JPH0621086B2 - Process for producing 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxydiphenyl - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenyl (hereinafter sometimes abbreviated as TMDDP). is there.

According to the method of the present invention, the target TMDDP can be produced with high selectivity and high yield.

The TMDDP obtained by the method of the present invention is a useful compound as a raw material for an epoxy compound and a stabilizer for petroleum products.

It is known that phenols with substituents can undergo self-condensation products such as diphenoquine, 4,4'-dihydroxydiphenyl and polyphenylene oxides by oxidative coupling.

However, the preparation of 4,4'-dihydroxydiphenyls from alkylphenols, for example US Pat.
No. 80,686, British Patent No. 2,047,232, etc., require an organic solvent or a stoichiometric amount of an organic reagent, and require oxidation coupling of 4,4 ′.
-Difficult to stop at the dihydroxydiphenyl stage,
The main products were mostly diphenoquinone and polyphenylene oxide.

In addition, using a copper amine complex as a catalyst in a water solvent,
A method for producing 4'-dihydroxydiphenyl (Japanese Patent Laid-Open No. 63-65834) has also been announced, but 600
Manufacturing on an industrial scale seems difficult, because a special apparatus such as a stirrer having a performance of 0 to 10000 rpm and a wrinkled Morton flask is required. And
When this special production method is carried out by an apparatus such as that used in the industrially processable method of the present invention, the conversion of alkylphenol and the yield of 4,4'-dihydroxydiphenyl are low, which is not a satisfactory level. It was

On the other hand, as a method of reducing diphenoquinone to dihydroxydiphenyl, for example, a method of reducing using a reducing agent such as sodium dithionite, hydrazine, etc. are known, in any case in the presence of an organic solvent The reduction reaction had to be carried out, which was industrially disadvantageous.

Further, JP-A-60-25944 proposes a method for producing 4,4'-bis- (2,6-di-t-butylphenol), but this method uses a specific organic solvent. , Which is to be reacted in a high temperature range, is not applicable to a water solvent system, and is industrially advantageous in a water solvent system 2,6
It has been desired to provide a method for obtaining TMDDP from dimethylphenol in good yield.

SUMMARY OF THE INVENTION The present invention has been completed through intensive studies to eliminate the above-mentioned drawbacks of the prior art.

That is, the present invention, after the oxidative coupling reaction of 2,6-dimethylphenol in the presence of a catalyst in an aqueous solution, and after stopping the supply of the oxygen-containing gas to the obtained reaction product,
The present invention provides a method for producing 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxydiphenyl, which comprises heat-treating the reaction product at a temperature of 50 to 150 ° C. .

DETAILED DESCRIPTION OF THE INVENTIONThe method of the present invention oxidatively couples 2,6-dimethylphenol in an aqueous solution in the presence of a catalyst, and a copper compound is used as a catalyst used in the aqueous solution. Either a cuprous compound or a cupric compound which gives copper ions in the above can be used.

Representative copper compounds that can be used in the method of the present invention include:
For example:

(1) Halides such as chloride, bromide and iodide.

(2) A basic halohydroxide represented by the following formula.

CuX.CuOH or CuX ₂ .Cu (OH) _{2 In the} formula, X is chlorine, bromine, iodine or fluorine.

(3) Carboxylates such as acetate and benzoate.

(4) Sulfate.

(5) Nitrate.

(6) Alkyl sulfate and aryl sulfate.

(7) carbonates and _{CuCO 3 -Cu (OH) 2,} Cu 2 CO 3 basic carbonates such as -CuOH.

(8) Hydroxide.

(9) Chlorates such as CuClO ₃ and Cu (ClO ₃ ) ₂ .

The amount of the copper compound used in the method of the present invention is
At least 0.0 per mol of 2,6-dimethylphenol
It is 1 to 0.1 mmol. The reaction occurs even if the amount is less than this range, but the reaction rate is slow and the yield is low.

For the oxidation coupling in an aqueous solution in the method of the present invention, it is preferable to add a surfactant to the reaction system to carry out the reaction. Here, the "surfactant" means a hydrophobic group in the molecule. And an organic compound having both hydrophilicity. Examples of this surfactant include fatty acid soap,
Alkyl sulfonate, alkyl benzene and alkyl naphthalene sulfonate, alkyl sulfate, alkyl ether sulfate, alkyl phosphate, alkyl ether phosphate and the like are used. The amount of surfactant used is 2,
At least 0.1 per mole of 6-dimethylphenol
200 millimoles is desirable, about 0.5 to about 1
Preferred results are obtained when it is 50 mmol, particularly preferably 1 to 15 mmol. The use of a larger amount of surfactant does not increase the yield of the desired TMDDP.

In the above oxidation coupling, the pH of the reaction mixture is preferably maintained within the range of 7 to 12 until the reaction is completed. Therefore, a basic substance or a basic boron compound can be added. When the former is used, a boron compound can be added together. In this way
If pH is maintained at 7-12, target TMD
The DP yield is increased.

Examples of the basic boron compound that can be used in the method of the present invention include lithium metaborate, sodium metaborate, sodium perborate, lithium tetraborate, borax,
Examples include trimethoxyborane and triphenoxyborane.
When a basic substance is used, a boron compound can be further added. Examples of the boron compound that can be added include boric acid, oxidized boric acid and the like in addition to the basic boron compound described above.

The basic substances that can be used to maintain the pH of the reaction mixture at 7 to 12 include alkali metal hydroxides, carbonates and bicarbonates in addition to the above basic boron compounds. Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, lithium carbonate, potassium carbonate and sodium bicarbonate.

In the method of the present invention, among the above, it is preferable to use a compound containing boron for pH adjustment. The use of this compound facilitates the pH control during the oxidative coupling reaction, increases the conversion rate of the raw material 2,6-dimethylphenol, and finally increases the yield of the desired TMDDP.

Although water is used as a reaction solvent in the method of the present invention, other substrates do not have to be soluble in water, and the reaction system may be a slurry or suspension. The components of the reaction mixture can be mixed by any appropriate method. Generally, in a suitable reaction vessel, 2,6-dimethylphenol, a surfactant, a copper compound, a basic substance, a boron compound and water are added in any order and mixed. However, in some cases it may be desirable to add a part of the copper compound during the reaction.
The yield of MDDP may increase. For example, in the case of carrying out the reaction on a large scale, a predetermined amount of the catalyst is divided into two equal parts, one of them is added at the start of the reaction, and the rest is added after 1 to 2 hours. When carrying out the reaction on a large scale, a large amount of tetramethyldiphenoquinone may be contained in the product when the whole amount of the catalyst is added at the start of the reaction. In such a case, the production of tetramethyldiphenoquinone can be suppressed by adding the catalyst in a divided manner. The decomposition does not have to be divided into two equal parts and may be added in any number of times.

The oxidizing agent used in the method of the present invention includes oxygen or an oxygen-containing gas such as air.

Oxygen and oxygen-containing gas may either be introduced directly into the reaction mixture or the reaction may be carried out under that atmosphere, but the former gives better results. When air is used as the oxygen-containing gas, it is more practical to pressurize because the reaction rate is faster.

Considering the reaction rate, the reaction temperature is preferably maintained at about 50 to 100 ° C. At temperatures lower than that, the reaction rate decreases and it is necessary to lengthen the reaction time.

The reaction time, reaction temperature, 2,
Depends on the amount of 6-dimethylphenol or copper compound used. However, if the reaction is carried out at atmospheric pressure, eg with oxygen, it is usually complete within about 10 hours.

After the oxidation coupling reaction in the presence of the catalyst of 2,6-dimethylphenol described above, the supply of the oxygen-containing gas to the reaction product system is stopped, and then the reaction product is heat-treated.

In this heat treatment, the above-mentioned oxidation coupling reaction product can be used as it is, but if necessary, the starting material 2,6-dimethylphenol is added to the reaction product to give 2,6- The molar ratio of dimethylphenol and by-produced tetramethyldiphenoquinone is 2/1 or more,
The heat treatment is preferably performed under the condition of 3/1 or more. In this case, if the molar ratio is less than 2/1, the target product is TMDD.
There is a problem that the yield of P is low and the purity is low.

The temperature of the heat treatment is 50 to 150 ° C., preferably 60.
It is in the range of up to 120 ° C., and normal pressure is usually selected, but it can be carried out under reduced pressure or under increased pressure.
Generally, this heat treatment can be performed within 1 to 20 hours, usually within 10 hours.

In the method of the present invention, the oxidation coupling reaction product (usually in a slurry state) is continuously heat-treated.

In this heat treatment, oxygen supply to the heat treatment system may be stopped. The atmosphere in the heat treatment system may be an oxygen atmosphere in which the oxygen-containing gas during the oxidative coupling reaction is stopped, or an inert atmosphere in which the system is replaced with a gas such as nitrogen, helium, or argon, or steam. However, heat treatment under an inert atmosphere gives preferable results.

In the method of the present invention, since the raw material 2,6-dimethylphenol forms an azeotropic mixture with water, the unreacted raw material is recovered as an azeotropic mixture with water from the reaction product obtained by the oxidative coupling reaction by distillation. However, if the distillation operation is performed under the above-mentioned heat treatment conditions at this time, it is industrially advantageous that the target TMDDP and unreacted raw material (azeotropic mixture with water)
Can be separated and collected.

A high-purity TMDDP can be easily obtained by washing the syrup obtained by passing the slurry after recovering the raw materials with an organic solvent (for example, aromatic hydrocarbon, alcohols or a mixed solution of water and alcohols). be able to.

Experimental Example Example 1 In a four-necked flask equipped with a baffle plate, 915 g (7.5 mol) of 2,6-dimethylphenol and 100 g (0.26 g of borax) were added.
Mol), 3.0 g of sodium lauryl sulfate, and ion-exchanged water were added, a thermometer, a gas introduction tube, a stirring blade, and a pressure gauge were attached, and the temperature was raised while heating with stirring. Contents temperature is 6
When the temperature reached 5 ° C, stirring was stopped for a while, 30 ml (0.30 mmol) of cupric acetate as an aqueous solution (10 mmol /) was quickly added, and stirring was restarted. While introducing oxygen, stirring was continued so that the temperature of the reaction mixture was kept at 70 ° C., introduction of oxygen was stopped after 8 hours, and a part of the reaction mixture was sampled and analyzed by a gas chromatograph method by an internal standard method. However, the conversion rate of the raw material 2,6-dimethylphenol was 93.4%, and the selectivity of 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxydiphenyl was 96.7.
It was in%. Moreover, when a part of the produced black-green solid substance was collected and analyzed by a spectrophotometric method, the selectivity of tetramethyldiphenoquinone was 2.8%, and the remaining unreacted raw material
The molar ratio of tetramethyldiphenoquinone to 2,6-dimethylphenol was 5/1.

The inside of the reactor was sufficiently replaced with nitrogen gas, and the temperature of the reaction mixture was heated up to 95 ° C. When the temperature of the reaction mixture reached 95 ° C, the temperature of the reaction mixture was kept at 95 ° C and stirring was continued for 3 hours. It was A part of each of the reaction mixture and the produced solid was collected and analyzed by the same method as described above, the raw material 2,
The conversion rate of 6-dimethylphenol is 9 with respect to the initial charge.
The selectivity of TMDDP was 6.0%, the selectivity of tetramethyldiphenoquinone was 0.2%. Subsequently, 1100 g of an azeotropic mixture of water and the unreacted starting material 2,6-dimethylphenol was distilled off from the reaction mixture by distillation,
When a part of each of the reaction mixture and the formed solid product was collected and analyzed by the same method as described above, the selectivity of TMDDP was 99.5% and the selectivity of tetramethyldiphenoquinone was 0.05%. . When the solid obtained after passing the slurry after recovering the unreacted raw materials was washed with toluene and dried, 853 g of TMDDP was obtained, and the purity was 99.6% by gas chromatographic analysis.

Example 2 Sodium hydroxide 6 was used instead of borax in Example 1.
Oxidative coupling reaction, heat treatment and distillation operation were carried out under the same method and conditions as in Example 1 except that 0 g (1.5 mol) was used.

The conversion rate of 2,6-dimethylphenol at the end of the reaction is 6
The selectivity of TMDDP was 6.2%, the selectivity of tetramethyldiphenoquinone was 4.0%. Further, the conversion of 2,6-dimethylphenol after the heat treatment was 70.8% with respect to the initial charged amount, and the selectivity of TMDDP was 9.
9.2%, the selectivity of tetramethyldiphenoquinone is 0.
3%, and the selectivity of TMDDP after distillation is 99.
4%, selectivity of tetramethyldiphenoquinone 0.07
It was in%.

Example 3 In Example 1, the heat treatment was performed under the same method and under the same conditions as in Example 1 except that the heat treatment was performed in the presence of oxygen while the introduction of oxygen was stopped at the end of the oxidation coupling reaction.

At the end of the oxidative coupling reaction, the conversion of 2,6-dimethylphenol was 94.0% and the selectivity of TMDDP was 96.
5%, selectivity of tetramethyldiphenoquinone is 3.1%
It was. After the heat treatment, the conversion of 2,6-dimethylphenol is 94.9%, the selectivity of TMDDP is 97.4%,
The selectivity of tetramethyldiphenoquinone was 2.2%. Also, after the heat treatment, the inside of the reactor was sufficiently replaced with nitrogen gas, and then distillation was carried out.
The selectivity of P was 99.5% and the selectivity of tetramethyldiphenoquinone was 0.1%.

Example 4 In Example 1, the second acetic acid was added in an aqueous solution (10 mmol /
Was carried out under the same procedure and conditions as in Example 1, except that 60 ml (0.60 mmol) was used as). Reaction start 5
When the introduction of oxygen was stopped after a lapse of time and analysis was performed, the conversion of 2,6-dimethylphenol was 84.3%, the selectivity of TMDDP was 88.7%, and the selectivity of tetramethyldiphenoquinone was 10.8%. It was. After the heat treatment, the conversion of 2,6-dimethylphenol was 94.8%, the selectivity of TMDDP was 99.2%, and the selectivity of tetramethyldiphenoquinone was 0.3%. The selectivity of TMDDP was 99.3% and the selectivity of tetramethyldiphenoquinone was 0.15%.

Comparative Example 1 GPC analysis of the solid product in the reaction mixture obtained by the oxidative coupling reaction under the same method and conditions as in Example 1 revealed that it contained 1.7% of polymer. 575 g of this reaction mixture was placed in a 1-glass autoclave, the inside of the reactor was sufficiently replaced with nitrogen gas, and the temperature of the reaction mixture was raised to 160 ° C. in a sealed state at 160 ° C. and a pressure of 7 ° C.
When the pressure reached kg / cm ³ G (self-pressure), the temperature of the reaction mixture was kept at 160 ° C. and stirring was continued for 2 hours.
When analyzed in the same manner as in Example 1, the conversion rate of the raw material 2,6-dimethylphenol was 97.7 based on the initial charged amount.
%, The selectivity of tetramethyldiphenoquinone is 0.04%
As a result of GPC analysis, the amount of polymer was 5.0%. Then, in the same manner as in Example 1, after collecting water and unreacted raw materials by distillation, filtration, washing with toluene, drying and analysis by the same method, a gas chromatograph (GC) purity of 9 was obtained.
121 g of 9.1% TMDDP was obtained. The content of tetramethyldiphenoquinone was 0.01% and the content of polymer was 1.2%.
The actual purity of DP was 97.8%.

Example 5 In Comparative Example 1, the temperature was 130 ° C. (pressure 2.8 kg /
cm ³ G) and the heat treatment was performed in the same manner as in Comparative Example 1. After the heat treatment, the conversion of 2,6-dimethylphenol was 96.5%, the selectivity of tetramethyldiphenoquinone was 0.09%, and the polymer content was 2.0%. The yield of TMDDP after recovery of unreacted raw materials was 122 g and GC purity was 9
9.5%, tetramethyldiphenoquinone 0.03%, polymer 0.5%, corrected TMDDP purity is 99.
It was 0%.

As a result of the same analysis of Example 1, the polymer content after heat treatment was 1.7%, and the obtained GC was
TMDDP with a purity of 99.6% contained 0.4% polymer and the corrected TMDDP had a purity of 99.1%.

EFFECTS OF THE INVENTION According to the method of the present invention, the production of tetramethyldiphenoquinone as a by-product is extremely reduced, and the target TM
It becomes possible to easily produce DDP with extremely high selectivity and high yield.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takahiro Sugawara 1315 Wakaguri, Ami-cho, Inashiki-gun, Ibaraki Sanryo Petrochemical Co., Ltd. (72) Inventor Makoto Imari 1315 Wakaguri, Ami-cho, Inashiki-gun, Ibaraki Address Sanritsu Yuka Co., Ltd. Central Research Laboratory (56) References Japanese Patent Publication No. 46-15293 (JP, B1) US Patent 4070383 (US, A)

Claims (1)

[Claims] 1. A reaction product in a slurry state after 2,6-dimethylphenol is subjected to an oxidative coupling reaction in a water solvent in the presence of a catalyst to stop the supply of an oxygen-containing gas to the obtained reaction product. 3,3 ', 5,5'-tetramethyl-4,4'- characterized by heat-treating the product at a temperature of 50 to 150 ° C
Method for producing dihydroxydiphenyl