SA between a chiral smectic C (SC ^* ) phase and an isotropic liquid (I) phase are used. It is required to have a phase. For that purpose, the SC host liquid crystal is required to have a sufficiently wide temperature range for the N phase as well as the SC phase. From this, the compound of (No. 4) is useful as a viscosity-reducing liquid crystal, and is also useful for obtaining good orientation because it does not narrow the temperature range of the N phase of the composition.

As described above, the compound represented by the general formula (I) can be used as a material of a field effect display cell such as a TN type or STN type in a state of being mixed with another nematic liquid crystal compound. It can be preferably used as an SC host liquid crystal for a ferroelectric liquid crystal in the state of a mixture with another liquid crystal compound exhibiting an SC phase, and as a ferroelectric liquid crystal composition obtained by further adding a chiral dopant thereto. it can.

The present invention also provides a liquid crystal composition containing at least one compound represented by formula (I) as a constituent. Preferred representative examples of the nematic liquid crystal compound that can be used by mixing with the compound represented by the general formula (I) of the present invention are, for example, 4-substituted benzoic acid 4-substituted phenyl ester and 4-substituted cyclohexanecarboxylic acid. 4-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted biphenylyl ester,
4- (4-Substituted cyclohexanecarbonyloxy) benzoic acid 4-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4-substituted phenyl ester, 4-
(4-Substituted cyclohexyl) benzoic acid 4-substituted cyclohexyl ester, 4,4′-substituted biphenyl, 1- (4
-Substituted phenyl) -4-substituted cyclohexane, 4,4 "
-Substituted terphenyl, 1- (4'-substituted biphenylyl)
-4-substituted cyclohexane, 1- (4-substituted cyclohexyl) -4- (4-substituted phenyl) cyclohexane, 2
-(4-Substituted phenyl) -5-substituted pyrimidine, 2-
(4′-Substituted biphenylyl) -5-substituted pyrimidine, 2
-(4-Substituted phenyl) -5- (4-substituted phenyl) pyrimidine, 2- (4-substituted phenyl) -5-substituted pyridine, 2- (4'-substituted biphenylyl) -5-substituted pyridine, 2- ( 4-substituted phenyl) -5- (4-substituted phenyl) pyridine etc. can be mentioned.

Examples of the compound exhibiting the SC phase which can be used by mixing with the compound represented by the general formula (I) of the present invention include, for example, the following general formula (A)

[0054]

[Chemical 11]

(In the formula, R ^a and R ^b represent a linear or branched alkyl group, an alkoxyl group, an alkoxycarbonyl group, an alkanoyloxy group or an alkoxycarbonyloxy group, which may be the same or different from each other. ), A phenylbenzoate compound represented by the general formula (B)

[0056]

[Chemical 12]

A pyrimidine compound represented by the formula (wherein R ^a and R ^b have the same meanings as in formula (A)) can be given. In addition, the general formula (A),
General formula (C) including (B)

[0058]

[Chemical 13]

(In the formula, R ^a and R ^b have the same meanings as in the general formula (A), and the ring L and the ring M are 1, 4 respectively.
-Phenylene group, 1,4-cyclohexylene group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, pyridazine-3,6
Represents a -diyl group, a 1,3-dioxane-2,5-diyl group or a halogen-substituted product thereof, which may be the same or different, and Z ^a is -COO-, -O.
_{CO -, - CH 2 O -} , - OCH 2 -, - CH 2 CH 2 -,
-C = C- or represents a single bond. The compound represented by () can be used for the same purpose. For the purpose of expanding the temperature range of the SC phase to a high temperature range, the general formula (D)

[0060]

[Chemical 14]

(Wherein R ^a and R ^b have the same meanings as in formula (A), and ring L, ring M and ring N have the same meanings as ring L and ring M in formula (C). Which may be the same or different from each other, Z ^a and Z ^b each have the same meaning as Z ^a in the general formula (C), and may be the same or different from each other). The represented tricyclic compounds can be used.

These compounds are represented by the general formula (I) of the present invention.
It is effective to use it as an SC host liquid crystal by mixing with the compound (1), but it is only necessary to show the SC phase as a composition, and it is not always necessary for each compound to show the SC phase.

By adding an optically active compound as a chiral dopant to the thus obtained SC matrix liquid crystal, a liquid crystal composition exhibiting the SC ^* phase in a wide temperature range including room temperature can be easily obtained.

Further, such an SC ^* liquid crystal composition can be used as a display cell by enclosing it as a thin film of about 1 to 20 μm between two transparent glass electrodes. In order to obtain a good contrast, it is necessary to have uniformly oriented monodomains, and many methods have been tried for this reason. In order to exhibit good orientation, it is necessary for the liquid crystal material to exhibit a phase sequence of IN ^* -SA-SC ^* from the high temperature side and to increase the helical pitch in the N ^* phase and SC ^* phase. is there.

[0065]

EXAMPLES The present invention will be further described below by showing Examples of the present invention. However, the invention is not limited to these examples.

The phase transition temperature was measured by using a polarizing microscope equipped with a temperature adjusting stage and a differential scanning calorimeter (DSC). The structure of the compound was confirmed by nuclear magnetic resonance spectrum ( ¹ H-NMR), mass spectrum (MS) and the like. CDCl _{3 in} NMR represents a solvent, s is a singlet, d is a doublet, t is a triplet, and quint.
et represents a quintuplet, m represents a multiplet, and, for example, dd
Represents a double double line, and b represents a wide line. J represents a coupling constant. M ^{+ in} MS represents the parent peak.

Example 1 Synthesis of 2-butyl 6-hydroxychroman (compound of general formula (II))

[0068]

[Chemical 15]

(1-a) Synthesis of 2- (2,5-dimethoxyphenyl) -1,3-dithiane 2,5-dimethoxybenzaldehyde 5 g, 1,3-propanedithiol 3.3 ml, trimethylsilyl polyphosphate (PPSE) 45 ml of dichloromethane solution was stirred at room temperature for 15 hours. The reaction solution was poured into 300 ml of a saturated aqueous solution of sodium hydrogen carbonate, and the reaction product was added with ether 400
Extracted with ml. The extract was concentrated and then recrystallized from a mixed solvent of hexane / ether / dichloromethane (4/2/1) to give 2- (2,5-dimethoxyphenyl) -1,
6.0 g (yield: 78%) of 3-dithiane was obtained.

Colorless needle crystal Melting point: 130 ° C. IR (KBr) 2960, 2930, 2850, 16
08, 1500, 1450, 1420, 1318, 12
72,1233,1200,1040,808,74
_{^{3,684cm -1 1 H NMR (CDCl 3}} ) δ 1.80~2.40
(M, 2H), 2.77 to 3.30 (m, 4H), 3.
80 (s, 3H), 3.87 (s, 3H), 5.72
(S, 1H), 6.84 (s, 2H), 7.22 (s,
1H) MS m / z 256 (M ⁺ , 100), 182 (7
4), 149 (93), 121 (48) Elemental analysis: Calculated as C ₁₂ H ₁₆ S ₂ O ₂ C: 56.22%; H, 6.29%; S, 2
5.01% Found: C, 56.06%; H, 6.20%; S, 2
4.98%

(1-b) 2- (2,5-dimethoxyphenyl) -2- (2-hydroxyhexyl) -1,3-
Synthesis of dithiane 2. (2,5-dimethoxyphenyl) -1,3-dithiane obtained in the above (1-a) 1.28 g (5 mmol) of T
To a 10 ml HF solution, 3.8 ml of a 1.6 M butyllithium-hexane solution was added at -78 ° C, and the mixture was stirred for 10 minutes. 0.72 ml of 1,2-epoxyhexane (6
Was added and the mixture was stirred overnight while warming to room temperature. After completion of the reaction, the reaction solution was treated with 1M hydrochloric acid, the reaction product was extracted with ethyl acetate, the extract solution was concentrated, and purified by column chromatography (Kieselgel 60, hexane / ethyl acetate = 5/1). , 2- (2
1.57 g of 5-dimethoxyphenyl) -2- (2-hydroxyhexyl) -1,3-dithiane (yield: 88%)
Got

Colorless oily substance Rf value: 0.4 (hexane / ethyl acetate = 2/1) IR (neat) 3500, 2950, 1490, 1
280, 1225, 1050, 810 cm ^{-1 1} H NMR (CDCl ₃ ) δ 0.85 (t, J =
7.2 Hz, 3 H), 1.18 to 1.48 (m, 6
H), 1.90 to 2.06 (m, 2H), 2.48.
(D, J = 2.2 Hz, 1H), 2.57 (dd, J =
14.9 and 8.4 Hz, 1H), 2.64 (dd,
J = 14.9 and 2.2 Hz, 1H), 2.79 (d
dd, J = 14.2, 8.5, and 4.4 Hz, 1
H), 2.84 to 2.93 (m, 3H), 3.63 to
3.70 (m, 1H), 3.80 (s, 3H), 3.8
1 (s, 3H), 6.81 (dd, J = 8.8 and
3.0Hz, 1H), 6.88 (d, J = 8, 8Hz,
1H), 7.55 (d, J = 3.0 Hz, 1H) MS m / z 356 (M ⁺ , 30), 255 (3
1), 163 (48), 85 (100) Elemental analysis: Calculated _{C 18 H 28 S 2 O 3} : C, 60.64%; H, 7.92%; S, 1
7.99% Found: C, 60.72%; H, 8.04%; S, 1
7.84%

(1-c) Synthesis of 1- (2,5-dimethoxyphenyl) -3-hydroxyheptane 2- (2,5-dimethoxyphenyl) -2- (2-) obtained in (1-b) above. Hydroxyhexyl) -1,3-dithiane 1.5 g (4.21 mmol) ethanol 20 m
45 ml of Raney-Nitzkel (W-4) ethanol suspension was added to the 1 solution, and the mixture was heated under reflux for 1.5 hours. The reaction solution was filtered through Celite, the filtrate was concentrated, and the obtained residue was purified by column chromatography (Kieselgel 60, toluene / ethyl ether = 10/1),
0.66 g (yield: 62%) of 1- (2,5-dimethoxyphenyl) -3-hydroxyheptane was obtained.

Colorless oily substance Rf value: 0.2 (hexane / ethyl acetate = 5/1) IR (neat) 3500, 2950, 1500, 1
225,1050 cm ^{-1 1} H NMR (CDCl ₃ ) δ
0.89 (t, J = 7.3 Hz, 3H), 1.24-
1.49 (m, 6H), 1.63 to 1.77 (m, 2
H), 2.06 (d, J = 3.6Hz, 1H), 2.6
7 (ddd, J = 13.6, 7.9, and 5.6H
z, 1H), 2.76 (dt, J = 13.6 and 8.
2Hz, 1H), 3.47 to 3.55 (m, 1H),
3.76 (s, 3H), 4.00 (s, 3H), 6.7
0 (dd, J = 8.8 and 3.0 Hz, 1H), 6.
74 (d, J = 3.0 Hz, 1H), 6.78 (d, J
= 8.8 Hz, 1H) MS m / z 252 (M ⁺ , 71), 177 (3
6), 152 (100), 151 (87), 121 (5)
5), 41 (31) High resolution MS (M ⁺ ): C ₁₅ H ₂₄ O ₃ Calculated value: 252.1723 Measured value: 252.1700

(1-d) Synthesis of 1- (2,5-dihydroxyphenyl) -3-hydroxyheptane 1- (2,5-dimethoxyphenyl) -3-hydroxyheptane obtained in (1-c) above 0 To a solution of 0.59 g (2.34 mmol) in 10 ml of dichloromethane, 1.72 ml (23.4 mmol) of dimethyl sulfide and 1.6 g (11.7 mmol) of aluminum chloride were added at 0 ° C.
Stir at room temperature for 5 hours. The reaction mixture was concentrated under reduced pressure, 30 ml of ethyl acetate was added, and the mixture was poured into 50 ml of 1M hydrochloric acid, the organic layer was separated, and the reaction product was mixed with 20 ml of ethyl acetate to 3 ml.
Extracted twice. The extract was dried over sodium sulfate, concentrated under reduced pressure, and the residue was subjected to column chromatography (Kies).
elgel60, toluene / ethyl ether = 2/1)
0.45 g of 1- (2,5-dihydroxyphenyl) -3-hydroxyheptane (yield: 86
%) Was obtained.

Brown powder Melting point: 97 ° C. IR (KBr) 3400, 2940, 1500, 14
50, 1380, 1260, 12160, 1200, 1
040,810 cm ^{-1 1} H NMR (CDCl ₃ ) δ 0.88 (t, J =
7.2Hz, 3H), 1.20 to 1.40 (m, 4
H), 1.45 (quintet, J = 7.1 Hz, 2
H), 1.66 to 1.80 (m, 2H), 1.80 (b
s, 1H), 2.59 (dt, J = 14.0 and 4.
7 Hz, 1 H), 2.85 (ddd, J = 14.0, 1
0.4, and 6.4 Hz, 1H), 3.47 to 3.5
7 (m, 1H), 4.49 (s, 1H), 6.58 (d
d, J = 7.1 and 1.9 Hz, 1H), 6.59
(S, 1H), 6.72 (bs, 1H), 6.73 (d
d, J = 7.1 and 1.9 Hz, 1H) MS m / z 224 (M ⁺ , 13), 206 (2
1), 123 (100) High resolution MS (M ⁺ ): C ₁₃ H ₂₀ O ₃ Calculated value: 224.1411 Measured value: 224.1433

(1-e) Synthesis of 2-butyl-6-hydroxychroman 0.40 g (1.8 mmol) of 1- (2,5-dihydroxyphenyl) -3-hydroxyheptane obtained in (1-d) above. 100 mg (0.54 mmol) of p-toluenesulfonic acid was added to a solution of 10) in 10 ml of toluene, and the mixture was heated under reflux for 5 hours. The reaction solution was poured into 50 ml of 1M hydrochloric acid, the reaction product was extracted with 30 ml of ethyl acetate three times, dried over sodium sulfate, and then concentrated under reduced pressure. The residue was purified by column chromatography (Kieselgel 60, hexane / ethyl acetate = 5/1), and 2-butyl-6 was used.
-350 mg of hydroxychroman (yield: 95%) was obtained.

Colorless needle crystals Melting point: 57 ° C. IR (KBr) 3400, 3000, 2940, 15
10, 1462, 1230, 1060, 822 cm ^{−1 1} H NMR (CDCl ₃ ) δ 0.93 (t, J = 7)
Hz, 3H), 1.32 to 1.77 (m, 7H), 1.
96 (dddd, J = 13.5, 6.2, 3.2, an
d2.2 Hz, 1H), 2.68 (ddd, J = 16.
6, 5.8, and 3.4 Hz, 1H), 2.80 (d
dd, J = 16.6, 11.2, and 6.2 Hz, 1
H), 3.90 (dddd, J = 9.8, 7.4, 5.
6, and 2.1Hz, 1H), 4.33 (bs, 1
H), 6.52 (d, J = 3.0 Hz, 1H), 6.5
7 (dd, J = 8.6 and 3.0 Hz, 1H), 6.
67 (d, J = 8.6 Hz, 1H) MS m / z 206 (M ⁺ , 42), 123 (10
0) Elemental analysis: C ₁₃ H ₁₈ O ₂ Calculated: C, 75.69%; H, 8.80% Found: C, 75.43%; H, 8.81%

Example 2 Synthesis of Liquid Crystal Compound (1) 2-Butyl-6- (trans-4-propylcyclohexyl) carbonyloxychroman (Compound No. 1)
Synthesis of

[0080]

[Chemical 16]

To a solution of 250 mg (1.46 mmol) of trans-4-propylcyclohexanecarboxylic acid in 2 ml of dichloromethane was added 330 mg (1.6 mmol) of dicyclohexylcarbodiimide (DCC), and 10
After stirring for a minute, 300 mg (1.46 mmol) of 2-butyl-6-hydroxychroman obtained in Example 1 and N,
30 mg of N-dimethylaminopyridine (DMAP) was added, and the mixture was stirred at room temperature overnight. The reaction mixture was concentrated under reduced pressure, 50 ml of ether was added, and the mixture was filtered through Celite. The filtrate was concentrated under reduced pressure, and the residue was subjected to column chromatography (Kiese).
lgel60, hexane / ethyl acetate = 10 / 1,20
/ 1) to give 2-butyl-6- (trans-4-propylcyclohexyl) carbonyloxychroman (446 mg, yield: 85%).

Colorless needle crystals Phase transition temperature: 39 ° C. (Cr → N), 57.5 ° C. (N-
I) IR (KBr) 2950,1758 (CO), 121
8,1150 cm ^{−1 1} H NMR (CDCl ₃ ) δ 0.89 (t, J =
7.3 Hz, 3 H), 0.93 (t, J = 7.3 Hz,
3H), 1.16 to 1.78 (m, 14H), 1.85.
(Dd, J = 13.8 and 3.3 Hz, 2H), 1.
97 (dtd, J = 13.5, 6.0, and 3.3H
z, 1H), 2.10 (dd, J = 13.8 and 3.
3 Hz, 2 H), 2.43 (tt, J = 12.0 and
3.5 Hz, 1 H), 2.71 (ddd, J = 16.
7,5.6, and3.5Hz, 1H), 2.82 (d
dd, J = 16.7, 11.1, and 6.0 Hz, 1
H), 3.95 (dddd, J = 9.9, 7.6, 5.
6, and 2.3 Hz, 1H), 6.72 to 6.78.
(M, 3H) MS m / z 358 (M ⁺ , 2), 206 (10
0), 123 (21) Elementary analysis: Calculated _{C 23 H 34 O 3: C} , 77.05%; H, 9.56% Found: C, 76.97%; H, 9.57%

Example 3 Synthesis of Liquid Crystal Compound (2) 2-Hexyl-6- [4- (4-octyloxyphenyl) benzoyloxy] chroman (Compound No. 2)
Synthesis of Example 2 In Example 2, 4- (4-octyloxyphenyl) benzoic acid was used in place of trans-4-propylcyclohexanecarboxylic acid, and 2-hexyl-6 was used in place of 2-butyl-6-hydroxychroman. -Hydroxychroman (this compound was synthesized in the same manner as in Example 1 except that 1,2-epoxyhexane was used instead of 1,2-epoxyhexane in Example 1). 2-hexyl-6- [4-
(4-octyloxyphenyl) benzoyloxy] chroman was obtained. The phase transition temperature of this compound is shown in Table 1.

Example 4 Synthesis of Liquid Crystal Compound (3) In the same manner as in Example 2, 2-hexyl-6- (4-octyloxybenzoyloxy) chroman (compound of No. 3) and 2-hexyl- 6- (trans-4-heptylcyclohexanecarbonyloxy) chroman (No.
4 compound) was obtained. The phase transition temperature of each compound is shown in Table 1.

Example 5 Preparation of Liquid Crystal Composition (1)-
Preparation of nematic liquid crystal composition Base liquid crystal (A) having the following composition

[0086]

[Chemical 17]

(In the above, the cyclohexane ring is in the trans configuration.
"%" Means "% by weight". ) Prepared
And shows a nematic (N) phase below 50.5 ° C.
It was The physical properties at 20 ° C and
Threshold voltage (V _th) Is as follows
It was

Dielectric anisotropy (Δε) 12.0 Refractive index anisotropy (Δn) 0.117 Threshold voltage (V _th ) 1.50 V

A liquid crystal composition (M-1) comprising 75% by weight of the base liquid crystal (A) and 25% by weight of the compound (No. 1) of Example 2 was prepared. The upper limit temperature (T _NI ) of the N phase of (M-1) and its physical properties were as follows.

Maximum temperature of N phase (T _NI ) 49.0 ° C. Dielectric anisotropy (Δε) 9.7 Refractive index anisotropy (Δn) 0.099 Threshold voltage (V _th ) 1.38 V

As described above, although the upper limit temperature of the nematic phase is hardly lowered, the threshold voltage is 1.38 V, which is about 20% lower than that of the base liquid crystal (A). On the contrary, since the dielectric anisotropy (Δε) is small, the elastic constant (K) of the compound (No. 1) is considered to be considerably small in view of the above formula (1). Further, although this composition (M-1) was left at a low temperature for a long time,
No precipitation or the like was observed. Therefore, (No. 1)
The compound is also excellent in compatibility with conventional liquid crystal compounds.

Example 6 Preparation of Liquid Crystal Composition (2)-
Preparation of SC base liquid crystal Base liquid crystal (B) showing an SC phase having the following composition

[0093]

[Chemical 18]

Was prepared. The phase transition temperature of this composition was as follows. Base liquid crystal (B): 12.5 ° C. (Cr → SC), 55.5
℃ (SC-SA), 64.5 ℃ (SA-N), 70 ℃
(N-I)

An SC host liquid crystal (M-2) comprising 90% by weight of this SC host liquid crystal (B) and 10% by weight of the compound of (No. 2) was prepared. The phase transition temperature of this SC host liquid crystal was as follows.

(M-2): 60.5 ° C. (SC-SA),
67 ° C (SA-N), 79.5 ° C (N-I)

Thus, compared to the base liquid crystal (B), SC
It is clear that the upper limit temperature of the phase has risen and the temperature range of the N phase has greatly expanded. Also, the base liquid crystal (B)
SC liquid crystal composition (M-3) consisting of 90% by weight and 10% by weight of the compound of (No. 3) was prepared, and 90% by weight of base liquid crystal (B) and 10% by weight of the compound of (No. 4).
SC liquid crystal compositions (M-4) each consisting of The phase transition temperatures of these compositions were as follows:

(M-3): 53 ° C. (SC-SA), 5
5.5 ° C (SA-N), 65.5 ° C (NI) (M-4): 46 ° C (SC-SA), 58 ° C (SA-)
N), 66 ° C (N-I)

(Example 7) Preparation of liquid crystal composition (3)-
Preparation of Ferroelectric Liquid Crystal Composition 95 wt% of SC host liquid crystal (M-2) obtained in Example 6
And a formula (C) having a cyanocyclopropane skeleton

[0100]

[Chemical 19]

SC consisting of 5% by weight of the chiral dopant of
^{* A} liquid crystal composition (M-5) was prepared. The phase transition temperature was as follows. (M-5): 57.5 ° C (SC ^* -SA), 71.5 ° C
(SA-N ^* ), 76.5 ° C (N ^* -I)

This SC ^* liquid crystal composition (M-5) was heated to the isotropic liquid (I) phase, and this was subjected to an alignment treatment by two transparent electrode plates (polyimide coating-rubbing) having a thickness of about 2 μm. Was filled in a glass cell composed of the above-mentioned) to prepare a display element. When this was gradually cooled to room temperature, uniformly oriented SC ^* phase cells were obtained. A rectangular wave having an electric field strength of 10 V _pp / μm and 50 Hz was applied to this cell, and the electro-optical response was measured. As a result, a high-speed response of 74 μsec at 25 ° C. was confirmed. At this time, the tilt angle was 23 °, and the contrast was very good.

(Embodiment 8) In the same manner as in Embodiment 7, SC
SC ^* liquid crystal compositions (M-7) and (M-8) each containing 95% by weight of the host liquid crystals (M-3) and (M-4) and 5% by weight of the chiral dopant of the formula (C) were prepared. . These phase transition temperatures and the electro-optical response of the display device produced in the same manner were as follows.

(M-7): 51.5 ° C. (SC ^* -S
A), 62 ° C. (SA-N ^* ), 67 ° C. (N ^* -I) Electro-optical response 68 μsec Contrast very good (M-8): 46 ° C. (SC ^* -SA), 62 ° C. (SA-
N ^* ), 66.5 ° C (N ^* -I) Electro-optical response 40 μsec Contrast very good

COMPARATIVE EXAMPLE A SC ^* liquid crystal composition (M-6) comprising 95% by weight of the base liquid crystal (B) and 5% by weight of the chiral dopant of the formula (C) was prepared. Met.

(M-6): 56 ° C. (SC ^* -SA), 6
5.5 ° C. (SA-N ^* ), 67.5 ° C. (N ^* -I) Since the temperature range of the N ^* phase is extremely narrow, the orientation is inferior to that of (M-5) and the contrast is lowered. did.

[0107]

The compound of the present invention represented by the general formula (I) is
The product can be easily manufactured industrially as shown in the examples.
It is chemically stable against heat, light, water, etc.
Excellent compatibility with nematic liquid crystals used
It Moreover, by adding a small amount to the base liquid crystal,
Threshold voltage without narrowing the temperature range of the tic phase
(V _th) Can be effectively reduced. Also books
The compound of the general formula (I) of the invention is an SC matrix of a ferroelectric liquid crystal.
It is also useful as a component of liquid crystals and can be added to form a composition.
The temperature range of the SC phase of the product can be expanded, and the viscosity
Can be reduced, so improve responsiveness
Is also possible.

Therefore, the compound represented by the general formula (I) of the present invention is very useful as a constituent material of a display optical switching element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hijiro Hiujiro 4-29-3-101 Kamizuruma, Sagamihara City, Kanagawa Prefecture (72) Inventor Tetsuo Kusumoto 1-9-2-102, Minamidai, Sagamihara City, Kanagawa Prefecture (72) Inventor Kenichi Sato 35-11 Kamimizo, Sagamihara City, Kanagawa Prefecture

Claims (3)

[Claims] 1. A compound represented by the general formula (I): (In the formula, R ¹ has 1 to 1 carbon atoms which may be substituted.
8 represents an alkyl group or an alkenyl group, X represents a single bond or -O-, and ring A and ring B are each independently substituted with a 1,4-cyclohexylene group or a fluorine atom. , 4-phenylene group, pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, pyrazine-2,5-diyl group or 1,3-dioxane-
Represents a 2,5-diyl group, m represents 0 or 1, and R
² represents an alkyl group having 1 to 12 carbon atoms. ) The compound represented by. 2. R ¹ is a linear alkyl group having 1 to 12 carbon atoms, and both ring A and ring B may be substituted with a 1,4-cyclohexylene group or a fluorine atom. The compound according to claim 1, which is a 4-phenylene group. 3. A liquid crystal composition containing the compound represented by the general formula (I) according to claim 1.