KR100425646B1 - Method of preparing 4,4'-biphenol - Google Patents

Abstract

The present invention relates to a method for producing 4,4'-biphenol, and the method for preparing 2,6-dialkylphenol of formula (2) by oxidative bonding reaction and reduction reaction in the presence of an alkali catalyst A reaction mixture containing 3 ', 5,5'-tetraalkyl-4,4'-biphenol as a main component is formed, the reaction mixture is dissolved in a hydrophobic organic solvent, and water or a low concentration acidic aqueous solution is added to the obtained solution. And dealkylating the obtained product in the presence of an acidic catalyst.

[Formula 1]

[Formula 2]

[Formula 3]

(In Formulas 2 to 3, R is a linear or branched alkyl group having 3 to 8 carbon atoms.)

The present production method is suitable for use as a raw material for heat-resistant resins or aromatic liquid crystal polyester resins because the alkali metal content is low, the color is low, and high purity biphenols can be produced economically.

Description

Method for producing 4,4'-biphenol {METHOD OF PREPARING 4,4'-BIPHENOL}

[Industrial use]

The present invention relates to a method for producing 4,4'-biphenol, and more particularly to a method for producing 4,4'-biphenol, which can produce 4,4'-biphenol having high purity with high purity. It is about.

[Prior art]

4,4'-biphenol (henceforth "biphenol") is a compound which attracts attention as a raw material of a heat resistant resin or aromatic liquid crystal polyester resin in recent years. Methods for producing such biphenols include alkali decomposing 4,4'-disulfonated biphenyl or 4,4'-dihalogenated biphenyl, combining 4-halogenated phenol in the presence of an alkali or reducing agent and a noble metal catalyst, 2,6-dibutylbutylphenol is combined by oxidation in the presence of an alkali catalyst and then reduced to 3,3 ', 5,5'-tetraterbutylbutyl-4,4'-biphenol (hereafter referred to as "tetraturity" Butyl biphenol ”) and deisobutylated tetrabutyl butyl biphenol in the presence of an acidic catalyst.

Among the above-mentioned methods, a method for deisobutylating tetrabutyl butylbiphenol is mainly used. Examples thereof include Japanese Patent Laid-Open No. 51-91238, Japanese Patent Laid-Open No. 55-72131, and Japanese Patent Laid-Open No. 58-189127 Japanese Patent Publication No. 60-23338, Japanese Patent Publication No. 63-301837, Japanese Patent Publication No. 64-83034, Japanese Patent Publication No. 64-90147, Japanese Patent Publication No. Hei 1-102037, Japanese Patent Publication Hei 2-169530, Japanese Patent Laid-Open No. Hei 10-212256, U.S. Patent 4,487,978, U.S. Patent 4,891,453, U.S. Patent 4,902,837, U.S. Patent 5,099,076 and U.S. Patent 5,324,868.

Briefly and briefly described the technical contents described in the above patents, the first step is to use a 2,6-dibutyl butyl phenol in the presence of a catalyst by the oxidative bond reaction using oxygen or air as an oxidizing agent A mixture of 3,3 ', 5,5'-tetraterbutylbutyl-4,4'-biphenoquinone (hereinafter referred to as "tetratertarybutylbiphenoquinone") is produced, and in a second step in the mixture After the tetrabutyl butyl biphenoquinone is reduced to produce tetrabutyl butyl biphenol, the third step is to debutylate the tetrabutyl butyl biphenol to produce a biphenol.

In this process, as the catalyst used in the oxidative bonding reaction process, alkali catalysts of sodium hydroxide or potassium hydroxide shown in Japanese Patent Application Laid-open No. Hei 10-273459 and Japanese Patent Application Laid-open No. Hei 10-273460 are generally used because of high economical efficiency. In the oxidative bonding reaction process, a method of pressurizing air with an oxidizing agent at a temperature of about 200 ° C is mainly used.

In addition, a reducing agent such as hydrogen may be used in the second reduction reaction, but as shown in Japanese Patent Laid-Open No. 4-154738, 2,6-dibutylbutylphenol, which is a raw material of the first stage oxidation reaction, is used as a reducing agent. The most economical method is to simultaneously perform the oxidation reaction and the reduction reaction.

The third step, debutylation, is generally carried out in the presence of an acidic catalyst and an organic solvent. In addition, studies have been conducted to increase the reaction rate in the second half of the reaction to increase the efficiency of the reaction. For example, Japanese Patent Laid-Open No. 10-212256 discloses a novel phenol as a acceptor of tertiary butyl group in the second half of the debutylation reaction. A method of accelerating the rate of debutylation reaction by adding an alkyl exchange reaction is described, and Japanese Patent Laid-Open No. 63-301837 and Japanese Patent Laid-Open No. 5-331087 describe the final temperature of the debutylation reaction. A method of completing the reaction by increasing to 250 ° C. is described.

However, the biphenols prepared by the above-mentioned methods contain excessive amounts of alkali catalyst metals used. Therefore, in order to lower the amount of alkali catalyst metal to the limit that is acceptable as a raw material of heat resistant resin or aromatic liquid crystal polyester resin, complex purification process must be carried out for a long time after the biphenol is produced, and expensive activated carbon must be used, which is uneconomical problem. There is this. In addition, in the debutylation reaction for the purpose of neutralizing the alkali catalyst used in the oxidation-bonding reaction, the non-phenol produced by the addition of the acid catalyst in excess of the required amount, the content of the acid catalyst is high and the alkali catalyst metal is high. There is a problem that the color of the deterioration.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing high purity 4,4'-biphenol having a low content of alkali metals and acidic catalytic ions.

Another object of the present invention is to provide a method for producing 4,4'-biphenol having excellent color.

In order to achieve the above object, the present invention provides a 3,3 ', 5,5'-tetraalkyl- of the general formula (3) by oxidative bonding reaction and reduction reaction of 2,6-dialkylphenol of the general formula (2) in the presence of an alkali catalyst Forming a reaction mixture comprising 4,4'-biphenol as a main component; Dissolving the reaction mixture in a hydrophobic organic solvent; Water or low concentration acidic aqueous solution is added to the obtained solution; It provides a process for producing 4,4'-biphenol of the formula (1) comprising the step of dealkylation reaction of the mixture obtained in the presence of an acidic catalyst.

[Formula 1]

[Formula 2]

[Formula 3]

(In Formulas 2 to 3, R is a linear or branched alkyl group having 3 to 8 carbon atoms.)

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method for producing 4,4'-biphenol (hereinafter referred to as "biphenol") of high heat resistance resin or aromatic liquid crystal polyester resin with high purity having low alkali metal content. As a result, biphenols produced by this production method exhibit excellent color.

In the production method of the present invention, first, 2,6-dialkylphenol of the following formula (2) is subjected to oxidative bonding and reduction in the presence of an alkali catalyst.

[Formula 2]

(In Formula 2, R is a linear or branched alkyl group having 3 to 8 carbon atoms)

The 2,6-dialkylphenols used as starting materials can form the final product biphenols, such as 2,6-dibutylbutylphenol, 2,6-distillylmil group and 2,6-ditertionalhexyl group. In addition, although the compound which belongs to 2, 6- dialkyl phenol can be used, 2, 6-dibutyl butyl phenol is the most preferable from an advantage of economics and process efficiency. 2,6-dibutylbutylphenol is generally prepared by addition reaction of isobutylene to phenol using an aluminum compound such as aluminum phenolate as a catalyst, and removal and purification of the aluminum compound as a catalyst.

The alkali catalyst may be any compound which exhibits alkalinity while having the characteristics of a catalyst which promotes an oxidative bond and a reduction reaction of 2,6-dialkylphenol without participating in the reaction. Sodium hydroxide or potassium hydroxide can be used. The alkali catalyst is preferably used in an amount of 0.5 to 3% by weight based on the weight of 2,6-dialkylphenol. If the amount of alkali catalyst used is less than 0.5% by weight, the reaction rate is markedly reduced, and if it exceeds 3% by weight, there is no additional advantage, and moreover, the process for removing the alkali catalyst is complicated, and the alkali catalyst is a final product. It is not preferable because it may remain as an impurity.

The oxidative bonding reaction is performed by adding an alkali catalyst to 2,6-dialkylphenol, and then adding oxygen gas or air as an oxidizing agent at a high temperature, and according to this process, 3,3 ', 5,5 '-Tetraalkyl-4,4'-biphenol (hereinafter referred to as "tetraalkylbiphenol") and 3,3'5,5'-tetraalkyl-4,4'-biphenoquinone (hereinafter referred to as "tetraalkyl ratio" Phenoquinone ”). When 2,6-dibutylbutylphenol is used as the 2,6-dialkylphenol, 3,3 ', 5,5'-tetratertarybutyl-4,4'-biphenol and 3,3', 5, 5'-tetratertarybutyl-4,4'-biphenoquinone is prepared. As for the said reaction temperature, 170-200 degreeC is preferable. If the reaction temperature is less than 170 ℃ reaction rate is slow, the production rate of tetraalkylbiphenoquinone is significantly increased, which is undesirable, if the reaction temperature exceeds 200 ℃, the color becomes darker to complicate the after-treatment process to remove the color, Dealkylation reactions may occur and are not preferred. In addition, the amount of oxidant added is preferably 80 to 300 ml / min, and when the amount is less than 80 ml / min, the reaction time is increased by two times or more, and when it exceeds 300 ml / min, the reaction time is shortened but the oxygen concentration in the reactor is increased. It is not desirable to increase the risk of explosion.

[Formula 3]

(In Formula 3, R is a linear or branched alkyl group having 3 to 8 carbon atoms.)

Subsequently, if the reaction continues while injecting an inert gas such as nitrogen gas, the produced tetraalkylbiphenoquinone and unreacted 2,6-dialkylphenol react to reduce the tetraalkylbiphenoquinone to tetraalkylbiphenol. The reaction is suitably carried out at 210 to 230 ° C., which is slightly higher than the oxidative bonding reaction. As such, when 2,6-dialkylphenol is used in excess of the desired amount, for example 5 to 10% by weight, to reduce the tetraalkylbiphenoquinone, tetraalkylbiphenol can be obtained using a simple process and apparatus. It is preferable to increase the yield.

The reactant obtained by the said process contains the tetraalkyl biphenol as a main component, and the alkali metal compound used as a catalyst is mixed. Hydrophobic organic solvent is added thereto to completely dissolve the reaction.

As the hydrophobic organic solvent, at least one solvent selected from a phenol compound or an aromatic hydrocarbon compound having at least one alkyl group as a substituent is preferable. Or a mixed solvent each selected from a phenol compound and an aromatic hydrocarbon compound having at least one or more alkyl groups as substituents.

It is preferable that the phenol compound is added in a weight ratio range of 1 to 4 times with respect to tetraalkyl biphenol, and the aromatic hydrocarbon compound is added in a weight ratio of 0.7 to 2 times with respect to tetraalkyl biphenol. When the said phenol compound or aromatic hydrocarbon compound is used in the said range, tetraalkyl biphenol is melt | dissolved completely and it is preferable.

Since the phenolic compound having at least one alkyl group as a substituent may be used as a solvent in a debutylation process, which is the next step, any phenolic compound having at least one alkyl group as a substituent may be used. Monobutyl butylphenol, 2,4-dibutyl butyl phenol, 2,5-dibutyl butyl phenol, 2,6-diary of butyl phenol, 3-tert butyl phenol and 4-tert butyl phenol 1 or more types of the butyl phenol phenols of a butyl phenol and a 3, 5- dibutyl butyl phenol can be used. It is preferable to use each phenolic compound purely, but as an impurity, phenol is permissible up to 5 weight% of the phenolic compound weight. In order to perform the present invention smoothly, it is preferable to use at least 50 wt% of monobutyl butylphenol as the phenol compound. More preferably, the content of monotertiary phenols is 60 to 90% by weight, most preferably 65 to 85% by weight.

Since the aromatic hydrocarbon compound may act as an impurity in the next step of dealtylation, it is preferable to use one that can be easily removed by distillation when the neutralization process is completed. As the aromatic hydrocarbon compound having such physical properties, at least one compound selected from benzene, toluene, xylene, trimethylbenzene, diethylbenzene, cumene, biphenyl, ethylbiphenyl, naphthalene, methylnaphthalene or tetrahydronaphthalene is used. Preferably, benzene, toluene or xylene, most preferably toluene.

Subsequently, water or a low concentration of an acidic aqueous solution of 5 to 20% is added to the obtained mixture. At this time, the aqueous solution layer and the organic solvent layer are separated, and the neutral metal salt is present in the aqueous solution layer while neutralizing the alkali metal compound used as the catalyst by water or acid to form an organic solvent insoluble and water-soluble neutral salt. The alkali metal compound can then be removed by removing the aqueous solution layer. When the concentration of the low concentration acidic aqueous solution is less than 5%, the input amount of the low concentration acidic aqueous solution is more than necessary for neutralization, and when it exceeds 20%, the reaction system becomes an acid condition, which causes dealkylation and reactor corrosion problems. not.

The addition amount of the low concentration acidic aqueous solution is required only to the extent (equivalent) to quantitatively neutralize the alkali metal compound used in the oxidative bonding reaction, when less than that is not preferable because the neutralization does not occur completely, the reaction system is acid conditions when used in excess This leads to dealkylation and reactor corrosion problems. As the acidic aqueous solution, a low concentration aqueous solution of an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid may be selected, but dilute sulfuric acid is preferable.

The neutralization process is preferably carried out at a temperature below the boiling point of the mixture, that is, 70 to 95 ℃ for effective neutralization reaction.

Subsequently, the dealkylation reaction of tetraalkyl biphenol in presence of an acidic catalyst produces biphenol of following General formula (1).

[Formula 1]

Biphenols produced during the dealkylation reaction have a very high melting point, and an organic solvent should be used to smoothly proceed the dealkylation reaction while maintaining fluidity of the reaction phase. At this time, the physical properties required for the organic solvent used are high solubility to tetraalkylbiphenol, dispersion ability to the resulting biphenol, do not interfere with the activity of the acidic catalyst used, isoalkyl generated by dealkylation due to high boiling point It is easy to separate from ene, there is no chemical change before and after the dealkylation reaction, and it is easy to recover and use repeatedly. As the organic solvent having such physical properties, alkylphenols are most preferred.

That is, the dealkylation process is carried out in the presence of an acidic catalyst by dissolving tetraalkylbiphenol in an alkylphenol solvent.

As the acidic catalyst, inorganic acids such as sulfuric acid, acidic earth earth or heteropoly acids, organic acids such as sulfonic acids or cation exchange resins are used.

Examples of the heteropolyacids include tungstic acid, tungsten silicic acid, and molybdic acid, and the sulfonic acids include methanesulfonic acid, fluorinated methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, benzenesulfonic acid chloride, toluenesulfonic acid, xylenesulfonic acid, and alkyls. Benzene sulfonic acid, phenol sulfonic acid, phenol disulfonic acid, naphthalene sulfonic acid or naphthalene disulfonic acid. Of these acidic catalysts, sulfuric acid or sulfonic acids are preferred in view of catalytic activity, separation from biphenols produced during the reaction, and economical efficiency. Among these, benzene sulfonic acid, toluene sulfonic acid, xylene sulfonic acid, naphthalene sulfonic acid or phenol sulfonic acid is preferable, and most preferably, benzene sulfonic acid, toluene sulfonic acid or xylene sulfonic acid. The use range of these acidic catalysts is preferably 0.3 to 5% by weight relative to tetraalkylbiphenol. When the amount of acidic catalyst used is less than 0.3% by weight, the reactivity is lowered, yield and reaction rate are lowered. When the amount of acidic catalyst is used is more than 5% by weight, the reaction rate is increased. (Neutralizing agent usage) and the process is complicated. That is, the amount over 5% by weight reduces the use effect in the production process.

The temperature of the dealkylation reaction is determined in consideration of the type of acidic catalyst, the amount of use and the reaction rate. In particular, the temperature of the dealkylation reaction is closely related to the yield, color, and purity of the resulting biphenol. The preferred temperature range in consideration of these factors is 170 to 220 ° C and more preferably 180 to 200 ° C.

It is preferable to carry out the dealkylation reaction while injecting an inert gas such as nitrogen gas to increase the yield of biphenols. In general, the dealkylation reaction is an endothermic reaction and a reversible reaction, so if the reaction temperature is high, the reaction occurs vigorously at the beginning of the reaction, thereby rapidly producing the desired product biphenol and the addition product isoalkylene, and the resulting biphenol is alkyl. Since the solubility in phenol solvents is low, it crystallizes and precipitates in the solvent. In addition, as the reaction proceeds, as the concentration of isoalkylene in the solvent increases, solubility in the solvent decreases and precipitates in the solvent. As such, since the biphenol and the isoalkylene are precipitated so that they do not participate in the reversible reaction, the dealkylation reaction can proceed more actively. However, as the reaction continues, the reversible reaction between biphenol and isoalkylene dissolved in the solvent and tetraalkylbiphenol, which is a raw material, does not precipitate at the end of the reaction and reaches an equilibrium state, thereby not reaching the complete end point. In the present invention, in order to solve this problem, a step of removing isoalkylene by adding an inert gas was carried out, it was possible to further increase the yield of biphenols.

The crystallized biphenol after the dealkylation reaction is present in a precipitated and dispersed state in an organic solvent and is obtained by cooling the temperature of the reaction mixture to a range of 110 to 80 ° C. In order to remove impurities such as colored components contained in the biphenol, it is preferable to wash with the same organic solvent, the biphenol produced by the present manufacturing method has the advantage of easy filtration and washing because of the large crystal size.

The prepared biphenol has a higher purity than the biphenol prepared by the conventional method, but in order to use it as a raw material of a heat resistant resin or an aromatic liquid crystal polyester resin, a very high purity is required, so a purification process should be performed. However, the purity of the biphenol prepared by the above method is higher than that of the conventional biphenol, so that the purification process can be carried out in a short time without using expensive activated carbon, which is economical. The method for purifying biphenols is most preferably recrystallized in a solvent. When the distillation process is used as a method for purifying biphenols, the boiling point of biphenols is too high and impossible, and washing alone is not enough.

Examples of the solvent used for recrystallization include ketones of acetone, methyl ethyl ketone, methyl isobutyl ketone or diethyl ketone, methyl alcohol, ethyl alcohol, 1-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol and isobutyl Alcohols of alcohol or tertiary butyl alcohol, phenol, 2-cresol, 3-cresol, 4-cresol, 2-tertiarybutylphenol, 3-tertiarybutylphenol, 4-tertiarybutylphenol, 2-chloride phenol or Phenols and water of 4-chloride phenol can be used, and it is preferable to mix and use 2 or more types out of these. In particular, a mixed solvent of acetone and water is most preferred because of high solubility in biphenols. The amount of the solvent used is 1 to 3% by weight based on the weight of biphenol.

Activated carbon may be used for color removal in the recrystallization process, but activated carbon is not preferable because it is expensive to process and activated carbon fine particles which are not filtered out may cause deterioration of the biphenol.

The biphenol obtained according to the preparation method of the present invention is in the form of a white crystalline powder having a melting point in the range of 282 to 283 ° C, an alkali metal content of less than 1 ppm, and an APHA of a 30% dimethyl sulfoxide solution is 30 or less. In the present specification, APHA is a unit representing the color of a solid compound, and mainly, after dissolving the solid compound in a solvent, the transmittance is measured to determine a value. The criterion is pure water with an APHA of zero. That is, APHA of 30% dimethyl sulfoxide solution is a value obtained by dissolving biphenol in 30% dimethyl sulfoxide solution and then measuring the transmittance, and it is an anti-coloring effect compared to the biphenol prepared by the conventional method with APHA of about 100. It can be seen that very good. In the present invention, since the alkali metal catalyst used in the oxidative bonding reaction is removed by neutralization and washing before the dealkylation reaction step, the metal content included in the final product is small, and the coloring prevention effect is also excellent.

As described above, the production method of the present invention was carried out a step of removing alkali metal compounds, which are alkali catalysts, after oxidation and reduction reactions in order to reduce the color problem of biphenols and to reduce the metal content. Conventionally, a method for producing a biphenol is performed by neutralizing and removing an alkali catalyst by using an excessive amount of an acidic catalyst used as a dealkylation reaction catalyst, without performing an alkali catalyst removal step separately. However, in the conventional method, the neutralization salts generated in the neutralization process of the alkali catalyst and the acidic catalyst remain in the final product, and the color becomes poor, and the purification process becomes long and complicated, such as washing and recrystallization several times after the reaction. There was a problem. In addition, it is difficult to obtain the purity (color) and the metal content of the required product even when the purification process is long and complicated.

In the present invention, in order to solve this problem, the hydrophobic organic solvent that can dissolve both the organic material and the neutralized salt prepared by focusing on the difference in the solubility of the neutralized salt and the organic material produced in the neutralization process of the alkali catalyst and the acidic catalyst. After dissolving in, a step of adding a dilute acid aqueous solution was performed. The neutralized salt formed according to this process was extracted toward the dilute acid aqueous solution so that all neutralized salts could be removed.

For a more clear description of the invention, reference is made to specific examples and comparative examples. The percentages indicated in each of the examples described means weight percent unless otherwise indicated, and the balance except for the amount of each component described in each composition below means acceptable impurities.

(Example 1)

In a 2-liter four-necked glass flask with a stirrer, thermometer and reflux condenser, a gas inlet tube was installed with one end almost touching the bottom of the flask. 1,238 grams of 2,6-dibutylbutylphenol was added to the glass flask. The glass flask was heated and dissolved when the temperature of the contents reached about 50 ° C., so that stirring was started at this temperature, 12.4 grams of sodium hydroxide in powder form was added, and the temperature was raised to 180 ° C. When the temperature reached 180 ° C., oxygen gas was introduced into the glass flask through the gas suction tube at a rate of 150 milliliters per minute. After about 5 hours, when the content of 2,6-dibutylbutylphenol in the reaction reaches 12%, the content of tetrabutylbutylbiphenoquinone is 3% and the content of tetrabutylbutyl biphenol is 84%, The input was stopped and replaced with nitrogen gas. The reaction temperature was further raised to 220 ° C. and reacted with stirring. The reaction was terminated after about 1 hour. The analysis result was 90% of tetraisobutyl biphenol, 0.2% of tetrabutyl butyl biphenoquinone and 6% of 2,6-dibutyl butylphenol.

The reaction mixture was placed in a stirrer, thermometer, dropping flask, reflux condenser and three liter four-necked glass flask with outlet at the bottom, and tertiary butylphenol mixture (2-tert-butylphenol 2.8%, 3-tertary) 5% butylphenol, 77.7% 4-tert-butylphenol and 9.4% 2,4-dibutylbutylphenol) were added to 610 grams and 610 grams of toluene and heated to 90 ° C. so that the contents were uniform. It was. While maintaining the temperature of the contents, 173.8 grams of dilute sulfuric acid at 9.1% concentration was added using a dropping flask, followed by stirring for 20 minutes. After the stirring was stopped and left for 30 minutes to completely separate the layers, the outlet of the bottom of the flask was opened to separate and remove the aqueous layer of the bottom of the flask. Subsequently, while maintaining the temperature, 158 grams of distilled water was added using a dropping flask, the mixture was stirred for 20 minutes, and the aqueous solution layer was separated and removed in the same manner as above.

Toluene was distilled off from the reaction mixture of the organic layer and transferred to a 3-liter four-necked glass flask equipped with a stirrer, thermometer, gas inlet and reflux condenser and added 6.2 grams of paratoluenesulfonic acid hydrate. The upper part of the reflux condenser was connected to a cooling collection flask cooled by a mixture of dry ice and acetone in order to capture the isobutylene generated.

Nitrogen gas was added little by little through the gas inlet to increase the temperature of the reactants. When the temperature reached 140 ° C., the contents started to flow, so the stirrer was operated slowly. Initially, the reaction was vigorous and the amount of isobutylene gas generated was large, so that the rate of temperature increase was slowly controlled and increased to 190 ° C. after about 3 hours. The reaction mixture initially turned into an opaque dispersion which was uniform and transparent but immediately with the production of biphenols. After 3 hours at this temperature, the rate of isobutylene production decreased. The reaction mixture was collected and analyzed by HPLC to measure the production rate of biphenol. As a result, it was 85 mol% with respect to tetrabutyl butyl biphenol as a raw material. Subsequently, the stirring speed and the nitrogen gas input were increased to release all isobutylene remaining in the reaction solution as much as possible. After 2 hours, the amount of isobutylene was extremely reduced. The reaction mixture was collected again and analyzed by HPLC. The yield was 96 mol%. At this time, the reaction was terminated by cooling. As a result of analyzing the reactants, the composition other than biphenols was 2% monobutyl butyl biphenol and 1% dibutyl butyl biphenol, and no tributyl butyl biphenol and tetrabutyl butyl biphenol as raw materials were detected.

In addition, the tertiary butylphenol mixture used as an organic solvent contains 2.7% of 2-butylbutylphenol, 5% of 3-butylbutylphenol, 72% of 4-butylbutylphenol, and 12% of 2,4-dibutylbutylphenol. Included.

The reaction mixture was cooled to 90 ° C. and the crystallized and precipitated biphenol was filtered, and the filtrate was washed with 716 grams of the same tertiary butylphenol mixed solvent used for the debutylation reaction.

The filtrate was added to 1,900 grams of acetone in water and dissolved by heating, and insoluble impurities were removed by thermal filtration.

After thermal filtration, the solution was cooled to 10 ° C., and the precipitated biphenol was filtered, washed with a small amount of acetone, and dried. The biphenol thus obtained was 365 grams.

In addition, the acetone aqueous solution collected after filtration contained biphenol, so that the solution was concentrated to about 1/2 and cooled, and the biphenol was recovered by filtration. This biphenol was slightly lower in purity, so it was washed and dried in an amount greater than the proportional acetone aqueous solution. The biphenol additionally obtained in this way was 70 grams.

Combined with the biphenols obtained above, the total recovery was 435 grams (86.1% of the theoretical yield calculated from tertarybutyl biphenol as a raw material). The purity was 99.9%, the APHA of the 30% dimethylsulfoxide solution was 23, and the sodium content was less than 1 ppm.

It was confirmed that the aromatic liquid crystal polyester resin prepared using about 15% of this biphenol was light color and there was no problem in using it as a raw material of the aromatic liquid crystal polyester.

The tertiary butylphenol mixture as an organic solvent recovered from the reaction mixture by filtration and distillation was 1,770 grams, and the composition contained 2-tert-butyl phenol 2.7%, 3-tert-butyl phenol 5%, 4-tert-butyl phenol It contains 80% and 11% 2,4-dibutylbutylphenol and it has been experimentally found to be reusable in the production of biphenols.

The recovery rate of isobutylene obtained by the debutylation reaction was 90% based on the theoretical value of the tetrabutylbutyl biphenol raw material, and 2,6-dibutylbutylphenol was prepared using the recovered isobutylene. There was no problem using it as a starting material for phenol.

(Example 2)

430 grams of purified biphenols (85.1% of theory yield) were obtained in the same manner as in Example 1 except that the same amount of potassium hydroxide was used instead of 12.4 grams of sodium hydroxide as an oxidation bonding reaction catalyst. The purity was 99.9%, the APHA of the 30% dimethylsulfoxide solution was 25, and the potassium content was less than 1 ppm.

It was confirmed that the aromatic liquid crystal polyester resin prepared by using about 15% of this biphenol was light color and there was no problem in using it as a raw material of the aromatic liquid crystal polyester.

In addition, the tertiary butylphenol mixture recovered in the same manner as in Example 1 can be used repeatedly and there is no problem in using the recovered isobutylene as a raw material of 2,6-dibutylbutylphenol.

(Comparative Example 1)

In the same manner as in Example 1, a 2-liter four-necked glass flask equipped with a stirrer, a thermometer, and a reflux condenser was installed so that one end almost reached the bottom of the flask. 1,238 grams of 2,6-dibutylbutylphenol was added thereto. The glass flask was heated to dissolve when the temperature of the contents reached about 50 ° C., so that stirring was started at this temperature, and then 12.4 grams of sodium hydroxide in powder form was added, followed by heating. When the temperature reached 180 ° C., oxygen gas was introduced at a rate of 150 milliliters per minute through the gas inlet tube. After about 5 hours, when the content of 2,6-dibutylbutylphenol in the reaction reaches 12%, the content of tetrabutylbutylbiphenoquinone is 3% and the content of tetrabutylbutyl biphenol is 84%, oxygen gas Was stopped and replaced with nitrogen gas. The reaction temperature was further raised to 220 ° C. and reacted with stirring. The reaction was terminated after about 1 hour. The analysis result was 90% of tetraisobutyl biphenol, 0.2% of tetrabutyl butyl biphenoquinone and 6% of 2,6-dibutyl butylphenol.

The reaction mixture was transferred to a 3-liter four-necked glass flask equipped with a stirrer, thermometer, gas inlet and reflux condenser and tertiary butylphenol mixture (2-tertarybutylphenol 2.8%, 3-tertarybutylphenol 5%, 1,054.9 grams and 65.2 grams of paratoluenesulfonic acid hydrate were added to 77.7% of 4-tert-butylphenol and 9.4% of 2,4-dibutylbutylphenol). In order to capture the isobutylene generated in the upper part of the reflux condenser, a cooling collection flask cooled by a dry ice and acetone mixture was connected.

Nitrogen gas was added little by little through the gas inlet to increase the temperature of the reactants. When the temperature reached 110 ° C., the contents started to flow, so the stirrer was operated slowly. Initially, the reaction was vigorous and the amount of isobutylene gas was generated. Therefore, the rate of temperature increase was controlled slowly, and after about 3 hours, the temperature was raised to 190 ° C. The reactants were heterogeneous and opaque from the outset, and the rate of isobutylene production decreased after 4 hours at this temperature. The reaction mixture was collected and analyzed by HPLC. The yield of the biphenol was measured, and 83 mol% of the tetrabutyl butyl biphenol as a raw material was obtained. Subsequently, the stirring speed and the input amount of nitrogen gas were increased to release all isobutylene remaining in the reaction solution as much as possible. After 2 hours, the amount of isobutylene was extremely reduced. The reaction mixture was collected and analyzed by HPLC. The yield was 94 mol%. At this time, the reaction was terminated by cooling. As a result of analyzing the reactants, the composition other than biphenols was 3% monobutyl butyl biphenol and 2% dibutyl butyl biphenol, and no tributyl butyl biphenol and tetrabutyl butyl biphenol as raw materials were detected.

From the next step was carried out in the same manner as in Example 1 to obtain 395 grams purified biphenol. The purity was 99.8%, the APHA of the 30% dimethylsulfoxide solution was 80 and the sodium content was 76 ppm.

The aromatic liquid crystalline polyester resin prepared using about 15% of this biphenol had coloration and slight foaming phenomenon of the specimen during high temperature treatment.

The composition of the tertiary butylphenol mixture as the organic solvent recovered from the reaction mixture by filtration and distillation includes 3% 2-tert-butyl phenol, 5% 3-tert-butyl phenol, 60% 4-tert-butyl phenol, It contains 20% 2,4-dibutylbutylphenol and a small amount of phenol and has been found to be reusable by the experiment.

In addition, isobutylene recovered in the same manner as in Example 1 had no problem in use as a raw material of 2,6-dibutylbutylphenol.

(Comparative Example 2)

An experiment was carried out in the same manner as in Comparative Example 1 except that the same amount of potassium hydroxide was used instead of 12.4 grams of sodium hydroxide as the oxidation bonding reaction catalyst used in Comparative Example 1 to obtain 400 grams of purified biphenol. The purity was 99.7%, the APHA of the 30% dimethylsulfoxide solution was 70 and the potassium content was 210 ppm.

The aromatic liquid crystalline polyester resin prepared using about 15% of this biphenol is colored and has a problem of being used as a raw material of the aromatic liquid crystalline polyester because the foaming phenomenon of the specimen was observed severely at high temperature.

In addition, the tertiary butylphenol mixture recovered in the same manner as in Example 1 can be used repeatedly and there is no problem in using the recovered isobutylene as a raw material of 2,6-dibutylbutylphenol.

(Comparative Example 3)

300 grams of biphenol obtained in Comparative Example 1 was dissolved in 350 grams of acetone aqueous solution. 12 grams of activated carbon was mixed and stirred therein, followed by thermal filtration to remove activated carbon. The filtrate was cooled to 10 ° C. to crystallize biphenol, filtered, washed with a small amount of acetone aqueous solution and dried to obtain 165 grams of purified biphenol. The purity was 99.9%, the APHA of the 30% dimethylsulfoxide solution was 17 and the sodium content was 1.5 ppm.

The aromatic liquid crystalline polyester resin manufactured using this biphenol 15% could be used as a raw material of aromatic liquid crystalline polyester as pale color.

However, this process consumed 12 grams of activated carbon and produced a 45% reduction in biphenol yield. Accordingly, the biphenol obtained in Comparative Example 3 is suitable for use as a raw material of heat resistant resins or aromatic liquid crystal polyester resins, but the economical efficiency of the refining process is lower than that of the present invention, and contamination due to activated carbon used to improve low purity is achieved. There is a possibility of a problem.

The production method of the present invention is suitable for use as a raw material for heat-resistant resins or aromatic liquid crystal polyester resins because the alkali metal content is low, the color is low, and high purity biphenols can be produced economically.

Claims (9)

Oxidative bonding reaction and reduction reaction of 2,6-dialkylphenol of the following formula (2) in the presence of an alkali catalyst to 3,3 ', 5,5'-tetraalkyl-4,4'-biphenol of the following formula (3) Forming a reaction mixture comprising; Dissolving the reaction mixture in a hydrophobic organic solvent which is at least one solvent of a phenol compound or an aromatic hydrocarbon compound having at least one alkyl group; Water or low concentration acidic aqueous solution is added to the obtained solution; Dealkylation reaction of the obtained product in the presence of an acidic catalyst Method for producing a 4,4'-biphenol of the formula (1) comprising a step. [Formula 1] [Formula 2] [Formula 3] (In Formulas 2 to 3, R is a linear or branched alkyl group having 3 to 8 carbon atoms.) The compound of claim 1, wherein the 2,6-dialkylphenol is 2,6-dibutylbutylphenol, and the 3,3 ', 5,5'-tetraalkyl-4,4'-biphenol is 3,3'. A method for producing 4,4'-biphenol, which is, 5,5'-tetratertarybutyl-4,4'-biphenol. delete The method for producing 4,4'-biphenol according to claim 1, wherein the phenol compound having at least one or more alkyl groups contains 50% by weight or more of monoalkylphenols. The method of claim 1, wherein the aromatic hydrocarbon compound is one or more compounds selected from benzene, toluene, xylene, trimethylbenzene, diethylbenzene, cumene, biphenyl, ethylbiphenyl, naphthalene, methylnaphthalene or tetrahydronaphthalene Process for the preparation of phosphorus 4,4'-biphenol. The method of claim 5, wherein the aromatic hydrocarbon compound is selected from the group consisting of benzene, toluene and xylene. The method for producing 4,4'-biphenol according to claim 1, wherein the alkali catalyst is sodium hydroxide or potassium hydroxide. The method of claim 1, wherein the dealkylation reaction is carried out while injecting an inert gas. The method for producing 4,4'-biphenol according to claim 1, wherein the low concentration acidic aqueous solution is dilute sulfuric acid.