Method for producing benzoxazine compound

Abstract

The present invention addresses the problem of providing a method whereby a high-purity benzoxazine compound can be produced by suppressing a decrease in purity due to high molecular weight during production of an allyl group-containing benzoxazine compound. As a solution, provided is a method for producing a benzoxazine compound represented by general formula (1), which is characterized by comprising a solvent distillation step in which a benzoxazine solution is distilled at a temperature of 20-85 DEG C to remove a solvent, and a solvent distillation step in which the solvent is removed from the benzoxazine solution. The benzoxazine solution contains a benzoxazine compound represented by general formula (1) and an ester-based solvent having a boiling point in the range of 30 DEG C to 90 DEG C at 1 atmospheric pressure. [chemical] # imgabs0 # [chemical] # imgabs1 #

Description

Technical Field

[0001] The present invention relates to a method for producing a benzoxazine compound, and more particularly to a method for producing a benzoxazine compound having a benzoxazine ring at both ends of a bonding group and further having an unsaturated group. Background Art

[0002] Benzoxazine compounds are compounds synthesized by reacting phenols, amines, and formaldehyde, and are well known as thermosetting resin raw materials that cure by ring-opening polymerization of benzoxazine rings without generating volatile byproducts by heating, and are used as raw materials for molded bodies that can be used as insulating substrate materials, liquid crystal alignment agents, semiconductor sealing resin compositions, etc. In these applications, stability at high temperatures or heat resistance with excellent reliability is required.

[0003] On the other hand, benzoxazine compounds generally have relatively high curing temperatures and have disadvantages such as brittle cured products. In addition, they are also expected to have higher heat resistance. In recent years, in order to improve these problems, benzoxazine compounds with crosslinking functional groups have been developed. Among them, it has been reported that the cured product of benzoxazine resins with allyl groups introduced has excellent heat resistance (Patent Document 1).

[0004] As a method for synthesizing a benzoxazine compound having an allyl group, for example, the following methods are known: a method in which allylamine is dissolved in dioxane, a formaldehyde solution is added dropwise and reacted at room temperature, and then bisphenol A is added and reacted at 100 to 120°C (Patent Document 1); a method in which bisphenol F, allylamine, and paraformaldehyde as raw materials are mixed together with a solvent at once and reacted (Non-Patent Document 1); and a method in which allylamine hydrochloride is added to an aqueous sodium hydroxide solution, paraformaldehyde is added, reacted at room temperature, and then bisphenol A and toluene as a solvent are added and reacted at 100°C (Patent Document 2).

[0005] Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2003-286320 Patent Document 2: Chinese Patent Application Publication No. 111138613 Non-patent literature Non-patent document 1: Polymer International 2012, Vol. 62, p. 966-973 Summary of the invention Regarding the above-mentioned conventionally known method for producing an allyl group-containing benzoxazine compound, the method described in Patent Document 2 has the following problems: since the reaction is carried out at a temperature of 100°C and toluene is used as the reaction solvent, a high temperature of 90°C or higher is required to remove the contained water when the solvent is distilled off after the reaction is completed, so that polymerization begins due to heat during the reaction and post-reaction treatment, thereby reducing the purity of the benzoxazine compound, and the viscosity increases and the handling property deteriorates as the polymerization proceeds. In the method described in Patent Document 1, in addition to carrying out the reaction at a temperature of 100 to 120°C, since dioxane is used as the solvent, a high temperature is required when distilling off the solvent, similar to toluene, and it is difficult to operate in terms of drainage treatment.

[0006] An object of the present invention is to provide a method for producing a high-purity benzoxazine compound by suppressing a decrease in purity due to a high molecular weight when producing a benzoxazine compound having an unsaturated group.

[0007] The present inventors have conducted intensive studies to solve the above problems and have found that the above problems can be solved by preparing a solution of a benzoxazine compound having an unsaturated group and a specific solvent and removing the solvent within a specific temperature range, thereby completing the present invention.

[0008] The present invention is as follows.

[0009] 1. A method for producing a benzoxazine compound represented by the general formula (1), characterized in that it comprises a solvent removal step, wherein the solvent is removed by distillation from a benzoxazine solution at a temperature in the range of 20°C to 85°C, wherein the benzoxazine solution contains the benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point in the range of 30°C to 90°C at 1 atmosphere. [Chemistry 1]

[0010] In the formula, R1 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R2 each independently represents a divalent hydrocarbon group having 1 to 10 carbon atoms, X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, a divalent group represented by the general formula (1a), or a divalent group represented by the general formula (1b), [Chemistry 2]

[0011] In the general formulae (1a) and (1b), R3 and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms; R3 and R4 may be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms as a whole; Ar1 ​​and Ar2 each independently represent an aryl group having 6 to 12 carbon atoms; and * each represents a bonding position.

[0012] 2. The production method according to 1., characterized in that the ester solvent is ethyl acetate.

[0013] 3. The production method according to 1., characterized in that the benzoxazine compound represented by the general formula (1) is one or more compounds selected from compounds (1-1) to (1-6), [Chemistry 3] .

[0014] 4. The production method according to 1., characterized in that the benzoxazine solution is a benzoxazine solution obtained by a reaction step, wherein the reaction step is carried out in the presence of a bisphenol compound represented by the general formula (2), formaldehyde, an amine compound represented by the general formula (3), and an ester solvent having a boiling point in the range of 30°C to 90°C at 1 atmosphere, [Chemistry 4]

[0015] In the formula, R1 and X have the same definitions as in the general formula (1). [Chemistry 5]

[0016] In the formula, R2 has the same definition as in the general formula (1).

[0017] 5. The production method according to 4., characterized in that the bisphenol compound represented by the general formula (2) is one or more compounds selected from bisphenol F, bisphenol A, bisphenol C, bisphenol Z, bisphenol TMC and 9,9-bis(4-hydroxyphenyl)fluorene, The bisphenol F is bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, bis(4-hydroxyphenyl)methane, The bisphenol A is 2,2-bis(4-hydroxyphenyl)propane, The bisphenol C is 2,2-bis(4-hydroxy-3-methylphenyl)propane, The bisphenol Z is 1,1-bis(4-hydroxyphenyl)cyclohexane, The bisphenol TMC is 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, The amine compound represented by the general formula (3) is allylamine.

[0018] According to the method for producing a benzoxazine compound of the present invention, the production of a compound having a molecular weight higher than that of the benzoxazine compound (hereinafter sometimes simply referred to as a "high molecular weight component") can be suppressed, and a benzoxazine compound having an unsaturated group with improved purity can be produced. DETAILED DESCRIPTION

[0019] <Method for producing benzoxazine compound of the present invention> The method for producing a benzoxazine compound represented by the general formula (1) of the present invention is a method comprising a solvent removal step, wherein the solvent is removed by distillation from a benzoxazine solution in a range of 20° C. to 85° C., wherein the benzoxazine solution contains the benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point in the range of 30° C. to 90° C. at 1 atmosphere.

[0020] [Chemistry 6]

[0021] (In the formula, R1 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R2 each independently represents a divalent hydrocarbon group having 1 to 10 carbon atoms, and X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, a divalent group represented by the general formula (1a), or a divalent group represented by the general formula (1b).) [Chemistry 7]

[0022] (In the general formulae (1a) and (1b), R3 and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms; R3 and R4 may be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms as a whole; Ar1 ​​and Ar2 each independently represent an aryl group having 6 to 12 carbon atoms; and * each represents a bonding position.) (Benzoxazine compound represented by general formula (1)) R1 in the general formula (1) is preferably independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 carbon atom (methyl), and particularly preferably a hydrogen atom. When R1 is not a hydrogen atom, the bonding position is preferably an ortho position on the benzene ring relative to the oxygen atom of the benzoxazine ring in the general formula (1).

[0023] In the general formula (1), each R2 is independently a divalent group having 1 to 10 carbon atoms, and specific examples thereof include a linear alkylene group having 1 to 10 carbon atoms such as methylene, ethylene, propane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, cyclohexane-1,3-diyl, and cyclohexane-1,4-diyl, a branched alkylene group having 3 to 10 carbon atoms, an alkylene group having 3 to 10 carbon atoms including a cyclic alkane, an alkylidene group having 2 to 10 carbon atoms such as an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, a cyclopentylidene group, and a cyclohexylidene group, or a divalent group having 6 to 10 carbon atoms including a benzene ring such as a phenylene group or a group represented by the following formula.

[0024] [Chemistry 8]

[0025] (Where * indicates the bonding position.) Among these, R2 is preferably a linear alkylene group having 1 to 10 carbon atoms, a branched alkylene group having 3 to 10 carbon atoms, an alkylene group having 3 to 10 carbon atoms including a cyclic alkane, or an alkylidene group having 2 to 10 carbon atoms, more preferably a linear alkylene group having 1 to 10 carbon atoms, a branched alkylene group having 3 to 10 carbon atoms, or an alkylene group having 3 to 10 carbon atoms including a cyclic alkane, further preferably a linear alkylene group having 1 to 6 carbon atoms, a branched alkylene group having 3 to 6 carbon atoms, or an alkylene group having 6 to 10 carbon atoms including a cyclic alkane, and particularly preferably a linear alkylene group having 1 to 4 carbon atoms or a branched alkylene group having 3 to 6 carbon atoms.

[0026] X in the general formula (1) is preferably a single bond, a divalent group represented by the general formula (1a), or a divalent group represented by the general formula (1b), more preferably a single bond or a divalent group represented by the general formula (1a), and particularly preferably a divalent group represented by the general formula (1a).

[0027] When X in the general formula (1) is the general formula (1a), R3 and R4 are more preferably each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, further preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and particularly preferably a hydrogen atom, a methyl group, or an ethyl group.

[0028] In addition, R3 and R4 may be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms as a whole. The cycloalkylidene group having 5 to 20 carbon atoms may contain an alkyl group as a branch. The cycloalkylidene group preferably has 5 to 15 carbon atoms, more preferably has 6 to 12 carbon atoms, and particularly preferably has 6 to 9 carbon atoms.

[0029] Specific examples of the cycloalkylidene group include a cyclopentylidene group (carbon number 5), a cyclohexylidene group (carbon number 6), a 3-methylcyclohexylidene group (carbon number 7), a 4-methylcyclohexylidene group (carbon number 7), a 3,3,5-trimethylcyclohexylidene group (carbon number 9), a cycloheptylidene group (carbon number 7), a bicyclo[2.2.1]heptane-2,2-diyl group (carbon number 7), a 1,7,7-trimethylbicyclo[2.2.1]heptane-2,2-diyl group (carbon number 10), a 4,7,7-trimethylbicyclo[2.2.1]heptane-2,2-diyl group (carbon number 10), a tricyclo[5.2.1.0 2,6 ] decane-8,8-diyl (carbon number 10), 2,2-adamantanylidene (carbon number 10), cyclododecylidene (carbon number 12), etc. Preferably, cyclohexylidene (carbon number 6), 3-methylcyclohexylidene (carbon number 7), 4-methylcyclohexylidene (carbon number 7), 3,3,5-trimethylcyclohexylidene (carbon number 9), cyclododecylidene (carbon number 12), more preferably cyclohexylidene (carbon number 6), 3,3,5-trimethylcyclohexylidene (carbon number 9), cyclododecylidene (carbon number 12), particularly preferably cyclohexylidene (carbon number 6) and 3,3,5-trimethylcyclohexylidene (carbon number 9).

[0030] When X in the general formula (1) is the general formula (1b), Ar1 and Ar2 are preferably each independently a benzene ring or a naphthalene ring, and more preferably both Ar1 and Ar2 are benzene rings. For example, when both Ar1 and Ar2 are benzene rings, the group represented by the general formula (1b) is a fluorenylidene group.

[0031] The bonding position of X to the two benzoxazine rings in the general formula (1) is preferably the ortho position or the para position on the benzene ring relative to the oxygen atom of the benzoxazine ring.

[0032] Specific examples of the benzoxazine compound represented by the general formula (1) include compounds (1-1) to (1-6) having the following chemical structures. The benzoxazine compound represented by the general formula (1) is preferably one or more compounds selected from the compounds (1-1) to (1-6).

[0033] [Chemistry 9]

[0034] (Ester solvents with a boiling point of 30°C to 90°C at 1 atmosphere) Specific examples of ester solvents having a boiling point at 1 atmosphere of 30°C to 90°C include methyl formate (32°C), ethyl formate (54°C), methyl acetate (57°C), ethyl acetate (77°C), methyl propionate (80°C), isopropyl acetate (88°C), etc. The temperature in parentheses shown here is the boiling point at 1 atmosphere. Among them, methyl acetate, ethyl acetate, methyl propionate, or isopropyl acetate is preferred, ethyl acetate or methyl propionate is more preferred, and ethyl acetate is particularly preferred.

[0035] (Solution) The method for producing a benzoxazine solution containing a benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point of 30°C to 90°C at 1 atmosphere is not particularly limited. Examples of the production method include a method of mixing and dissolving the benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point of 30°C to 90°C at 1 atmosphere; or a method of producing the benzoxazine solution by a reaction step in the presence of a bisphenol compound represented by the general formula (2), formaldehydes, an amine compound represented by the general formula (3), and an ester solvent having a boiling point of 30°C to 90°C at 1 atmosphere, as described later.

[0036] The amount of the ester solvent having a boiling point of 30° C. to 90° C. at 1 atm relative to the benzoxazine compound represented by the general formula (1) in the benzoxazine solution is not particularly limited. The benzoxazine solution used in the solvent removal step may be a solution in which the benzoxazine compound is completely dissolved in the ester solvent, or a part of the benzoxazine compound may be present in the form of a solid, oily substance, liquid droplets, or the like.

[0037] (Solvent removal process) The solvent removal step in the present invention is a step of removing the solvent by distillation at a temperature in the range of 20° C. to 85° C. from a benzoxazine solution containing a benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point in the range of 30° C. to 90° C. at 1 atmosphere.

[0038] The temperature range in the solvent distillation step is 20°C to 85°C, preferably 30°C to 55°C, more preferably 30°C to 50°C, and particularly preferably 30°C to 45°C. If the solvent can be distilled off within the above temperature range, the pressure may be either normal pressure or reduced pressure. When the solvent distillation step is performed under reduced pressure, the temperature can be easily set to the above temperature range, and the solvent can also be distilled off at a lower temperature, which is preferred. The pressure when the solvent is distilled off under reduced pressure can be, for example, set to a range of 0.1 kPa to 95 kPa, more preferably 0.1 kPa to 70 kPa, and further preferably 0.1 kPa to 50 kPa. By distilling off the ester solvent from the benzoxazine solution by distillation within this temperature range, the generation of high molecular weight components can be suppressed, and the decrease in the purity of the benzoxazine compound in the solvent distillation step can be suppressed, so that an allyl group-containing benzoxazine compound with improved purity can be produced.

[0039] The amount of solvent removed can be adjusted according to the process and treatment after the solvent distillation process, so that the amount of solvent contained in the benzoxazine compound after the solvent is distilled off by the solvent distillation process can be adjusted. For example, when the benzoxazine compound is taken out from the container after the solvent distillation process, it can be made into a state that almost does not contain an ester solvent. Specifically, for example, the content of the ester solvent relative to the benzoxazine compound obtained by the solvent distillation process is set to 5% by weight or less, preferably 3% by weight or less, more preferably 1.5% by weight or less, and further preferably 1.0% by weight or less. In addition, in order to increase the concentration of the benzoxazine compound in the benzoxazine solution, the solvent can also be removed by the solvent distillation process until the concentration at which the benzoxazine compound does not precipitate. In addition, the ester solvent can also be removed by distillation from the benzoxazine solution by the solvent distillation process to precipitate the solid of the benzoxazine compound and form a slurry.

[0040] <Reaction process> The benzoxazine solution containing the benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point of 30°C to 90°C at 1 atmosphere, which is subjected to the solvent distillation step of the present invention, can be produced by a reaction step in the presence of a bisphenol compound represented by the general formula (2), formaldehydes, an amine compound represented by the general formula (3), and an ester solvent having a boiling point of 30°C to 90°C at 1 atmosphere.

[0041] (Bisphenol compound represented by general formula (2)) The bisphenol compound used in the reaction step is a compound represented by the general formula (2).

[0042] [Chemistry 10]

[0043] (In the formula, R1 and X have the same definitions as in the general formula (1).) The definition and preferred embodiment of R1 in the general formula (2) are the same as those in the general formula (1). When R1 in the general formula (2) is not a hydrogen atom, the bonding position is preferably an ortho position on the benzene ring relative to the hydroxyl group of the benzene ring in the general formula (2).

[0044] The definition and preferred embodiment of X in the general formula (2) are the same as those in the general formula (1). The bonding position of X in the general formula (2) to the two benzoxazine rings is preferably the ortho position or the para position relative to the hydroxyl group.

[0045] Specific examples of the bisphenol compound represented by the general formula (2) include bisphenol F (bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, bis(4-hydroxyphenyl)methane), bisphenol A (2,2-bis(4-hydroxyphenyl)propane), bisphenol C (2,2-bis(4-hydroxy-3-methylphenyl)propane), bisphenol Z (1,1-bis(4-hydroxyphenyl)cyclohexane), bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane) and 9,9-bis(4-hydroxyphenyl)fluorene. Preferred bisphenol compounds represented by general formula (2) are at least one compound selected from the compounds listed in the specific examples. More preferred compounds are at least one compound selected from bisphenol F (bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, bis(4-hydroxyphenyl)methane), bisphenol A (2,2-bis(4-hydroxyphenyl)propane), bisphenol TMC (1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane) and 9,9-bis(4-hydroxyphenyl)fluorene. In addition, bisphenol F (bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, bis(4-hydroxyphenyl)methane) may be a mixture of these compounds, and such a mixture may be used.

[0046] (Formaldehyde) Specific examples of the formaldehydes used in the reaction step include formaldehyde solution, trioxymethylene, and paraformaldehyde.

[0047] (Amine compounds) The amine compound used in the reaction step is a compound represented by the general formula (3).

[0048] [Chemistry 11]

[0049] (In the formula, R2 has the same definition as in the general formula (1).) The definition and preferred embodiment of R2 in the general formula (2) are the same as those in the general formula (1).

[0050] Specific examples of the amine compound represented by the general formula (3) include allylamine, 4-allylaniline, 3-butene-1-amine, 4-pentene-1-amine, and 4-vinylcyclohexaneamine. Allylamine is particularly preferred.

[0051] The amine compound can also be used as a salt with an inorganic acid such as hydrochloric acid or sulfuric acid. In this case, the reaction step is carried out in the presence of an alkaline aqueous solution obtained by dissolving sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate or the like in water.

[0052] (catalyst) In the reaction process, a catalyst for promoting the reaction is not particularly required, but an acid catalyst or a base catalyst may be used as required. At this time, usable acid catalysts include concentrated hydrochloric acid, hydrogen chloride gas, trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, benzoic acid and mixtures thereof, and usable base catalysts include sodium hydroxide, sodium carbonate, triethylamine, triethanolamine and mixtures thereof, but are not limited thereto.

[0053] (Amount used) In the reaction step, the amount of formaldehyde used is preferably in the range of 4.0 to 20.0 mol, more preferably 4.0 to 16.0 mol, and even more preferably 4.0 to 12.0 mol, based on 1 mol of the bisphenol compound represented by the general formula (2).

[0054] The amount of the amine compound represented by the general formula (3) used is preferably in the range of 2.0 to 10.0 mol, more preferably in the range of 2.0 to 8.0 mol, and even more preferably in the range of 2.0 to 6.0 mol, based on 1 mol of the bisphenol compound represented by the general formula (2).

[0055] The amount of the ester solvent having a boiling point of 30° C. to 90° C. at 1 atmosphere used is not particularly limited as long as it does not inhibit the reaction, but is preferably in the range of 0.5 to 5 times by weight, more preferably 1 to 3 times by weight, based on the bisphenol compound represented by the general formula (2).

[0056] As the solvent, other solvents may be used in combination in addition to ester solvents having a boiling point of 30° C. to 90° C. at 1 atmosphere, as long as the type and amount of the solvent do not hinder the reaction and the solvent distillation step can be performed within the above-mentioned temperature range. Examples of the types of solvents that can be used include toluene, xylene, chloroform, dichloromethane, tetrahydrofuran, and dioxane.

[0057] (Reaction conditions) The reaction temperature in the reaction step is in the range of 10 to 80°C, preferably 20 to 60°C, more preferably 20 to 50°C, and particularly preferably 30 to 50°C.

[0058] The reaction may be carried out under normal pressure, or under increased pressure or reduced pressure.

[0059] There is no limitation on the method for mixing the bisphenol compound represented by the general formula (2), formaldehydes and amine compounds represented by the general formula (3) as raw materials. For example, the following methods can be cited: (A) a method of mixing an amine compound represented by the general formula (3) into a mixture containing a bisphenol compound represented by the general formula (2) and formaldehydes to carry out a reaction; (B) a method of mixing a bisphenol compound represented by the general formula (2) into a mixture containing formaldehydes and an amine compound represented by the general formula (3). These mixtures may contain the above-mentioned solvent or catalyst, and the method for mixing the catalyst is also not limited. It is preferred to mix the catalyst before mixing the amine compound represented by the general formula (3).

[0060] In the production method of the present invention, there is no limitation on the method of mixing the raw material mixture with the remaining raw materials, but from the perspective of reaction selectivity and suppression of the formation of high molecular weight components as by-products, it is preferred to mix continuously or intermittently, for example, for 10 minutes to 2 hours, rather than mixing all at once.

[0061] As another embodiment, the step of discharging water from the raw materials or water generated in the reaction to the outside of the system may also be included. The step of removing the generated water from the reaction solution is not particularly limited, and can be performed by azeotropic distillation of the generated water and the solvent in the reaction solution. The generated water can be discharged to the outside of the reaction system using, for example, an isobaric dropping funnel equipped with a stopcock, a Dean condenser, a Dean-Stark apparatus, or the like.

[0062] The benzoxazine solution obtained by the above reaction step can also be washed by a washing step, wherein the washing step is to wash with water or an alkaline aqueous solution obtained by dissolving sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, etc. in water. After washing with the alkaline aqueous solution, it is preferably washed with water so that the alkali does not remain in the reaction solution. In the above reaction step, by using an ester solvent having a boiling point of 30° C. to 90° C. at 1 atmosphere, the obtained reaction solution can be separated from water, so the washing step can be performed after the reaction step, so that the benzoxazine compound can be produced by an efficient process.

[0063] The solution obtained in the above-mentioned reaction step may contain salts and unreacted paraformaldehyde, and a filtration step may be performed to remove these by filtration.

[0064] The benzoxazine compound represented by the general formula (1) obtained by the above-mentioned solvent distillation step can be maintained as it is if it is a benzoxazine compound in a fluid state at room temperature. If it is a benzoxazine compound in a solid state at room temperature, it can be heated to a fluid state and taken out from the container where the solvent distillation step is performed, or added to a poor solvent to precipitate it, or a solvent is added to the reaction mixture to crystallize it, and then filtered to take out the benzoxazine compound. It is preferred that the solid of the benzoxazine compound filtered out is dried to remove the solvent contained in the solid. The benzoxazine compound taken out by the above method can also be further made into a high-purity product by a common purification method such as washing with a solvent or water or recrystallization.

[0065] (Other aspects of the present invention) As another embodiment of the present invention, there can be mentioned a production method comprising the following steps: a reaction step of obtaining a benzoxazine solution containing a benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point in the range of 30°C to 90°C at 1 atmosphere, and a solvent removal step of removing the solvent by distillation at a temperature in the range of 20°C to 85°C from the solution obtained in the reaction step. There can also be mentioned a production method comprising the washing step and / or the filtration step between the reaction step and the solvent removal step.

[0066] Example Hereinafter, the present invention will be further specifically described by way of examples.

[0067] <Analysis method> 1. Analysis of reaction liquid composition and purity (gel permeation chromatography: GPC) The purity of each benzoxazine compound synthesized by the production method of the present invention is defined as the area percentage of the benzoxazine compound obtained by this analysis.

[0068] Device: HLC-8320 / manufactured by Tosoh Corporation Detector: Differential Refractometer (RI) [Measurement conditions] Flow rate: 1mL / min Eluent: Tetrahydrofuran Temperature: 40℃ Wavelength: 254nm Measurement sample: 1 g of the composition containing the benzoxazine compound was diluted 200 times with tetrahydrofuran.

[0069] <Example 1> 19.5 g of water and 19.5 g of NaOH (granular) were placed in a 500 mL four-necked flask equipped with a thermometer, a stirrer, and a cooling tube, and stirred. 19.5 g of allylamine hydrochloride was added to the alkaline solution, and stirred for 1 hour under a nitrogen atmosphere. Then, 39.1 g of paraformaldehyde (purity: 92%) was added in small amounts and stirred for 5 hours. 93 g of ethyl acetate and 50 g of bisphenol F were added to the solution, and stirred at 30-40°C for 13 hours. During the process, 46 g of ethyl acetate was added because the viscosity increased. The reaction solution was analyzed by high performance liquid chromatography (HPLC), and the disappearance of bisphenol F was confirmed. The reaction solution was analyzed by GPC, and the proportion of benzoxazine compounds present in the reaction solution was 65% by area, and the remaining 35% by area was a compound with a higher molecular weight than the benzoxazine compound, that is, a high molecular weight component.

[0070] After the reaction was completed, the salt and unreacted paraformaldehyde were removed by filtration, and the filtrate was washed with 50 mL of water for 5 times.

[0071] The washed filtrate was distilled under reduced pressure at 40° C. to remove the solvent. The pressure during distillation was gradually reduced to 1.4 kPa in the end.

[0072] After the solvent was distilled off and cooled, 55 g of a benzoxazine compound was obtained as a fluid oil. The amount of solvent contained in the oil was 1.0% by weight. The obtained oil was measured by GPC under the above-mentioned analysis conditions, and the purity was 61% by area, and the high molecular weight component was 39% by area.

[0073] <Comparative Example 1> 19.5 g of water and 19.5 g of NaOH (granular) were placed in a 500 mL four-necked flask equipped with a thermometer, a stirrer, and a cooling tube, and stirred. 19.5 g of allylamine hydrochloride was added to the alkaline solution, and stirred for 1 hour under a nitrogen environment. Then, 39.1 g of paraformaldehyde (purity: 92%) was added in small amounts and stirred for 5 hours. 93 g of toluene and 50 g of bisphenol F were added to the solution, and stirred at 90°C for 1.5 hours. The reaction solution was analyzed by HPLC, and the disappearance of bisphenol F was confirmed. The reaction solution was analyzed by GPC, and the proportion of benzoxazine compounds present in the reaction solution was 38% by area, and the remaining 62% by area was a high molecular weight component.

[0074] After the reaction was completed, the salt and unreacted paraformaldehyde were removed by filtration, and the filtrate was washed with 50 mL of water for 5 times.

[0075] The washed filtrate was distilled under reduced pressure at 60 to 90° C. to remove the solvent. The pressure during distillation was gradually reduced to 1.4 kPa.

[0076] After the solvent was distilled off and cooled, a benzoxazine compound was obtained as a solid without fluidity. The amount of solvent contained in the solid was 1.0% by weight. The obtained benzoxazine compound was measured by GPC under the above-mentioned analysis conditions, and the purity was 32% by area, and the content of high molecular weight components was 68% by area.

[0077] <Example 2> After adding 130 g (1.3 mol) of allylamine hydrochloride to a 2L four-necked flask equipped with a thermometer, a stirrer, a cooling tube, and a dropping funnel, 110 g (1.3 mol) of a 48% NaOH aqueous solution was slowly added over 5 minutes while stirring and confirming the temperature rise. After confirming that the pH of the water layer was about 9 to 10, 107 g (3.3 mol) of paraformaldehyde (purity: 92%) was added in small portions over 30 minutes. At this time, it was confirmed that the temperature of the reaction system rose from 30°C to 55°C. Then, the mixture was cooled with air while stirring, and after confirming that the temperature dropped to 30°C, it was stirred at 30°C for 1 hour.

[0078] After the stirring was completed, 586 g of ethyl acetate and 210 g of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane were added to the flask. Then, the temperature of the liquid in the flask was raised to 55°C, and the reaction was carried out at 55°C for 24 hours, at 60°C for 3 hours, at 65°C for 5 hours, and at 70°C for 1 hour. The reaction liquid was analyzed by HPLC, and the disappearance of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane was confirmed. After the reaction was completed, the temperature of the liquid in the flask was cooled to 40°C. The reaction liquid was analyzed by GPC, and the ratio of the benzoxazine compound present in the reaction liquid was 75 area%, and the remaining 25 area% was a high molecular weight component.

[0079] After 400 g of pure water was mixed with the reaction completed liquid, the mixture was stirred for 30 minutes, and after the mixture was allowed to stand and separation from the organic layer was confirmed, the aqueous layer was removed. This water washing operation was performed 6 times, and the pH of the aqueous layer was confirmed to be 7 to 8.

[0080] Then, the solvent was removed by distillation under reduced pressure at 40° C. After the solvent was removed, the mixture was cooled to obtain a non-fluid solid benzoxazine compound. The obtained benzoxazine compound was measured by GPC under the above-mentioned analysis conditions, and the purity was 70% by area, and the content of high molecular weight components was 30% by area.

[0081] The obtained distillation residue was heated to 90°C, flowed into a metal bucket, cooled to room temperature, and crushed to obtain 250 g of a yellow solid benzoxazine compound. The amount of solvent contained in the solid was 1.0% by weight. The yield was 78 mol% relative to the 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane used.

[0082] The obtained solid 1 As a result of H-NMR analysis, peaks derived from 3,3,5-trimethylcyclohexylidene were observed at around 0.4 and 0.8 to 1.0 ppm, a peak derived from benzoxazine moiety was observed at around 3.3 to 4.0 ppm, a peak derived from allylamine was observed at 4.8 to 5.2 ppm, and a peak derived from aromatics was observed at around 6.6 to 7.3 ppm. From this analysis result, it was clear that it was the target compound, the benzoxazine compound.

[0083] Table 1 summarizes the purity and change rate of the benzoxazine compound before and after the solvent removal step for the benzoxazine compound obtained in Comparative Example 1 not according to the production method of the present invention and the benzoxazine compound obtained in Examples 1 and 2 according to the production method of the present invention.

[0084] [Table 1]

[0085] From these results, it is clear that the production method of the present invention can suppress the decrease in purity in the solvent distillation step and can produce a benzoxazine compound with improved purity.

Claims

1. A method for producing a benzoxazine compound represented by general formula (1), characterized in that: The method comprises a solvent distillation step, wherein the solvent distillation step is to remove the solvent by distilling a benzoxazine solution at a temperature within a range of 20° C. to 85° C., wherein the benzoxazine solution contains a benzoxazine compound represented by the general formula (1) and an ester solvent having a boiling point within a range of 30° C. to 90° C. at 1 atmosphere. [Chemistry 1] In the formula, R1 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R2 each independently represents a divalent hydrocarbon group having 1 to 10 carbon atoms, X represents a single bond, an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, a divalent group represented by the general formula (1a), or a divalent group represented by the general formula (1b), [Chemistry 2] In the general formulae (1a) and (1b), R3 and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms; R3 and R4 may be bonded to each other to form a cycloalkylidene group having 5 to 20 carbon atoms as a whole; Ar1 ​​and Ar2 each independently represent an aryl group having 6 to 12 carbon atoms; and * each represents a bonding position.

2. The manufacturing method according to claim 1, characterized in that: The ester solvent is ethyl acetate.

3. The manufacturing method according to claim 1, characterized in that: The benzoxazine compound represented by the general formula (1) is one or more compounds selected from compounds (1-1) to (1-6), [Chemistry 3] 。 4. The manufacturing method according to claim 1, characterized in that: The benzoxazine solution is a benzoxazine solution obtained by a reaction step, wherein the reaction is carried out in the presence of a bisphenol compound represented by the general formula (2), formaldehyde, an amine compound represented by the general formula (3), and an ester solvent having a boiling point in the range of 30° C. to 90° C. at 1 atmosphere, [Chemistry 4] In the formula, R1 and X have the same definitions as in the general formula (1). [Chemistry 5] In the formula, R2 has the same definition as in the general formula (1).

5. The manufacturing method according to claim 4, characterized in that: The bisphenol compound represented by the general formula (2) is one or more compounds selected from the group consisting of bisphenol F, bisphenol A, bisphenol C, bisphenol Z, bisphenol TMC and 9,9-bis(4-hydroxyphenyl)fluorene. The bisphenol F is bis(2-hydroxyphenyl)methane, 2-hydroxyphenyl-4-hydroxyphenylmethane, bis(4-hydroxyphenyl)methane, The bisphenol A is 2,2-bis(4-hydroxyphenyl)propane, The bisphenol C is 2,2-bis(4-hydroxy-3-methylphenyl)propane, The bisphenol Z is 1,1-bis(4-hydroxyphenyl)cyclohexane, The bisphenol TMC is 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, The amine compound represented by the general formula (3) is allylamine.

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