JPH0459748A - Carboxylic acid ester compounds, liquid crystal compounds and liquid crystal compositions - Google Patents

Abstract

NEW MATERIAL:A compound of formula I (R<1> is 3-20C alkyl or alkoxy, 3-20C halogenated alkyl; C* is asymmetric carbon; R<2> is 2-10C alkyl). EXAMPLE:4-[4'-(6''-n-decyloxy-2''-naphthoyloxy)benzoyloxy]-benzoic acid R-1'''- methylhepty ester. USE:A compound for liquid crystal compositions. The compound of formula I is a liquid crystal compound, optically active and especially useful for display elements having characteristics such as action temperatures in a wide range, large switching rates, switching threshold voltages in a proper range and acting in reduced consumption powers. PREPARATION:For example, a compound of formula II is esterified with a compound of formula III to obtain a compound of formula IV, which is reduced with H2 gas in the presence of a reduction catalyst such as Pd/C. The resultant compound of formula V is condensed with a compound of formula VI (R' is group of formula VII) to obtain the component of formula I.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to novel carboxylic acid ester compounds and liquid crystal compounds. More specifically, the present invention relates to novel carboxylic acid ester compounds and liquid crystal compounds used in display elements and the like.

i Mitateboshi Gokami Ej Many display devices such as office automation equipment that have been used in the past are driven in TN (twisted nematic) mode.

However, when this method is adopted, in order to change the displayed image, it is necessary to change the molecular position of the liquid crystal compound, which increases the driving time and also requires additional time to change the molecular position of the liquid crystal compound. There is a problem in that the voltage applied, that is, the power consumption also increases.

On the other hand, a switching element using a ferroelectric liquid crystal compound can function as a switching element simply by changing the alignment direction of the molecules of the liquid crystal compound, so that the switching time can be significantly shortened. Furthermore, since the product (PsXE) of the spontaneous polarization (Ps) of the ferroelectric liquid crystal compound and the electric field strength (E) is the effective energy intensity for changing the orientation direction of molecules, power consumption is also extremely low. Since such ferroelectric liquid crystal compounds have two stable states, or bistability, depending on the direction of the applied electric field, their switching threshold characteristics are also very good, making them useful as display devices for moving images. Particularly suitable for use.

When such a ferroelectric liquid crystal compound is used in an optical switch/notching element, etc., the ferroelectric liquid crystal compound must have an operating temperature range of around room temperature or lower;
Many characteristics are required, such as a wide operating temperature range, a high (fast) switching speed, and a switching threshold voltage within an appropriate range.

However, regarding the conventionally known ferroelectric liquid crystal compounds, for example, R.B. Meyer et al.
, the paper [J.
) Volume 36, page L-69, 1975], Masaaki Taguchi, Takamasa Harada's paper [Proceedings of the 11th LCD Symposium 16
8, 1985], even though ferroelectric liquid crystal compounds generally have a narrow operating temperature and a wide operating temperature range, ferroelectric liquid crystals do not have sufficient other properties. No substance that is practically satisfactory has been obtained.

OBJECTS OF THE INVENTION The present invention aims to provide novel carboxylic acid ester compounds.

Furthermore, the present invention particularly provides a liquid crystal that can be used to form a display device, etc., which has excellent characteristics such as a wide operating temperature range, a high switching speed, a switching threshold voltage within an appropriate range, and operation with extremely low power consumption. The purpose is to provide compounds.

Summary of the Invention The carboxylic acid ester compound of the present invention has the following formula % formula % [However, in formula [A], R1 has 3 to 2 carbon atoms.
0 alkyl group, an alkoxy group having 3 to 20 carbon atoms, and a halogenated alkyl group having 3 to 20 carbon atoms, and is asymmetric (asymmetric).
It represents a carbon atom, and R2 represents an alkyl group having 2 to 10 carbon atoms.

Furthermore, the liquid crystal compound according to the present invention is characterized by being represented by the above formula [A].

Further, the liquid crystal composition of the present invention is characterized by containing at least one type of carboxylic acid ester compound represented by the above formula [A].

The present invention provides novel carboxylic acid ester compounds. By using this carboxylic acid ester compound as a liquid crystal compound, it is possible to manufacture various devices with excellent properties such as a wide operating temperature range, high switching speed, extremely low power consumption, and stable contrast. can.

Detailed Description of the Invention Next, the carboxylic acid ester compound of the present invention will be specifically described.

The carboxylic acid ester compound of the present invention has the following formula % formula % [] However, in formula [A], R1 has 3 to 2 carbon atoms.
0 alkyl group, an alkoxy group having 3 to 20 carbon atoms, and a halogenated alkyl group having 3 to 20 carbon atoms. ClI4 represents an asymmetric carbon atom, and R2 is a carbon atom. It represents an alkyl group of number 2 to 10.

In the above formula [A], when R1 is an alkyl group having 3 to 20 carbon atoms, such alkyl group may be in any form of linear, branched, or alicyclic. The molecules of carboxylic acid esters in which R1 is a linear alkyl group have a rigid structure in which the molecules extend straight, and therefore exhibit excellent liquid crystallinity. Such a linear alkyl group is preferably an alkyl group having 6 to 20 carbon atoms, and specific examples of such a linear alkyl group include hexyl group, heptyl group, octyl group, Examples include nonyl group, decyl group, undecyl group, dodecyl group, tetradecyl group, hexadecyl group and octadecyl group.

Further, when R1 is a halogenated alkyl group having 3 to 20 carbon atoms, examples of the halogenated alkyl group include F, CQ, Br, Examples include groups substituted with halogen atoms such as and .

Further, when R1 is an alkoxy group having 3 to 20 carbon atoms, examples of such an alkoxy group include an alkoxy group having an alkyl group as described above. Specific examples of such alkoxy groups include hexoxy group, heptoxy group, octyloxy group,
Mention may be made of nonyloxy, decyloxy, undecyloxy, dodecyloxy, tetradecyloxy, heptadecyloxy, hexadecyloxy and octadecyloxy.

When the carboxylic acid ester compound of the present invention is used as a liquid crystal compound, compounds in which R1 in formula [A] is an alkoxy group, particularly an alkoxy group having 7 to 16 carbon atoms, are highly useful.

In addition, in the above formula [A], R2 has 2 to 1 carbon atoms.
0, preferably 2 to 6 alkyl groups.

Specific examples of such alkyl groups include ethyl, propyl, butyl, pentyl, hexyl, heptyl and octyl groups. Among these alkyl groups, hexyl group (-06Hl
Compounds having s ) are particularly useful as liquid crystal compounds.

The group represented by R2 as described above is bonded to an asymmetric carbon atom C*, and a hydrogen atom and a methyl group <-CR2) are bonded to this asymmetric carbon atom, and the remaining bond is bonded to the p-phenylene group (first phenylene group) through an ester bond.

This p-phenylene group is bonded to another p-phenylene group (second phenylene group) via an ester bond.

Furthermore, this phenylene group has 2.
It is bonded to a 6-naphthalene group.

In particular, when the carboxylic acid ester compound of the present invention is used as a liquid crystal compound, it is preferable that the entire molecule is linear. Therefore, as a liquid crystal compound, two p-phenylene groups and a 2,6-naphthalene group are used. The compounds of the present invention in which each of these are bonded via an ester bond are particularly excellent.

The other bond of this naphthalene group is bonded to R1 above.

Therefore, specific examples of the carboxylic acid ester compound of the present invention represented by the above formula [A] include, for example, the following formulas [1] to
Compounds represented by [16] can be mentioned.

[4] [5] [6co<n-c, 6H33)-o#coo(uxcoo (4
Σcoo-t'u<cm2),,-C' 3H3... [1] [7co(rr-C, t+H29)-0eC00eCOOGCO
O-('H(012)s ”a&3... [2 pieces... [8] (n-C, 2H26)-0#coQ Yutaka cooGc00-
9”1l (CI+J-rcH.

ul13 R3... [10 [11] [12] [16] The carboxylic acid ester compound of the present invention can be produced by using a combination of known synthesis techniques.

For example, the above carboxylic acid ester compound can be synthesized according to the synthetic route shown below. In addition, in the example of the reaction route shown below, the case where R1 is an alkoxy group is made into an example, and the synthesis example of the carboxylic acid ester compound of this invention is demonstrated.

[13 pieces (blank below)'-''3 [14 pieces l-1'3 [15 pieces That is, for example, first, 6-n-alkoxynaphthalene-2-carboxylic acid and 4-hydroxybenzoic acid benzyl ester, 4-(6''-n-flufoxy 2 °-Naphthoyloxy)benzoic acid benzyl ester is obtained.

4-(6°-n-alkoxy-2°-naphthoyloxy)benzoic acid benzyl ester obtained as described above was poured into a solvent such as tetrahydrofuran, and palladium-
4-(6°-n-alkoxy-2′-naphthoyloxy)benzoic acid is obtained by reduction using hydrogen gas in the presence of a reduction catalyst such as carbon.

Then, using 4-N,N-dimethylaminopyridine and methylene chloride as solvents, while dropping a solution of N,N'-dicyclohexylcarbodiimide, an ester compound obtained from hydroxybenzoic acid and an alcohol having an asymmetric carbon is added. and 4-(6°-n
The carboxylic acid ester compound of the present invention can be obtained by reacting with -alkoxy-2°-naphthoyloxy)benzoic acid.

Note that the above method is an example of a method for producing the carboxylic acid ester compound of the present invention, and the carboxylic acid ester compound of the present invention should not be interpreted to be limited by such a production method.

The carboxylic acid ester compound represented by the formula [A] obtained as described above can be used as a raw material for synthesis of organic compounds, and can also be suitably used, for example, as a liquid crystal compound.

Among these carboxylic acid ester compounds,
As a liquid crystal compound, a compound in which R1 is an alkoxy group having 6 to 18 carbon atoms and R2 is a hexyl group, particularly a compound represented by formula [5], exhibits excellent liquid crystal properties.

Table 1 shows the phase transition temperature of this liquid crystal compound [5]. In addition, in the tables shown below, Cry represents a crystalline phase, Sm
C'' stands for chiral smectic C phase, SmA stands for smectic A phase, and ISO stands for isotropic liquid.

JI3... [5] Table 1 [5] 100°C 137°C 181°C As illustrated in Table 1, many of the liquid crystal compounds of the present invention exhibit a smectic phase over a wide temperature range.

Conventionally, when a liquid crystal compound is used alone, there are almost no known liquid crystal compounds that exhibit a smectic phase over a wide range of temperatures like this compound.

The liquid crystal compound of the present invention not only exhibits a smectic phase over a wide range of temperatures, but also an optical switching element manufactured using such a liquid crystal compound has excellent high-speed response.

Although the liquid crystal compound of the present invention can be used alone, it is preferable to mix it with other liquid crystal compounds and use it as a liquid crystal composition. For example, the liquid crystal compound of the present invention can be used as a main ingredient in a chiral smectic liquid crystal composition or as an auxiliary agent in a liquid crystal composition containing another compound exhibiting smectic A as a main ingredient.

In other words, a liquid crystal compound exhibiting ferroelectricity induces an optical switching phenomenon by applying a voltage, and by utilizing this phenomenon, a display device with good responsiveness can be manufactured (for example, 56-107216, JP-A-59-118744, Japanese Patent Application No. 2-1166392).

Ferroelectric liquid crystal compounds that can be used in such display devices include chiral smectic C phase, chiral smectic F phase, chiral smectic C phase, chiral smectic H phase, chiral smectic I phase, chiral smectic J phase, or chiral smectic phase. A compound that exhibits either phase. However, display elements using such liquid crystal compounds generally have a high (slow) response speed other than the chiral smectic C phase (Sm C" phase), so conventionally, display devices were driven using the chiral smectic C phase, which has a low (fast) response speed. It was thought that it would be practically advantageous to do so.

However, the method of driving a display element in the smectic A phase as already proposed by the present inventors (Japanese Patent Application No. 62-1
57808), the ferroelectric liquid crystal compound of the present invention can be used not only in the chiral smectic C phase but also in the smectic A phase. Therefore, by blending the liquid crystal compound of the present invention with other liquid crystal compounds, it is possible to obtain a liquid crystal composition that has a wide range of liquid crystal temperatures and further has faster electro-optical compatibility.

When producing a liquid crystal composition using the liquid crystal compound of the present invention, this liquid crystal compound can be used as a main agent or as an auxiliary agent, as described above.

In the liquid crystal composition containing the liquid crystal compound of the present invention, the content of the liquid crystal compound represented by the above formula [A] is as follows:
It can be appropriately set in consideration of the characteristics of the liquid crystal compound used, the viscosity of the composition, the operating temperature, the intended use, etc. In particular, the liquid crystal compound is usually used in an amount ranging from 1 to 99% by weight, preferably from 5 to 75% by weight, based on the total weight of the liquid crystal substances in the liquid crystal composition.

Further, one or more types of liquid crystal compounds of the present invention may be blended in the liquid crystal composition.

In such a liquid crystal composition, examples of compounds exhibiting a chiral smectic C phase that can be blended with the liquid crystal compound represented by the above formula [A] include (+)-
4'-(2''-methylbutyloxy)phenyl-6-octyloxynaphthalene-2-carboxylic acid ester, 4°-decyloxyphenyl-6-((+)-2''-methylbutyloxy)naphthalene-2- A liquid crystal that can constitute a liquid crystal composition by blending a carboxylic acid ester and a carboxylic acid ester compound represented by the above formula [A], which is a compound other than the above-mentioned compound exhibiting a chiral smectic C phase. Examples of compounds include: CH30-@-CH=N<le or 4H.

Schiff base-based liquid crystal compounds such as (c6u, 3)o@-CH=N@CN, azoxy-based liquid crystal compounds such as (C4H9)0kuDcoo@cau + 5(C7H1
5) Benzoic acid ester liquid crystal compounds such as oGcoo@cN can be mentioned.

Typical examples include cyclohexylcarboxylic acid ester liquid crystal compounds such as , phenyl liquid crystal compounds such as , terphenyl liquid crystal compounds such as , phenylcyclohexyl liquid crystal compounds such as , and pyrimidine liquid crystal compounds such as . In addition to nematic liquid crystal compounds, cholesteric liquid crystal compounds such as cholesterin hydrochloride, cholesterin nonanoate, and cholesterin oleate, and known smectic liquid crystal compounds can be mentioned.

In addition, when forming, for example, a display element using the liquid crystal compound according to the present invention, in addition to the above-mentioned liquid crystal compound, for example, a conductivity imparting agent and a life-enhancing agent may be used together with ordinary liquid crystal compounds. Additives may be added.

A liquid crystal composition can be prepared by mixing the liquid crystal compound of the present invention, the liquid crystal compound as described above, and other additives by a conventional method.

A liquid crystal element using such a liquid crystal composition can be prepared.

FIG. 1 shows an example of a cross section of a liquid crystal element using the liquid crystal composition as described above.

As shown in Figure 1, this liquid crystal element basically consists of two
A transparent substrate (hereinafter also referred to as a substrate) 1a.

1b and a gap 3 defined by the two substrates 1a and lb, and a liquid crystal composition 4 filled in the gap 3 between the cells.

At least one of the substrates 1a, lb must be transparent, and usually glass or transparent plastic such as polycarbonate is used as the substrate.

At least one of the substrates 1a and 1b is usually coated with indium oxide on at least the surface facing the liquid crystal composition (the inner surface of the substrate).
Electrodes 5a and 5b made of tin or the like are provided. Further, as the substrate, a transparent electrode substrate in which a transparent electrode is integrally formed on the substrate as described above can also be used.

Furthermore, alignment control PLs 6a and 6b are provided on at least one surface of the substrate as described above that is in contact with the liquid crystal composition. Although the alignment control film may be provided on one substrate, it is preferable that the alignment side mi is patterned on both substrates. FIG. 1 shows an embodiment in which two alignment control films are provided, one for each substrate, and these alignment control films are indicated by 6a and 6b. Such an oriented flJ film can be made of, for example, polyimide, polyvinyl alcohol, polyamideimide, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, polyamide, polystyrene, siloxane polyimide, cellulose resin, melamine resin, urea resin,
Polymer film formed from a polymer compound such as acrylic resin or conductive polymer; electron beam photoresist such as cyclized rubber photoresist, phenol novolak photoresist, polymethyl methacrylate, and epoxidized 1,4-polybutadiene A film formed from a cured resist; and 5inS Sin, Ge01A120. ,
This is a vapor deposited film formed from inorganic compounds such as y2o, ZrO, MgF2, and CeF. As the orientation control film, a polyamide film or an obliquely deposited SiO film is particularly suitable.
A film or a vapor-deposited film of an inorganic compound such as a GeO film is preferred. Such an alignment control film may be provided on the surface of one of the substrates facing the liquid crystal, but two films in total are provided, one on the surface of each substrate facing the liquid crystal composition. It is preferable.

Such an alignment control film can be produced by applying the above-mentioned resin to the surface of the substrate in contact with the liquid crystal using, for example, a spin code method, by applying heat treatment after such application, or by pasting a resin film. , after applying photosensitive resin,
Various methods can be adopted depending on the material used, such as a method of curing by irradiating energy rays, a method of vapor depositing an inorganic material, etc.

Furthermore, it is preferable that this alignment control film is subjected to an alignment treatment. Here, the alignment treatment refers to a treatment for aligning liquid crystal molecules in a predetermined direction. For example, when polyimide is used, it is performed by rubbing the polyimide in one direction with a cloth, etc. This polyimide can be subjected to orientation treatment by a rubbing method.

The thickness of such an alignment control film is usually 0.005 to 0.2
5 pm, preferably within the range of 0.01 to 0.15 pm.

When an alignment control film is disposed on each substrate, the alignment control film as described above may be disposed so that the direction of the liquid crystal compound regulated by the alignment control film is constant.

In particular, the two alignment control films are arranged so that the liquid crystal compound oriented by the regulating force of one alignment control film and the liquid crystal compound oriented by the regulating force of the other alignment control film are approximately parallel to each other. It is preferable. By arranging the alignment control film in this manner, the initial alignment of the liquid crystal composition injected into the cell is improved, and a liquid crystal element with excellent contrast and the like can be obtained.

The cell filled with the liquid crystal composition includes two substrates 1a and lb on which alignment control films 6a and 6b are formed as described above.
A gap 3 is formed which is filled with liquid crystal material.

Such a gap 3 can be formed, for example, by arranging the substrates 1a and 1b with spacers 7 interposed therebetween. By arranging the spacer 7 in this way, it is possible to secure the gap 3 for filling the liquid crystal composition, and it is also possible to prevent the liquid crystal composition from leaking. Note that the gap 3 can be formed using a spacer forming a side wall as described above, and can also be formed by blending particles (internal spacer) having a predetermined particle size into the liquid crystal composition. can.

The width of the gap formed in this way is usually 1.5 to 7
μm, preferably within the range of 1.8 to 5 μm.

In such a liquid crystal element, various thin films such as a photoconductive film, a light blocking film, and a light reflecting film may be further provided.

In such a liquid crystal element, the cell gap 3 as described above is filled with a liquid crystal composition containing the carboxylic acid ester compound of the present invention in an oriented state.

At least one deflection plate is disposed outside the cell thus formed. In Figure 1,
The deflection plates are shown at 8a, 8b. This deflection plate 8a
, 8b, the arrangement relationship between the two is set so that the deflection plane is usually 70 to 110 degrees. Furthermore, the liquid crystal element 10 filled with a liquid crystal compound and initially aligned (the liquid crystal composition filled in the gaps between the cells) is placed between the two deflection plates such as the deflection plate 8a, the liquid crystal element 10, and the deflection plate. 8b
It is preferable to determine the positional relationship of the champion so that the light beam transmitted through the light beam is in the brightest or darkest state.

The liquid crystal element as described above can be driven, for example, by the following method.

The first method is to interpose a thin film cell filled with an oriented liquid crystal compound between two polarizing plates, apply an external electric field to this thin film cell, and change the orientation vector of the ferroelectric liquid crystal compound. , is a method of displaying using the polarization properties of two polarizing plates and the birefringence of a ferroelectric liquid crystal compound.

When a chiral smectic phase is formed in such a thin film cell, the liquid crystal compound exhibits bistability. Utilizing this property, it is possible to reverse the electric field and cause the liquid crystal compound to transition from one stable state to another stable state. Optical switching can then be performed using these two stable states.

Among the liquid crystal compounds of the present invention, ferroelectric liquid crystal compounds exhibiting a chiral smectic phase have spontaneous polarization.
- When a variable voltage is applied, there is a memory effect even after the electric field is erased. Therefore, by utilizing this memory effect, it is possible to maintain a constant state in which voltage continues to be applied to the thin film cell.

Therefore, a display device having such a thin film cell can reduce power consumption. Furthermore, in this case the contrast of the display device is stable and yet very sharp.

Furthermore, in a switching element using a chiral smectic liquid crystal compound, switching is possible simply by changing the orientation direction of the molecules, and since the primary term of electric field strength acts on the drive, low voltage drive is possible.

Furthermore, if this switching element is used, a high-speed response of several tens of microseconds or less can be realized, so the scanning time of each element can be significantly shortened, making it possible to manufacture a large-screen display with many scanning lines.

Further, even in the smectic A phase of the liquid crystal compound of the present invention, which does not have bistability, when an electric field is applied, the molecules are induced to tilt, so optical switching can be performed using this property. Furthermore, since the liquid crystal compound of the present invention exhibits two or more stable states even in a liquid crystal phase with low symmetry, optical switching can be performed in the same manner as in the case of the smectic A phase.

A second display method using the liquid crystal compound of the present invention is a method of mixing the liquid crystal compound of the present invention and a dichroic dye and utilizing the dichroism of the dye. This is a method of displaying by changing the wavelength of light absorbed by the dye by changing the orientation direction of the compound. The dye used in this case is usually a dichroic dye, and examples of such dichroic dyes include azo dyes, naphthoquinone dyes, cyanine dyes, and anthraquinone dyes.

In addition, in a liquid crystal element using a liquid crystal composition containing the liquid crystal compound of the present invention, various commonly used display methods can be employed in addition to the display methods described above. That is, a liquid crystal element using a liquid crystal composition containing the liquid crystal compound of the present invention can be used for electric address display such as static drive, simple matrix drive, and composite matrix drive, optical address display, thermal address display, electron beam address display, etc. It can be driven depending on the driving method.

Such a liquid crystal element can be used as various devices such as a White Tiller color display device, a cholesteric-nematic phase transition display device, and a device for preventing reverse domain generation in a TN cell.

Further, the above liquid crystal element can be used in a memory type liquid crystal display element such as a thermal writing type display element or a laser writing type display element.

Furthermore, elements using liquid crystal compounds with ferroelectric properties are
In addition to the above-mentioned uses, it can be preferably used for optical switching elements such as optical shutters and liquid crystal printers, and liquid crystal elements such as piezoelectric elements and pyroelectric elements.

Effects of the Invention The present invention provides a novel carboxylic acid ester compound.

This new carboxylic acid ester compound is optically active, and since the naphthalene ring and two benzene rings are bonded through ester bonds, it exhibits a smectic phase over a wide temperature range including room temperature, and exhibits ferroelectric properties. It can be preferably used as a liquid crystal compound.

By blending the same type and/or other types of liquid crystal compounds with this liquid crystal compound, the temperature range can be expanded without impairing the ferroelectricity of this liquid crystal compound.

Therefore, by using such a liquid crystal compound or liquid crystal composition, it is possible to obtain a display element or the like that has high-speed response over a wide temperature range.

Further, this liquid crystal compound or a liquid crystal composition containing this liquid crystal compound exhibits a smectic phase over a wide temperature range and can be preferably used as an antiferroelectric compound.

Furthermore, the scanning time of liquid crystal displays manufactured using such devices is significantly reduced.

Further, since the liquid crystal compound of the present invention has spontaneous polarization, by filling a thin film cell with the liquid crystal compound, a device having a memory effect even after erasing the electric field can be obtained.

In such a device, power consumption can be reduced and stable contrast can be obtained. Low voltage drive is also possible. Since such a device utilizes the smectic phase of a carboxylic acid ester compound, it is preferably used as an optical switching element used in a wide temperature range.

Next, examples of the present invention will be shown, but the present invention is not limited to these examples.

X Fengdanyu 4-[4°-(6”-total decyloxy-2-naphthoyloxy)benzoyloxy]-benzoic acid R-1”’-Methylheptyl ester synthesis step 1 6-decyloxynaphthalene-2 -carboxylic acid 1.62
g (5 mmol), 1.14 g (5 mmol) of 4-hydroxybenzoic acid benzyl ester, 0.12 g (1 mmol) of 4-N,N-dimethylaminopyridine and 20 ml of methylene chloride was added to NN'-dicyclo. 10 ml of a methylene chloride solution containing 1.03 g (5 mmol) of xylcarbodiimide was added dropwise over 1 hour with stirring.

The mixture was further reacted at room temperature for 10 hours.

The reaction mixture was filtered and the resulting filtrate was concentrated.

The concentrate was separated using column chromatography to obtain 2.30 g (4.28 mmol) of 4-(6°-n-decyloxy-2°-naphthoyloxy)benzoic acid benzyl ester as a white solid. Ta.

Second stage 4-(6°-n-decyloxy-2 obtained in the first stage)
°-naphthoyloxy)benzoic acid benzyl ester 2°15 g (4 mmol), 1 g of 5% palladium-carbon catalyst
1 Hydrogen gas was bubbled into a mixture of 30 ml of tetrahydrofuran at room temperature for 8 hours while stirring.

Next, the reaction mixture was filtered using Celite, a filter aid, and the resulting filtrate was concentrated to obtain 4-(6'-n-decyloxy-2°-naphthoyloxy)benzoic acid 1, which was a white solid. .57 g (3.52 mmol) were obtained.

3rd step 4-(6'-n-decyloxy-2 obtained in the 2nd step)
°-Naphthoyloxy)benzoic acid 0.45 g (1 mmol), 4-hydroxybenzoic acid R-1°-methylheptyl ester 0.21 g (1 mmol), 4-N, N-
In a mixture of 0.012 g (0.1 mmol) of dimethylaminopyridine and 10 ml of methylene chloride, N, N'
- 2 ml of a methylene chloride solution containing 0.21 g (1 mmol) of dicyclohexylcarboimide was added at room temperature under stirring for 1 hour.
It dripped over time.

Further, the reaction was allowed to proceed at room temperature for 8 hours.

The reaction mixture was filtered and the resulting filtrate was concentrated.

The concentrate was separated using column chromatography to obtain 0.52 g of a colorless semi-solid.

When the FD-mass spectrum of this semi-solid was measured, the value of M/e was 696.

As a result of analysis of this semi-solid, the obtained compound was found to be the target 4-[4'-(6''-n-decyloxy-2'°-naphthoyloxy')benzoyloxy]-benzoic acid R- It was identified as 1''-methylheptyl ester.

Example 2 As a result of measuring the phase transition temperature of the compound obtained in Example 1, the values shown in Clothing 1 were obtained.

Example 3 A composition consisting of 49% by weight of the compound obtained in Example 1 and 51% by weight of the compound [BJ] represented by the following formula was prepared, and the phase transition temperature of this composition was measured.

The results are shown in Table 2.

Table 2 10...Liquid crystal element [5]

Claims (5)

[Claims] (1) A carboxylic acid ester compound characterized by being represented by the following formula [A]; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ... [A] [However, in formula [A], R^1 has 3 carbon atoms
It is a type of group selected from the group consisting of ~20 alkyl groups, C3-20 alkoxy groups, and C3-20 halogenated alkyl groups, where C* represents an asymmetric carbon atom, and R^ 2 represents an alkyl group having 2 to 10 carbon atoms]. (2) A liquid crystal compound characterized by being represented by the following formula [A]; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ... [A] [However, in formula [A], R^1 is Number of carbon atoms: 3
It is a type of group selected from the group consisting of ~20 alkyl groups, C3-20 alkoxy groups, and C3-20 halogenated alkyl groups, where C* represents an asymmetric carbon atom, and R^ 2 represents an alkyl group having 2 to 10 carbon atoms]. (3) In the above formula [A], R^1 is the number of carbon atoms 7
3. The liquid crystal compound according to claim 2, wherein R^2 is a hexyl group. (4) A liquid crystal composition characterized by containing at least one type of carboxylic acid ester compound represented by the following formula [A]; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ... [A] [However, In formula [A], R^1 is a carbon atom number of 3
It is a type of group selected from the group consisting of ~20 alkyl groups, C3-20 alkoxy groups, and C3-20 halogenated alkyl groups, where C* represents an asymmetric carbon atom, and R^ 2 represents an alkyl group having 2 to 10 carbon atoms]. (5) In the above formula [A], R^1 is the number of carbon atoms 7
5. The liquid crystal composition according to claim 4, wherein R^2 is a hexyl group.