JP7631795B2 - Method for producing bisphenol and method for producing polycarbonate resin - Google Patents

Description

The present invention relates to a method for producing bisphenol. It also relates to a method for producing polycarbonate resin using the bisphenol.

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 WO 2019/39520

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

Bisphenols are usually produced by condensing a ketone or aldehyde with an aromatic alcohol in the presence of an acid catalyst to produce bisphenols (Patent Documents 1 and 2).

For example, the example in Patent Document 1 describes a method of obtaining a bisphenol compound by adding hydrochloric acid to a mixture of orthocresol and acetone, stirring the mixture, and then adding 95% by mass of sulfuric acid dropwise over a period of 0.7 to 2 hours.

The example in Patent Document 2 describes a method of obtaining bisphenol by adding sulfuric acid to orthocresol and then supplying acetone.

However, in the production of bisphenol on a kg or ton scale, it takes time to supply sulfuric acid to a reaction vessel, and the aromatic alcohol reacts with the sulfuric acid to form aromatic alcohol sulfonic acid, resulting in a decrease in yield. Therefore, further improvement of the production method is required.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing bisphenol with a high yield, and a method for producing a polycarbonate resin with a good color tone by using the bisphenol obtained by the above-mentioned bisphenol production method.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that bisphenol can be produced with a high yield by supplying a ketone or aldehyde and sulfuric acid to a mixed solution containing an aromatic alcohol and sulfuric acid, and causing a condensation reaction between the aromatic alcohol and the ketone or aldehyde, and thus completed the present invention.

That is, the present invention relates to the following inventions.
[1]
A method for producing bisphenol by reacting an aromatic alcohol with a ketone or an aldehyde in the presence of sulfuric acid, comprising the steps of:
A method for producing bisphenol, comprising: a first step of preparing a first mixed liquid containing sulfuric acid and the aromatic alcohol; and a second step of supplying the ketone or aldehyde and sulfuric acid to the first mixed liquid.
[2]
The method for producing bisphenol according to [1], wherein in the second step, sulfuric acid is supplied after the ketone or aldehyde is supplied or in parallel with the supply of the ketone or aldehyde.
[3]
The method for producing bisphenol according to [1] or [2], wherein the amount of the aromatic alcohol sulfonic acid produced when the first mixture is held at 50° C. for 3 hours from immediately after preparation is 5.0 mol % or less relative to the aromatic alcohol.
[4]
The method for producing bisphenol according to any one of [1] to [3], wherein in the first mixture, a mass ratio of sulfuric acid to the aromatic alcohol is 0.01 or more and 1.00 or less.
[5]
The method for producing bisphenol according to any one of [1] to [4], wherein a ratio of a mass of sulfuric acid contained in the first mixed liquid in the first step to a total mass of the sulfuric acid contained in the first mixed liquid in the first step and the sulfuric acid supplied to the first mixed liquid in the second step is 0.05 or more and 0.90 or less.
[6]
The method for producing bisphenol according to any one of [1] to [5], wherein the first mixed liquid further contains one or more selected from the group consisting of thiols, aromatic hydrocarbons, and aliphatic alcohols.
[7]
The method for producing bisphenol according to any one of [1] to [6], wherein in the second step, one or more selected from a thiol, an aromatic hydrocarbon, and an aliphatic alcohol is further supplied to the first mixed liquid.
[8]
The method for producing bisphenol according to any one of [1] to [7], wherein the aromatic alcohol includes at least one selected from the group consisting of phenol, orthocresol, and 2,6-dimethylphenol.
[9]
The method for producing bisphenol according to any one of [1] to [8], wherein the ketone includes one or more selected from acetone, 3,3,5-trimethylcyclohexanone, cyclohexanone, and acetophenone.
[10]
The method for producing bisphenol according to any one of [1] to [9], wherein the bisphenol comprises one or more selected from 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)phenylethane, and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
[11]
A method for producing a polycarbonate resin, comprising a step of polymerizing a polycarbonate using a bisphenol produced by the method for producing a bisphenol according to any one of [1] to [10].

The present invention provides a method for producing bisphenol with a high yield. In a preferred embodiment of the present invention, the amount of aromatic alcohol sulfonic acid produced as a by-product can be reduced. Furthermore, polycarbonate resin can be efficiently produced using bisphenol produced by the method for producing bisphenol.

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.

1. Method for producing bisphenol
The present invention relates to a method for producing bisphenol, which comprises subjecting an aromatic alcohol to a condensation reaction (hereinafter sometimes simply referred to as "reaction") with a ketone or an aldehyde in the presence of sulfuric acid as an acid catalyst to produce bisphenol.

The present inventors have found that when sulfuric acid is used as a catalyst, a large amount of aromatic alcohol sulfonic acid is produced as a by-product by contacting sulfuric acid with an aromatic alcohol, resulting in the loss of aromatic alcohol, and that if aromatic alcohol sulfonic acid remains in the product, it acts as an activity-reducing component in the melt polymerization reaction. They have also found that by supplying a ketone or aldehyde and sulfuric acid to a mixed liquid containing sulfuric acid and an aromatic alcohol, the by-production of aromatic alcohol sulfonic acid is suppressed, and bisphenol can be produced with a high yield. In other words, the present inventors have found that the quality of the obtained bisphenol is affected by the mixing order of the raw materials when preparing the reaction liquid. In particular, when the production scale is large, the time until the preparation of the reaction liquid and the completion of the bisphenol production reaction are long, and therefore the quality of the obtained bisphenol is greatly affected by the mixing order of the raw materials when preparing the reaction liquid. In this specification, a large production scale refers to a case in which the yield of bisphenol produced is about 100 kg to 10 tons. The embodiment described below can be suitably used for the production of bisphenol on such a scale.

[1-1. First step and second step]
One embodiment of the present invention is a method for producing bisphenol by reacting an aromatic alcohol with a ketone or an aldehyde in the presence of sulfuric acid, characterized in that the method includes a first step of preparing a first mixed liquid containing sulfuric acid and the aromatic alcohol, and a second step of supplying the ketone or the aldehyde and sulfuric acid to the first mixed liquid.

The present inventors speculate as follows about the reason why bisphenol can be produced in good yield by such a production method.
That is, a large amount of sulfuric acid sulfonates aromatic alcohol and produces aromatic alcohol sulfonic acid as a by-product. The by-produced aromatic alcohol sulfonic acid deteriorates the polymerization activity and also leads to loss of aromatic alcohol, which is undesirable. Therefore, it is preferable to reduce the amount of sulfuric acid mixed with aromatic alcohol, but if the amount of sulfuric acid is reduced, the sulfuric acid is diluted with the by-product water generated in the condensation reaction, which reduces the reaction rate and leads to a decrease in yield. However, by mixing a part of the total sulfuric acid used in the condensation reaction with aromatic alcohol and additionally supplying the remaining sulfuric acid after the start of the reaction to produce bisphenol, it is believed that the aromatic alcohol can be sulfonated and the decrease in the sulfuric acid concentration in the reaction solution can be suppressed, thereby realizing a high yield.

[1-1-1. Bisphenol]
The bisphenol produced is usually a compound represented by the following general formula (1).

R ¹ to R ⁴ each independently include 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, etc. may be substituted or unsubstituted. The alkyl group and the alkoxy group may be linear, branched, or cyclic. Specific 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, 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, 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-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 include a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, etc. The alkyl group, the alkoxy group, the aryl group, etc. 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, such as cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, 3,3,5-trimethylcyclohexylidene, cycloheptylidene, cyclooctylidene, cyclononylidene, cyclodecylidene, cycloundecylidene, cyclododecylidene, fluorenylidene, xanthonylidene, and thioxanthonylidene.

Specifically, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-
1,1-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)phenylethane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 3,3-bis(4-hydroxyphenyl)pentane, 3,3-bis(4-hydroxy-3-methylphenyl)pentane, 2, Examples of the hydroxyphenyl ether include, but are not limited to, 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, and 4,4-bis(4-hydroxy-3-methylphenyl)heptane.

Among these, the preferred bisphenol is any one selected from the group consisting of 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, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and 1,1-bis(4-hydroxyphenyl)phenylethane.

[1-1-2. Aromatic alcohols]
The aromatic alcohol 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.

^R2 and ^R3 are preferably hydrogen atoms because the condensation reaction is difficult to proceed if they are sterically bulky. ^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 alkyl group can be an alkyl group having 1 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms.

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, phenylphenol, and the like. Among these, any one selected from the group consisting of phenol, methylphenol, and dimethylphenol is preferred, methylphenol or dimethylphenol is more preferred, and methylphenol is even more preferred.

[1-1-3. Ketones or aldehydes]
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 alkyl group can be an alkyl group having 1 to 12 carbon atoms or an alkyl group having 1 to 6 carbon atoms. For example, ^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 the general formula (3) include aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, pentanaldehyde, hexanealdehyde, heptanealdehyde, octanaldehyde, nonanealdehyde, decanaldehyde, undecanealdehyde, and dodecanealdehyde; ketones such as acetone, butanone, pentanone, hexanone, heptanone, octanone, nonanone, decanone, undecanone, and dodecanone; benzaldehyde, phenyl methyl ketone (acetone, phenyl methyl ketone ... aryl alkyl ketones such as phenyl 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, 3,3,5-trimethylcyclohexanone, cycloheptanone, cyclooctanone, cyclononanone, cyclodecanone, cycloundecanone, and cyclododecanone. Among these, acetone, 3,3,5-trimethylcyclohexanone, cyclohexanone, and acetophenone are preferred.

When the amount of ketone or aldehyde is large relative to the aromatic alcohol used as the raw material, the ketone or aldehyde is likely to polymerize, and when the amount is small, the aromatic alcohol remains unreacted. 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.

[1-1-4. Acid catalyst]
In the process for producing bisphenol, sulfuric acid is used as the acid catalyst because it has excellent reaction efficiency, is non-volatile, and places little strain on the equipment.

When the molar ratio (moles of sulfuric acid/moles of aromatic alcohol) of the total sulfuric acid used in the condensation reaction to the aromatic alcohol as a raw material is low, the sulfuric acid is diluted with the by-produced water as the condensation reaction proceeds, and the reaction takes time. When the molar ratio is high, 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 total sulfuric acid used in the condensation reaction to the aromatic alcohol as a 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.

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 in the reaction solution (concentration of the aqueous sulfuric acid 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 with a high yield. Therefore, the concentration of sulfuric acid is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. The upper limit of the concentration of sulfuric acid is usually 99.5% by mass or less or 99% by mass or less. The concentrations of sulfuric acid used in the first and second steps may be the same or different.

If the ratio of sulfuric acid in the first mixed solution to the total amount of sulfuric acid used in the condensation reaction is too low, the amount of catalyst may be insufficient, and it may be difficult to produce bisphenol with a high yield. If the ratio is too high, it takes a long time to mix the aromatic alcohol with sulfuric acid, during which time aromatic alcohol sulfonic acid is by-produced. Therefore, the molar ratio of sulfuric acid to aromatic alcohol in the first mixed solution is preferably 0.01 or more, more preferably 0.05 or more. The upper limit is preferably 1.00 or less, more preferably 0.70 or less, and even more preferably 0.50 or less.

The ratio of the mass of sulfuric acid contained in the first mixed liquid in the first step to the total mass of the sulfuric acid contained in the first mixed liquid in the first step and the sulfuric acid supplied to the first mixed liquid in the second step is usually 0.05 or more, preferably 0.10 or more, more preferably 0.20 or more, and usually 0.90 or less, preferably 0.85 or less, more preferably 0.80 or less, from the viewpoint of simultaneously suppressing the by-production of aromatic alcohol sulfonic acid and maintaining a sufficient reaction rate.

In the second step, the timing of supplying sulfuric acid to the first mixed solution is not particularly limited, and may be before or after the supply of ketone or aldehyde, or may be in parallel with the supply of ketone or aldehyde, but is preferably after the supply of ketone or aldehyde or in parallel with the supply of ketone or aldehyde. In addition, if the sulfuric acid concentration in the reaction solution is insufficient, the self-condensation reaction of ketone or aldehyde is more likely to occur than the reaction to produce bisphenol, which is not preferable. Therefore, the timing to start supplying sulfuric acid is preferably when the amount of ketone or aldehyde supplied to the first mixed solution (supply rate of ketone or aldehyde) is within 90% of the total amount of ketone or aldehyde as the raw material, more preferably within 70%, and most preferably within 50%.
Furthermore, when sulfuric acid and an aromatic alcohol are supplied to a reaction tank in the first step to prepare a first mixed liquid, and a ketone or an aldehyde and sulfuric acid are supplied to the reaction tank in the second step, the sulfuric acid supplied to the reaction tank in the first step and the sulfuric acid supplied to the reaction tank in the second step may be supplied from the same container or from separate containers.

As the other acid catalyst, hydrogen chloride gas, hydrochloric acid, aromatic sulfonic acids such as p-toluenesulfonic acid, aliphatic sulfonic acids such as methanesulfonic acid, and strong acids such as phosphoric acid may be used in combination with sulfuric acid. The other acid catalyst may be contained in the first mixed liquid in the first step, or may be supplied to the first mixed liquid together with sulfuric acid in the second step, or both of these modes may be adopted.

In this embodiment, a portion of the total sulfuric acid supplied to the condensation reaction of the aromatic alcohol with a ketone or an aldehyde is mixed with the aromatic alcohol to form a first mixed liquid, and the remaining sulfuric acid is supplied to this first mixed liquid, thereby suppressing the by-production of aromatic alcohol sulfonic acid caused by contact of a large amount of sulfuric acid with the aromatic alcohol.
More specifically, the amount of aromatic alcohol sulfonic acid produced when the first mixed liquid is held at 50°C for 3 hours immediately after preparation is usually 5.0 mol % or less, preferably 4.0 mol % or less, and more preferably 3.0 mol % or less, relative to the aromatic alcohol (charged amount).
In this specification, "immediately after preparation" refers to the time when the total amounts of sulfuric acid and aromatic alcohol used in the preparation of the first mixed liquid are both present in any one system. For example, in the case of preparing the first mixed liquid by supplying sulfuric acid to aromatic alcohol being stirred, the time refers to the time when the supply of the total amount of sulfuric acid used in the preparation of the first mixed liquid has been completed.
The amount of aromatic alcohol sulfonic acid produced is measured by liquid chromatography such as high performance liquid chromatography.

By suppressing the by-production of aromatic alcohol sulfonic acid, the loss of aromatic alcohol is suppressed, and the yield of bisphenol is improved. The efficiency of conversion of aromatic alcohol to bisphenol can be evaluated by the selectivity represented by the following formula. According to the production method of this embodiment, a high selectivity of, for example, 92 mol % or more, 95 mol % or more, or 97 mol % or more can be realized.
Selectivity (mol%) = aromatic alcohol converted to bisphenol (mol) / aromatic alcohol converted (mol) × 100
In the above formula, the amount of aromatic alcohol converted to bisphenol and the converted aromatic alcohol are measured by liquid chromatography such as high performance liquid chromatography.

[1-1-5. Thiol cocatalyst]
The condensation reaction of the aromatic alcohol with the ketone or aldehyde may be carried out in the presence of a thiol as a co-catalyst. The thiol may be contained in the first mixed liquid, or may be supplied to the first mixed liquid in the second step, or both of these modes may be adopted. When supplying the thiol to the first mixed liquid in the second step, the thiol may be supplied to the first mixed liquid separately from the ketone or aldehyde and sulfuric acid, or may be mixed with the ketone or aldehyde and, if necessary, an organic solvent described below and then supplied to the first mixed liquid.

Examples of thiols include mercaptocarboxylic acids such as mercaptoacetic acid, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, and 4-mercaptobutyric acid, 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, pentadecyl mercaptan, and mercaptophenol.

If the molar ratio of thiol to ketone or aldehyde ((moles of thiol/moles of ketone) or (moles of thiol/moles of aldehyde)) is low, the effect of improving the selectivity of bisphenol by using thiol cannot be obtained, and if it is high, thiol may be mixed into bisphenol, resulting in deterioration of quality. For these reasons, the lower limit of the molar ratio of thiol to 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.

[1-1-6. Organic solvent]
The condensation reaction of the aromatic alcohol with the ketone or aldehyde 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 any combination and ratio of two or more. For example, a mixed solvent of an aromatic hydrocarbon and an aliphatic alcohol may be used. The organic solvent may be contained in the first mixed liquid, or may be supplied to the first mixed liquid in the second step, or both of these modes may be adopted. When the organic solvent is supplied to the first mixed liquid in the second step, the organic solvent may be supplied to the first mixed liquid separately from the ketone or aldehyde and sulfuric acid, or may be mixed with the ketone or aldehyde and supplied to the first mixed liquid.

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

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

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.

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, more preferably 1 or more. The upper limit can be adjusted to 50 or less, or 30 or less, depending on the type of organic solvent, within the range in which bisphenol precipitates.

It is preferable to use a solvent in which bisphenol is low in solubility because the bisphenol produced is easily precipitated and the loss when recovering bisphenol from the reaction solution after the reaction is completed (for example, loss to the filtrate during crystallization) can be reduced. Examples of solvents in which bisphenol is low in solubility include aromatic hydrocarbons. For this reason, it is preferable for the organic solvent to contain aromatic hydrocarbons as the main component, and it is preferable for the organic solvent to contain 55% by mass or more of aromatic hydrocarbons, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[1-1-7. Operation]
The method for preparing the first mixed solution in the first step is not particularly limited, and any known method can be used, for example, a method in which an aromatic alcohol, sulfuric acid, and other components as necessary are mixed by stirring or the like. In this case, the order of mixing is not important.

In the second step, the method of supplying the ketone or aldehyde and sulfuric acid to the first mixed liquid is not particularly limited. In the supply of sulfuric acid, the supply of the ketone or aldehyde, and the supply of other components such as thiols and organic solvents, the target may be supplied to the first mixed liquid all at once or in portions. However, since the reaction that produces bisphenol is an exothermic reaction, it is preferable to supply the target in portions, such as by dropping it little by little.

[1-1-8. Reaction conditions]
As described above, in the method for producing bisphenol according to the present embodiment, as the condensation reaction proceeds, precipitation of bisphenol occurs, so that the reaction liquid changes to a slurry liquid, and the condensation reaction is carried out in a slurry state. A slurry liquid is a suspension in which a solid is dispersed in a liquid. Specifically, the slurry liquid is a three-phase slurry liquid in which solid bisphenol is dispersed in a liquid containing an organic phase (unreacted aromatic alcohol, ketone, aldehyde, etc.) and an aqueous phase (sulfuric acid, generated water, etc.).
The smaller the amount of bisphenol precipitated, the more the amount of decomposition products of bisphenol tends to increase. Therefore, it is preferable to appropriately select the presence or absence of an organic solvent, the reaction time, the reaction temperature, etc., to precipitate a certain amount or more of bisphenol in the slurry liquid. For example, the slurry concentration of the slurry liquid at the end of the reaction (mass of solid bisphenol/mass of slurry liquid x 100 (%)) can be 15 mass% or more or 20 mass% or more. In addition, the slurry concentration of the slurry liquid at the end of the reaction may be controlled by setting an upper limit of 50 mass% or less, 40 mass% or less, 35 mass% or less, etc.

If the reaction temperature of the condensation reaction is too low, the condensation reaction will not proceed easily, so it 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, will proceed, and if a thiol is used as a co-catalyst, the oxidative decomposition of the thiol will proceed easily, so 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 of the condensation reaction is adjusted appropriately depending on the reaction conditions such as the type of bisphenol to be 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 of the condensation reaction is defined as starting at the time when the supply of the ketone or aldehyde to the first mixed solution is started in the second step. For example, in the case where the ketone or aldehyde is supplied to the first mixed solution over one hour and then reacted for one hour, the reaction time is two hours.
The condensation reaction can be terminated, for example, by adding water or a base in an amount equal to or greater than the amount of the acid catalyst used to reduce the concentration of the acid catalyst.

[1-1-9. Reaction apparatus]
Since the reaction for producing bisphenol proceeds with a strong acid as a catalyst, it is preferable that the surface of the inner wall of the reaction vessel 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.

[1-2. Purification process]
The method for producing bisphenol according to the present embodiment can include a purification step of purifying bisphenol after a reaction step of obtaining a slurry liquid in which bisphenol is dispersed.

The purification of bisphenol can be carried out by a conventional method. For example, it can be purified by a simple means such as crystallization or column chromatography. Specifically, after the condensation reaction, the organic phase obtained by separating the reaction solution is washed with water or saline, and further neutralized and washed with sodium bicarbonate water, if necessary. The washed organic phase is then cooled and crystallized. When a large amount of aromatic alcohol is used, the excess aromatic alcohol is distilled off before the crystallization, and then the crystallization is carried out.
When the organic phase containing bisphenol is washed with water, the end point of the washing can be controlled by the electrical conductivity of the aqueous phase to be removed. If metal salts of aromatic alcohol sulfonic acid, sulfuric acid, etc. remain in the organic phase containing bisphenol, they cause deterioration in color tone, so the electrical conductivity of the aqueous phase after washing is preferably 100 μS/cm or less, more preferably 50 μS/cm or less, and even more preferably 10 μS/cm or less.

[1-3. Uses of bisphenol]
The obtained bisphenol 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 and color fading inhibitors for thermal recording materials, bactericides, and antibacterial and antifungal agents.

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.

2. Method for producing polycarbonate resin
A method for producing a polycarbonate resin using the obtained bisphenol as a raw material will be described. The polycarbonate resin can be produced by, for example, a method of subjecting bisphenol and a carbonate diester such as diphenyl carbonate to an ester exchange reaction in the presence of an alkali metal compound and/or an alkaline earth metal compound. The ester exchange reaction can be carried out by appropriately selecting a known method, but an example using bisphenol and diphenyl carbonate as raw materials will be described below.

In the method for producing polycarbonate resin, 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 is usually used. As the transesterification catalyst, it is preferable to use an alkali metal compound and/or an alkaline earth metal compound. These may be used alone or in any combination and ratio of two or more. In practical terms, it is preferable 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.

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 orthocresol, 2,6-xylenol, toluene, sodium hydroxide, sulfuric acid, dodecanethiol, methanol, acetone, cyclohexanone, sodium hydrogen carbonate, and cesium carbonate were all reagents manufactured by Wako Pure Chemical Industries, Ltd.
Diphenyl carbonate used was a product manufactured by Mitsubishi Chemical Corporation.

[analysis]
(Quantitative analysis of aromatic alcohol sulfonic acid)
Quantitative analysis of aromatic alcohol sulfonic acid was carried out by high performance liquid chromatography according to the following procedure and conditions.
Equipment: Shimadzu LC10A
Imtakt Unison UK-C18 3μm 250×4.6mmI.
D
- Low pressure gradient method - Analysis temperature: 40°C
Eluent composition:
Solution A: 10 mM ammonium acetate aqueous solution 1 L + acetic acid 2 mL
B solution: a solution of acetonitrile:methanol = 5:1. At analysis time 0 min, the eluent composition was A solution:B solution = 70:30 (volume ratio, the same applies below), and from analysis time 0 to 35 min, the eluent composition was gradually changed to A solution:B solution = 10:90, and from analysis time 35 to 45 min, the A solution:B solution = 10:90.
Flow rate: 0.8 mL/min Detection wavelength: 280 nm

(pH Measurement)
The pH was measured using a pH meter "pH METERES-73" manufactured by Horiba, Ltd., with respect to 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.
If the amount of metal in the product bisphenol is high, it will cause a deterioration in color.

(Terminal Hydroxyl Group (OH) Concentration of Polycarbonate Resin)
The terminal hydroxyl group (OH) concentration of the polycarbonate resin was measured by colorimetric determination in accordance with the titanium tetrachloride/acetic acid method (see Makromol. Chem. 88, 215 (1965)).

(Viscosity average molecular weight (Mv))
The viscosity average molecular weight (Mv) was determined by dissolving the polycarbonate resin in methylene chloride (concentration: 6.0 g/L), measuring the specific viscosity (ηsp) at 20° C. using an Ubbelohde viscometer, and calculating the viscosity average molecular weight (Mv) according to the following formula.
ηsp/C=[η](1+0.28ηsp)
[η]=1.23×10 ⁻⁴ Mv ^0.83

(Pellet YI)
Pellet YI (transparency of polycarbonate resin) was evaluated by measuring the YI value (yellowness index value) of polycarbonate resin pellets in reflected light in accordance with ASTM D1925.
・Apparatus: Konica Minolta spectrophotometer CM-5
Measurement conditions:
A measurement diameter of 30 mm and SCE were selected. A petri dish calibration glass CM-A212 was fitted into the measurement section, and a zero calibration box CM-A124 was placed over it to perform zero calibration, followed by white calibration using the built-in white calibration plate. Measurements were then performed using the white calibration plate CM-A210, and it was confirmed that L* was 99.40±0.05, a* was 0.03±0.01, b* was -0.43±0.01, and YI was -0.58±0.01.
The pellets were measured by filling a cylindrical glass container with an inner diameter of 30 mm and a height of 50 mm with the pellets to a depth of about 40 mm. The pellets were removed from the glass container and the measurement was repeated twice, and the average value of the three measurements was used.

Example 1
[First step]
280 g of toluene, 15 g of methanol, and 230 g (2,130 mmol) of ortho-cresol were placed in a 1 L separable flask equipped with a thermometer, a first dropping funnel, a second dropping funnel, a jacket, and an anchor-type stirring blade under a nitrogen atmosphere, and the internal temperature was adjusted to 10° C. or lower. Then, 71.3 g of 98% by mass sulfuric acid (the mass ratio of sulfuric acid to cresol was 71.3 g × 0.98 ÷ 230 g = 0.30) was slowly added with stirring, and the mixture was stirred at an internal temperature of 5° C. for 3 hours to obtain a first mixed liquid.

[Second step]
In a 500 mL Erlenmeyer flask, 50 g of toluene, 61 g (1,052 mmol) of acetone, and 5.4 g of dodecanethiol were mixed to prepare an acetone solution, which was then placed in the first dropping funnel. The acetone solution was dropped into the first mixed liquid over 0.5 hours (dropping time), and half of the acetone solution was dropped so that the temperature of the liquid in the separable flask did not exceed 10° C., to obtain a first reaction liquid.
23.8 g of 98% by weight sulfuric acid (the mass ratio of sulfuric acid to cresol is 23.8 g x 0.98 ÷ 230 g = 0.10) was placed in the second dropping funnel. Then, the acetone solution remaining in the first dropping funnel was dropped into the first reaction liquid, and sulfuric acid was dropped from the second dropping funnel. At this time, the sulfuric acid was dropped so that the dropping was completed before the acetone solution, and the acetone solution was dropped over 0.5 hours (dropping time) so that the temperature of the liquid inside the separable flask did not exceed 10 ° C. After the dropping was completed, the mixture was stirred for 1 hour (reaction maturation time) while maintaining the internal temperature at 10 ° C., and the condensation reaction was further advanced, whereupon bisphenol C precipitated during the course of the dropping, and a slurry reaction liquid was obtained.

[Neutralization and washing process]
To the obtained slurry reaction liquid, 190 g of a 25% by mass aqueous sodium hydroxide solution was supplied, and the internal temperature was raised from 10° C. to 75° C. to dissolve the precipitated bisphenol C. After reaching 75° C., the mixture was left to stand to separate the oil and water, and the lower aqueous phase was extracted to obtain a first organic phase and a first aqueous phase. A part of the obtained first aqueous phase was taken out, and the amount of cresol sulfonic acid produced was confirmed by high performance liquid chromatography to be 2.74% by mass, and the substance amount relative to the supplied cresol was 2.05 mol %. Similarly, the amount of bisphenol C in the first organic phase was confirmed to be 82.8 mol % relative to the raw cresol, and the selectivity was 95.3 mol %.

[Cleaning process]
100 g of desalted water was added to the obtained first organic phase, and the temperature was raised to 80° C., mixed for 30 minutes, and allowed to stand to separate the oil and water. The aqueous phase was removed to obtain a second organic phase.
To the obtained second organic phase, 100 g of a 1.5% by mass sodium hydrogen carbonate solution was added, mixed at 80° C. for 30 minutes, and allowed to stand to separate into oil and water. The aqueous phase was removed to obtain a third organic phase.
Subsequently, the obtained third organic phase was repeatedly washed at 80° C. as shown below until the electrical conductivity of the aqueous phase to be removed was 10.0 μS/cm or less.

(First wash)
100 g of desalted water was added to the obtained third organic phase, mixed for 30 minutes, and allowed to stand, and the lower aqueous phase was removed to obtain an organic phase (washed once with water). The pH and electrical conductivity of the removed aqueous phase were pH 9.3 and 405.0 μS/cm.

(Second wash)
To the obtained organic phase (washed once with water), 100 g of desalted water was added, mixed for 30 minutes, allowed to stand, and the lower aqueous phase was removed to obtain an organic phase (washed twice with water). The pH and electrical conductivity of the removed aqueous phase were pH 8.5 and 50.5 μS/cm.

(3rd wash)
To the obtained organic phase (washed twice with water), 100 g of desalted water was added, mixed for 30 minutes, allowed to stand, and the lower aqueous phase was removed to obtain an organic phase (washed three times with water). The pH and electrical conductivity of the removed aqueous phase were pH 7.9 and 18.3 μS/cm, respectively.

(4th wash)
To the obtained organic phase (washed 3 times with water), 100 g of desalted water was added, mixed for 30 minutes, allowed to stand, and the lower aqueous phase was removed to obtain an organic phase (washed 4 times with water). The pH and electrical conductivity of the removed aqueous phase were pH 7.4 and 8.4 μS/cm.
The number of washing steps until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less was four.

[Crystallization process]
The obtained organic phase (washed four times with water) was cooled from 80° C. to 20° C. and maintained at 20° C. to precipitate bisphenol C. Thereafter, it was cooled to 10° C., and after the temperature reached 10° C., solid-liquid separation was performed using a centrifuge to obtain a crudely purified wet cake.
The resulting crude wet cake was washed by sprinkling 300 g of toluene thereon, and solid-liquid separation was carried out using a centrifuge to obtain a refined wet cake.
The obtained purified wet cake was subjected to distillation at an oil bath temperature of 100° C. under reduced pressure to remove low boiling fractions using an evaporator equipped with an oil bath, thereby obtaining 198 g of white bisphenol C (773 mmol, cresol based yield: 773 mmol × 2 ÷ 2130 mmol × 100 = 72.6 mol %).

Example 2
Example 1 was repeated except that the amount of sulfuric acid used in the first step was 23.8 g (the mass ratio of sulfuric acid to cresol was 23.8 g × 0.98 ÷ 230 g = 0.10) and the amount of sulfuric acid used in the second step was 71.3 g (the mass ratio of sulfuric acid to cresol was 71.3 g × 0.98 ÷ 230 g = 0.30).

The cresol sulfonic acid in the first aqueous phase was 0.18% by mass, and the amount of the substance relative to the fed cresol was 0.13 mol %. The amount of bisphenol C produced in the first organic phase was 80.3 mol % relative to the feed cresol, and the selectivity was 97.4 mol %.
The number of washings until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less was 3. Furthermore, 191 g (746 mmol, cresol-based yield: 746 mmol×2÷2130 mmol×100=70.0 mol%) of white bisphenol C was obtained.

Example 3
[First step]
The same procedure as in Example 2 was carried out to obtain a first reaction solution.

[Second step]
In a 500 mL Erlenmeyer flask, 50 g of toluene, 61 g (1,052 mmol) of acetone, and 5.4 g of dodecanethiol were mixed to prepare an acetone solution, which was then placed in the first dropping funnel. The acetone solution was dropped into the first mixed liquid over 1.0 hour (dropping time), and the entire amount of the acetone solution was dropped so that the temperature of the liquid in the separable flask did not exceed 10° C., thereby obtaining a first reaction liquid.
71.3 g of 98% by weight sulfuric acid (the mass ratio of sulfuric acid to cresol is 71.3 g x 0.98 ÷ 230 g = 0.10) was placed in the second dropping funnel. Then, the dropping of the acetone solution and the dropping of the sulfuric acid into the first reaction liquid were started at the same time. The acetone solution and the sulfuric acid were dropped into the first reaction liquid so that the temperature of the liquid in the separable flask did not exceed 10°C, thereby obtaining a second reaction liquid. After the dropping was completed, the mixture was stirred for 1 hour (reaction maturation time) while maintaining the internal temperature at 10°C, and the condensation reaction was further advanced, whereupon bisphenol C precipitated during the course of the reaction, obtaining a slurry reaction liquid.

[Neutralization and washing process]
The same procedure as in Example 2 was carried out. The cresol sulfonic acid content in the first aqueous phase was 0.25% by mass, and the amount of the substance relative to the fed cresol was 0.19 mol %. The amount of bisphenol C produced in the first organic phase was 79.6 mol % relative to the feed cresol, and the selectivity was 97.3 mol %.
The number of washings until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less was 3. Furthermore, 188 g (734 mmol, cresol-based yield: 734 mmol×2÷2130 mmol×100=68.9 mol%) of white bisphenol C was obtained.

Example 4
[First step]
The same procedure as in Example 2 was carried out to obtain a first reaction solution.

[Second step]
In a 500 mL Erlenmeyer flask, 50 g of toluene, 61 g (1,052 mmol) of acetone, and 5.4 g of dodecanethiol were mixed to prepare an acetone solution, which was then placed in the first dropping funnel. The acetone solution was dropped into the first mixed liquid over 1.0 hour (dropping time), and the entire amount of the dropping liquid was dropped so that the temperature of the liquid in the separable flask did not exceed 10° C., thereby obtaining a first reaction liquid.
71.3 g of 98% by mass sulfuric acid (the mass ratio of sulfuric acid to cresol was 71.3 g×0.98÷230 g=0.10) was placed in the second dropping funnel and added dropwise to the first reaction liquid so that the temperature of the liquid inside the separable flask did not exceed 10° C., thereby obtaining a second reaction liquid. After the dropwise addition was completed, the mixture was stirred for 1 hour (reaction maturation time) while maintaining the internal temperature at 10° C. to further advance the condensation reaction, during which bisphenol C precipitated, and a slurry reaction liquid was obtained.

[Neutralization and washing process]
The same procedure as in Example 2 was carried out. The cresol sulfonic acid content in the first aqueous phase was 0.12 mass %, and the amount of the substance relative to the fed cresol was 0.09 mol %. The amount of bisphenol C produced in the first organic phase was 80.1 mol % relative to the feed cresol, and the selectivity was 97.5 mol %.
The number of washings until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less was 3. Furthermore, 190 g (742 mmol, cresol-based yield: 723 mmol×2÷2130 mmol×100=69.7 mol%) of white bisphenol C was obtained.

Example 5
Example 1 was repeated except that the amount of sulfuric acid used in the first step was 18.2 g (the mass ratio of sulfuric acid to cresol was 18.2 g × 0.98 ÷ 230 g = 0.08) and the amount of sulfuric acid used in the second step was 76.8 g (the mass ratio of sulfuric acid to cresol was 76.8 g × 0.98 ÷ 230 g = 0.33).

The cresol sulfonic acid in the first aqueous phase was 0.07% by mass, and the amount of the substance relative to the fed cresol was 0.05 mol %. The amount of bisphenol C produced in the first organic phase was 74.2 mol % relative to the feed cresol, and the selectivity was 97.3 mol %.
The number of washings until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less was 3. Furthermore, 175 g (684 mmol, cresol-based yield: 684 mmol×2÷2130 mmol×100=64.2 mol%) of white bisphenol C was obtained.

<Comparative Example 1>
Example 1 was repeated except that the amount of sulfuric acid used in the first step was 95 g (the mass ratio of sulfuric acid to cresol was 95 g × 0.98 ÷ 230 g = 0.40) and the amount of sulfuric acid used in the second step was 0 g (the mass ratio of sulfuric acid to cresol was 0 g × 0.98 ÷ 230 g = 0).

The cresol sulfonic acid in the first aqueous phase was 6.93 mass %, and the amount of the substance based on the fed cresol was 5.19 mol %. The amount of bisphenol C produced in the first organic phase was 76.1 mol % based on the feed cresol, and the selectivity was 91.4 mol %.
The number of washings until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less was 6. Furthermore, 180 g (703 mmol, cresol-based yield: 703 mmol×2÷2130 mmol×100=66.0 mol%) of white bisphenol C was obtained.

Table 1 shows the mass ratio of sulfuric acid to cresol in the first mixed solution, the mass ratio of sulfuric acid dropped in the second step to cresol, the amount of cresol sulfonic acid in the first aqueous phase, the number of water washings until the electrical conductivity of the removed aqueous phase reached 10.0 μS/cm or less, and the bisphenol C yield for Examples 1 to 5 and Comparative Example 1.
As can be seen from Table 1, by using an appropriate amount of sulfuric acid in each of the first and second steps, the by-production of cresol sulfonic acid is suppressed, the number of water washing steps required to reduce the amount of remaining metal salts to a desired level is reduced, and bisphenol C can be obtained in good yield.

Example 6
In a 150 mL glass reaction vessel equipped with a stirrer and a distillation tube, 100.00 g (0.39 mol of bisphenol C) of the bisphenol C obtained in Example 2, 86.49 g (0.4 mol) of diphenyl carbonate, and 479 μL of a 400 ppm by mass aqueous solution of cesium carbonate were placed. The glass reaction vessel was depressurized to about 100 Pa, and then the operation of returning the pressure to atmospheric pressure with nitrogen was repeated three times to replace the inside of the reaction vessel with nitrogen. Thereafter, the reaction vessel was immersed in an oil bath at 200° C. to dissolve the contents.

The stirrer was rotated at 100 revolutions per minute, and the pressure in the reaction vessel was reduced from 101.3 kPa absolute pressure to 13.3 kPa over 40 minutes while distilling off the phenol by-product of the oligomerization reaction of bisphenol C and diphenyl carbonate in the reaction vessel. The pressure in the reaction vessel was then maintained at 13.3 kPa, and the transesterification reaction was carried out for 80 minutes while further distilling off the phenol. The temperature outside the reaction vessel was then raised to 250°C, and the pressure in the reaction vessel was reduced from 13.3 kPa absolute pressure to 399 Pa over 40 minutes, and the distilled phenol was removed from the system.

Then, the temperature outside the reaction tank was raised to 280°C, and the absolute pressure inside the reaction tank was reduced to 30 Pa, allowing the polycondensation reaction to proceed. The polycondensation reaction was terminated when the agitator in the reaction tank reached a predetermined stirring power. The time from raising the temperature to 280°C to the end of the polymerization (second-stage polymerization time) was 195 minutes.

The reactor was then pressurized with nitrogen to an absolute pressure of 101.3 kPa, and then the gauge pressure was increased to 0.2 MPa. The polycarbonate resin was extracted in the form of strands from the bottom of the reactor, yielding strand-shaped polycarbonate resin.

The strands were then pelletized using a rotary cutter to obtain pelletized polycarbonate resin.
The viscosity average molecular weight (Mv) of the obtained polycarbonate resin was 24,800, and the pellet YI was 7.8.

<Comparative Example 2>
Example 6 was carried out in the same manner as in Example 6, except that the bisphenol C obtained in Comparative Example 1 was used instead of the bisphenol C obtained in Example 2. When the bisphenol C obtained in Comparative Example 1 was used, the polymerization reaction did not proceed at all, and no polycarbonate resin was obtained.

The bisphenols produced by the bisphenol production method of the present invention are useful as raw materials for resins such as polycarbonate resins, epoxy resins, and aromatic polyester resins, as well as additives such as hardeners, color developers, and anti-fading agents, as well as bactericides, antibacterial agents, and antifungal agents.

Claims (10)

A method for producing bisphenol by reacting an aromatic alcohol with a ketone or an aldehyde in the presence of sulfuric acid, comprising the steps of:
The method includes a first step of preparing a first mixed liquid containing sulfuric acid and the aromatic alcohol, and a second step of supplying the ketone or aldehyde and sulfuric acid to the first mixed liquid,
a molar ratio of sulfuric acid to aromatic alcohol in the first mixture is 0.01 or more and 0.70 or less;
A method for producing bisphenol. The method for producing bisphenol according to claim 1, wherein in the second step, sulfuric acid is supplied after the ketone or aldehyde is supplied or in parallel with the supply of the ketone or aldehyde. 3. The method for producing bisphenol according to claim 1 or 2, wherein the amount of aromatic alcohol sulfonic acid produced when the first mixture is held at 50° C. for 3 hours from immediately after preparation is 5.0 mol % or less relative to the aromatic alcohol. 4. The method for producing bisphenol according to claim 1, wherein a ratio of a mass of sulfuric acid contained in the first mixed liquid in the first step to a total mass of the sulfuric acid contained in the first mixed liquid in the first step and the sulfuric acid supplied to the first mixed liquid in the second step is 0.05 or more and 0.90 or less. The method for producing bisphenol according to claim 1 , wherein the first mixed liquid further contains one or more selected from the group consisting of thiols, aromatic hydrocarbons, and aliphatic alcohols. 6. The method for producing bisphenol according to claim 1 , wherein in the second step, one or more selected from the group consisting of thiols, aromatic hydrocarbons, and aliphatic alcohols is further supplied to the first mixed liquid. The method for producing bisphenol according to any one of claims 1 to 6 , wherein the aromatic alcohol comprises at least one selected from the group consisting of phenol, orthocresol, and 2,6-dimethylphenol. The method for producing bisphenol according to any one of claims 1 to 7 , wherein the ketone comprises at least one selected from the group consisting of acetone, 3,3,5-trimethylcyclohexanone, cyclohexanone, and acetophenone. The method for producing bisphenol according to any one of claims 1 to 8, wherein the bisphenol comprises one or more selected from 2,2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)phenylethane, and 1,1 -bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane. A method for producing a polycarbonate resin, comprising a step of polymerizing a polycarbonate using a bisphenol produced by the method for producing a bisphenol according to any one of claims 1 to 9 .