JPS61268641A - Production of 3,3',5,5'-tetramethyl-4,4'-dihydroxydiphenyl - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield and selectivity, easily, by carrying out the oxidative coupling reaction of 2,6-dimethylphenol in an aqueous solution in the presence of the catalyst, stopping the supply of an O2-containing gas after the reaction, and heating the reaction product. CONSTITUTION:2,6-Dimethylphenol is subjected to oxidative coupling reaction with an O2-containing gas at 50-100 deg.C under atmospheric pressure for <=10hr in an aqueous solution using a cuprous or cupric compound such as cuptic acetate as a catalyst, in the presence of a surfactant such as sodium laurylsulfate, and keeping the pH of the reaction system to 7-12 by the addition of a basic substance such as NaOH or a boron-containing basic compound such as borax. The supply of the O2-containing gas to the reaction product is stopped, and the product is heated at 50-150 deg.C under atmospheric pressure for <=10hr to obtain the objective compound. USE:Raw material of epoxide compound, stabilizer for petroleum product, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to 3.3',5.5'-tetramethyl-4,4
The present invention relates to a method for producing '-dihydroxydiphenyl (hereinafter sometimes abbreviated as TMDDP).

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

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

It is known that phenols with prior art substituents can become self-condensation products such as diphenoquinone, 414'-dihydroxydiphenyl and polyphenylene oxide by oxidative coupling.

However, for example, U.S. Pat.
The methods described in British Patent No. 180,686 and British Patent No. 2,047,232 require an organic solvent or a stoichiometric amount of an organic reagent;
It was difficult to stop the process at the 4'-dihydroxydiphenyl stage, and the main products were in most cases diphenoquinone or polyphenylene oxide.

In addition, using a copper amine complex as a catalyst in an aqueous solvent, 4+
A method for producing 4'-dihydroxydiphenyl (Japanese Unexamined Patent Application Publication No. 1983-65834) has also been announced;
It requires special equipment such as a stirrer with a performance of 0 to 10,000 rpm and a wrinkled Morton flask, and is thought to be difficult to manufacture on an industrial scale. When this special production method was carried out using an apparatus such as the one used in the industrializable method of the present invention, the conversion rate of alkylphenol and the yield of 4,4'-dihydroxydiphenyl were low and were not at a satisfactory level. .

On the other hand, there are known methods for reducing diphenoquinone to dihydroxydiphenyl, such as using a reducing agent such as sodium dithionite or hydrazine. A reduction reaction had to be carried out, which was industrially disadvantageous.

In addition, 4°4'-
A method for producing bis-(2,6-di-t-butylphenol) has been proposed, but this method uses a specific organic solvent,
Since the reaction is carried out in a high temperature range and cannot be applied to an aqueous solvent system, it has been desired to provide an industrially advantageous method for obtaining TMDDP from 2,6-dimethylphenol in a high yield in an aqueous solvent system. .

SUMMARY OF THE INVENTION In order to eliminate the drawbacks of the above-mentioned prior art, the present invention has been completed after intensive studies.

That is, the present invention subjects 2,6-dimethylphenol to an oxidative coupling reaction in the presence of a catalyst in an aqueous solution, and after stopping the supply of oxygen-containing gas to the resulting reaction product, heat-treating the reaction product. 3, 3, 5, 5
A method for producing '-tetramethyl-4,4'-dihydroxydiphenyl is provided.

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention involves the oxidative coupling of 2,6-dimethylphenol in the presence of a catalyst in an aqueous solution, in which a copper compound is used as the catalyst; Either cupric compounds or cupric compounds that provide copper ions can be used.

Typical 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) Basic octoday hydroxide as represented by the following formula.

CuX a Cu0H or CuX2・Cu(OH)z
In the formula, X is chlorine, bromine, iodine or fluorine.

(3) Carboxylate salts, such as acetate, benzoate, etc.

(4) Sulfate.

(5) Nitrates.

(6) Alkyl sulfates and aryl sulfates.

(7) Carbonate and CuC0a -Cu(OH)z
, basic carbonates such as CuzCOs-CuOH.

(8) Hydroxide.

(9) Chlorates such as CuCtOa, Cuα203)2.

The amount of copper compound used in the method of the present invention is:
2. At least 0.0% per mole of 6-dimethylphenol.
01-0.1 mmol. Although the reaction can occur in amounts smaller than this range, the reaction rate is slow and the yield is low.

In the oxidative 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. refers to an organic compound having both a radical and a hydrophilic device.Surfactants include, for example, fatty acid soaps, alkyl sulfonates, alkylbenzene and alkylnaphthalene sulfonates, alkyl sulfates, alkyl ether sulfates, alkyl phosphorus. Acid salts, alkyl ether phosphates, etc. are used.The amount of surfactant used is 2.
Preferably, the amount is from 0.1 to 200 mmol per mole of 6-dimethylphenol, preferably from about 0.5 to about 150 mmol, and particularly preferably from 1 to 15 mmol. Even if a larger amount of surfactant is used, the yield of the desired TMDDP will not increase.

In the oxidative coupling described above, it is preferable to maintain the pH of the reaction mixture 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 using the former, a boron compound can also be added. When the pH is maintained at 7 to 12 in this way, the target TM
The yield of DDP is increased.

Examples of basic boron compounds that can be used in the method of the present invention include lithium metaborate, sodium metaborate,
Examples include sodium perborate, lithium tetraborate, borax, trimethoxyborane, and triphenoxyborane. Further, when using a basic substance, a boron compound can be further added, and the boron compounds that can be added include:
In addition to the basic boron compounds described above, for example boric acid,
Contains boron oxide.

Basic substances that can be used to maintain the pH of the reaction mixture between 7 and 12 include alkali metal hydroxides, carbonates, and bicarbonates, in addition to the basic boron compounds mentioned above. 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 compounds, it is preferable to use a compound containing boron for pH adjustment. Use of this compound facilitates pH control during the oxidative coupling reaction, increases the conversion rate of the raw material 2.6-dimethylphenol, and ultimately increases the yield of the desired TMDDP.

Although water is used as a reaction solvent in the method of the present invention, it is not necessary that other substrates are soluble in water, and the reaction system may be a slurry or suspension. Additionally, the components of the reaction mixture can be mixed in any suitable manner. Generally, 2,6-dimethylphenol, surfactant, copper compound, basic material, boron compound, and water are added and mixed in any order in a suitable reaction vessel. However, in some cases, it may be better to add a portion of the copper compound during the reaction to achieve the desired T.
The yield of MDDP may be increased. For example, when carrying out a large-scale reaction, a predetermined amount of catalyst is divided into two parts, one of which is added at the start of the reaction, and the remaining part is added 1 to 2 hours later. When carrying out the reaction on a large scale, if the entire amount of catalyst is added at the beginning of the reaction, the product may contain a large amount of tetramethyldiphenoquinone. In such a case, the formation of tetramethyldiphenoquinone can be suppressed by adding the catalyst in portions. Note that it is not necessary to divide the mixture into two equal parts, and it does not matter how many times it is added.

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 gases can be introduced directly into the reaction mixture or the reaction can be carried out in that atmosphere, although the former gives better results. When air is used as the oxygen-containing gas, it is more practical to pressurize it because it speeds up the reaction.

The reaction temperature is desirably maintained at about 50 to 100°C in consideration of reaction rate. At lower temperatures, the reaction rate decreases and the reaction time needs to be increased.

The time it takes for the reaction to complete depends on the reaction pressure and reaction temperature L.
It depends on the amount of 2.6-dimethylphenol and copper compound used. However, if the reaction is carried out at atmospheric pressure, for example using oxygen, it is usually complete within about 10 hours.

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

In this heat treatment, the above-mentioned oxidative coupling reaction product can be used as it is, but if necessary, raw material 2,6-dimethylphenol may be added to the reaction product to remove the 2,6-dimethylphenol in the reaction product. - Heat treatment under conditions where the molar ratio of dimethylphenol and by-produced tetramethyldiphenoquinone is ``/s or more, preferably s or more.In this case, if the molar ratio is smaller than Vl, the desired product is obtained. TMD
A problem arises in that the yield of DP is low and the purity is low.

The temperature of the above heat treatment is 50 to 150°C, preferably 60°C.
The temperature range is from 120° C. to 120° C., and the pressure is usually normal pressure, but it can also be carried out under reduced pressure or pressurized conditions.

Generally, this heat treatment can be carried out for 1 to 20 hours, usually within 10 hours.

In the method of the present invention, the oxidative coupling reaction product (usually in a slurry state) may be continuously heat-treated, or the reaction product may be separated and water, an organic solvent, or a mixture thereof is added. After that, heat treatment may be performed.

In this heat treatment, it is sufficient if the supply of oxygen to the heat treatment system is stopped. The atmosphere in the heat treatment system may be an oxygen atmosphere with the oxygen-containing gas stopped during the oxidative coupling reaction, or it may be inert by replacing the system with a gas such as nitrogen, helium, argon, or water vapor. Although it is possible to perform the heat treatment under an atmosphere, preferable results are obtained when the heat treatment is performed under an inert atmosphere.

In the method of the present invention, the raw material 2,6-dimethylphenol forms an azeotrope with water, so the unreacted raw material is distilled from the reaction product obtained by the oxidative coupling reaction to form an azeotrope with water. However, if the distillation operation is carried out under the above-mentioned heat treatment conditions at this time, it is industrially advantageous to separate and recover the target TMDDP and the unreacted raw material (azeotropic mixture with water).

High purity TMDDP can be easily obtained by washing the P slag obtained by filtering the slurry after raw material recovery with an organic solvent (for example, aromatic hydrocarbons, alcohols, or a mixture of water and alcohols). can be obtained.

】” Kai 1 Example 1 915 f (7.5 mol) of 2,6-dimethylphenol and 100 f of borax were placed in a 7-t four-bottle flask with baffle plates.
(0.26 mol), sodium lauryl sulfate 3.0? ,
Ion-exchanged water was added, a thermometer, a gas introduction tube, a stirring blade, and a pressure gauge were attached, and the temperature was raised while stirring. When the temperature of the contents reached 65°C, stirring was temporarily stopped, and 30 d of cupric acetate was made into an aqueous solution (IQ mmol,/l).
(0.30 mmol) was added quickly and stirring was resumed. Stirring was continued to maintain the temperature of the reaction mixture at 70°C while introducing oxygen, and after 8 hours, the introduction of oxygen was stopped, and a portion of the reaction mixture was sampled and analyzed by gas chromatography using an internal standard method. , conversion of raw material 2,6-dimethylphenol (tJ is 93.4% Te, 3°3'1
The selectivity of 515'-tetramethyl-4,4'-dihydroxydiphenyl was 96.7%. In addition, when a part of the produced black-rimmed solid was collected and analyzed by spectrophotometry, the selectivity of tetramethyldiphenoquinone was 2.8%, and the selectivity of tetramethyldiphenoquinone was 2.8%, relative to the remaining unreacted raw material 2,6-dimethylphenol. The molar ratio of tetramethyldiphenoquinone is 5/1
Met.

The inside of the reactor was sufficiently purged with nitrogen gas, and the temperature of the reaction mixture was heated until it reached 95°C, and when it reached 95°C, the temperature of the reaction mixture was kept at 95°C and stirred for 3 hours. continued. A portion of the reaction mixture and a portion of the produced solid were collected and analyzed in the same manner as above, and it was found that raw material 2
The conversion rate of ,6-dimethylphenol was 96.0% based on the initial charge amount, the selectivity of TMDDP was 99.3%, and the selectivity of tetramethyldiphenoquinone was 0.2%. Subsequently, an azeotropic mixture of water and 2,6-dimethylphenol as a starting material was distilled off from the reaction mixture by 1100f, and a portion of each of the reaction mixture and the produced solid was collected and analyzed in the same manner as above. As a result, the selectivity of TMDDP was 99.5%, and the selectivity of tetramethyldiphenoquinone was 0.05%. When the solid obtained by filtering the slurry after recovering the unreacted raw materials was washed with toluene and dried, 853f TMDDP was obtained, and the purity was determined to be 99.6% by gas chromatography analysis.

Example 2 Sodium hydroxide 6 was used instead of borax in Example 1.
0? The oxidative coupling reaction, heat treatment, and distillation operations were carried out in the same manner and under the same conditions as in Example 1, except that (1.5 mol) was used.

The E conversion rate of 2,6-dimethylphenol at the end of the reaction is 6
The selectivity for TMDDP was 95.5%, and the selectivity for tetramethyldiphenoquinone was 4.0%. In addition, the conversion rate of 2,6-dimethylphenol after heat treatment was 70.8% with respect to the initial charge amount, and the selectivity of TMDDP was 9.
9.2%, and the selectivity of tetramethyldiphenoquinone was 0.
3%, and the selectivity of TMDDP after distillation is 99.
4%, "selectivity of tetramethyldiphenoquinone is 0.0
It was 7%.

Example 3 Heat treatment was carried out in the same manner and under the same conditions as in Example 1, except that heat treatment was carried out in the presence of oxygen while the introduction of oxygen was stopped at the end of the oxidative coupling reaction in Example 1. .

At the end of the oxidative coupling reaction, the conversion rate of 2,6-dimethylphenol was 94.0%, and the selectivity of TMDDP was 96.
．． 5%, selectivity for tetramethyldiphenoquinone is 3.1
%Met. The conversion rate of 2.6-dimethylphenol after heat treatment was 94.9%, and the selectivity of TMDDP was 97.4.
%, and the selectivity for tetramethyldiphenoquinone was 2.2%. In addition, when distillation was carried out after the reactor was sufficiently purged with nitrogen gas after the heat treatment, the T
The selectivity of KDDP was 99.5%, and the selectivity of tetramethyldiphenoquinone was 0.1%.

Example 4 In Example 1, cupric acetate was added to an aqueous solution (10 mmol/
The process was carried out in the same manner and under the same conditions as in Example 1, except that 60d (0.60 mmol) was used as L). Reaction start 5
After some time, the introduction of oxygen was stopped and analysis revealed that 2,6-
The conversion rate of dimethylphenol was 84.3%, TMDDP
The selectivity for tetramethyldiphenoquinone was 88.7%, and the selectivity for tetramethyldiphenoquinone was 10.8%. Also, 2,6 after heat treatment
- Conversion rate of dimethylphenol is 94.8%, TMDD
The selectivity of P is 99.2%, the selectivity of tetramethyldiphenoquinone is 0.3%, and the selectivity of TMDDP after distillation is 99.3%, and the selectivity of tetramethyldiphenoquinone is 0. It was .15%.

According to the method of the present invention, the production of tetramethyldiphenoquinone as a by-product is extremely low, and the desired TM
It becomes possible to easily produce DDP with extremely high selectivity and high yield.

Claims (1)

[Claims] (1) 2,6-dimethylphenol is subjected to an oxidative coupling reaction in the presence of a catalyst in an aqueous solution, and after stopping the supply of oxygen-containing gas to the obtained reaction product, the reaction product is heat-treated. Characteristic method for producing 3,3',5,5'-tetramethyl-4,4'-dihydroxydiphenyl.