JP7615916B2 - Method for producing bisphenol and method for producing polycarbonate resin - Google Patents

Description

The present invention relates to a method for producing bisphenol and a method for producing polycarbonate resin using the bisphenol produced by this method.

Bisphenols are useful as raw materials for polymeric materials such as polycarbonate resins, epoxy resins, and aromatic polyester resins. Representative bisphenols include, for example, 2,2-bis(4-hydroxyphenyl)propane and 2,2-bis(4-hydroxy-3-methylphenyl)propane (see Patent Documents 1 and 2).

JP 2014-40376 A JP 2020-37530 A

Bisphenols are used for a wide range of purposes as raw materials for various resins such as polycarbonate resin, and their uses are expected to continue to expand in the future.

There are two methods for producing polycarbonate resin: interfacial polymerization and melt polymerization. The melt polymerization method does not use a solvent, and instead heats and melts the raw materials bisphenol and diphenyl carbonate, and polymerizes them using an ester exchange catalyst. Compared to the interfacial polymerization method, this method produces a larger amount of polycarbonate resin per volume of the polymerization tank, allowing for more efficient production of polycarbonate resin.

In the melt polymerization method, the raw materials and catalyst supplied to the polymerization tank become the polycarbonate resin product as is, so the quality of the raw material bisphenol is important. In particular, since transesterification catalysts are generally basic metal salts, if there are acidic components in the raw material bisphenol, the transesterification catalyst will be neutralized and deactivated, and it may not be possible to obtain polycarbonate resin with the desired molecular weight. Such acidic components are called polymerization activity inhibitors.

According to Patent Document 2, bisphenol having excellent color tone and polymerization activity can be produced by dissolving the produced bisphenol, adjusting the pH of the organic phase containing bisphenol to 8.5 or more, and then washing with water. However, when hydrogen chloride gas or a specific concentration of organic acid and sulfuric acid are used as a catalyst, the solubility of the catalyst in the organic phase containing bisphenol is high, so that the organic phase containing bisphenol must be sufficiently contacted with a basic aqueous solution to neutralize the catalyst so that polymerization activity inhibitors do not remain in the product bisphenol. For this purpose, it is preferable to stir the organic phase containing bisphenol and the basic aqueous phase so that they are suspended. However, since the stirring rotation speed and power are limited in industrial ^m3 scale production, it is difficult to mix them to the same extent as in the lab scale. In order to wash to the same quality as in the lab scale, multiple neutralizations and washings are required, so a large amount of wastewater is generated and the wastewater treatment costs are also high. Therefore, the development of a method for producing bisphenol that can more efficiently remove polymerization activity inhibitors has been an issue.

The present invention has been made in consideration of these circumstances, and aims to provide a method for producing bisphenol that has a low content of polymerization activity inhibitors and excellent polymerization activity. The present invention also aims to provide a method for producing high-quality polycarbonate resin using bisphenol obtained by this bisphenol production method.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that bisphenol with excellent polymerization activity can be produced by mixing a basic nitrogen-containing compound with an organic phase containing bisphenol obtained in a bisphenol production reaction and precipitating a bisphenol solid from this mixture by crystallization, and thus completed the present invention.

That is, the present invention relates to the following inventions:

[1] A method for producing bisphenol, comprising a reaction step in which an aromatic alcohol is reacted with a ketone or aldehyde in the presence of an acid catalyst to produce bisphenol, a neutralization step in which acidic components in the organic phase containing bisphenol obtained in the reaction step are neutralized, and a crystallization step in which bisphenol solids are extracted from the organic phase containing bisphenol that has been subjected to the neutralization step, in which a basic nitrogen-containing compound is added to the organic phase containing bisphenol in the neutralization step.

[2] The method for producing bisphenol according to [1], wherein the neutralization step includes a first neutralization step in which a basic aqueous solution is added to the organic phase containing bisphenol, and the mixture is mixed, followed by separation into two phases and removal of the aqueous phase, and a second neutralization step in which the basic nitrogen-containing compound is added to the organic phase containing bisphenol obtained in the first neutralization step, and the pH of the aqueous phase removed in the first neutralization step is 7.5 or higher.

[3] The method for producing bisphenol according to [1] or [2], wherein the boiling point of the basic nitrogen-containing compound is 120°C or lower.

[4] The method for producing bisphenol according to any one of [1] to [3], wherein the amount of the basic nitrogen-containing compound added is 0.01 to 10 mass% relative to the organic phase containing the bisphenol.

[5] The method for producing bisphenol according to any one of [1] to [4], wherein the bisphenol is any one selected from the group consisting of 2,2-bis(4-hydroxy-3-methylphenyl)propane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

[6] A method for producing a polycarbonate resin using bisphenol produced by the method for producing bisphenol described in any one of [1] to [5].

According to the present invention, a basic nitrogen-containing compound is mixed with an organic phase containing bisphenol, and bisphenol solids are extracted from this mixture by crystallization to obtain product bisphenol. This makes it possible to efficiently remove polymerization activity poisoning substances present in the organic phase containing bisphenol, and to obtain bisphenol with excellent polymerization activity. In addition, high-quality polycarbonate resins with the desired molecular weight can be produced using bisphenol produced by this bisphenol production method.

The following describes in detail the embodiments of the present invention, but the description of the constituent elements described below is one example (representative example) of the embodiment of the present invention, and the present invention is not limited to the following content as long as the gist of the present invention is not changed. Note that when the expression "~" is used in this specification, it is used as an expression including the numerical values or physical property values before and after it.

[Method for producing bisphenol]
The process for producing bisphenol of the present invention comprises a reaction step of reacting an aromatic alcohol with a ketone or an aldehyde in the presence of an acid catalyst to produce bisphenol, a neutralization step of neutralizing acidic components in an organic phase containing bisphenol obtained in the reaction step, and a crystallization step of extracting bisphenol solids from the organic phase containing bisphenol that has been subjected to the neutralization step, and is characterized in that a basic nitrogen-containing compound is added to the organic phase containing bisphenol in the neutralization step.

That is, the inventors have found that by mixing an organic phase containing bisphenol with a basic nitrogen-containing compound and crystallizing the mixture, it is possible to efficiently remove acidic compounds, including polymerization activity inhibitors, contained in the organic phase containing bisphenol, and reduce the number of times required for neutralization. Note that a basic aqueous solution may be added prior to the addition of the basic nitrogen-containing compound to perform neutralization, or water may be supplied to the organic phase containing bisphenol before or after the addition of the basic nitrogen-containing compound to remove most of the salts that are easily soluble in water. The crystallization process may also be performed multiple times until the desired bisphenol purity is achieved.

<Reaction Step>
In the reaction step, an aromatic alcohol and a ketone or an aldehyde are reacted (condensation reaction) in the presence of an acid catalyst to produce a bisphenol.

[Bisphenol]
The bisphenol produced by the bisphenol production method of the present invention (hereinafter, sometimes referred to as "the bisphenol of the present invention") is usually a compound represented by the following general formula (1).

In the general formula (1), R ¹ to R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an amino group, etc. The alkyl group, the alkoxy group, the aryl group, the amino group, etc. may be substituted or unsubstituted. Examples of ^{R 1} to R ⁴ include a hydrogen atom, a fluoro group, a chloro group, a bromo group, an iodo group, a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a n-butyl group, an i-butyl group, a t-butyl group, a n-pentyl group, an i-pentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, a n-decyl group, a n-undecyl group, a n-dodecyl group, a methoxy group, an ethoxy group, a n-propoxy group, an i-propoxy group, a n-butoxy group, an i-butoxy group, a t-butoxy group, a n-pentyloxy group, an i ... Examples of the aryloxy group include an n-butyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a benzyl group, a phenyl group, a tolyl group, a 2,6-dimethylphenyl group, an amino group, a methylamino group, a dimethylamino group, a diethylamino group, and a phenylamino group.
Of these, ^R2 and ^R3 are preferably hydrogen atoms since the condensation reaction is difficult to proceed if they are sterically bulky.

^R5 and ^R6 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or the like. The alkyl group, alkoxy group, aryl group, or the like may be substituted or unsubstituted. For example, a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, an i-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, a t-butoxy group, an n-pentyl group, an i-pentyl group, an Examples of such aryloxy groups include an n-butyloxy group, an i-pentyloxy group, an n-hexyloxy group, an n-heptyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a benzyl group, a phenyl group, a tolyl group, and a 2,6-dimethylphenyl group.

^R5 and ^R6 may be bonded or bridged to each other between the two groups, or ^R5 and ^R6 may be bonded together with adjacent carbon atoms to form a cycloalkylidene group which may contain heteroatoms, such as cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, cycloheptylidene, cyclooctylidene, cyclononylidene, cyclodecylidene, cycloundecylidene, cyclododecylidene, fluorenylidene, xanthonylidene, and thioxanthonylidene.

Specific examples of the bisphenols used in the present invention include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 3,3-bis(4-hydroxyphenyl)pentane, 3,3-bis(4-hydroxy-3-methylphenyl)pentane, 2,2-bis(4 -hydroxyphenyl)pentane, 2,2-bis(4-hydroxy-3-methylphenyl)pentane, 3,3-bis(4-hydroxyphenyl)heptane, 3,3-bis(4-hydroxy-3-methylphenyl)heptane, 2,2-bis(4-hydroxyphenyl)heptane, 2,2-bis(4-hydroxy-3-methylphenyl)heptane, 4,4-bis(4-hydroxyphenyl)heptane, 4,4-bis(4-hydroxy-3-methylphenyl)heptane, and the like, but are not limited to these.

Among these, the preferred bisphenol is any one selected from the group consisting of 2,2-bis(4-hydroxy-3-methylphenyl)propane (bisphenol C), 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and more preferably any one selected from the group consisting of 2,2-bis(4-hydroxy-3-methylphenyl)propane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

[Aromatic alcohol]
The aromatic alcohol used as a raw material for producing the bisphenol of the present invention is usually a compound represented by the following general formula (2).

In formula (2), R ¹ to R ⁴ have the same meanings as R ¹ to R ⁴ in formula (1) above.

As described above, if ^R2 and ^R3 are sterically bulky, the condensation reaction is difficult to proceed, so they are preferably hydrogen atoms. Also, ^R1 to ^R4 are preferably each independently a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, or an amino group, and more preferably a hydrogen atom or an alkyl group. For example, a compound in which ^R1 and ^R4 are each independently a hydrogen atom or an alkyl group, and ^R2 and ^R3 are a hydrogen atom, can be mentioned. The number of carbon atoms in the alkyl group is preferably 1 to 12, more preferably 1 to 6.

Specific examples of the compound represented by the above general formula (2) include phenol, methylphenol (cresol), dimethylphenol (xylenol), ethylphenol, propylphenol, butylphenol, methoxyphenol, ethoxyphenol, propoxyphenol, butoxyphenol, aminophenol, benzylphenyl, and phenylphenol. Among these, any one selected from the group consisting of phenol, methylphenol, and dimethylphenol is preferred, methylphenol or dimethylphenol is more preferred, and methylphenol (orthocresol) is even more preferred.

[Ketone or aldehyde]
The ketone or aldehyde is usually a compound represented by the following general formula (3).

In formula (3), R ⁵ and R ⁶ have the same meanings as R ⁵ and R ⁶ in formula (1) above.

Preferably, ^R5 and ^R6 are each independently a hydrogen atom, an alkyl group, an aryl group, or a cycloalkylidene group formed by ^R5 and ^R6 bonding together with adjacent carbon atoms. The number of carbon atoms in the alkyl group is preferably 1 to 12, more preferably 1 to 6. In particular, it is preferred that ^R5 and ^R6 are each independently an alkyl group, or a cycloalkylidene group formed by ^R5 and ^R6 bonding together with adjacent carbon atoms.

Specific examples of compounds represented by general formula (3) include aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, pentylaldehyde, hexylaldehyde, heptylaldehyde, octylaldehyde, nonylaldehyde, decylaldehyde, undecylaldehyde, and dodecylaldehyde; ketones such as acetone, butanone, pentanone, hexanone, heptanone, octanone, nonanone, decanone, undecanone, and dodecanone; benzaldehyde, furanaldehyde, and the like. aryl alkyl ketones such as phenyl methyl ketone, phenyl ethyl ketone, phenyl propyl ketone, cresyl methyl ketone, cresyl ethyl ketone, cresyl propyl ketone, xylyl methyl ketone, xylyl ethyl ketone, and xylyl propyl ketone; and cyclic alkane ketones such as cyclopropanone, cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclononanone, cyclodecanone, cycloundecanone, and cyclododecanone.

[Aromatic alcohol/ketone or aldehyde molar ratio]
When the amount of ketone or aldehyde is large relative to the aromatic alcohol as a raw material, the ketone or aldehyde is easily polymerized, and when the amount is small, the aromatic alcohol is lost in an unreacted state. For these reasons, the lower limit of the molar ratio of aromatic alcohol to ketone or aldehyde ((moles of aromatic alcohol/moles of ketone) or (moles of aromatic alcohol/moles of aldehyde)) is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. The upper limit is preferably 15 or less, more preferably 10 or less, and even more preferably 8 or less.

[Acid Catalyst]
Examples of the acid catalyst used in the method for producing bisphenol of the present invention include sulfuric acid, hydrochloric acid, hydrogen chloride gas, phosphoric acid, aromatic sulfonic acids such as p-toluenesulfonic acid, aliphatic sulfonic acids such as methanesulfonic acid, etc. These may be used alone or in combination of two or more.
Among them, the acid catalyst is preferably any one or more selected from the group consisting of sulfuric acid, hydrochloric acid, and hydrogen chloride gas, more preferably sulfuric acid and/or hydrogen chloride gas. From the viewpoints of excellent reaction efficiency, no volatility of the catalyst, and less burden on the equipment, sulfuric acid is particularly preferred as the acid catalyst.

Sulfuric acid is an acidic liquid represented by _the chemical formula _H2SO4 . Generally, sulfuric acid is used as an aqueous solution of sulfuric acid diluted with water, and is called concentrated sulfuric acid or dilute sulfuric acid depending on its concentration. For example, dilute sulfuric acid is an aqueous solution of sulfuric acid with a mass concentration of less than 50 mass%.
If the concentration of sulfuric acid used (concentration of sulfuric acid aqueous solution) is low, the amount of water increases, so that the reaction for producing bisphenol does not proceed easily, the reaction time for producing bisphenol increases, and it may be difficult to produce bisphenol efficiently. Therefore, the concentration of sulfuric acid used is preferably 70 mass% or more, more preferably 75 mass% or more, and even more preferably 80 mass% or more. The upper limit of the concentration of sulfuric acid used is usually 99.5 mass% or less or 99 mass% or less.

If the molar ratio of the acid catalyst such as sulfuric acid to the aromatic alcohol raw material (moles of acid catalyst/moles of aromatic alcohol) is low, the acid catalyst such as sulfuric acid will be diluted by the water by-produced as the condensation reaction proceeds, and the reaction will take time. If the molar ratio is high, by-products caused by the acid catalyst, for example, when the acid catalyst is sulfuric acid, the aromatic alcohol may be sulfonated and a large amount of aromatic alcohol sulfonic acid may be produced. For these reasons, the molar ratio of the acid catalyst such as sulfuric acid to the aromatic alcohol raw material is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more. The upper limit is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less.

[Thiol cocatalyst]
In the present invention, a thiol promoter can be used as a promoter in the condensation reaction of an aromatic alcohol with a ketone or an aldehyde. The use of a thiol promoter can increase the selectivity of the produced bisphenol.

Examples of thiol promoters include mercaptocarboxylic acids such as mercaptoacetic acid, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, and 4-mercaptobutyric acid; alkyl thiols such as methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, pentyl mercaptan, hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan (decanethiol), undecyl mercaptan (undecanethiol), dodecyl mercaptan (dodecanethiol), tridecyl mercaptan, tetradecyl mercaptan, and pentadecyl mercaptan; and aryl thiols such as mercaptophenol. These may be used alone or in combination of two or more.

When using these thiol promoters, if the molar ratio of the thiol promoter to the ketone or aldehyde ((moles of thiol promoter/moles of ketone) or (moles of thiol promoter/moles of aldehyde)) is low, the effect of improving the selectivity of bisphenol by using the thiol promoter cannot be obtained, and if it is high, it may be mixed into the bisphenol, resulting in a deterioration in quality. For these reasons, the lower limit of the molar ratio of the thiol promoter to the ketone or aldehyde is preferably 0.001 or more, more preferably 0.005 or more, and even more preferably 0.01 or more. The upper limit is preferably 1 or less, more preferably 0.5 or less, and even more preferably 0.1 or less.

[Organic solvent]
The reaction for producing bisphenol may be carried out in the presence of an organic solvent. Examples of the organic solvent include aromatic hydrocarbons, aliphatic alcohols, and aliphatic hydrocarbons. These solvents may be used alone or in combination of two or more. For example, a mixed solvent of aromatic hydrocarbons and aliphatic alcohols may be used.

Examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, and mesitylene.

Examples of the aliphatic alcohol include monohydric alkyl alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, n-pentanol, i-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, n-undecanol, and n-dodecanol; and polyhydric alcohols such as ethylene glycol, diethylene glycol, and triethylene glycol.
From the viewpoint of reaction efficiency and the like, the aliphatic alcohol is preferably a monohydric alkyl alcohol having 1 to 12 carbon atoms, and more preferably a monohydric alkyl alcohol having 1 to 8 carbon atoms.

Examples of aliphatic hydrocarbons include hexane, heptane, octane, nonane, decane, undecane, and dodecane.

The aromatic alcohol raw material may be used in large quantities to replace the organic solvent. In this case, unreacted aromatic alcohol is lost, but this loss can be reduced by recovering and purifying it by distillation or other methods and reusing it.

When an organic solvent is used, if the mass ratio of the organic solvent to the raw material ketone or aldehyde ((mass of ketone/mass of organic solvent) or (mass of aldehyde/mass of organic solvent)) is too high, the ketone or aldehyde and the aromatic alcohol do not react easily, and the reaction takes a long time. If the ratio is too low, the resulting bisphenol may cause poor mixing or may promote the polymerization of the ketone or aldehyde. For these reasons, the mass ratio of the organic solvent to the ketone or aldehyde is preferably 0.5 or more, and more preferably 1 or more. The upper limit may be adjusted to a range in which precipitation of the bisphenol occurs depending on the type of organic solvent, and may be 50 or less or 30 or less.

The organic solvent used is preferably one in which bisphenol has a low solubility, because the resulting bisphenol is more likely to precipitate and the loss (e.g., loss to the filtrate during crystallization) during recovery of the bisphenol from the reaction solution after the reaction is completed can be reduced. Examples of solvents in which bisphenol has a low solubility include aromatic hydrocarbons. For this reason, the organic solvent preferably contains aromatic hydrocarbons as the main component, and the organic solvent preferably contains 55% by mass or more of aromatic hydrocarbons, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[Reaction method]
In the condensation reaction between an aromatic alcohol and a ketone or an aldehyde, it is preferable to supply a solution containing a ketone or an aldehyde to a solution containing an aromatic alcohol and an acid catalyst to carry out the condensation reaction.
In this case, the method of supplying the solution containing a ketone or an aldehyde may be a method of supplying the solution all at once or a method of supplying the solution in portions. However, since the reaction for producing bisphenol is an exothermic reaction, a method of supplying the solution in portions, such as by dropping the solution little by little, is preferred.

The solution containing an aromatic alcohol and an acid catalyst may consist of an aromatic alcohol and an acid catalyst, or may contain other components, for example, a solution containing an aromatic alcohol, an acid catalyst, and an organic solvent.
The solution containing a ketone or aldehyde may be composed of a ketone or aldehyde, or may contain other components. For example, when a thiol promoter is used, it is preferable to mix the thiol promoter with a ketone or aldehyde before use in the reaction. The method of mixing the thiol promoter with a ketone or aldehyde may be to supply the ketone or aldehyde to the thiol promoter, or to supply the thiol promoter to the ketone or aldehyde. The solution containing a ketone or aldehyde may contain an organic solvent.

[Reaction conditions]
If the reaction temperature for the production reaction of bisphenol is too low, the condensation reaction does not proceed easily, and therefore the reaction temperature is preferably −30° C. or higher, more preferably −20° C. or higher, and even more preferably −15° C. or higher. If the reaction temperature is too high, a side reaction, the self-condensation reaction of acetone or ketone, proceeds, and when a thiol promoter is used, the oxidative decomposition of thiol tends to proceed, and therefore the reaction temperature is preferably 50° C. or lower, more preferably 45° C. or lower, and even more preferably 40° C. or lower.

The reaction time is adjusted as appropriate depending on the reaction conditions, such as the type of bisphenol produced, the reaction temperature, and the production scale, but is usually 500 hours or less, and may be 400 hours or less or 350 hours or less. If the reaction time is too long, the produced bisphenol will decompose, so the reaction time is preferably 30 hours or less, more preferably 25 hours or less, and even more preferably 20 hours or less. The lower limit of the reaction time is usually 0.5 hours or more, preferably 1 hour or more, and more preferably 1.5 hours or more.

The reaction time includes the time it takes to mix the ketone or aldehyde with the aromatic alcohol. For example, if a ketone or aldehyde is supplied to a mixed solution of an aromatic alcohol and an acid catalyst over a period of one hour, and then the reaction is allowed to proceed for one hour, the reaction time is two hours.

The reaction can also be stopped by, for example, adding an amount of water or base equal to or greater than the amount of the acid catalyst used to reduce the concentration of the acid catalyst.

[Reaction Apparatus]
Since the reaction for producing bisphenol proceeds with a strong acid as a catalyst, it is preferable that the inner wall surface of the reaction vessel used is made of a corrosion-resistant material. In particular, it is preferable to use a reaction vessel made of glass lining, which has excellent corrosion resistance.

<Neutralization process>
The neutralization step preferably comprises a first neutralization step in which a basic aqueous solution is added to and mixed with the bisphenol-containing organic phase obtained in the reaction step, and the resulting mixture is separated into two phases and the aqueous phase is removed, and a second neutralization step in which a basic nitrogen-containing compound is added to the bisphenol-containing organic phase that has been subjected to the first neutralization step, and preferably further comprises a washing step in which the bisphenol-containing organic phase that has been subjected to the second neutralization step is washed with water.

[First neutralization step]
In the first neutralization step, the basic aqueous solution to be added to and mixed with the organic phase containing the bisphenol obtained in the reaction step may be an aqueous solution of a basic compound other than the basic nitrogen-containing compound described below, such as sodium hydroxide, sodium carbonate, or sodium hydrogen carbonate.

The basic nitrogen-containing compound described below is generally expensive, and the cost required for neutralization is high when the acidic components in the organic phase containing bisphenol are neutralized only with the basic nitrogen-containing compound. Therefore, it is preferable to add and mix an aqueous solution of a basic compound such as an alkali metal hydroxide or an alkaline earth metal hydroxide or carbonate that does not contain nitrogen atoms as described above, prior to neutralization with the basic nitrogen-containing compound, to previously neutralize most of the acidic components in the organic phase containing bisphenol obtained in the reaction step.
Examples of the acidic components in the organic phase containing bisphenol include residual acid catalysts and acidic compounds produced as by-products during the reaction.

If the basic compound concentration of the basic aqueous solution used is too high, there is a risk that acidic components will remain in the organic phase due to the salting out effect, and there is also a concern that bisphenol in the organic phase will decompose. If the concentration is too low, a large amount of basic aqueous solution will be required to neutralize the organic phase, which is undesirable. From this perspective, the basic compound concentration of the basic aqueous solution is preferably about 0.5 to 25% by mass, particularly about 1.0 to 20% by mass, although this varies depending on the type of basic compound used.

The first neutralization step is preferably carried out by adding and mixing a basic aqueous solution to an organic phase containing bisphenol, separating the resulting mixture into two phases, and adjusting the pH of the resulting aqueous phase to 7.5 or higher.
If the pH of the aqueous phase is too high, bisphenol will turn into a bisphenol salt, increasing the amount of bisphenol lost through neutralization, whereas if the pH of the aqueous phase is too low, the first neutralization step cannot be carried out to sufficiently neutralize most of the acidic components in the organic phase containing bisphenol.
From this viewpoint, the pH of the aqueous phase separated in the first neutralization step is preferably 12 or less, particularly preferably 11 or less, and 7.5 or more, particularly preferably 8.0 or more.

The amount of basic aqueous solution to be added to the organic phase containing bisphenol should be an amount sufficient to separate an aqueous phase of the desired pH as described above, and is set appropriately depending on the type and concentration of the basic compound in the basic aqueous solution used.

<Second neutralization step>
In the second neutralization step, a basic nitrogen-containing compound is added to the organic phase containing the bisphenol obtained in the first neutralization step to neutralize acidic components such as residual polymerization activity inhibitors.

The basic nitrogen-containing compound to be added to the bisphenol-containing organic phase in the second neutralization step is not particularly limited as long as it has one or more nitrogen atoms in its structure and is basic in aqueous solution, but it is preferable to select a compound that is miscible with the bisphenol-containing organic phase and forms a uniform liquid composition.

For example, ammonia, aliphatic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, triethanolamine, and tetraethylethylenediamine, aromatic amines such as aniline, phenethylamine, toluidine, and catecholamine, and heterocyclic amines such as pyrrolidine, piperidine, piperazine, morpholine, pyrrole, pyrazole, imidazole, pyridine, pyridazine, pyrimidine, and oxazole can be used. In addition, a basic ion exchange resin modified with a basic nitrogen-containing compound can be used. The basic nitrogen-containing compounds represented by these compounds can be used alone or in combination of two or more.

Among these basic nitrogen-containing compounds, compounds having a boiling point of 120°C or less are preferred. If the boiling point is higher than 120°C, the basic nitrogen-containing compound is likely to remain in the bisphenol even after the crystallization step described below and subsequent treatments such as solvent removal, and is not economical because heating is required to recover the basic nitrogen-containing compound by distillation.

The amount of the basic nitrogen-containing compound added is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more, based on the organic phase containing bisphenol. The upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

Theoretically, the amount of the basic nitrogen-containing compound to be added should be equal to or greater than the reaction equivalent of the polymerization catalyst poisoning substance present in the organic phase containing bisphenol. However, since it is difficult to accurately quantify the polymerization catalyst poisoning substance in the organic phase, it is preferable to add an excess amount. However, if the basic nitrogen-containing compound is added in large excess, a large amount of the basic nitrogen-containing compound may remain in the product bisphenol. In that case, it is not preferable because it deteriorates the color tone of the product bisphenol and the polycarbonate resin using this bisphenol.
Therefore, suitable upper and lower limits are set for the amount of the basic nitrogen-containing compound added.

The mixing time of the second neutralization step is important because it is necessary to bring the organic phase containing bisphenol into sufficient contact with the basic nitrogen-containing compound in order to neutralize the polymerization-active poisoning substances contained in the organic phase containing bisphenol. If the mixing time is too short, the polymerization-active poisoning substances will not be neutralized sufficiently, which is undesirable. If the mixing time is too long, a side reaction will occur due to the basic nitrogen-containing compound, which is undesirable and is also inefficient from the viewpoint of production efficiency. For this reason, the time required to mix the organic phase containing bisphenol with the basic nitrogen-containing compound is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more, and is preferably 10 hours or less, more preferably 5 hours or less, and even more preferably 2 hours or less.

[Cleaning process]
The bisphenol-containing organic phase that has been through the second neutralization step is preferably subjected to a washing step prior to the crystallization step in which the bisphenol-containing organic phase is mixed with desalted water, and then separated into a bisphenol-containing organic phase and an aqueous phase, and the aqueous phase is removed to obtain an organic phase containing bisphenol. This is in order to thoroughly remove impurities such as by-products, residual acid catalyst, residual promoter, basic compounds, and basic nitrogen-containing compounds in the produced bisphenol and to obtain high-purity bisphenol.
The washing step is preferably carried out multiple times as necessary so that the electrical conductivity of the separated aqueous phase after washing is 10 μS/cm or less, particularly 9 μS/cm or less, and more particularly 8 μS/cm or less.
Here, desalted water refers to water having an electrical conductivity of 2 μS/cm or less, such as ion-exchanged water or pure water.

<Crystallization process>
The organic phase containing bisphenol after the neutralization step is subjected to a crystallization step. The crystallization step is a step of cooling the organic phase containing bisphenol after the neutralization step to precipitate bisphenol solids and obtain a slurry liquid containing bisphenol. The crystallization temperature is not particularly limited, but is usually 0° C. or higher, preferably 5° C. or higher, and usually 30° C. or lower, preferably 25° C. or lower.

The bisphenol precipitated in the crystallization process can be recovered by solid-liquid separation using filtration, centrifugation, decantation, etc. In order to adjust the bisphenol purity to the desired level, the recovered bisphenol may be dissolved again in an organic solvent and the crystallization process may be carried out multiple times.

The bisphenol precipitated in the crystallization step and recovered by solid-liquid separation may be subjected to a solvent removal treatment by heating, reducing pressure, air drying, etc., as necessary, to obtain bisphenol substantially free of the solvent.
In order to improve the handling properties, the powder properties may be controlled by pulverization, classification, etc.

<Uses of bisphenol>
The bisphenol of the present invention can be used as a constituent, curing agent, additive, or precursor thereof for various thermoplastic resins such as polyether resins, polyester resins, polyarylate resins, polycarbonate resins, polyurethane resins, and acrylic resins, and various thermosetting resins such as epoxy resins, unsaturated polyester resins, phenolic resins, polybenzoxazine resins, and cyanate resins, which are used for various applications such as optical materials, recording materials, insulating materials, transparent materials, electronic materials, adhesive materials, and heat-resistant materials. It is also useful as an additive for color developers, color fading inhibitors, bactericides, and antibacterial and antifungal agents for thermal recording materials, etc.

Of these, it is preferable to use it as a raw material (monomer) for thermoplastic resins and thermosetting resins, since it can impart good mechanical properties, and it is more preferable to use it as a raw material for polycarbonate resins and epoxy resins. It is also preferable to use it as a color developer, and it is particularly preferable to use it in combination with a leuco dye or a discoloration temperature regulator.

[Method of producing polycarbonate resin]
The method for producing the polycarbonate resin of the present invention using bisphenol as a raw material will be described below.
The polycarbonate resin can be produced by, for example, a method of transesterifying bisphenol with a carbonate diester such as diphenyl carbonate in the presence of an alkali metal compound and/or an alkaline earth metal compound as a transesterification catalyst. The transesterification can be carried out by appropriately selecting a known method, but an example using the bisphenol and diphenyl carbonate of the present invention as raw materials will be described below.

In the method for producing a polycarbonate resin of the present invention, it is preferable to use an excess amount of diphenyl carbonate relative to the bisphenol. The amount of diphenyl carbonate used relative to the bisphenol is preferably large in that the produced polycarbonate resin has fewer terminal hydroxyl groups and the thermal stability of the polymer is excellent, and is preferably small in that the transesterification reaction rate is fast and it is easy to produce a polycarbonate resin of the desired molecular weight. For these reasons, the amount of diphenyl carbonate used relative to 1 mole of bisphenol is usually 1.001 moles or more, preferably 1.002 moles or more, and usually 1.3 moles or less, preferably 1.2 moles or less.

As a method for supplying the raw materials, the bisphenol and diphenyl carbonate of the present invention can be supplied in solid form, but it is preferable to melt one or both and supply them in a liquid state.

When producing a polycarbonate resin by the transesterification reaction of diphenyl carbonate and bisphenol, a transesterification catalyst (hereinafter sometimes simply referred to as "catalyst") is usually used. It is preferable to use an alkali metal compound and/or an alkaline earth metal compound as the transesterification catalyst. These may be used alone or in any combination and ratio of two or more types. For practical purposes, it is desirable to use an alkali metal compound.

The amount of catalyst used per mole of bisphenol or diphenyl carbonate is usually 0.05 μmol or more, preferably 0.08 μmol or more, more preferably 0.10 μmol or more, and usually 100 μmol or less, preferably 50 μmol or less, more preferably 20 μmol or less.

By using a catalyst in an amount within the above range, it is easy to obtain the polymerization activity required to produce a polycarbonate resin of the desired molecular weight, and it is easy to obtain a polycarbonate resin that has excellent polymer color, does not undergo excessive polymer branching, and has excellent fluidity during molding.

In producing a polycarbonate resin by the above method, it is preferred to continuously feed both of the above raw materials to a raw material mixing tank, and then continuously feed the resulting mixture and the transesterification catalyst to a polymerization tank.
In the production of polycarbonate resins by the transesterification method, usually, both raw materials are fed into a raw material mixing tank, stirred uniformly, and then fed into a polymerization tank to which a catalyst is added, thereby producing a polymer.

In the production of polycarbonate resin using the bisphenol of the present invention, the polymerization reaction temperature is preferably 80 to 400°C, particularly 150 to 350°C. The polymerization time is adjusted appropriately depending on the ratio of raw materials and the molecular weight of the desired polycarbonate resin, but since a long polymerization time can cause quality deterioration such as deterioration in color tone, it is preferably 10 hours or less, and more preferably 8 hours or less. The lower limit of the polymerization time is usually 0.1 hours or more, or 0.3 hours or more.

The bisphenol of the present invention has a sufficiently reduced amount of polymerization activity inhibitors and has excellent polymerization activity, making it possible to efficiently produce polycarbonate resins of the desired molecular weight. For example, high-quality polycarbonate resins with a viscosity average molecular weight (Mv) of 10,000 to 100,000 can be produced in a short period of time.

The present invention will be explained in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as the gist of the invention is not exceeded.

[Raw materials and reagents]
The toluene, acetone, cyclohexanone, orthocresol, methanol, sulfuric acid, dodecanethiol, triethylamine, pyridine, sodium hydroxide, sodium hydrogen carbonate, and cesium carbonate were all reagents manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.
Diphenyl carbonate used was a product manufactured by Mitsubishi Chemical Corporation.

[Measurement and evaluation method]
<pH Measurement>
The pH was measured using a pH meter (pH METER ES-73, manufactured by Horiba, Ltd.) on the aqueous phase at 25° C. taken out of the flask.

<Electrical Conductivity>
The electrical conductivity was measured using a conductivity meter COND METER D-71 manufactured by Horiba, Ltd., for the aqueous phase at 25° C. taken out of the flask.

<Initial Polymerization Activity Test>
When bisphenol and diphenyl carbonate react, phenol is produced as a by-product. The initial activity of the polymerization reaction was evaluated from the phenol production rate.
The phenol production rate was measured by high performance liquid chromatography (hereinafter referred to as LC) according to the following procedure and conditions.
・Analytical equipment: Shimadzu Corporation LC-2010A
Imtakt Scherzo SM-C18
3μm 250mm x 3.0mm ID
Method: Isocratic method Analysis temperature: 40°C
Eluent composition:
Solution A: Ammonium acetate: acetic acid: dechlorinated water = 3.000 g: 1 mL: 1 L solution Solution B: Ammonium acetate: acetic acid: acetonitrile = 1.500 g: 1 mL: 900 mL solution Solution A: Solution B = 10:90 (volume ratio)
Analysis time: 20 minutes Flow rate: 0.34 mL/min Detection wavelength: 254 nm

The phenol production rate (initial polymerization activity) was calculated by the following formula.
Phenol production rate (initial polymerization activity)=LC area of phenol÷(LC area of phenol+LC area of diphenyl carbonate+LC area of bisphenol C)×100(%)
The LC area refers to the area of a peak detected by high performance chromatography.

The more the amount of components that inhibit the reaction with diphenyl carbonate in bisphenol, the lower the phenol production rate, and vice versa. The more phenol produced, the better the polymerization activity.
The calculated phenol production rate was evaluated based on the following criteria.
⊚: Phenol production rate is 12.0 area% or more ◯: Phenol production rate is 5.0 area% or more and less than 12.0 area% △: Phenol production rate is 2.0 area% or more and less than 5.0 area% ×: Phenol production rate is less than 2.0 area%

Example 1
[Reaction step]
A separable flask equipped with a thermometer, a dropping funnel, a jacket, and an anchor-type stirring blade was charged with 280.0 g of toluene, 12.0 g of methanol, and 230.4 g of ortho-cresol under a nitrogen atmosphere, and while maintaining the internal temperature at 10° C. or lower, 76.0 g of 98% by mass sulfuric acid was added with stirring to prepare mixed solution A1.
Next, 65.0 g of acetone (amount of substance: 1.12 mol), 5.4 g of dodecanethiol, and 50.0 g of toluene were placed in the dropping funnel to prepare a mixed liquid B1.
While maintaining mixed liquid A1 at 10° C. or less, mixed liquid B1 in the dropping funnel was added dropwise to mixed liquid A1 over 45 minutes with stirring to obtain a reaction liquid of bisphenol C. The reaction liquid of bisphenol C was further stirred for 1 hour while maintaining the temperature at 20° C. to obtain reaction liquid C1 of bisphenol C.

120 g of 25% by weight sodium hydroxide solution was then added to the bisphenol C reaction solution C1, and the mixture was stirred and heated to 75°C, after which it was allowed to stand to separate the oil and water. After the oil-water separation, the aqueous phase was removed from the bottom of the separable flask, and an organic phase D1 containing bisphenol C was obtained.

[Neutralization process]
At 75 ° C., 120 g of 3 mass % sodium bicarbonate solution was added to the obtained organic phase D1, and the mixture was stirred to neutralize and separate oil and water. Stirring was performed at 250 rpm, assuming a problem (insufficient mixing) on the ^m3 scale.
After the oil-water mixture was separated, the aqueous phase was removed from the bottom of the separable flask to obtain an organic phase E1 containing bisphenol C. At this time, the pH of the removed aqueous phase was 9.2.

5.0 g of triethylamine was added to the obtained organic phase E1 and stirred for 20 minutes to obtain organic phase F1 containing bisphenol C. The addition rate of triethylamine to organic phase E1 was 0.8 mass%. (The mass of organic phase E1 was the total of acetone, orthocresol, toluene, and dodecanethiol supplied in the reaction process. Triethylamine (5.0 g) / organic phase E1 (630.8 g) x 100 = 0.8 mass%)

After the addition of triethylamine, 100 g of demineralized water was added to the organic phase F1 containing bisphenol C, which was then stirred and allowed to stand to separate into oil and water. After the oil-water separation, the aqueous phase was removed from the bottom of the separable flask. This operation was repeated, and the organic phase F1 was washed until the electrical conductivity of the removed aqueous phase reached 5.0 μS/cm. The resulting organic phase was designated organic phase G1.

[Crystallization process]
The organic phase G1 containing bisphenol C was gradually cooled from 75° C. to 5° C. to precipitate crystals containing bisphenol C. The obtained liquid containing the crystals containing bisphenol C was subjected to solid-liquid separation using a centrifuge to obtain a cake containing bisphenol C.

To the cake containing bisphenol C, 150 g of toluene was added, and suspension washing was performed while loosening the cake, followed by solid-liquid separation using a centrifuge. This procedure was repeated two more times to obtain a refined cake.
The low boiling fractions were distilled off from the refined cake using an evaporator equipped with an oil bath at an oil bath temperature of 100° C. under reduced pressure, thereby obtaining white bisphenol C.

[Initial Polymerization Activity Test]
4.7 g of bisphenol C obtained in the above crystallization step, 4.5 g of diphenyl carbonate, and 20 μL of an aqueous cesium carbonate solution adjusted to 453 ppm were placed in a PTFE test tube, and heated at 190° C. for 1 hour using an aluminum block heater.
A portion of the resulting molten liquid was taken out and the yield of phenol produced by reaction with diphenyl carbonate was examined by high performance liquid chromatography, revealing that phenol was produced in an amount of 8.7 area %.

Example 2
[Reaction step]
The same procedure as in Example 1 was carried out to obtain an organic phase D2 containing bisphenol C.

[Neutralization process]
The same procedures as in Example 1 were carried out except that 10.0 g of pyridine was used instead of 5.0 g of triethylamine, and pyridine was added to and mixed with the organic phase E2 containing bisphenol C to obtain an organic phase F2.
The addition rate of pyridine to the organic phase E2 was 1.6% by mass. (The mass of the organic phase E2 was the total of acetone, orthocresol, toluene, and dodecanethiol supplied in the reaction step. Pyridine (10.0 g)/organic phase E2 (630.8 g)×100=1.6% by mass.)

100 g of desalted water was added to organic phase F2, and the mixture was stirred and then allowed to stand to separate the oil and water. After the oil and water separation, the aqueous phase was removed from the bottom of the separable flask. This operation was repeated, and organic phase F2 was washed until the electrical conductivity of the removed aqueous phase reached 5.0 μS/cm. The resulting organic phase was designated organic phase G2.

[Crystallization process]
The organic phase G2 containing bisphenol C was subjected to crystallization and cake washing in the same manner as in Example 1 to obtain white bisphenol C.

[Initial Polymerization Activity Test]
Using the bisphenol C obtained in the above crystallization step, an initial polymerization activity test was carried out in the same manner as in Example 1, and the phenol production rate by the reaction with diphenyl carbonate was confirmed, and it was found that 9.2 area % of phenol was produced.

<Comparative Example 1>
[Reaction step]
The same procedure as in Example 1 was carried out to obtain an organic phase D3 containing bisphenol C.

[Neutralization process]
At 75°C, 3% by mass sodium bicarbonate solution was added to the obtained organic phase D3, and the mixture was stirred at 250 rpm to neutralize, and oil-water separation was performed. After oil-water separation, the aqueous phase was removed from the bottom of the separable flask to obtain an organic phase E3 containing bisphenol C. At this time, the pH of the removed aqueous phase was 9.2. This operation was repeated again to obtain an organic phase E3-2.
100 g of desalted water was added to the organic phase E3-2, and the mixture was stirred and then allowed to stand to separate the oil and water. After the oil and water separation, the aqueous phase was removed from the bottom of the separable flask. This operation was repeated to wash the organic phase E3-2 until the electrical conductivity of the removed aqueous phase reached 5.0 μS/cm. The resulting organic phase was designated as organic phase G3.

[Crystallization process]
The organic phase G3 containing bisphenol C was subjected to crystallization and cake washing in the same manner as in Example 1 to obtain white bisphenol C.

[Initial Polymerization Activity Test]
Using the bisphenol C obtained in the above crystallization step, an initial polymerization activity test was carried out in the same manner as in Example 1, and the phenol production rate by the reaction with diphenyl carbonate was confirmed, and it was found that 0.3 area % of phenol was produced.

Example 3
[Reaction step]
A separable flask equipped with a thermometer, a dropping funnel, a jacket, and an anchor-type stirring blade was charged with 100.0 g of toluene, 6.0 g of methanol, and 115.0 g of ortho-cresol under a nitrogen atmosphere, and while maintaining the internal temperature at 10° C. or lower, 48.0 g of 98% by mass sulfuric acid was added with stirring to prepare mixed solution A4.
Next, 48.0 g of cyclohexanone, 3.0 g of dodecanethiol, and 25.0 g of toluene were placed in the dropping funnel to prepare a mixed liquid B4.
While maintaining mixed solution A4 at 10°C or less, mixed solution B4 in the dropping funnel was added dropwise to mixed solution A4 over 45 minutes with stirring to obtain a reaction solution of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane. The reaction solution of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane was heated to 50°C and stirred for 1 hour to obtain a reaction solution of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane C4.

100 g of 25% by weight sodium hydroxide solution was then added to reaction liquid C4, which was then stirred and heated to 80°C, after which it was allowed to stand to separate the oil and water phases. After separation of the oil and water phases, the aqueous phase was removed from the bottom of the separable flask, and an organic phase D4 containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane was obtained.

[Neutralization process]
To the obtained organic phase D4, 80 g of a 3% by mass sodium hydrogen carbonate solution was added and stirred at 80° C. to neutralize the mixture, and oil-water separation was performed. The stirring was performed at 250 rpm as in Example 1.
After the oil-water separation, the aqueous phase was removed from the bottom of the separable flask to obtain an organic phase E4 containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane. The pH of the removed aqueous phase was 8.9.
2.0 g of triethylamine was added to the obtained organic phase E4 and stirred for 20 minutes to obtain organic phase F4 containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane. The addition rate of triethylamine to organic phase E4 was 0.7 mass%. (The mass of organic phase E4 was the sum of cyclohexanone, orthocresol, toluene, and dodecanethiol supplied in the reaction step. Triethylamine (2.0 g)/organic phase E4 (291.0 g)×100=0.7 mass%)

100 g of demineralized water was added to this organic phase F4, and the mixture was stirred and then allowed to stand to separate the oil and water. After the oil and water separation, the aqueous phase was removed from the bottom of the separable flask. This operation was repeated, and the organic phase F4 was washed until the electrical conductivity of the removed aqueous phase reached 5.0 μS/cm. The resulting organic phase was designated organic phase G4.

[Crystallization process]
The organic phase G4 containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane was gradually cooled from 75° C. to 5° C. to precipitate crystals containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane. The liquid containing the obtained crystals was subjected to solid-liquid separation using a centrifuge to obtain a cake containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

To the cake containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 100 g of toluene was added, and the cake was suspended and washed while being loosened, and then subjected to solid-liquid separation using a centrifuge. This procedure was repeated two more times to obtain a refined cake.
The low boiling fractions were distilled off from the purified cake using an evaporator equipped with an oil bath at an oil bath temperature of 100° C. under reduced pressure, yielding white 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

[Initial Polymerization Activity Test]
5.4 g of 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane obtained in the above crystallization step, 4.5 g of diphenyl carbonate, and 20 μL of an aqueous cesium carbonate solution adjusted to 453 ppm were placed in a PTFE test tube, and heated at 190° C. for 1 hour using an aluminum block heater.
A portion of the resulting molten liquid was taken out and the yield of phenol produced by the reaction with diphenyl carbonate was examined by high performance liquid chromatography, which revealed that phenol was produced in an amount of 12.7 area %.

<Comparative Example 2>
[Reaction step]
The same procedure as in Example 3 was carried out to obtain an organic phase D5 containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

[Neutralization process]
To the obtained organic phase D5, 80 g of a 3% by mass sodium hydrogen carbonate solution was added and stirred at 80° C. to neutralize the mixture, and oil and water were separated. The stirring was performed at 250 rpm in the same manner as in Example 1.
After the oil-water separation, the aqueous phase was removed from the bottom of the separable flask to obtain an organic phase E5 containing bisphenol. The pH of the removed aqueous phase was 9.0. This operation was repeated again to obtain an organic phase E5-2.
100 g of desalted water was added to the organic phase E5-2, and the mixture was stirred and then allowed to stand to separate the oil and water. After the oil and water separation, the aqueous phase was removed from the bottom of the separable flask. This operation was repeated to wash the organic phase E5-2 until the electrical conductivity of the removed aqueous phase reached 5.0 μS/cm. The resulting organic phase was designated as organic phase G5.

[Crystallization process]
The organic phase G5 containing 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane was subjected to crystallization and cake washing in the same manner as in Example 3 to obtain white 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane.

[Initial Polymerization Activity Test]
Using the 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane obtained in the above crystallization step, an initial polymerization activity test was carried out in the same manner as in Example 3, and the phenol production rate by the reaction with diphenyl carbonate was confirmed. As a result, 0.5 area % of phenol was produced.

The following Table 1 shows the basic nitrogen-containing compounds and their amounts added in the examples and comparative examples, as well as the results of the initial polymerization activity test. From this Table 1, it can be seen that bisphenol with excellent polymerization activity can be obtained by mixing the bisphenol obtained by reaction with a basic nitrogen-containing compound, neutralizing it, and then crystallizing it.

The bisphenol produced by the bisphenol production method of the present invention is useful as a resin raw material such as a polycarbonate resin, an epoxy resin, an aromatic polyester resin, etc., or as an additive such as a curing agent, a color developer, an anti-fading agent, or other bactericide, antibacterial, antifungal, etc.

Claims (5)

The process comprises a reaction step of reacting an aromatic alcohol with a ketone or an aldehyde in the presence of an acid catalyst to produce bisphenol, a neutralization step of neutralizing acidic components in an organic phase containing bisphenol obtained in the reaction step, and a crystallization step of extracting bisphenol solids from the organic phase containing bisphenol that has been subjected to the neutralization step,
In the neutralization step, a basic nitrogen-containing compound is added to the organic phase containing the bisphenol ,
The method for producing bisphenol, wherein the neutralization step comprises a first neutralization step of adding a basic aqueous solution to the bisphenol-containing organic phase and mixing the mixture, followed by separation into two phases and removing the aqueous phase, and a second neutralization step of adding the basic nitrogen-containing compound to the bisphenol-containing organic phase obtained in the first neutralization step, wherein the aqueous phase removed in the first neutralization step has a pH of 7.5 or higher . 2. The method for producing bisphenol according to claim 1 , wherein the boiling point of the basic nitrogen-containing compound is 120° C. or lower. The method for producing bisphenol according to claim 1 or 2 , wherein the amount of the basic nitrogen-containing compound added is 0.01 to 10% by mass based on the organic phase containing bisphenol. The method for producing bisphenol according to any one of claims 1 to 3, wherein the bisphenol is any one selected from the group consisting of 2,2-bis(4-hydroxy-3-methylphenyl)propane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and 1,1-bis(4-hydroxy- 3 -methylphenyl)cyclohexane. A method for producing a polycarbonate resin , comprising producing bisphenol by the method for producing bisphenol according to any one of claims 1 to 4 and using the produced bisphenol .