Method for producing an ether compound

Abstract

To provide a method for producing an ether compound, capable of obtaining a target compound while suppressing the production of by-products (di-etherified bodies).SOLUTION: A method for producing an ether compound (C) includes: a step (1) of performing an etherification reaction in the presence of a specific hydroquinone compound (A), a specific alcohol compound (B), and an aqueous solution containing a basic compound (I) and a hydrophobic organic solvent; and a step (2) of recovering a hydrophobic organic solvent layer from a mixed liquid yielded in the etherification reaction, and further mixing the hydrophobic organic solvent layer with an aqueous solution of a basic compound (II), followed by recovering a basic aqueous solution of the ether compound (C).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing an ether compound which is an intermediate in the production of liquid crystal compounds.

Background Art

[0002] An ether compound having a phenolic hydroxyl group (for example, (6-hydroxyhexyl)oxy-4-phenol: HHOP, etc.) is useful as an intermediate in the production of a reverse-dispersible liquid crystal compound used in an antireflection film of an organic EL display device, etc. For example, in Patent Documents 1 and 2, as a method for producing HHOP, a production method in which hydroquinone (HYQ) and an alcohol compound are subjected to an etherification reaction under basic conditions in a nitrogen atmosphere is disclosed.

Chemical Formula

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the production methods described in Patent Documents 1 and 2, since there may be many by-products (di-etherified products) that have reacted excessively in the final product, it is not always a suitable production method for an intermediate in the production of a film for an organic EL display device.

[0005] Therefore, an object of the present invention is to provide a method for producing an ether compound that can obtain a target compound while suppressing the formation of by-products (di-etherified products).

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the production method of the present invention can solve the above problems, and have completed the present invention. That is, the present invention includes the following preferred embodiments.

[0007] [1] Formula (A):

Chemical formula

Chemical formula

[10] The amount of the reducing agent in the step (1) is 0.01 mol or more and 0.5 mol or less per 1 mol of the alcohol compound (B), the method according to any one of [5] to [9].

Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for producing an ether compound capable of obtaining a target compound while suppressing the formation of by-products (dietherified products).

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0010] The production method of the present invention is represented by the formula (A):

Chemical formula

Chemical formula

[0011] [Step (1)] In step (1) of the production method of the present invention, an etherification reaction is carried out in the presence of an aqueous solution containing the hydroquinone compound (A) represented by the formula (A), the alcohol compound (B) represented by the formula (B), and the basic compound (I) and a hydrophobic organic solvent.

[0012] Formula (A) used in the present invention:

Chemical formula

[0013] Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an s-butyl group, a t-butyl group, and the like. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0014] Among these, as the hydroquinone compound (A), those in which R 1 ~R 4 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms are preferred. Specific examples of such a hydroquinone compound (A) include compounds represented by the following formulas (A-1) to (A-7).

Chemical formula

[0015] Formula (B) used in the present invention:

Chemical formula

[0016] Examples of the alkylene group having 1 to 9 carbon atoms which may have a substituent include a methylene group, an ethylene group, a trimethylene group, a 1-methylethylene group, a 2-methylethylene group, a tetramethylene group, a 1-methyltrimethylene group, a 2-methyltrimethylene group, a 3-methyltrimethylene group, a 1-ethylethylene group, a 2-ethylethylene group, a propylene group, a hexamethylene group, an octamethylene group, and the like. Further, examples of the alkylene group having 2 to 5 carbon atoms which may have a substituent that R 6 , R 7 can take include those among the above-described alkylene groups having 2 to 5 carbon atoms. Examples of the halogen atom include the same ones as those exemplified in the hydroquinone compound (A). Examples of the fluoroalkyl group having 1 to 4 carbon atoms include a trifluoromethyl group, a trifluoroethyl group, a pentafluoroethyl group, a trifluoropropyl group, a heptafluoropropyl group, a nonafluorobutyl group, and the like. Examples of the alkyl group having 1 to 4 carbon atoms include the same ones as those exemplified in the hydroquinone compound (A). Examples of the aryl group which may have a substituent include a phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthracenyl group, 2-anthracenyl group, 9-anthracenyl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 2-fluorenyl group, 3-fluorenyl group, 4-fluorenyl group, 2-phenylphenyl group, 3-phenylphenyl group, 4-phenylphenyl group, etc., and groups in which a hydrogen atom is substituted with an alkyl group, cycloalkyl group, alkoxy group, cycloalkoxy group, aryl group, halogen atom, etc. Examples of the cycloalkyl group include a cyclohexyl group, cyclohexylmethyl group, etc., and examples of the cycloalkoxy group include a cyclohexyloxyl group, etc.

[0017] Among these, as the alcohol compound (B), those in which R 5 is an alkylene group having 1 to 9 carbon atoms which may have a substituent and X is a halogen atom are preferred, and those in which R 5 is a hexamethylene group and X is a chlorine atom, that is, the alcohol compound (B) is particularly preferably chlorohexanol.

[0018] The amount of the hydroquinone compound (A) is preferably 1.0 mol or more, more preferably 1.1 mol or more, still more preferably 1.2 mol or more, and preferably 2.0 mol or less, more preferably 1.7 mol or less, still more preferably 1.5 mol or less, relative to 1 mol of the alcohol compound (B). When the amount of the hydroquinone compound (A) is within the above lower limit and the above upper limit, by-products are less likely to be generated.

[0019] The basic compound (I) preferably contains at least one selected from the group consisting of hydroxide salts, carbonates and bicarbonates. Examples of the hydroxide salt include lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, calcium hydroxide, etc. Examples of the carbonate include sodium carbonate, potassium carbonate, cesium carbonate, calcium carbonate, magnesium carbonate, etc. Examples of the hydrogen carbonate include lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, cesium hydrogen carbonate and the like. Among the above basic compounds (I), hydroxide salts are preferred because by-products are less likely to be formed and compound (C-1) can be easily obtained in a high yield. Sodium hydroxide or potassium hydroxide is more preferred.

[0020] The amount of the basic compound (I) in step (1) is preferably 1.0 mol or more, more preferably 1.1 mol or more, still more preferably 1.2 mol or more, and preferably 2.0 mol or less, more preferably 1.5 mol or less, per 1 mol of the alcohol compound (B). When the amount of the basic compound (I) is not less than the above lower limit and not more than the above upper limit, by-products are less likely to be formed and compound (C-1) can be easily obtained in a high yield. Further, a neutralization step after the reaction is unnecessary.

[0021] In step (1), the reaction (etherification reaction) between the hydroquinone compound (A) and the alcohol compound (B) is carried out in the presence of an aqueous solution containing the basic compound (I) and a hydrophobic organic solvent. By carrying out the etherification reaction in the presence of an aqueous solution containing the basic compound (I) and a hydrophobic organic solvent, it is easy to suppress the formation of the dietherified product of the hydroquinone compound (A). Further, since the acid generated as the etherification reaction proceeds can be neutralized, the reaction easily proceeds.

[0022] A hydrophobic organic solvent is an organic solvent that is immiscible with water, such as aromatic organic solvents like benzene, toluene, xylene (o-xylene, m-xylene, p-xylene or a mixture thereof), mesitylene, cymene, cumene, durene, chlorobenzene, diphenyl ether, anisole, thioanisole, etc.; hydrocarbon organic solvents like heptane, octane, nonane, decane, undecane, dodecane, n-hexane, cyclohexane, methylcyclohexane, etc.; ether solvents like dimethyl ether, diethyl ether, etc.; halogenated hydrocarbon solvents like carbon tetrachloride, trichloroethylene, etc.; higher alcohol solvents like t-butyl alcohol, cyclohexanol, etc.; ketone solvents like methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Among these, from the viewpoints of reactivity, economy, and handleability, aromatic organic solvents, hydrocarbon organic solvents, and ether solvents are preferred. The hydrophobic organic solvent may be used alone or in combination of two or more. The mixing ratio when using two or more in combination is not particularly limited.

[0023] The amount of the hydrophobic organic solvent is preferably 0.5 part by mass or more, more preferably 0.8 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 1 part by mass of the alcohol compound (B). When the amount of the hydrophobic organic solvent is not less than the lower limit and not more than the upper limit, by-products are less likely to be generated. Also, there is a tendency to be excellent in productivity.

[0024] The method of mixing an aqueous solution containing a hydroquinone compound (A), an alcohol compound (B), and a basic compound (I) with a hydrophobic organic solvent is not particularly limited. For example, a method of mixing, in any order, a predetermined amount of an aqueous solution containing a hydroquinone compound (A), an alcohol compound (B), and a basic compound (I) and a hydrophobic organic solvent at once by stirring or the like; a method of mixing a part of the predetermined amount of the aqueous solution containing a hydroquinone compound (A), an alcohol compound (B), and a basic compound (I) and a hydrophobic organic solvent, and then mixing the remaining part into the reaction system; a method of continuously dropping and mixing a hydrophobic organic solvent into a system in which a hydroquinone compound (A) and an alcohol compound (B) are mixed with an aqueous solution containing a basic compound (I); a method of continuously dropping and mixing an aqueous solution containing a basic compound (I) into a system in which a hydroquinone compound (A) and an alcohol compound (B) are mixed with a hydrophobic organic solvent, etc. may be mentioned. Further, as the aqueous solution containing the basic compound (I), a previously prepared one may be used, or water and the basic compound (I) may be separately added to the reaction system to prepare the aqueous solution in the reaction system. In the present invention, from the viewpoint of improving the yield of the compound (C-1), a method of continuously dropping an aqueous solution of the basic compound (I) into a system in which the hydroquinone compound (A) and the alcohol compound (B) are mixed with a hydrophobic organic solvent is preferable. In this case, in order to dissolve the hydroquinone compound (A) and the alcohol compound (B), water may be previously added to the system in addition to the hydrophobic organic solvent. The amount of water in this case is preferably 2 to 10 parts by mass with respect to 1 part by mass of the alcohol compound.

[0025] From the viewpoint of suppressing the oxidation of the hydroquinone compound (A) which can cause coloring, the etherification reaction in step (1) is preferably carried out in the presence of a reducing agent.

[0026] The reducing agent preferably contains at least one selected from the group consisting of sulfites, bisulfites, and thiosulfates. Examples of the sulfite include sodium sulfite, potassium sulfite, calcium sulfite, magnesium sulfite, ammonium sulfite, etc. Examples of the bisulfite include sodium bisulfite, potassium bisulfite, ammonium bisulfite and the like. Examples of the thiosulfate include sodium thiosulfate, potassium thiosulfate, calcium thiosulfate, magnesium thiosulfate, ammonium thiosulfate and the like. Among the above reducing agents, sulfite is preferable because of its higher effect of suppressing coloring, and sodium sulfite or potassium sulfite is more preferable.

[0027] The amount of the reducing agent in step (1) is preferably 0.01 mol or more, more preferably 0.1 mol or more, and preferably 0.5 mol or less, more preferably 0.3 mol or less, per 1 mol of the alcohol compound (B). When the amount of the reducing agent is equal to or more than the lower limit and equal to or less than the upper limit, oxidation of the hydroquinone compound (A) that may cause coloring is easily suppressed.

[0028] In step (1), compounds other than the above compounds may be contained in the reaction system to improve reactivity. Such compounds are not limited as long as they do not affect the etherification reaction. Examples include N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide, n-butyl alcohol, ethylene glycol and the like. The amount of the compound is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, and preferably 0.1 part by mass or less, more preferably 0.05 part by mass or less, per 1 part by mass of the alcohol compound (B). When the amounts of these compounds are equal to or more than the lower limit and equal to or less than the upper limit, the reaction easily proceeds smoothly.

[0029] In order to suppress the oxidation of the hydroquinone compound (A) and make the etherification reaction proceed more easily, step (1) is preferably carried out under an inert gas atmosphere. Examples of the inert gas include nitrogen gas, argon gas and the like.

[0030] The reaction temperature in step (1) is not particularly limited, but is preferably 15°C or higher, more preferably 40°C or higher, still more preferably 70°C or higher, and preferably 200°C or lower, more preferably 150°C or lower, still more preferably 100°C or lower. When the reaction temperature is at or above the lower limit and at or below the upper limit, by-products are less likely to be formed and the reaction easily proceeds smoothly.

[0031] The reaction time is also not particularly limited and may be appropriately adjusted according to the reaction temperature, but is usually 1 hour or more and 72 hours or less, preferably 12 hours or more and 60 hours or less. The progress of the reaction can be confirmed by known analytical means (for example, thin layer chromatography, high performance liquid chromatography, gas chromatography, infrared spectroscopic analysis, etc.).

[0032] The etherification reaction in step (1) can specifically be carried out, for example, by the following method. Into a predetermined reaction vessel (for example, a reaction vessel equipped with a stirrer, a cooling device, etc.), a hydroquinone compound (A), an alcohol compound (B), a hydrophobic organic solvent, and optionally water and a reducing agent are added in predetermined amounts under an inert atmosphere. The order of addition of these is not particularly limited. Then, an aqueous solution containing a basic compound (I) is added, and the mixture is stirred at the above-mentioned predetermined temperature for a predetermined time.

[0033] [Step (2)] In step (2) of the production method of the present invention, the hydrophobic organic solvent layer is recovered from the reaction mixture obtained by the etherification reaction in step (1), and further, after mixing the hydrophobic organic solvent layer and an aqueous solution of a basic compound (II), a basic aqueous solution of the compound (C-1) represented by formula (C-1) is recovered.

[0034] Formula (C-1): [Chemical formula] In the compound represented by, R 1 ~R 5Examples thereof include those similar to those exemplified by the hydroquinone compound (A) and the alcohol compound (B). M represents a monovalent metal element. Examples of the monovalent metal element include sodium, lithium, potassium, cesium, and the like. Among these, sodium is preferable from the viewpoint of the price of the basic compound.

[0035] In step (2), the method for recovering the hydrophobic organic solvent layer from the reaction mixture is not particularly limited, and for example, methods known to those skilled in the art such as solvent extraction, solid-phase extraction, and organic phase solidification can be used. However, the solvent extraction method is preferable because the operation is simpler. When carried out by the solvent extraction method, for example, after the reaction mixture in step (1) is adjusted to 30 to 70 °C and allowed to stand for 1 to 60 minutes, the organic layer can be recovered using, for example, a separatory funnel, a countercurrent extraction device, or the like.

[0036] The operation of recovering the organic layer may be carried out a plurality of times as necessary. For example, when recovering the organic layer by the solvent extraction method, an aqueous solution of the basic compound (II) or water may be added to the organic layer recovered after the first liquid separation operation, and the above liquid separation operation may be repeated to further recover the organic layer. By carrying out such an operation a plurality of times, the compound (C-1) can be easily obtained in a high yield.

[0037] The basic compound (II) used for preparing the aqueous solution of the basic compound (II) to be mixed with the recovered hydrophobic organic solvent layer preferably contains at least one selected from the group consisting of hydroxide salts, carbonate salts, and bicarbonate salts. Examples of the hydroxide salt include lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, calcium hydroxide, and the like. Examples of the carbonate salt include sodium carbonate, potassium carbonate, cesium carbonate, calcium carbonate, magnesium carbonate, and the like. Examples of the bicarbonate salt include lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, cesium bicarbonate, and the like. Among the above basic compounds (II), hydroxide salts are preferred because they react with the unreacted hydroquinone compound (A) and are easily removed, and sodium hydroxide or potassium hydroxide is more preferred. Further, the basic compound (II) may be the same as or different from the basic compound (I) used in step (I).

[0038] The amount of the basic compound (II) in step (2) is preferably 0.5 mol or more, more preferably 0.7 mol or more, and preferably 2.0 mol or less, more preferably 1.5 mol or less, per 1 mol of the alcohol compound (B). When the amount of the basic compound (II) is within the above lower limit and the above upper limit, it easily reacts with the unreacted hydroquinone compound (A) and easily forms a salt with the ether compound (C). In step (2), by adding the basic compound (II) within the above range, the by-product dietherified product can be easily transferred to the organic layer and removed from the aqueous layer.

[0039] The recovered hydrophobic organic solvent layer may contain a compound other than the basic compound (II) to improve the solubility of the by-product (dietherified product). Such compounds are not limited as long as they do not affect the yields of the compounds (C-1) and (C-2), and examples thereof include toluene, xylene, isopropyl alcohol, and the like. The amount of the compound used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, per 1 part by mass of the alcohol compound (B). When the amounts of these compounds are within the above lower limit and the above upper limit, the removal of the by-product (dietherified product) proceeds smoothly.

[0040] The method of mixing an aqueous solution of the basic compound (II) with the hydrophobic organic solvent layer is not particularly limited. For example, a method of adding a predetermined amount of the aqueous solution of the basic compound (II) to the hydrophobic organic solvent layer at once and then stirring, a method of adding a part of the aqueous solution of the basic compound (II) to the hydrophobic organic solvent layer, stirring, and then adding the remaining part to the hydrophobic organic solvent layer, a method of continuously dropping the aqueous solution of the basic compound (II) into the hydrophobic organic solvent layer and mixing, etc. can be mentioned. In the present invention, in order to improve the yield of the compound (C-1), a method of continuously dropping the aqueous solution of the basic compound (II) into the hydrophobic organic solvent layer is preferred.

[0041] From the viewpoint of suppressing the oxidation of side reaction products that can cause coloring, step (2) is preferably carried out in an inert gas atmosphere. Examples of the inert gas include nitrogen gas, argon gas, etc.

[0042] The reaction temperature in step (2) is not particularly limited, but is preferably 15°C or higher, more preferably 40°C or higher, still more preferably 60°C or higher, and preferably 200°C or lower, more preferably 150°C or lower, still more preferably 100°C or lower. When the reaction temperature is above the lower limit and below the upper limit, the extraction of the compound (C-1) from the hydrophobic organic solvent proceeds smoothly.

[0043] The reaction time is also not particularly limited and may be appropriately adjusted according to the reaction temperature, but is usually 10 minutes or more and 12 hours or less, preferably 30 minutes or more and 6 hours or less.

[0044] In the above step (2), after mixing with the aqueous solution of the basic compound (II), Formula (C-1):

Chemical formula

[0045] Examples of the method for obtaining the compound (C-1) from the aqueous layer include a method of cooling the aqueous layer to precipitate the compound (C-1), a method of evaporating the aqueous solution of the aqueous layer by heating or the like to precipitate the compound (C-1), etc. However, a method of cooling the aqueous layer is preferred to prevent thermal decomposition.

[0046] The cooling temperature when cooling the aqueous layer may be appropriately changed according to the amount of the compound (C-1) dissolved in the aqueous layer and the solubility of the compound (C-1), but it is usually 5 to 25°C.

[0047] The atmosphere for obtaining the compound (C-1) from the aqueous layer is preferably carried out under an inert gas atmosphere from the viewpoint of suppressing the oxidation of side reaction products that may cause coloring. Examples of the inert gas include nitrogen gas, argon gas, etc.

[0048] The precipitated compound (C-1) can be separated by a known method such as filtration, washed with water or the like, and then dried.

[0049] The precipitated compound (C-1) may be further washed with water. The washing time can be adjusted as appropriate, but from the viewpoint of sufficiently removing the remaining basic compound (II), it is preferably 5 minutes or more, more preferably 10 minutes or more, and from the viewpoint of productivity, it is preferably 60 minutes or less, more preferably 35 minutes or less.

[0050] The amount of water used for washing is not particularly limited as long as the remaining basic compound (II) can be sufficiently removed, but it is usually 3 parts by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more of the produced compound (C-1). The water temperature during water washing is preferably 5 to 25°C from the viewpoints of the removal efficiency of the remaining basic compound (II) and the solubility of the compound (C-1).

[0051] After washing with water, a drying treatment may be carried out using a known dryer such as a hot air dryer or a vacuum dryer. The drying is preferably carried out at a temperature of 30 to 80 °C. When the drying temperature is within the above range, the decomposition of the compound (C-1) is less likely to occur, and the drying proceeds appropriately, which is preferable. The drying time may be appropriately changed depending on the drying temperature, but is usually 1 to 48 hours.

[0052] By passing through the above steps (1) and (2), the production method of the present invention can obtain an aqueous solution containing the compound (C-1) with a small amount of by-products and unreacted hydroquinone compound content. Therefore, a high-quality ether compound (C) can be obtained by the production method of the present application.

[0053] Furthermore, in step (2), when the basic compound (II) is added (preferably in an excessive amount), the basic compound (II) not only reacts with the unreacted hydroquinone compound (A), but is also used for the neutralization of the compound (C-2). Therefore, the ether compound (C-2) will exist in the aqueous layer as the water-soluble compound (C-1). Since the compound (C-1) exists in the aqueous layer, the separation from the dietherified product dissolved in the organic layer becomes easier.

[0054] The above compound (C-1) can be converted into the compound (C-2) by an appropriate method.

[0055] [Step (3)] In the production method of the present invention, after the above steps (1) and (2), it is preferable to include step (3) of adding an acid to the basic aqueous solution of the compound (C-1). By passing through step (3), the compound (C-1) can be neutralized to the compound (C-2). In addition, the yield of the compound (C-2) can be improved. Conventionally, in the production method of an ether compound having a phenolic hydroxyl group, by-products (dietherified products, oligomers of hydroquinone compounds that cause coloring, etc.) are not removed, and the removal of unreacted hydroquinone compounds is carried out by washing the organic layer with a weakly basic aqueous solution. In the present invention, by performing step (3), unreacted hydroquinone compounds and oligomers of hydroquinone compounds as by-products can be removed more efficiently.

[0056] As the acid in step (3), water-soluble ones are preferred, and either inorganic acids or organic acids can be used. Examples of inorganic acids include hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, boric acid, and the like. Examples of organic acids include formic acid, acetic acid, citric acid, oxalic acid, lactic acid, malic acid, succinic acid, tartaric acid, methanesulfonic acid, and the like. Among these acids, since the yield of compound (C-2) is more likely to be improved, it is preferably included at least one selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid.

[0057] The amount of the acid in step (3) is preferably 1.0 mol or less, more preferably 0.7 mol or less, relative to 1 mol of the alcohol compound (B). The lower limit of the amount of the acid is usually 0.05 mol or more relative to 1 mol of the alcohol compound (B). When the amount of the acid is below the above upper limit, the yield of compound (C-2) is likely to be improved, and it is easy to remove the acid by subsequent washing.

[0058] The step of adding the acid in step (3) can be carried out by any method. For example, a method of adding a predetermined amount of the acid to the basic aqueous solution at once and then stirring, a method of adding a part of the acid to the basic aqueous solution, stirring, and then adding the remaining part to the basic aqueous solution, a method of continuously dropping the acid into the basic aqueous solution and mixing, and the like can be mentioned. In the present invention, in order to improve the yield and filterability of compound (C-2), a method of continuously dropping the acid into the basic aqueous solution is preferred.

[0059] After mixing the acid, the crystals in the aqueous solution are separated by a known method such as filtration, washed with water or the like, and dried to obtain compound (C-2).

[0060] The atmosphere for washing is not particularly limited and may be appropriately selected according to the method used for washing. In the present invention, it is usually carried out in the air atmosphere.

[0061] The washing time can be adjusted as appropriate, but from the viewpoint of sufficiently removing the residual acid, it is preferably 5 minutes or more, and from the viewpoint of productivity, it is preferably 60 minutes or less, more preferably 40 minutes or less, and even more preferably 35 minutes or less.

[0062] The amount of water used for washing is not particularly limited as long as the residual acid can be sufficiently removed, but it is usually 3 parts by mass or more, preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more of the produced compound (C-2). The water temperature during water washing is preferably 10 to 30 °C from the viewpoints of the removal efficiency of the residual acid and preventing excessive dissolution of the compound (C-2).

[0063] After water washing, a drying treatment may be carried out using a known dryer such as a hot air dryer or a vacuum dryer. The drying is preferably carried out at a temperature of 30 to 80 °C. When the drying temperature is within the above range, the compound (C-2) is less likely to deteriorate, and the drying proceeds appropriately, which is preferable. The drying time may be appropriately changed depending on the drying temperature, but it is usually 1 to 48 hours.

[0064] The thus-obtained compound (C-1) or compound (C-2) is preferably used as a raw material for a polymerizable compound that is an intermediate in the production of a reverse-dispersible liquid crystal compound. This production method can obtain the compound (C-1) and / or compound (C-2) while suppressing the formation of by-products (dietherified products), and thus is suitable as a production method for the ether compound (C) that is an intermediate used in the production of liquid crystal compounds.

Examples

[0065] Hereinafter, the present invention will be described more specifically by way of examples. In the examples, “%” and “parts” mean mass % and parts by mass, respectively, unless otherwise specified.

[0066] [Measurement of Yield and Mass Fraction of Dietherified Product] In the examples and comparative examples, the yield of (6-hydroxyhexyl)oxy-4-phenol and the mass fraction of its dietherified product were calculated from the area values of the peak areas by high performance liquid chromatography (HPLC) analysis. High-purity products of (6-hydroxyhexyl)oxy-4-phenol and its dietherified product were used as standard substances respectively, and the purity and the number of moles of (6-hydroxyhexyl)oxy-4-phenol and its dietherified product were calculated from their calibration curves, and the yield and the mass fraction were calculated from the ratio to the number of moles of the alcohol compound used in the preparation. For the salt of (6-hydroxyhexyl)oxy-4-phenol in Example 1, the purity was corrected from the ratio of the salt of (6-hydroxyhexyl)oxy-4-phenol to the molecular weight of (6-hydroxyhexyl)oxy-4-phenol, and the yield was calculated.

[0067] [Measurement conditions for HPLC] Apparatus: SHIMAZU LC (manufactured by Shimadzu Corporation) Column: YMC-Pack C4 Column temperature: 40 °C Eluent A: 10 mM ammonium formate / water Eluent B: 10 mM ammonium formate / (water / acetonitrile = 1 / 9) Gradient conditions: Solution B; 5% → 35 min → 55% → 5 min → 100% (10 min) Flow rate: 1.0 mL / min Sample injection volume: 5 μm Detection wavelength: 220 nm

[0068] [Measurement of transmittance] A THF solution (100 mg / 10 g) of the obtained (6-hydroxyhexyl)oxy-4-phenol was set in a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation), and the transmittance at 450 nm was measured.

[0069] Example 1 Step (1): 49.0 g of hydroquinone [1.3 molar equivalents relative to chlorohexanol] and 46.7 g of chlorohexanol were added into a 1 L-separable flask equipped with a stirrer, Dimroth condenser, and thermometer, and 46.7 g of toluene [hydrophobic organic solvent; 1.0 part by mass relative to chlorohexanol], 145 g of water [3.1 parts by mass relative to chlorohexanol], and 0.5 g of N-methylpyrrolidone [0.01 part by mass relative to chlorohexanol] were added and purged with nitrogen. Subsequently, 58.6 g of a 28% by mass aqueous sodium hydroxide solution [1.2 molar equivalents relative to chlorohexanol] was added dropwise, and the mixture was kept at 80 °C for 48 hours. Step (2): After the above heat retention, the mixture was cooled to 65 °C, and the aqueous layer was removed by liquid separation operation, and the hydrophobic organic solvent layer (hereinafter also referred to as "organic layer") was recovered. 187 g of a 20% by mass aqueous sodium sulfate solution [4.0 parts by mass relative to chlorohexanol] was added to the organic layer, and after keeping warm for 30 minutes, the aqueous layer was removed again by liquid separation operation. 187 g of toluene [4.0 parts by mass relative to chlorohexanol] and 397 g of water [8.5 parts by mass relative to chlorohexanol] were added to the newly obtained organic layer, and then 48.9 g of a 28% by mass aqueous sodium hydroxide solution [1.0 molar equivalent relative to chlorohexanol] was added dropwise, and the mixture was kept warm for 30 minutes. Then, the aqueous layer was removed by liquid separation operation.

[0070] After step (2), after the aqueous layer was removed by liquid separation operation, it was cooled to 25 °C. The precipitated crystals were filtered and washed with 467 g of water [10.0 parts by mass relative to chlorohexanol]. The obtained crystals were dried at 40 °C for 24 hours to obtain a salt of (6-hydroxyhexyl)oxy-4-phenol. The yield was 49.2%.

[0071] Example 2 After performing step (1) and step (2) under the same conditions as in Example 1, the aqueous layer was cooled to 25 °C after liquid separation. Step 3: 21.5 g of 78% by mass sulfuric acid (0.5 molar equivalent relative to chlorohexanol) was added dropwise to the aqueous layer. The crystals were filtered and washed with 467 g of water (10.0 parts by mass relative to chlorohexanol). The obtained crystals were dried at 40 °C for 24 hours to obtain (6-hydroxyhexyl)oxy-4-phenol. The yield was 65.3%.

[0072] Example 3 The procedure was the same as in Example 2, except that 6.5 g of sodium sulfite (0.15 molar equivalent relative to chlorohexanol) was added simultaneously with hydroquinone in step (1). The yield was 54.7%.

[0073] Comparative Example 1 After carrying out the reaction in step (1) under the same conditions as in Example 1 for 48 hours, the aqueous layer was removed by liquid separation and cooled to 25 °C. The crystals were filtered and washed with 467 g of water (10.0 parts by mass relative to chlorohexanol). The obtained crystals were dried at 40 °C for 24 hours to obtain (6-hydroxyhexyl)oxy-4-phenol.

[0074] The production conditions of Examples 1 to 3 and Comparative Example 1 are shown in Table 1, and the results are shown in Table 2.

[0075]

Table 1

[0076]

Table 2

[0077] In the production method of Comparative Example 1, a large amount of the dietherified product was contained in the final product. Also, since the transmittance at 450 nm was low, it was considered that a large amount of by-products (such as oligomers of hydroquinone compounds) causing coloring were contained. On the other hand, in the production methods of Examples 1 to 3, the amount of the dietherified product in the final product was small and the transmittance at 450 nm was also high.

Claims

1. Formula (A): 【Chemical Formula 1】 [In formula (A), R １ ~R ４ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom] A hydroquinone compound (A) represented by, formula (B): 【Chemical Formula 2】 [In formula (B), R ５ represents an alkylene group having 1 to 9 carbon atoms which may have a substituent, or a group represented by -R ６ -(O-R ７ )n-, R ６ , R ７ each represents an alkylene group having 2 to 5 carbon atoms which may have a substituent, R ６ , R ７ may be the same or different from each other. n represents a positive integer from 1 to 5. X represents a halogen atom, a group represented by -O-S(=O)-R ８ , or a group represented by -O-C(=O)-R ８ , R ８ represents a fluoroalkyl group having 1 to 4 carbon atoms, an alkyl group having 1 to 4 carbon atoms, or an aryl group which may have a substituent] An alcohol compound (B) represented by, an aqueous solution containing a basic compound (I), a hydrophobic organic solvent, and a step (1) of performing an etherification reaction in the presence of one or more compounds selected from the group consisting of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide, n-butyl alcohol, and ethylene glycol, and Recovering the hydrophobic organic solvent layer from the reaction mixture obtained by the etherification reaction, and further, after mixing the hydrophobic organic solvent layer and an aqueous solution of a basic compound (II), formula (C-1): 【Chemical Formula 3】 [In formula (C-1), R １ ~R ５ are as defined in the above formulas (A) and (B), and M represents a monovalent metal element] A process (2) for recovering a basic aqueous solution of the compound (C-1) represented by The ether compound (C) represented by the formula (C-1) or formula (C-2): [Chemical Formula 4] [In formula (C-2), R １ ~R ５ are as defined in the above formulas (A) and (B)] A method for producing an ether compound (C).

2. The method according to claim 1, further comprising a step (3) of adding an acid to the basic aqueous solution of the compound (C-1) after the step (2).

3. The method according to claim 1 or 2, wherein the basic compound (I) contains at least one selected from the group consisting of hydroxide salts, carbonate salts, and bicarbonate salts.

4. The method according to any one of claims 1 to 3, wherein the basic compound (II) contains at least one selected from the group consisting of hydroxide salts, carbonate salts, and bicarbonate salts.

5. The method according to any one of claims 1 to 4, wherein the etherification reaction in the step (1) is carried out in the presence of a reducing agent.

6. The method according to claim 5, wherein the reducing agent contains at least one selected from the group consisting of sulfite salts, bisulfite salts, and thiosulfate salts.

7. The method according to claim 2, wherein the acid in the step (3) contains at least one selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid.

8. The method according to any one of claims 1 to 7, wherein the amount of the basic compound (II) in the step (2) is 0.5 mol or more and 2.0 mol or less per 1 mol of the alcohol compound (B).

9. The method according to claim 2 or 7, wherein the amount of the acid in the step (3) is 1.0 mol or less per 1 mol of the alcohol compound (B).

10. The method according to claim 5 or 6, wherein the amount of the reducing agent in the step (1) is 0.01 mol or more and 0.5 mol or less per 1 mol of the alcohol compound (B).

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