CN104788275A - Manufacturing method for liquid crystal material - Google Patents

Abstract

The present invention relates to a method for manufacturing liquid crystal materials. Specifically relate to the manufacture method of the compound represented by general formula (1), the resistivity value of the compound represented by general formula (1) is defined as, contain formula (A-1) and (A-2 with the mass ratio of 1:1 ) and a liquid crystal composition (M-1) having a resistivity value of 1.0×10 ¹³ Ω·m or more by adding 20% by mass of a compound represented by the general formula (1) to 80% by mass When the resistivity value is higher than 8.0×10 11 Ω·m, the compound represented by the general formula (1) with a resistivity value of less than 8.0×10 ¹¹ Ω·m is precipitated by any one of methods (I) to (V). For the obtained crystal, The compound represented by the crystalline general formula (1) is collected by filtration from a solution containing any one of solvents (VI) to (XI), and the solvent used for recrystallization contained in the filtered crystals is distilled off to obtain the above-mentioned A compound represented by the general formula (1) in a crystalline state with a defined resistivity value of 8.0×10 ¹¹ Ω·m or more.

Description

Manufacturing method of liquid crystal material

This application is a divisional application of a Chinese patent application with an application date of November 17, 2010, an application number of 201010552287.0, and an invention title of "Method for Manufacturing Liquid Crystal Material".

technical field

The present invention relates to a method for the manufacture of liquid crystal materials having high resistivity values.

Background technique

Liquid crystal display devices are widely used in consumer and industrial applications represented by liquid crystal televisions, mobile phones, personal computers, and the like. These products have a relatively long service life, ranging from several years to more than ten years. In order to operate normally during this period, high stability is required for the liquid crystal materials used in them. A representative stability index of a liquid crystal material is a resistivity value. In order for a liquid crystal display element to function properly, the liquid crystal material used therein must have a sufficiently high resistivity value, and also must suppress deterioration over time.

In order to improve the stability of liquid crystal materials, many studies have been conducted so far. For example, as a method for removing moisture and metal ions in a liquid crystal material, a method of contacting a liquid crystal material with silica gel (refer to Patent Document 1), a method of contacting a liquid crystal material with activated alumina (refer to Patent Document 2), and using A method of treating with an ion exchange resin (see Patent Document 3), and a method of contacting a liquid crystal material with a zeolite (see Patent Document 4). Furthermore, it is disclosed that by placing a liquid crystal compound between a pair of opposing electrodes and applying an electric field, metal ions such as Na ⁺ , K ^{+ ,} etc., or SO ₄ ^2- , NO ₃ ^- , Cl ^- that have a large mobility caused by the electric field are removed. Methods of plasmonic impurities, etc. (see Patent Documents 5 to 7). These refining methods are methods for removing impurities already contained in the liquid crystal material.

On the other hand, the demand for liquid crystal materials involves many aspects such as high-speed response and high contrast. These physical properties cannot be achieved by a single compound, but a mixture of various liquid crystal compounds is used as a liquid crystal composition to meet the requirements. At this time, it is important to accurately weigh each liquid crystal compound so that the mixing ratio thereof corresponds exactly to the target value. This is because if the mixing ratio varies, the physical properties will change, making it impossible to prepare a liquid crystal composition that satisfies the requirements.

Here, most liquid crystal compounds are solid at room temperature. Therefore, if almost all of the solvent is distilled off from the liquid crystal compound in a solution state dissolved in a solvent, crystallization proceeds at once, and the whole becomes an integrated solid. If the liquid crystal compound is used without the solvent being completely distilled off, it is unfavorable because problems such as a decrease in stability occur. Therefore, it is necessary to remove the solvent carried in the crystals of the liquid crystal compound under reduced pressure. However, if the resulting solid block is large, the solvent brought inside cannot be removed because it does not volatilize. In addition, if it is obtained as a block, the weighing when preparing the liquid crystal composition must be carried out while crushing the block, so the handling becomes extremely difficult, and the accuracy of weighing cannot be ensured. On the other hand, if the liquid crystal compound is prepared as a powder, both distillation of the solvent and fine adjustment at the time of weighing become easy. However, in the purification method described above, the liquid crystal material is treated in a liquid crystal state or a solution state, and the liquid crystal compound obtained after the treatment does not become a powder. In addition, these methods require special equipment and complicated operations for implementation, and thus are disadvantageous in terms of productivity.

Recrystallization is effective in order to obtain liquid crystal compounds simply as powders, and there are many examples of refining liquid crystal compounds by recrystallization in practice (Patent Document 8). Recrystallization is carried out by dissolving the compound in a solvent, utilizing a difference in solubility due to temperature difference, evaporation of the solvent, change in the mixing ratio of the solvent, etc., to precipitate crystals, and to collect the crystals by filtration. At this time, uniform and fine crystals can be obtained by adjusting the precipitation rate of crystals and the like. The powder obtained in this way has fine particles of the liquid crystal compound, so the solvent can be easily distilled off, and since it is easy to pick up, it is easy to weigh, and the addition amount can be finely adjusted.

In order to obtain a liquid crystal material with a high resistivity value, each liquid crystal compound constituting the material also needs to have a high resistivity value. When recrystallization is performed as the final process before weighing, there is a requirement for quality, so the recrystallization The latter liquid crystal compound must have a high resistivity value. However, since general-grade solvents contain ionic components and the like, if they are used for recrystallization, there is a problem that the resistivity value of the recrystallized liquid crystal compound cannot reach a practical level due to the influence of these components. Solvents are generally purified by distillation, but distillation cannot remove impurities near the boiling point, and cannot remove trace metal ion components.

As above, although a simple and practical method of obtaining liquid crystal compounds with high resistivity values through recrystallization is eagerly desired, no specific solution has been reported so far.

prior art literature

Patent Document 1: Japanese Patent Application Laid-Open No. 62-210420

Patent Document 2: Japanese Patent Application Laid-Open No. 58-1774

Patent Document 3: Japanese Patent Application Laid-Open No. 52-59081

Patent Document 4: Japanese Patent Application Laid-Open No. 63-261224

Patent Document 5: Japanese Patent Application Laid-Open No. 50-108186

Patent Document 6: Japanese Patent Application Laid-Open No. 51-11069

Patent Document 7: Japanese Patent Application Laid-Open No. 4-86812

Patent Document 8: Japanese Patent Laid-Open No. 2007-176818

Contents of the invention

The problem to be solved by the invention

The problem to be solved by the present invention is to provide a simple method for producing a liquid crystal compound having a high resistivity value through a recrystallization operation, a liquid crystal composition using the liquid crystal compound obtained by the production method, and a liquid crystal display element.

Solution to the problem

The inventors of the present invention conducted intensive studies on the subject compound of the present invention, found that the above-mentioned problems can be solved by a specific production method, and completed the present invention.

The present invention provides:

1. A method for producing a compound represented by general formula (1), characterized in that,

The resistivity value of the compound represented by the general formula (1) is defined as the compound represented by the formulas (A-1) and (A-2) contained in a mass ratio of 1:1 and the resistivity value is 1.0×10 ¹³ Ω The resistivity value of the liquid crystal composition obtained by adding 20% by mass of the compound represented by the general formula (1) to 80% by mass of the liquid crystal composition (M-1) of m or more,

By any one of the following methods (I) to (V), the compound represented by the general formula (1) whose resistivity value is less than 8.0×10 ¹¹ Ω·m is precipitated, and the obtained crystal is obtained from the The compound represented by the general formula (1) in a crystalline state is collected by filtration from any solvent solution of the following (VI) to (XI), and the solvent used for recrystallization contained in the filtered crystals is distilled off to obtain the above-mentioned A compound represented by general formula (1) in a crystalline state with a defined resistivity value of 8.0×10 ¹¹ Ω·m or more;

Among them, general formula (1) is:

In formula (1), R ¹ represents an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or an alkenyloxy group with 2 to 6 carbon atoms ,

a means 1, 2 or 3,

^A1 and ^A2 each independently represent a group selected from the group consisting of the following (a) group, (b) group and (c) group:

(a) trans-1,4-cyclohexylene, in which one methylene group or two or more non-adjacent methylene groups may be replaced by -O- or -S-,

(b) 1,4-phenylene, one -CH= or two or more non-adjacent -CH= in this group may be replaced by nitrogen atoms,

(c) 1,4-bicyclo(2.2.2)octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2 ,6-diyl, and chroman-2,6-diyl,

The hydrogen atoms contained in the above-mentioned (a) group, (b) group or (c) group can be replaced by fluorine atom, trifluoromethyl group, trifluoromethoxy group or chlorine atom respectively, and there are multiple A ¹ , they are the same or different from each other,

Z ¹ represents a single bond, -CH ₂ CH ₂ -, -CH=CH-, -C≡C-, -CH ₂ O-, -OCH ₂ -, -CF ₂ O-, -OCF ₂ -, -COO- or -OCO-, when there are multiple Z ^1s , the multiple existing Z ^1s are the same or different from each other,

^Y1 represents a hydrogen atom, a fluorine atom, a chlorine atom, a trifluoromethyl group, a trifluoromethoxy group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a group having 1 to 6 carbon atoms Alkoxy or alkenyloxy with 2 to 6 carbon atoms;

Formulas (A-1) and (A-2) are:

The method of (I)～(V) is:

(1) after being dissolved in a solvent, crystallization is separated out from the solution obtained,

(II) dissolved in a solvent, and after purifying the solution by column chromatography (column chromatography) filled with an adsorbent, crystals are precipitated from the obtained solution,

(III) Dissolving in a solvent, purifying the solution by column chromatography filled with an adsorbent, and then partially concentrating the obtained solution to precipitate crystals,

(IV) Dissolve in a solvent, and after purifying the solution by column chromatography filled with an adsorbent, add one or more nonpolar solvents and/or one or more polar solvents to the obtained solution After the solvent, the crystals were precipitated,

(V) Dissolve in a solvent, refine the solution by column chromatography filled with an adsorbent, and then partially concentrate the obtained solution, and further add one or more than two non-polar solvents and/or After one or more polar solvents, the crystals are precipitated;

The solvent of (VI)～(XI) is:

(VI) Solvents consisting of only one non-polar solvent,

(VII) a solvent formed of two or more non-polar solvents,

(VIII) a solvent formed from 1 non-polar solvent and 1 polar solvent,

(IX) A solvent formed of two or more nonpolar solvents and one polar solvent,

(X) A solvent consisting of one nonpolar solvent and two or more polar solvents,

(XI) a solvent formed from two or more nonpolar solvents and two or more polar solvents,

The non-polar solvents and polar solvents of (VI) to (XI) are solvents that satisfy the requirements shown in any one of the following (i) to (iii):

(i) In the purification process of the compound represented by the general formula (1) by column chromatography packed with an adsorbent, the column used for eluting the compound represented by the general formula (1) has passed through the column packed with the adsorbent non-polar or polar solvents,

(ii) non-polar solvents whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions is 0.05 ppb or less,

(iii) Polar solvents whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions is less than 1.0 ppb;

2. The recrystallization method carried out at this time;

3. The liquid crystal compound obtained by the production method of the present application;

4. A liquid crystal composition containing a liquid crystal compound obtained by the production method of the present application;

5. A liquid crystal display element using a liquid crystal composition containing a liquid crystal compound obtained by the production method of the present application.

Invention effect

According to the production method of the present invention, a liquid crystal compound having a high resistivity value can be obtained through a simple recrystallization operation. Therefore, according to the present invention, it is useful in that a liquid crystal composition for producing a liquid crystal display element that can be used for a long period of time can be obtained.

Detailed ways

In general formula (1), at least one of ^A1 or ^A2 is preferably selected from group (A):

or group (B):

Further, in group (B), the following structures are more preferred:

When at least one of A ¹ or A ² is selected from group (A), it is preferable that the other is selected from trans-1,4-cyclohexylene, 1,4-phenylene, or group (A).

When at least one of ^A1 or ^A2 is selected from group (A), ^Y1 is preferably a fluorine atom, and ^R1 is preferably methyl, ethyl, propyl, butyl, pentyl, vinyl, or methoxy , ethoxy, propoxy, butoxy, pentyloxy, 3-butenyloxy and 4-pentenyloxy, more preferably methyl, ethyl, vinyl, propyl, butyl, ethylene group, 3-butenyl group or pentyl group, Z ¹ is preferably a single bond, -CH ₂ CH ₂ -, -CF ₂ O- or -OCF ₂ .

When at least one of ^A1 or ^A2 is selected from group (B), R1 ^{and Y1} are each independently preferably methyl, ethyl, propyl, butyl, pentyl, vinyl, methoxy, Ethoxy, propoxy, butoxy, pentyloxy, 3-butenyloxy and 4-pentenyloxy, Z ¹ is preferably a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -CF ₂ O- or OCF ₂ -.

A liquid crystal composition in which 20% by mass of a compound represented by general formula (1) is added to a liquid crystal composition (M-1) having a resistivity value of 1.0×10 ¹³ Ω·m or more has a resistivity value of less than 8.0×10 At ¹¹ Ω·m, a liquid crystal display element using a liquid crystal composition containing a compound represented by the general formula (1) may sometimes cause display defects. On the other hand, 20% by mass of the general formula When the resistivity value of the liquid crystal composition of the compound represented by (1) is 8.0×10 ¹¹ Ω·m or more, this does not occur, and it can be operated without problems even in long-term use. In order to obtain higher reliability, it is desirable to increase the resistivity value, but if the refining process is repeated to increase the resistivity value, the yield will decrease, making it impossible to manufacture at low cost. Therefore, practically, a liquid crystal composition in which 20% by mass of a compound represented by the purified general formula (1) is added to a liquid crystal composition (M-1) having a resistivity value of 1.0×10 ¹³ Ω·m or more The resistivity value of is preferably 8.0×10 ¹¹ Ω·m, preferably 1.0×10 ¹² Ω·m, preferably 5.0×10 ¹² Ω·m, preferably 1.0×10 ¹³ Ω·m. The higher the resistivity value, the better, but there is a limit to the fact that the liquid crystal compound is an organic substance.

When the resistivity value of the compound represented by the general formula (1) before purification used in the present invention is sufficiently high, the purification of the present invention is not necessary. In addition, if it is too low, it is necessary to repeat the present invention many times. Therefore, the lower limit value is preferably 9.9×10 ¹¹ Ω·m, preferably 8.0×10 ¹¹ Ω·m, preferably 5.0×10 ¹¹ Ω·m, preferably 1.0×10 ¹¹ Ω·m, preferably 1.0×10 ¹⁰ Ω·m, preferably 1.0×10 ⁹ Ω·m, preferably 1.0×10 ⁸ Ω·m, the upper limit is preferably 9.9×10 ¹¹ Ω·m, preferably 8.0×10 ¹¹ Ω·m, preferably 5.0×10 ¹¹ Ω·m, preferably 1.0×10 ¹¹ Ω·m, preferably 1.0×10 ¹⁰ Ω·m, preferably 1.0×10 ⁹ Ω·m, preferably 1.0×10 ⁸ Ω·m.

Before the purification of the present invention, other purification methods or recrystallization are not necessary as long as they have a level of purity that can withstand use. However, in order to obtain a liquid crystal compound of sufficient purity, it is preferable to perform other purification methods or recrystallization in advance. In addition, the chemical purity of the compound represented by the general formula (1) before purification used in the present invention is not particularly limited, but since it is used without other purification after the purification of the present invention, it is desired to have high chemical purity, and it is preferably used in the gas phase Chromatography (column: DB-1, carrier gas: helium) has an area ratio of 95% or more, preferably 97% or more, preferably 99% or more, preferably 99.5% or more, more preferably 99.8% or more . At this time, in determining the chemical purity, the compound that does not lower the resistivity value or the compound that has confirmed its characteristics, confirmed its influence, and stipulated the allowable concentration can be contained in the compound represented by the general formula (1). in the compound.

As the kind of non-polar solvent used in the purification of the present application, preferred are hexane or its structural isomers, heptane or its structural isomers, octane or its structural isomers, petroleum ether, benzene, toluene, di Toluene or cumene, more preferably hexane or its structural isomers, heptane or its structural isomers, or toluene. These can be used individually or in 2 or more types.

In addition, as the kind of polar solvent used in the purification of this application, methanol, ethanol, 1-propanol, 2-propanol, acetone, 2-butanone, ethyl acetate, ether, tetrahydrofuran, methyl-tert-butyl base ether, acetonitrile or propionitrile, more preferably methanol, ethanol, acetone or 2-butanone. These may be used alone or in combination of two or more.

In addition, it is preferable to perform column chromatography before recrystallization to remove ionic impurities that cause a decrease in the resistivity value. As the refining agent used in column chromatography, silica gel, alumina or both of them are preferably used. When using both sides, they may be mixed and filled, or may be filled in layers. The refined preparation can also be used after washing with pure water or an organic solvent in advance. In addition, as alumina, acidic, basic or neutral alumina can be used. The developing solvent is preferably a single or mixed solvent selected from hexane and its structural isomers, heptane and its structural isomers, and toluene. Since ionic impurities are removed by column chromatography, the concentration of ions contained in the developing solvent is not limited, and commercially available primary products can be used. Since the solution obtained after column chromatography is free of ionic impurities that cause a decrease in resistivity, the resistivity value will not be affected even if the solvent used in recrystallization is contained. Therefore, part or all of the solvent may or may not be distilled off from the solution after column chromatography.

For recrystallization, a single or mixed solvent selected from hydrocarbon-based solvents whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions is 0.05 ppb or less may be used. no limit. When the sum of the ion concentrations of the solvents to be used exceeds 0.05 ppb, for example, ion exchange resins, silica gel, alumina, and other refining agents can be used alone or in combination to make it 0.05 ppb or less. In addition, when purification by column chromatography is performed before recrystallization, if the solution obtained by distilling or not distilling off a part of the solvent from the solution after the purification is suitable for recrystallization, the recrystallization solvent may not be added.

As for the usage-amount of the solvent at the time of precipitation of recrystallized crystal|crystallization, 0.5 mL - 100 mL can be used with respect to 1 g of the compound represented by General formula (1) as a whole. However, if the amount of the solvent used is small, the compound represented by the general formula (1) will remain in an increased amount without being dissolved, and the effect of improving the resistivity will decrease. On the other hand, if the amount of solvent used is large, the amount of precipitated crystals decreases and the recovery rate decreases. Therefore, the lower limit of the amount of solvent used is preferably 0.8 mL, preferably 1 mL, preferably 2 mL, preferably 3 mL, preferably 4 mL, with respect to 1 g of the compound represented by the general formula (1) as the upper limit. The value is likewise preferably 50 mL, preferably 30 mL, preferably 20 mL, preferably 10 mL, preferably 8 mL, preferably 5 mL.

Recrystallization can be performed by dissolving the compound represented by the general formula (1) in a solvent and then cooling to a temperature lower than the temperature at the time of dissolution. The compound is preferably completely dissolved, but undissolved parts may remain within the range in which the effect of improving the resistivity is not reduced and the subsequent operations of crystallization and filtration are not hindered. The insoluble compound remaining is preferably 10% by mass or less, preferably 5% by mass or less, preferably 3% by mass or less, preferably 1% by mass or less, preferably 0.5% by mass or less of the total amount.

It can also be cooled during crystallization, and it can be rapidly cooled or slowly cooled. After cooling, the temperature may be kept constant, or crystals may be precipitated while gradually cooling. Moreover, when precipitating a crystal|crystallization, you may stir or you may leave still. Stirring is preferably performed when the size of the crystals is uniform and the crystal size does not become too large. In addition, as another method of recrystallization, after dissolving the compound represented by the general formula (1) in a solvent with high solubility, it is also possible to add a solvent with low solubility to precipitate crystals and perform recrystallization. At this time, cooling may or may not be particularly performed.

In addition, when the solvent is added after the crystals are precipitated, if the amount added is large, the precipitated crystals will be dissolved again, which is not preferable; if the temperature of the added solvent is high, the precipitated crystals will be dissolved again, which is not preferable. of. Therefore, the amount of solvent after addition is preferably controlled to be 1.5 times or less, preferably 1.2 times or less, and preferably 1.1 times or less the solvent amount in the precipitation step. The temperature of the added solvent is preferably 30°C or lower, preferably 20°C or lower, preferably 10°C or lower, more preferably ±5°C of the temperature of the added solution.

In addition, in order to take out the precipitated crystals and collect the crystals by filtration, natural filtration, vacuum filtration, pressure filtration or centrifugal filtration can be used. In addition, in order to prevent the influence of oxidation caused by oxygen in the air or to prevent moisture from being carried into the crystals, the filtration is preferably performed in a rare gas or nitrogen atmosphere. Moreover, as a filter agent, what is used in a normal filtration process, such as cellulose including paper, glass fiber, a membrane filter, and diatomaceous earth, can be used. In addition, the filtration may be performed at room temperature, may be cooled, or may be heated.

The present invention is a method for producing a compound represented by general formula (1) in combination with the following steps:

(A) a step of dissolving a compound represented by general formula (1) in an organic solvent;

(B) A step of injecting the solution obtained in (A) into a column chromatography filled with the refined preparation, and loading the compound represented by the general formula (1) on the refined preparation;

(C) a step of causing the developing solvent to flow through the column chromatography to elute the compound represented by the general formula (1);

(D) a step of precipitating crystals from the solution obtained in (A);

(E) a step of precipitating crystals from the solution obtained in (C);

(F) After the solvent is completely distilled off from the solution obtained in (C), it is dissolved in a new organic solvent to precipitate crystals;

(G) a step of precipitating crystals after distilling off a part of the solvent from the solution obtained in (C);

(H) A step of depositing crystals after distilling off a part of the solvent from the solution obtained in (C), or adding an organic solvent to adjust the amount of the solvent without distilling off the solvent;

(I) a step of filtering the crystals precipitated in any one of steps (D) to (H);

(J) A step of distilling off the solvent used for recrystallization from the crystals obtained in (I). However, the steps of (B) and (C) can be omitted.

It should be noted that "immediately before" in the claims means that the above-mentioned steps are not interposed between each other and no other steps are interposed therebetween.

In the present invention, purification by column chromatography is performed in the steps (B) and (C) above. By performing this step, ionic impurities in the organic solvent used can be removed. Therefore, the sum of the above-mentioned ion concentrations is not limited for the polar solvent and the non-polar solvent that pass through the column chromatography, and it is also possible to use a commercially available primary product.

In the present invention, when any one or more of the following (a) to (f) is satisfied, after recrystallization, there will be a polar solvent when the crystals are collected by filtration, and the static electricity generated in the filtration step can be quickly alleviated. Therefore, it is very useful in reducing the risk of disasters caused by static electricity.

(a) A polar solvent is used as a component of the organic solvent used in (A).

(b) A polar solvent is used for the operation of (B).

(c) A polar solvent is added to the developing solvent of (C).

(d) A polar solvent is added before, during, or immediately after the steps of (D) to (H).

(e) A polar solvent is added immediately before the step of (I) or during the step.

(f) A polar solvent is contained as an impurity in the compound represented by the general formula (1) before purification.

It should be noted that no matter whether the polar solvent is added by any of the above methods, if the process of distilling off the solvent is introduced before the crystallization by filtration, and the polar solvent is completely distilled off through this process, the static electricity will not be relieved. Effect. In this case, in order to alleviate the static electricity when the crystals are filtered out, it is necessary to add a polar solvent again after distilling off the solvent and before collecting the crystals by filtration.

Among the ways in which static electricity generated during the filtration of crystals can be quickly relieved, representative ways are as follows, but the present invention is not limited to these examples.

1.(A)→(B)→(C)→Add polar solvent→(E)→(I)→(J)

2. (A)→(B)→(C)→(E)→Add polar solvent→(I)→(J)

3. (A)→(B)→(C)→Add polar solvent→(G)→(I)→(J)

4. (A)→(B)→(C)→(G)→Add polar solvent→(I)→(J)

5. In the process of (A)→(B)→(C)→(F), add a polar solvent before crystallization→(I)→(J)

6. (A)→(B)→(C)→(F)→add polar solvent→(I)→(J)

7. In the process of (A)→(B)→(C)→(H), add a polar solvent before crystallization→(I)→(J)

8. (A)→(B)→(C)→(H)→add polar solvent→(I)→(J)

9. (A)→Add polar solvent→(D)→(I)→(J)

10.(A)→(D)→Add polar solvent→(I)→(J)

11. Add a polar solvent to the solution obtained in (A)→(B)→(C)→(E)→(I)→(J)

12. (A)→(B)→Add a polar solvent to the developing solution of (C)→(E)→(I)→(J)

For polar solvents, as long as the total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions is less than 1.0ppb alcohol solvents, ketone solvents, ester solvents, ether solvents Or a single or mixed solvent selected from nitrile solvents, and the preparation method is not limited. When the sum of the above ion concentrations of the solvents to be used exceeds 1.0 ppb, for example, ion exchange resins, silica gel, alumina and other refining agents can be used alone or in combination to make it 1.0 ppb or less.

Among the solvents used in steps (B) and (C), if the proportion of non-polar solvent is small, that is, if the proportion of polar solvent is large, the polarity of the entire solution will increase, and the effect of column chromatography will decrease. Therefore, among the solvents used in these steps, the ratio of the nonpolar solvent is preferably 80% by volume or more, preferably 90% by volume or more, and more preferably 95% by volume or more. In addition, in the solvent contained immediately before the crystallization is filtered, the ratio of the non-polar solvent is preferably 50% by volume or more, preferably 60% by volume or more, preferably 70% by volume or more, preferably 80% by volume or more, preferably 90% by volume. volume % or more. However, depending on the ratio of the polar solvent and the non-polar solvent, the solubility of the compound represented by the general formula (1) may increase, and the yield of recrystallization may decrease, so caution is required. Here, the proportion of the nonpolar solvent being 80% by volume means, for example, a mixed solvent of 80 mL of the nonpolar solvent and 20 mL of the polar solvent.

Among the aspects satisfying the aforementioned (a) to (f), typical ones are shown below, but the present invention is not limited to these examples.

13. (A)→(B)→(C)→(E)→(I)→(J)

14. (A)→(B)→(C)→(F)→(I)→(J)

15. (A)→(B)→(C)→(G)→(I)→(J)

16. (A)→(B)→(C)→(H)→(I)→(J)

17. (A)→(D)→(I)→(J)

In the methods exemplified above, in 11-13, since all the solvents used are treated with adsorbents during column chromatography, commercially available solvents of first-grade quality can be used, and since there is no concentration in the process, operation, so it is very useful especially in terms of easy operation.

In the recrystallization step, the solvent used for the recrystallization after filtration of the crystals can be removed under reduced pressure at room temperature or while heating. At this time, the heating method is not particularly limited, and any method can be used as long as it can be controlled within a range of several degrees above and below the set temperature. Considering the ease of implementation, a method of immersing a container containing a liquid crystal compound into a container filled with a solution having a temperature adjustment function or a method of heating a container containing a liquid crystal compound with a heater with a cover, etc., further A method of heating by installing a flow path through which a heated liquid flows through a rack on which a liquid crystal compound is placed. In addition, when the solvent is distilled off, since the liquid crystal compound is cooled by the heat of vaporization, the aforementioned scheme can also be performed using a solution without heating for the purpose of reducing temperature drop. In addition, without using these methods, it is also possible to distill off the solvent without controlling the temperature. In order to shorten working time, the lower limit temperature is preferably 20°C, preferably 30°C, preferably 35°C, and more preferably 40°C. As the upper limit temperature, a higher upper limit temperature is preferable because the evaporation rate of the solvent is increased when the temperature is increased. However, if the temperature is too high, decomposition and oxidation of the liquid crystal compound may occur, which is not preferable. In addition, if it is heated above the melting point, it will become an integrated solid when it is cooled to room temperature after drying, and it cannot be obtained as a powder, which is not preferable. Therefore, preferably below the melting point, preferably 60°C, preferably 55°C, preferably 50°C, preferably 45°C, preferably 40°C. The solvent can be distilled off either by keeping the container or shelf containing the liquid crystal compound stationary or by moving it. However, from the viewpoint of efficiency, it is preferable to rotate or vibrate them.

The crystals obtained by the production method of the present invention and the crystals of the present invention are then mixed with other liquid crystal compounds without further other purification to prepare a liquid crystal composition. After preparing the liquid crystal composition, treatment with filtration or a refining agent may be performed as necessary.

It is preferable that the solvent used for recrystallization is not included in the liquid crystal compound, but it may be at or below a concentration that does not cause adverse effects when preparing a liquid crystal composition. The concentration thereof is preferably 200 ppm or less, preferably 100 ppm or less, preferably 50 ppm or less, more preferably 20 ppm or less.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, "%" in the composition of a following Example and a comparative example means "mass %". In the analysis of the ion concentration in the solvent, use an ion chromatograph (chromatographic column: IC NI-424, developing solvent: 8mM 4-hydroxybenzoic acid+2.8mM bis(2-hydroxyethyl)iminotris(hydroxymethyl) methane+2mM phenylboronic acid+5μM trans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid), lithium ion, sodium ion, ammonium ion, Potassium, magnesium and calcium concentrations. The resistivity value of the liquid crystal composition is obtained by putting the liquid crystal composition in a measurement cell and measuring the resistance value at 25° C. at an applied voltage (DC) of 1 V. The purity was calculated from the area ratio of gas chromatography (column: DB-1, carrier gas: helium).

In addition, among the solvents used, those whose ion concentration is not described are commercially available first-class products.

(Example 1) Recrystallization of a compound represented by formula (1-1) (1)

20% ^of the formula The resistivity value of the liquid crystal composition of the compound represented by (1-1) (purity: 99.90%) was 1.0×10 ¹¹ Ω·m.

Dissolve 25 g of the compound represented by the formula (1-1) in 100 mL of hexane, inject it into a column chromatography (diameter 3 cm) filled with 10 g of silica gel and 10 g of alumina in two layers, and make it flow until the surface of the solution and the filling The agent layer is consistent. Further, 100 mL of hexane was added as a developing solvent to elute the compound adsorbed on the filler. To about 220 mL of the obtained solution was added 4 mL of ethanol whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.20 ppb, stirred at 5° C. for 10 minutes for crystallization, and then - Let stand in the freezer at 18°C for 16 hours. To filter off the crystalline components, pour into a Nutsche funnel with filter. The charge potential of the crystal obtained on the filter was measured, and it was 0.0 kV, and no static electricity was found. The obtained crystals were transferred to an eggplant-shaped flask, the pressure was reduced (266 Pa) with a vacuum pump, and the solvent was distilled off while rotating the eggplant-shaped flask. At this point, the flask was immersed in a hot water bath at 45°C to control the temperature. After 20 hours, 22.5 g of the compound represented by the formula (1-1) was obtained as powdery crystals. The amount of residual solvent in the crystal was 60 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.0×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 2) Recrystallization (2) of the compound represented by formula (1-1)

In Example 1, the same operation was performed using 4 mL of acetone whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions was 0.13 ppb instead of ethanol. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 22.4 g. The amount of residual solvent in the crystal was 58 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.4×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 3) Recrystallization of a compound represented by formula (1-1) (3)

In Example 1, after the solvent was distilled off from about 220 mL of the solution obtained after column chromatography under reduced pressure to form about 150 mL, lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions were added. The same operation was performed for 4 mL of ethanol whose total concentration was 0.20 ppb. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 23.4 g, and the yield was improved. The amount of residual solvent in the crystal was 58 ppm, and the purity was 99.97%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 1.8×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 4) Recrystallization of a compound represented by formula (1-1) (4)

In Example 1, crystallization was performed without adding ethanol to about 220 mL of the solution obtained after column chromatography, and lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions were added immediately before the crystals were filtered out. The total concentration of 0.20ppb ethanol 4mL, stirred for about 1 minute, poured into the Nutsche funnel with filter, and then performed the same drying operation. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 22.4 g. The amount of residual solvent in the crystal was 62 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the compound represented by the obtained formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.0×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 5) Recrystallization of Compound Represented by Formula (1-1) (5)

In Example 1, the solvent was distilled off from about 220 mL of the solution obtained after column chromatography under reduced pressure, and 24.9 g of the obtained solid was heated and dissolved in lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and Add 1 mL of ethanol with a total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions to 0.20 ppb in 50 mL of hexane with a total concentration of calcium ions of 0.03 ppb, and perform crystallization in the same manner. operate. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 24.0 g, and the yield was improved. The amount of residual solvent in the crystal was 50 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the compound represented by the obtained formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.2×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 6) Recrystallization of Compound Represented by Formula (1-1) (6)

In Example 5, 50 mL of a hexane/toluene mixed solvent (volume ratio 4/1) was used to dissolve the compound represented by formula (1-1) during column chromatography, and a hexane/toluene mixed solvent was used as the developing solvent (Volume ratio 4/1) 75mL, the same operation will be carried out later. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 23.8 g. The amount of residual solvent in the crystal was 65 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 1.8×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Comparative Example 1) Recrystallization of Compound Represented by Formula (1-1) (7)

The ion concentration of commercially available first-grade hexane was analyzed, and the result was that the total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.20ppb. In Example 5, 24.9 g of a solid obtained by distilling off the solvent from the solution obtained by column chromatography under reduced pressure was dissolved in 50 mL of hexane while warming, and lithium ions, sodium ions, ammonium ions, and potassium ions were added. The total concentration of ions, magnesium ions, and calcium ions was 0.20 ppb ethanol 1 mL, and the operations after the crystallization operation were performed in the same manner. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) was 5.6×10 ¹¹ Ω·m. Compared with before the refining process, the improvement of the resistivity value was insufficient, and it could not be used as a liquid crystal composition material for liquid crystal display elements.

(Comparative Example 2) Recrystallization of Compound Represented by Formula (1-1) (8)

The ion concentration of commercially available first-grade acetone was analyzed, and the result was that the sum of the concentrations of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 1.35ppb. In Example 5, 24.9 g of a solid obtained by distilling off the solvent from the solution obtained by column chromatography under reduced pressure was dissolved in lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions while warming. To 50 mL of hexane whose total concentration was 0.03 ppb, 1 mL of first-grade acetone was added, and operations after the crystallization operation were performed in the same manner. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) was 3.2×10 ¹¹ Ω·m. Compared with before the refining process, the improvement of the resistivity value was insufficient, and it could not be used as a liquid crystal composition material for liquid crystal display elements.

(Example 7) Recrystallization (9) of the compound represented by formula (1-1)

In Example 1, the solvent was distilled off from about 220 mL of the solution obtained after column chromatography under reduced pressure, and 24.9 g of the obtained solid was heated and dissolved in lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and The same crystallization operation was performed in 50 mL of hexane whose total concentration of calcium ions was 0.03 ppb. Add 1 mL of ethanol with a total concentration of 0.20 ppb of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions immediately before the crystals are collected by filtration, stir for about 1 minute, and inject into a Nutsche funnel with a filter. Thereafter, the same drying operation is performed. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 23.9 g. The amount of residual solvent in the crystal was 60 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the compound represented by the obtained formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.0×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 8) Recrystallization of Compound Represented by Formula (1-1) (10)

20% ^of the formula The resistivity value of the liquid crystal composition obtained from the compound represented by (1-1) (purity: 99.90%) was 1.0×10 ¹¹ Ω·m.

25 g of the compound represented by the formula (1-1) was heated and dissolved in 50 mL of hexane whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.03 ppb, and lithium ions, sodium ions, and The total concentration of ions, ammonium ions, potassium ions, magnesium ions, and calcium ions was 0.20 ppb in 1 mL of ethanol, stirred at 5°C for 10 minutes to crystallize, and then left to stand in a freezer at -18°C for 16 hours. To filter out the crystalline components, pour into a Nutsche funnel with filter. The charged potential of the crystal obtained on the filter was measured and found to be 0.0 kV, and no static electricity was found. The obtained crystals were transferred to an eggplant-shaped flask, and the pressure was reduced (266 Pa) with a vacuum pump, and the solvent was distilled off while rotating the eggplant-shaped flask. At this time, the flask was immersed in a hot water bath at 45°C, and the temperature was controlled. After 20 hours, 23.8 g of the compound represented by the formula (1-1) was obtained as powdery crystals. The amount of residual solvent in the crystal was 60 ppm, and the purity was 99.97%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 1.6×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 9) Recrystallization of a compound represented by formula (1-1) (11)

In Example 8, 25 g of the compound represented by formula (1-1) was heated and dissolved in 50 mL of hexane whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.03 ppb, The same crystallization operation was performed without adding ethanol. Add 1 mL of ethanol with a total concentration of 0.20 ppb of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions immediately before the crystals are collected by filtration, stir for about 1 minute, and then pour into a Nutzer funnel with a filter. Thereafter, the same drying operation is performed. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 24.0 g. The amount of residual solvent in the crystal was 65 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 1.8×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 10) Recrystallization of Compound Represented by Formula (1-1) (12)

In Example 1, in dissolving the compound represented by formula (1-1) during column chromatography, 100 mL of hexane/ethanol mixed solvent (volume ratio 50/1) was used, and hexane/ethanol mixed solvent ( Volume ratio 50/1) 100 mL, the operation after crystallization was performed similarly without adding ethanol to the obtained solution. The charge potential of the crystal obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 22.3 g. The amount of residual solvent in the crystal was 58 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 1.4×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 11) Recrystallization of Compound Represented by Formula (1-1) (13)

In Example 1, the centrifuge filter to which the filter cloth made from PTFE was attached was used in the filtration process of a crystal, and other operations were performed in the same manner. The absolute value of the charging potential of the crystals obtained on the filter cloth was 0.2 kV, and static charging was hardly observed. The compound represented by the formula (1-1) obtained after drying was 22.5 g. The amount of residual solvent in the crystal was 55 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 1.4×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 12) Recrystallization of Compound Represented by Formula (1-1) (14)

20% ^of the formula The resistivity value of the liquid crystal composition obtained from the compound represented by (1-1) (purity: 99.90%) was 1.0×10 ¹¹ Ω·m. 100 g of the compound represented by the formula (1-1) was dissolved in 400 mL of hexane, and purified by column chromatography (filler: silica gel and alumina, developing solvent: 400 mL of hexane). About 900 mL of the obtained solution was stirred at 5 degreeC for 10 minutes and crystallized, and it left still in the freezer of -18 degreeC for 16 hours. To filter out the crystalline components, pour into a Nutsche funnel with filter. The obtained crystals were transferred to an eggplant-shaped flask, the pressure was reduced (266 Pa) with a vacuum pump, and the solvent was distilled off while rotating the eggplant-shaped flask. At this time, the flask was immersed in a hot water bath at 45°C, and the temperature was controlled. After 20 hours, 90.0 g of the compound represented by the formula (1-1) was obtained as powdery crystals. The amount of residual solvent in the crystals was 56 ppm. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 3.0×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Comparative Example 3) Recrystallization of Compound Represented by Formula (1-1) (15)

In Example 12, after distillation of the solution obtained after column chromatography under reduced pressure to obtain the compound represented by formula (1-1) as crystals, 800 mL of commercially available first-grade hexane was added and dissolved. The obtained solution was subjected to the same recrystallization and drying operations as in Example 1. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) was 6.0×10 ¹¹ Ω·m. Compared with before the refining process, the improvement of the resistivity value was insufficient, and it could not be used as a liquid crystal composition material for liquid crystal display elements.

(Example 13) Recrystallization of Compound Represented by Formula (1-1) (16)

In Example 12, a part of the solvent was distilled off from about 900 mL of the solution obtained by column chromatography to obtain about 300 mL, and the same recrystallization and drying operations were performed. The yield of the obtained compound represented by the formula (1-1) was 93.3 g, and the yield was improved. The resistivity value of the liquid crystal composition obtained by adding 20% of this compound to the liquid crystal composition (M-1) was 3.0×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 14) Recrystallization of Compound Represented by Formula (1-1) (17)

In Example 12, 200 mL of a hexane/toluene mixed solvent (volume ratio 4/1) was used to dissolve the compound represented by formula (1-1) during column chromatography, and a hexane/toluene mixed solvent was used as a developing solvent (Volume ratio 4/1) 300mL, carry out the same operation. The yield of the compound represented by the obtained formula (1-1) was 89.5 g. The resistivity value of the liquid crystal composition obtained by adding 20% of this compound to the liquid crystal composition (M-1) was 2.8×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 15) Recrystallization of Compound Represented by Formula (1-1) (18)

20% ^of the formula The resistivity value of the liquid crystal composition obtained from the compound represented by (1-1) (purity: 99.90%) was 1.0×10 ¹¹ Ω·m. 25 g of the compound represented by the formula (1-1) was dissolved in 100 mL of hexane, injected into a column chromatography (diameter 3 cm) filled with 10 g of silica gel and 10 g of alumina in two layers, and allowed to flow until the surface of the solution and The filler layer is consistent. Further, 100 mL of hexane was added as a developing solvent to elute the compound adsorbed on the filler. The solvent was distilled off from the resulting solution under reduced pressure. 24.9 g of the obtained crude body was heated and dissolved in 50 mL of hexane whose total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions, and calcium ions was 0.03 ppb, and stirred at 5°C for 10 minutes to crystallize. After analysis, it was placed in a freezer at -18°C for 16 hours. To filter out the crystalline components, pour into a Nutsche funnel with filter. The obtained crystals were transferred to an eggplant-shaped flask, the pressure was reduced (266 Pa) with a vacuum pump, and the solvent was distilled off while rotating the eggplant-shaped flask. At this time, the flask was immersed in a hot water bath at 45°C, and the temperature was controlled. After 20 hours, 23.4 g of the compound represented by the formula (1-1) was obtained as powdery crystals. The amount of residual solvent in the crystal was 60 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.8×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Comparative Example 4) Recrystallization of Compound Represented by Formula (1-1) (19)

In Example 15, 24.9 g of the crude product obtained by distilling off the solvent from the solution obtained by column chromatography under reduced pressure was dissolved in 50 mL of commercially available first-grade hexane while warming, and the same recrystallization was performed. and dry operation. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) was 6.0×10 ¹¹ Ω·m. Compared with before the refining process, the improvement of the resistivity value was insufficient, and it could not be used as a liquid crystal composition material for liquid crystal display elements.

(Example 16) Recrystallization of Compound Represented by Formula (1-1) (20)

20% ^of the formula The resistivity value of the liquid crystal composition obtained from the compound represented by (1-1) (purity: 99.90%) was 1.0×10 ¹¹ Ω·m. The compound 50g represented by this formula (1-1) is heated and dissolved in the concentration sum of lithium ion, sodium ion, ammonium ion, potassium ion, magnesium ion and calcium ion in the hexane 50mL that is 0.03ppb, carries out and embodiment 1 The same recrystallization and drying operations. The yield of the compound represented by the obtained formula (1-1) was 23.4 g, and its purity was 99.97%. The resistivity value of the liquid crystal composition obtained by adding 20% of this compound to the liquid crystal composition (M-1) was 2.0×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Comparative Example 5) Recrystallization of Compound Represented by Formula (1-1) (21)

In Example 16, 50 mL of commercially available first-grade hexane was used as the recrystallization solvent, and the same recrystallization and drying operations were performed. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) was 5.0×10 ¹¹ Ω·m. Compared with before the refining process, the improvement of the resistivity value was insufficient, and it could not be used as a liquid crystal composition material for liquid crystal display elements.

(Example 17) Recrystallization of Compound Represented by Formula (1-1) (22)

In Example 15, 50 mL of a hexane/toluene mixed solvent (volume ratio 4/1) was used for dissolving the compound represented by formula (1-1) during column chromatography, and a hexane/toluene mixed solvent was used for the developing solvent (Volume ratio 4/1) 75mL, carry out the same operation. The yield of the compound represented by the obtained formula (1-1) was 23.0 g, and its purity was 99.97%. The resistivity value of the liquid crystal composition obtained by adding 20% of this compound to the liquid crystal composition (M-1) was 2.6×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 18) Treatment of Recrystallization Solvent Using Ion Exchange Resin

The ion concentration of commercially available first-grade ethanol was analyzed, and the result was that the sum of the concentrations of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 1.84ppb. A glass chromatographic tube was filled with 5 g of a mixture of cation exchange resin and anion exchange resin, and 50 mL of first-grade ethanol was passed through to wash the ion exchange resin. Afterwards, 100 mL of first-grade ethanol was introduced and collected in a clean glass flask. The resulting ethanol was analyzed, and the result was that the sum of the concentrations of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.15 ppb. Using the obtained ethanol, the method described in Example 1 was carried out in the same manner. As a result, the charge potential of the crystals obtained on the filter was 0.0 kV, and no static charge was observed. The compound represented by the formula (1-1) obtained after drying was 22.5 g. The amount of residual solvent in the crystal was 56 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.4×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 19) Treatment of Solvent Using Silica Gel and Aluminum Oxide

The ion concentration of commercially available first-grade hexane was analyzed, and the result was that the total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.20ppb. A glass chromatographic tube was filled with 5 g each of silica gel and alumina, and 50 mL of first-grade hexane was poured into it for washing. Afterwards, 150 mL of first-grade hexane was introduced and collected in a clean glass flask. The resulting hexane was analyzed, and the result was that the sum of the concentrations of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions was 0.03 ppb. Using the obtained hexane, the same procedure as described in Example 1 was carried out. As a result, the charged potential of the crystal obtained on the filter was 0.0 kV, and no static electricity was observed. The compound represented by the formula (1-1) obtained after drying was 22.4 g. The amount of residual solvent in the crystal was 60 ppm, and the purity was 99.98%. The resistivity value of the liquid crystal composition obtained by adding 20% of the obtained compound represented by the formula (1-1) to the liquid crystal composition (M-1) with a resistivity value of 1.0×10 ¹³ Ω·m was 2.2×10 ¹² Ω·m.

In addition, a liquid crystal display element using a liquid crystal composition containing a compound represented by formula (1-1) was produced, and as a result, favorable characteristics were exhibited that display defects did not occur.

(Example 20)

In Example 1, the same operation was carried out using the compounds shown in the following table instead of the compounds represented by the formula (1-1). For any compound, the charge potential of the crystals obtained on the filter during the filtration operation was 0.0 kV, and no static charge was observed. Here, the resistivity value in a table is the resistivity value of the liquid crystal composition which added 20% of each compound to liquid crystal composition (M-1).

Table 1

In addition, as a result of producing a liquid crystal display device using the liquid crystal composition containing each compound after handling, it showed favorable characteristics that display defects did not occur.

Claims (34)

1. A method for producing a compound represented by general formula (1), characterized in that, The resistivity value of the compound represented by the general formula (1) is defined as the compound represented by the formulas (A-1) and (A-2) contained in a mass ratio of 1:1 and the resistivity value is 1.0×10 ¹³ Ω The resistivity value of the liquid crystal composition obtained by adding 20% by mass of the compound represented by the general formula (1) to 80% by mass of the liquid crystal composition (M-1) of m or more, By any one of the following methods (I) to (V), the compound represented by the general formula (1) whose resistivity value is less than 8.0×10 ¹¹ Ω·m is precipitated, and the obtained crystal is obtained from the The compound represented by the general formula (1) in a crystalline state is collected by filtration from any solvent solution of the following (VI) to (XI), and the solvent used for recrystallization contained in the filtered crystals is distilled off to obtain the above-mentioned A compound represented by general formula (1) in a crystalline state with a defined resistivity value of 8.0×10 ¹¹ Ω·m or more; Among them, general formula (1) is: In formula (1), R ¹ represents an alkyl group with 1 to 6 carbon atoms, an alkenyl group with 2 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or an alkenyloxy group with 2 to 6 carbon atoms , a means 1, 2 or 3, ^A1 and ^A2 each independently represent a group selected from the group consisting of the following (a) group, (b) group and (c) group: (a) trans-1,4-cyclohexylene, in which one methylene group or two or more non-adjacent methylene groups may be replaced by -O- or -S-, (b) 1,4-phenylene, one -CH= or two or more non-adjacent -CH= in this group may be replaced by nitrogen atoms, (c) 1,4-bicyclo(2.2.2)octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2 ,6-diyl, and chroman-2,6-diyl, The hydrogen atoms contained in the above-mentioned (a) group, (b) group or (c) group can be replaced by fluorine atom, trifluoromethyl group, trifluoromethoxy group or chlorine atom respectively, and there are multiple A ¹ , they are the same or different from each other, Z ¹ represents a single bond, -CH ₂ CH ₂ -, -CH=CH-, -C≡C-, -CH ₂ O-, -OCH ₂ -, -CF ₂ O-, -OCF ₂ -, -COO- or -OCO-, when there are multiple Z ^1s , the multiple existing Z ^1s are the same or different from each other, ^Y1 represents a hydrogen atom, a fluorine atom, a chlorine atom, a trifluoromethyl group, a trifluoromethoxy group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or a group having 1 to 6 carbon atoms Alkoxy or alkenyloxy with 2 to 6 carbon atoms; Formulas (A-1) and (A-2) are: The method of (I)～(V) is: (1) after being dissolved in a solvent, crystallization is separated out from the solution obtained, (II) dissolve in a solvent, and after purifying the solution by column chromatography filled with an adsorbent, crystals are precipitated from the obtained solution, (III) Dissolving in a solvent, purifying the solution by column chromatography filled with an adsorbent, and then partially concentrating the obtained solution to precipitate crystals, (IV) Dissolve in a solvent, and after purifying the solution by column chromatography filled with an adsorbent, add one or more nonpolar solvents and/or one or more polar solvents to the obtained solution After the solvent, the crystals were precipitated, (V) Dissolve in a solvent, refine the solution by column chromatography filled with an adsorbent, and then partially concentrate the obtained solution, and then add one or more non-polar solvents and/or one or two After the above polar solvent, the crystallization is separated out; The solvent of (VI)～(XI) is: (VI) Solvents consisting of only one non-polar solvent, (VII) a solvent formed of two or more non-polar solvents, (VIII) a solvent formed from 1 non-polar solvent and 1 polar solvent, (IX) A solvent formed of two or more nonpolar solvents and one polar solvent, (X) A solvent consisting of one nonpolar solvent and two or more polar solvents, (XI) a solvent formed from two or more nonpolar solvents and two or more polar solvents, The non-polar solvents and polar solvents of (VI) to (XI) are solvents that satisfy the requirements shown in (i) below: (i) In the purification process of the compound represented by the general formula (1) by column chromatography packed with an adsorbent, the column used for eluting the compound represented by the general formula (1) has passed through the column packed with the adsorbent non-polar solvents or polar solvents. 2. The manufacturing method according to claim 1, characterized in that, after dissolving the compound represented by the general formula (1) whose resistivity value is less than 8.0×10 ¹¹ Ω·m in a solvent, the The adsorbent is purified by column chromatography, and after a part of the solvent is distilled off from the obtained solution, the crystals of the compound represented by the general formula (1) are precipitated without adding a solvent, or directly obtained from The crystallization of the compound represented by the general formula (1) is precipitated in the solution of the general formula (1), and when the precipitated crystals are filtered, the solvent in the solution that exists together with the crystals does not contain polar solvents but consists of only one or two or more non-polar solvents. Solvents formed by solvents. 3. The production method according to claim 1, characterized in that, when filtering the precipitated crystals of the compound represented by the general formula (1), the solvent in the solution present with the crystals is formed only by non-polar solvents A mixed solvent formed of one or more than two solvents, before crystallization, further add one or two of which the total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions is less than 0.05ppb more than one non-polar solvent. 4. The manufacturing method according to claim 1 or 3, characterized in that, using column chromatography filled with an adsorbent, the resistivity value is shown to be less than 8.0×10 ¹¹ Ω·m according to claim 1. After refining the compound represented by formula (1), after distilling off part or all of the solvent in the obtained solution, or without distilling off the solvent, further adding lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions One or two or more nonpolar solvents whose total ion concentration is 0.05 ppb or less, after recrystallization, the solvent used for recrystallization is distilled off from the crystals of the compound represented by the general formula (1). 5. The production method according to claim 1, characterized in that, when filtering the precipitated crystals of the compound represented by general formula (1), the solvent in the solution that exists together with the crystals is at least one non-polar solvent and at least one polar solvent. 6. The manufacturing method according to claim 1 or 5, characterized in that, adding 1 or more than 2 non-polar solvents and/or 1 or more than 2 polar solvents makes it possible to utilize recrystallization to separate out The amount of the solvent used when the compound represented by the formula (1) is crystallized is 0.5 mL to 100 mL per 1 g of the compound represented by the general formula (1). 7. The production method according to claim 1 or 5, characterized in that, after the crystallization of the compound represented by the general formula (1) is precipitated and before the crystallization is filtered, one or more compounds according to claim 1 are added. 2 or more polar solvents. 8. The production method according to claim 1 or 5, wherein after purification of the compound represented by the general formula (1) by column chromatography filled with an adsorbent and after the compound represented by the general formula (1) Before the crystallization, add one or two or more polar solvents described in claim 1. 9. The production method according to claim 1 or 5, wherein the compound described in claim 1 is added to the developing solvent used when the compound represented by the general formula (1) is purified by column chromatography filled with an adsorbent. One or more polar solvents mentioned above. 10. The production method according to claim 1 or 5, characterized in that, before the purification of the compound represented by the general formula (1) by column chromatography filled with an adsorbent, one or more compounds according to claim 1 are added. 2 or more polar solvents. 11. The production method according to claim 1 or 5, wherein the solvent and The operation of adding a solvent directly precipitates crystals. 12. The production method according to claim 1 or 5, wherein after purification of the compound represented by the general formula (1) by column chromatography filled with an adsorbent, a part of the solvent is distilled off from the obtained solution, A crystallization precipitation step is performed. 13. The production method according to claim 1 or 5, wherein after the solvent is distilled off from the obtained solution after purification by column chromatography filled with an adsorbent, lithium ions, sodium ions, ammonium ions, One or more non-polar solvents whose total concentration of potassium ions, magnesium ions and calcium ions is less than 0.05ppb, and/or the concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions After dissolving the compound represented by the general formula (1) in one or two or more polar solvents with a total of 1.0 ppb or less, the crystallization step of the compound represented by the general formula (1) is performed. 14. The manufacturing method according to claim 1 or 5, characterized in that, before the crystallization process, the total concentration of lithium ions, sodium ions, ammonium ions, potassium ions, magnesium ions and calcium ions is added to be 0.05 One or two or more non-polar solvents below ppb, adjust the amount of solvent. 15. The manufacturing method according to claim 1 or 5, wherein the polar solvent used is one selected from alcohol solvents, ketone solvents, ester solvents, ether solvents or nitrile solvents or two or more solvents. 16. The manufacturing method according to claim 15, wherein the alcohol solvent is methanol, ethanol, 1-propanol or 2-propanol, the ketone solvent is acetone or 2-butanone, and the ester solvent is acetic acid Ethyl ester, the ether solvent is diethyl ether, tetrahydrofuran or methyl-tert-butyl ether, and the nitrile solvent is acetonitrile or propionitrile. 17. The production method according to claim 16, wherein the polar solvent used is one or two or more solvents selected from methanol, ethanol, acetone, or 2-butanone. 18. The production method according to claim 1 or 5, wherein the proportion of the hydrocarbon solvent in the solvent in the solution that exists with the crystal when the precipitated crystal of the compound represented by the general formula (1) is filtered is It is 50 volume% or more. 19. The production method according to claim 1 or 5, characterized in that, in the solvent in the solution that exists with the crystal when the crystal of the compound represented by the precipitated general formula (1) is filtered, the ratio of the hydrocarbon solvent is It is 90 volume% or more. 20. The production method according to any one of claims 1 to 3, characterized in that, in general formula (1), at least one of ^A1 and ^A2 represents the following groups: 21. The production method according to any one of claims 1 to 3, wherein, in the general formula (1), Y ¹ represents a fluorine atom. 22. The production method according to any one of claims 1 to 3, characterized in that, in general formula (1), ^R is methyl, ethyl, propyl, butyl or pentyl, and ^Z represents Single bond, -CH ₂ CH ₂ -, -CF ₂ O- or -OCF ₂ -. 23. The production method according to any one of claims 1 to 3, characterized in that, in general formula (1), at least one of ^A1 and ^A2 represents the following groups: 24. The production method according to any one of claims 1 to 3, characterized in that, in general formula ( ¹ ), R and Y ^each independently represent methyl, ethyl, propyl, butyl, Pentyl, vinyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, 3-butenyloxy or 4-pentenyloxy, Z ¹ represents a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -CF ₂ O- or -OCF ₂ -. 25. The production method according to any one of claims 1 to 3, characterized in that, in general formula (1), at least one of ^A1 and ^A2 represents the following groups: 26. The production method according to any one of claims 1 to 3, wherein the non-polar solvent used is a hydrocarbon solvent. 27. The production method according to claim 26, wherein the hydrocarbon solvent used is from hexane and its structural isomers, heptane and its structural isomers, octane and its structural isomers 1 or more solvents selected from the group consisting of petroleum ether, benzene, toluene, xylene, and cumene. 28. The production method according to claim 26, wherein the hydrocarbon solvent used is one selected from hexane and its structural isomers, heptane and its structural isomers, and toluene or 2 or more solvents. 29. The production method according to any one of claims 1 to 3, wherein at least one of the solvents in the solution present with the crystals when the precipitated crystals of the compound represented by the general formula (1) is filtered is One is a non-polar solvent refined with an adsorbent. 30. The production method according to any one of claims 1 to 3, characterized in that at least one of the solvents in the solution present with the crystals when the precipitated crystals of the compound represented by the general formula (1) is filtered is One is a solvent treated with an ion exchange resin. 31. The production method according to any one of claims 1 to 3, wherein at least one of the solvents in the solution present with the crystals when the precipitated crystals of the compound represented by the general formula (1) is filtered is One is a solvent that has been chromatographed on a column packed with an adsorbent. 32. The production method according to any one of claims 1 to 3, characterized in that silica gel, alumina or a mixture thereof is used as the adsorbent. 33. The production method according to any one of claims 1 to 3, wherein when column chromatography is used for purification, hexane and its structural isomers, heptane and its structural isomers, and One or more solvents selected from toluene are used as developing solvents. 34. The production method according to any one of claims 1 to 3, wherein the resistivity value of the compound represented by the general formula (1) obtained in a crystalline state is 1.0×10 ¹² Ω·m above.