JP3065734B2 - Cinnamic acid derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention provides a compound exhibiting a novel liquid crystal, a method for producing the same, a composition containing the compound, and a liquid crystal device using the same.

[0002]

2. Description of the Related Art A large number of liquid crystal compounds are known as nematic liquid crystals. Although these are currently the mainstream of compounds or compositions used in liquid crystal display devices, they have the problem that the response speed is slow and only a response speed on the order of several milliseconds can be obtained. It is said that performance is approaching its limit.

As a solution to the disadvantages of the conventional liquid crystal display device, the use of a liquid crystal having bistability has been proposed by Clark and Ragawell (Japanese Patent Application Laid-Open No. Sho.
No. 6-107216). This bistable liquid crystal is
It is called a ferroelectric liquid crystal, and it is noted that a high-speed response and a memory property can be obtained. In particular, in recent years, the practical use of the liquid crystal has been actively studied, and the development of a practical ferroelectric liquid crystal material has been urgently required.

Generally, a ferroelectric liquid crystal is a compound having an optically active site and is expressed in a series of smectic phases having a molecular orientation in which the major axis of the molecule is tilted from the normal direction of the layer. Among them, chiral smectic C (hereinafter, S
Abbreviated as _C ^* . ) Phase has practically excellent properties due to its relatively low voltage operability.

[0005] As described above, the ferroelectric liquid crystal has a very fast response speed due to the spontaneous polarization, can exhibit a bistable state with memory properties, and has an excellent viewing angle. Therefore, it is suitable as a material for a display having a large capacity and a large screen.

As such a ferroelectric liquid crystal, 1975
Year, R. B. 4- (4-) synthesized by Meyer et al.
n-decyloxybenzylideneamino) cinnamic acid-2-methylbutyl ester (hereinafter abbreviated as DOBAMBC) is known (J. Physique 36).
L-69 (1975)).

However, since DOBAMBC contains a Schiff base in its structure, its chemical stability is difficult.
Therefore, various physically and chemically stable compounds have been sought as ferroelectric liquid crystal materials. Currently, 4- (4-nalkyloxyphenyl) -1-carboxylic acid-2-methylbutyl ester and other esters have been developed. The main focus has shifted to the search for systemic compounds. However, these ester compounds show no S _C ^* phase, or even if they do, the temperature range where the S _C ^* phase is shown is narrow, and furthermore, a monotropic liquid crystal showing a different phase series when the liquid crystal is heated and cooled. Because
There are few things that can withstand actual use (LiquidCry
stals and OrderedFluids 4
(1984)).

[0008]

Compounds conventionally used as ferroelectric liquid crystals include optically active alcohols as raw materials for optically active sites, specifically, 2-methylbutanol, 2-octanol, and 3-methylpentanol. And so on. However, these alcohols are expensive and have problems in terms of production cost.

Therefore, we have already developed an amino acid derivative using an inexpensive and readily available amino acid as a raw material for an optically active substance (see Japanese Patent Application Laid-Open No. 3-109366).
This compound has a lower temperature than conventional liquid crystal compounds even when an inexpensive and easily available amino acid is used as an optically active material, and has a smectic liquid crystal, particularly a smectic phase including a ferroelectric S _C ^* phase, over a wide temperature range. Are obtained. However, the temperature at which the S _C ^* phase of this amino acid derivative is around 100 ° C.
Since it is as small as nC / cm ² , it has been desired to develop a compound having a large spontaneous polarization at a lower temperature as a liquid crystal material.

The present invention relates to a novel compound exhibiting a smectic phase at a temperature close to ordinary temperature, exhibiting a larger spontaneous polarization than that of an optically active compound, and exhibiting a smectic C phase including a ferroelectric S _C ^* phase. It is intended to provide compositions containing them.

The optically active compound exhibiting liquid crystal provided by the present invention exhibits ferroelectricity, particularly S _C ^* phase, alone or as a liquid crystal composition containing at least one of these compounds, and exhibits electro-optical properties. An object of the present invention is to provide a novel liquid crystal compound which can be a component of a ferroelectric liquid crystal display element used as a switching element.

[0012] Among the compounds provided by the present invention, even a compound containing no optically active carbon can be mixed with another optically active liquid crystal compound to form a ferroelectric liquid crystal composition as a liquid crystal composition. It is an object of the present invention to provide a compound useful as a mixing component for forming a composition exhibiting a smectic C ^* phase at a low temperature over a wide temperature range.

[0013]

Means for Solving the Problems As a result of intensive studies, the present inventors consider that peptide bonding of amino acids is involved as a cause of a high temperature of a liquid crystal compound, and α-hydroxy acid is substituted for amino acid. It has been found that lowering the temperature is possible if used, and the present invention has been made based on this finding.

The compound provided by the present invention has the general formula (1)

Embedded image (Wherein R is a linear alkyl group having 6 to 16 carbon atoms, X is an alkyl group having 1 to 6 carbon atoms, Y is CH ₃ , CH ₂ CH (C
_{H 3) 2, CH (CH} 3) 2 and CH (CH ₃₎ CH ₂
One group selected from CH _3, Z represents one group selected from CN, CH ₃ and H. ) Is cinnamic acid derivative.

The structure of the cinnamic acid derivative of the present invention is represented by the general formula (1)
Α-hydroxy acid ester moiety represented by 4)

Embedded image And a cinnamic acid derivative moiety represented by the general formula (15) as a core moiety

Embedded image And the two are linked by an ester bond.

First, in the α-hydroxy acid ester portion, hydrogen, Y, and —COOX are bonded to carbon C, and the hydroxyl group portion forms an ester bond. X represents an alkyl group having 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms. If the carbon number is 7 or more, it is difficult to obtain raw materials,
Synthesis also becomes difficult.

Y is CH ₃ , CH ₂ CH (CH ₃ ) ₂ , C
Represents a kind of group selected from H (CH ₃ ) ₂ and CH (CH ₃ ) CH ₂ CH. The raw material for forming the α-hydroxy acid ester moiety may be a hydroxy acid ester having a hydroxyl group at the α-position, and specifically reacts the NH ₂ group of lactic acid or amino acid with nitrous acid at a low temperature by a conventional method. The one derived by this is used. The raw material amino acids are specifically L-alanine, L-leucine,
L-valine, L-isoleucine and the like;
Both amino acids and racemates may be used, and an amino acid having an optically active site is used.

In the cinnamic acid derivative part, Z is first bonded to the carbon at the α-position of the unsaturated hydrocarbon group of the cinnamic acid, and the carboxylic acid part forms an ester bond with the hydroxyl group of the α-hydroxy acid ester. Z represents one selected from CN, CH ₃ and H. A biphenyl group is bonded to the para position of the benzene ring of cinnamic acid via an ester bond, and R is bonded to the 4 ′ position of the biphenyl group via an ether bond.

Here, the introduction of the biphenyl group stabilizes the liquid crystal phase. Further, when the carbon in the α-hydroxy acid ester portion is asymmetric carbon, an effect that the liquid crystal exhibits ferroelectricity can be obtained. R represents a linear alkyl group having 6 to 16 carbon atoms, and particularly preferably has 12 to 14 carbon atoms. When the number of carbon atoms is less than 6, the temperature range in which a liquid crystal phase is displayed becomes narrow. When the number of carbon atoms is 17 or more, the liquid crystallinity is lowered, and it is often difficult to obtain raw materials.

As described above, the present invention uses an α-hydroxy acid ester in the side chain of a smectic liquid crystal,
It is characterized in that a cinnamic acid derivative is introduced as a core portion, and a biphenyl group is further bound.

[0021] That is, by using the α- hydroxy acid ester, even at room temperature in combination with cinnamic acid derivative indicates a higher order smectic phase and S _C phase in a wide temperature range near room temperature, in particular an optically active compound S _c ^* phase,
That is, it has become possible to express ferroelectricity. .

The compound exhibiting liquid crystal provided by the present invention is a novel cinnamic acid derivative which can be used for a liquid crystal display device having excellent responsiveness and memory properties, and particularly includes a compound exhibiting S _C ^* phase. It is a novel liquid crystal compound that can be used in the field of electro-optical switching devices as a component of a ferroelectric liquid crystal display device.

The compound of the present invention which exhibits ferroelectricity can be used as a ferroelectric liquid crystal device. Also, the compound of the present invention may be compounded with already known ferroelectric liquid crystals, which may or may not exhibit ferroelectricity, to increase or decrease the temperature region exhibiting ferroelectricity, or to improve the responsiveness. It can be added to a liquid crystal that is not optically active to have ferroelectricity. Since the compound of the present invention shows a smectic phase even at room temperature, it is also effective as a material for mixing with other liquid crystal compounds.

The compound according to the present invention can be produced according to the following production method. The α-substituted-4-oxycinnamic acid represented by the general formula (2) is acetylated for protection with acetic anhydride-pyridine to obtain a compound of the general formula (3), and the compound represented by the general formula (4) -Reaction with a hydroxy acid to produce an ester represented by the general formula (5), excluding the acetyl group, to give an α-substituted-4-oxycinnamic acid ester of the general formula (6).

Embedded image A carboxylic acid represented by the general formula (7)

Embedded image Is reacted to produce the cinnamic acid derivative represented by the general formula (1).

Embedded image

The process for producing the compound according to the present invention can be considered in two stages. That is, first, the compound represented by the general formula (3) is obtained from the compound represented by the general formula (2), and the compound represented by the general formula (4) is reacted with the compound represented by the general formula (5). A route from which a compound represented by the general formula (6) is obtained to a compound represented by the general formula (6) (hereinafter referred to as reaction A); and a compound represented by the general formula (6) and a compound represented by the general formula (7) It comprises two stages of the process of reacting the compound represented by the formula (1) to reach the compound represented by the general formula (1) (hereinafter referred to as reaction B).

<< Reaction A >>

Embedded image (In the formula, Z represents one of CN, CH ₃ and H.)
When Z is CN or H, a commercially available compound can be used. When Z is CH ₃ ,
It can be synthesized by a conventionally known method shown below. That is, it can be obtained by reacting 4-hydroxybenzaldehyde and propionic anhydride with potassium propionate.

The compound of general formula (2) is reacted with acetic anhydride-pyridine to acetylate the hydroxyl group to give a compound of general formula (3).

The compound of the general formula (3) is esterified with an α-hydroxy acid ester represented by the general formula (4) and thionyl chloride to obtain a general formula (5). The α-hydroxy acid ester used here is obtained by converting an amino group of commercially available lactic acid, glycolic acid or a commercially available amino acid (alanine, valine, leucine, isoleucine, etc.) into a hydroxyl group by a method using nitrous acid and sulfuric acid. The obtained α-hydroxy acid and an alcohol having a carbon chain corresponding to the substituent X are dehydrated and condensed in the presence of sulfuric acid.

The compound represented by the general formula (6) is obtained by removing the protecting group of the compound represented by the general formula (5) using a 1N aqueous solution of LiOH.

<< Reaction B >> The compound represented by the general formula (7) can be reacted with p-hydroxybiphenylcarboxylic acid and alkyl bromide in an alkaline solution to obtain the desired p-alkoxybiphenylcarboxylic acid. it can.

Prior to the reaction of this compound with the compound represented by the general formula (6) obtained by the reaction A, the compound is subjected to acid chloride by heating to reflux with thionyl chloride, and then to the compound represented by the general formula (6). By heating and refluxing with pyridine (benzene, ether, etc.) in a solvent, the desired compound, a cinnamic acid derivative represented by the general formula (1), is obtained.

The cinnamic acid derivative obtained here can be used alone as an optically active compound as a ferroelectric liquid crystal compound having excellent response and memory properties.
When mixed with some liquid crystal compounds to form a liquid crystal composition,
It can be used as a ferroelectric liquid crystal display exhibiting S _c ^* phase.

As another preferred liquid crystalline compound, a compound represented by the following general formula (8) can be mentioned.

Embedded image

The compound represented by formula (8) is exemplified by the following formula (9) (Japanese Patent Application No. 1-158993).
A tranexamic acid derivative represented by

Embedded image An amine derivative represented by the following general formula (10) (Japanese Patent Application No. 2-86948);

Embedded image A tranexamic acid derivative represented by the following general formula (11) (Japanese Patent Application No. 2-149487);

Embedded image An amine derivative represented by the following general formula (12),

Embedded image And the like.

The ratio of the cinnamic acid derivative of the present invention to these other liquid crystal compounds or a mixture thereof is preferably at least about 2% or more based on the whole liquid crystal composition.

In the cinnamic acid derivative of the present invention, even if the number of carbon atoms of the alkyl group of R or X in the general formula (1) is slightly increased or decreased, the effect on liquid crystallinity is not so large.

[0037]

The compound represented by the general formula (1) in the present invention is a smectic liquid crystal compound using a biphenyl group and cinnamic acid as a core portion and an α-hydroxy acid as a side chain portion, and is useful as a liquid crystal. It is a novel cinnamic acid derivative.

When an amino acid was directly used as a cinnamic acid derivative, the spontaneous polarization was small at a high temperature. However, the temperature was lowered by using lactic acid and an α-hydroxy acid derived from an amino acid, and an optically active compound was an optically inactive compound. The spontaneous polarization was almost twice as large as that of.

Further, by introducing a biphenyl group into the cinnamic acid derivative portion, the liquid crystal layer is stabilized and the smectic X
A phase (S _x ) and a smectic C phase (S _c ) appeared, and the optically active compound showed ferroelectricity.

[0040]

The compounds of the present invention will be described in more detail with reference to the following Examples, which, however, are not intended to restrict the scope of the present invention.

Hereinafter, I, N ^* , A, C, C ^* , X, X ^* ,
K is an isotropic phase, a cholesteric phase (optical activity),
Smectic A phase, Smectic C phase, Chiral Smectic C phase, Smectic X phase, Chiral Smectic X
Shows phases and crystals.

The compound of the present invention was purified by silica gel column chromatography and recrystallization from ethyl acetate and hexane. The phase transition point measurements shown below may be slightly affected by the purity of the material.

(Example 1) [1-1] Synthesis of α-cyano-4-acetoxycinnamic acid 9.5 g of commercially available α-cyano-4-hydroxycinnamic acid was dissolved in 50 ml of pyridine, and 10 ml of acetic anhydride was added thereto. Was added dropwise, and the mixture was stirred and reacted at room temperature for 3 hours. Next, the reaction solution was dropped into a 5 wt% aqueous hydrochloric acid solution, and the precipitated reaction product was separated by filtration, washed with water and dried to obtain 10 g of 4-acetoxy-α-cyanocinnamic acid.

[1-2] 2- (S) -hydroxy-3-
Synthesis of methyl-butanoate 15 g of L-valine are dissolved in 200 ml of 0.5 molar sulfuric acid. Over a period of 1.5 hours, a cold solution of 13 g of sodium nitrite in 50 ml of water was added dropwise, keeping the temperature between 0 and -2 ° C. The reaction mixture was kept stirring at room temperature overnight, then the pH was adjusted to 6 by adding solid sodium bicarbonate. 50
The solution was concentrated under reduced pressure at about 70 ° C. to about 70 ml. 40% H ₃
The solution was acidified to pH 3 with PO ₄ and the crude product was extracted into THF. The THF solution was washed with brine, dried over MgSO ₄ and concentrated under reduced pressure to give 13 g of a yellow oil.

13 g of the above oily substance was added to 80 ml of ethanol.
And 3 ml of concentrated sulfuric acid is added thereto, and the mixture is heated under reflux at 70 ° C. for 3 hours. After completion of the reaction, ethanol was distilled off under reduced pressure, and the residue was poured into ice-cold water (80 ml) and extracted with ether (50 ml × 3). The ether extract was washed successively with water (50 ml × 2) and brine, dried over Na ₂ SO ₄ , and the solvent was distilled off under reduced pressure to give 7.25 g of ethyl 2- (S) -hydroxy-3-methylbutanoate. I got

[1-3] Synthesis of α-cyano-4-acetoxycinnamic acid-1- (S) -ethoxycarbonyl-2-methylpropyl ester 2.31 g of α-cyano-4-acetoxycinnamic acid, thionyl chloride 7 0.21 ml of DMF1drop is heated under reflux for about 2 hours to form an acid chloride. Thionyl chloride is distilled off,
1.46 g of the compound synthesized in (1-2) and pyridine 4.
04 ml, 25 ml of ether and 1 drop of DMF were added, and the mixture was heated under reflux for about 5 hours to complete the esterification.

After the post-treatment, purification was carried out by silica gel column chromatography to obtain 1.91 g of α-cyano-4-acetoxycinnamic acid-1 (S) -ethoxycarbonyl-2-methylpropyl ester.

[1-4] Synthesis of α-cyano-4-hydroxycinnamic acid-1 (S) -ethoxycarbonyl-2-methylpropyl ester 0.95 g of the compound synthesized in [1-3] was added to THF 10m
and add 5 ml of 1N LiOH dropwise. The mixture is stirred at room temperature for about 5 hours, and the acetoxy group is selectively hydrolyzed and eliminated. After purification by column chromatography, 0.23 g of the target α-cyano-4-hydroxycinnamic acid-1-ethoxycarbonyl-2-methylpropyl ester was obtained.

[1-5] 4-oxycarbonyl (4'-
n-Lauryloxybiphenyl) α-cyanocinnamic acid-1
Synthesis of (S) -ethoxycarbonyl-2-methylpropyl ester 0.30 g of lauryloxybiphenylcarboxylic acid, 0.57 ml of thionyl chloride and 1 drop of DMF are heated under reflux for about 2 hours to form an acid chloride. Thionyl chloride was distilled off, and 0.23 g of the compound synthesized in (1-4), 0.26 ml of pyridine, 12 ml of toluene and 1 drop of DMF were added, and the mixture was heated under reflux for about 5 hours to complete the esterification. After post-treatment, purified by column chromatography recrystallization,
0.3 g of the desired compound was obtained.

The structure of the obtained product was confirmed by measurement of infrared absorption spectrum and elemental analysis' H-NMR. Next, the results of measuring the phase transition temperature of this substance are shown in Table 1. The phase transition temperature was determined by both visual observation with a polarizing microscope and differential scanning calorimetry. FIG. 1 shows the temperature dependence of spontaneous polarization. Table 1 shows the response speed. Spontaneous polarization and response speed were measured by the following methods.

<Measurement of spontaneous polarization> After heating the compound to make an isotropic liquid, a vacuum injection method was applied between two glass substrates (with ITO transparent electrodes) via a 3.3 μm-thick polyethylene terephthalate film. To form a thin-film liquid crystal cell. After that, the spacer edge method (Ishik
awa et al. , JapaneseJourna
l of Applied Physics, Vol.
23, no. 4, p. L21, 1984), the S _A phase was oriented by slow cooling while applying a temperature gradient, and further lowered to the S _A -S _C ^* transition temperature.

While lowering the temperature from this state, a triangular wave voltage application method (Miyasato et al., Japan
anise Journal of Applied
Physics, Vol. 22, no. 10, p. L6
61, 1983), and a spontaneous polarization temperature change as shown by a curve 1 in FIG. 1 was obtained.

<Measurement of Response Speed> _A rectangular wave voltage (10 to 5) was applied to the same thin film liquid crystal cell as described above at a temperature below the S _A -S _C ^* transition.
0 Vp-p, 50 Hz), and the response speed τ is obtained from the half-width tw of the domain-inverted current peak obtained at this time by the formula (I). Τ = tw / 1.75 (I) This is expressed as (II) The response speed τ ′ is calculated by applying the equation when the applied voltage is 50 V (the applied voltage is E (V)), and τ ′ = (E / 50) τ (II) This value is also shown in Table 1. .

Example 2 In the general formula (1), R is C
₁₂ H ₂₅ , X is C ₂ H ₅ , Y is CH (CH ₃ ) CH ₂ CH
₃ and a compound in which Z is CN was synthesized in the same manner as in Example 1. Further, the fact that the obtained compound had the desired structure was confirmed by infrared absorption spectrum and 'H-NMR in the same manner as in Example 1. The phase transition temperature, the temperature dependence of spontaneous polarization, and the response speed of these substances were measured in the same manner as in Example 1.

Table 1 also shows examples of the phase transition temperature and the response speed of the compound obtained in Example 2. FIG. 1 shows the temperature dependence of spontaneous polarization. These results show that the cinnamic acid derivative according to the present invention exhibits a smectic phase at a relatively low temperature of room temperature to 120 ° C. and in a wide temperature range. Among these smectic phases, those exhibiting ferroelectricity, and particularly useful chiral smectic C phase (S _C ^* phase) are more advantageous as those exhibiting higher spontaneous polarization values at lower temperatures.

[0056]

[Table 1]

Example 3 The compound synthesized in Example 1 was mixed with the following non-chiral amine liquid crystal (A) at various ratios, and the phase transition temperature was measured to obtain a phase diagram as shown in FIG. I got These liquid crystal compositions exhibited ferroelectricity over a wide temperature range.

Embedded image A liquid crystal composition prepared by adding 20% by weight of the compound synthesized in Example 1 to 80% by weight of (A) is made of a glass plate with a transparent electrode, which is coated with polyimide and rubbed. When the cell was injected into a 3.3 μm cell and a rectangular wave voltage (30 V _PP , 50 Hz) was applied, clear light / dark switching was exhibited. The response speed determined by the change in the transparent light intensity (10 to 90%) is about 3 at 50 ° C.
It was 00 μsec.

Example 4 A ferroelectric liquid crystal composition was prepared by adding 20% by weight of the compound synthesized in Example 1 to 80% by weight of the following non-chiral amine liquid crystal (B). .

Embedded image This liquid crystal composition exhibits ferroelectricity over a wide temperature range, and its phase transition is Met. Next, the composition was injected into the cell in the same manner as in Example 3, and a square wave voltage (30 V _PP , 50 Hz) was applied. As a result, clear light-dark switching was exhibited, and a change in transmitted light intensity (10 to 90%) was observed. The obtained response speed was about 500 μsec at 60 ° C.

[0059]

As described above, the compound of the present invention uses inexpensive and easily available lactic acid and amino acid, and has a smectic phase and a
An optically active compound exhibits a particularly useful S _C ^* phase.

Particularly, as a feature of the compound of the present invention, when the compound itself contains an optically active carbon, it is mixed with a liquid crystal having various other smectic C phases (need not be chiral). , As a component for mixing a liquid crystal composition having a S _c ^* phase, or in the case of a compound which does not itself contain optically active carbon, is mixed with a compound having optical activity to form S
_This compound is useful as a component for mixing a liquid crystal composition having a _c ^* phase, and is suitable for improving a temperature region exhibiting ferroelectricity, spontaneous polarization, and responsiveness.

Thus, alone or in other nematics,
By appropriately blending with a smectic or ferroelectric liquid crystal, a novel compound useful as a material for a liquid crystal display device applying an electro-optical effect in a practical temperature range could be easily provided at low cost.

[Brief description of the drawings]

FIG. 1 shows the temperature dependence of spontaneous polarization.
2 corresponds to the compounds of Examples 1 and 2, respectively.

FIG. 2 shows a phase transition temperature curve of a mixture of 4- (N-heptyl-N-methylaminomethyl) benzoic acid 4 ″ -nonyloxycarbonyl-4′-biphenyl ester and the compound obtained in Example 1.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-239250 (JP, A) JP-A-62-174046 (JP, A) JP-A-3-109366 (JP, A) JP-A-4- 316545 (JP, A) JP-A-3-218338 (JP, A) JP-A-3-284656 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 69/94 C07C 255 / 38 CA (STN) REGISTRY (STN)

Claims (9)

(57) [Claims] 1. A compound of the general formula (1) (Wherein R is a linear alkyl group having 6 to 16 carbon atoms, X is an alkyl group having 1 to 6 carbon atoms, Y is CH ₃ , CH ₂ CH (C
_{H 3) 2, CH (CH} 3) 2 and CH (CH ₃₎ CH ₂
One group selected from CH _3, Z represents one group selected from CN, CH ₃ and H. A cinnamic acid derivative represented by). 2. A compound of the general formula (2) (Wherein Z represents a kind of group selected from CN, CH _3, and H). The compound represented by the general formula (3) is reacted with acetic anhydride in pyridine to add a protecting group. (In the formula, Z is the same as in the general formula (2).) After obtaining a compound represented by the general formula (4), (Where X is an alkyl group having 1 to 6 carbon atoms, Y is CH ₃ , C
H ₂ CH (CH ₃ ) ₂ , CH (CH ₃ ) ₂ and CH
A group selected from (CH ₃ ) CH ₂ CH ₃ or Z
Represents a kind of group selected from CN, CH ₃ and H. ), And reacted with an α-hydroxy acid represented by the general formula (5). (Where X is an alkyl group having 1 to 6 carbon atoms, Y is CH ₃ , C
H ₂ CH (CH ₃ ) ₂ , CH (CH ₃ ) ₂ and CH
(CH ₃ ) a kind of group selected from CH ₂ CH ₃ , Z is C
Represents a kind of group selected from N, CH ₃ and H. ), And after removing the protecting group, the compound of the general formula (6) (Where X, Y and Z are the same as in general formula (5)), and then general formula (7) (In the formula, R represents a straight-chain alkyl group having 6 to 16 carbon atoms.)
A method for producing a cinnamic acid derivative represented by the general formula (1), characterized by reacting with a compound represented by the formula: 3. A liquid crystal composition comprising the cinnamic acid derivative according to claim 1 as a compounding component. 4. A liquid crystal composition comprising the cinnamic acid derivative according to claim 1 and at least one compound represented by the general formula (8) as a compounding component. Embedded image 5. The liquid crystal composition according to claim 3, comprising the cinnamic acid derivative according to claim 1 and at least one compound represented by the general formula (9) as a compounding component. Embedded image 6. The liquid crystal composition according to claim 3, comprising the cinnamic acid derivative according to claim 1 and at least one compound represented by the general formula (10) as a compounding component. Embedded image 7. A liquid crystal composition according to claim 3, comprising the cinnamic acid derivative according to claim 1 and at least one compound represented by the general formula (11) as a compounding component. Embedded image 8. The liquid crystal composition according to claim 3, which comprises the cinnamic acid derivative according to claim 1 and at least one compound represented by the general formula (12) as a compounding component. Embedded image 9. A liquid crystal device comprising at least one of the derivative according to claim 1 or the liquid crystal composition according to claim 3.