JPH1149711A - Method for producing trimethylhydroquinone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for mass-producing trimethylhydroquinone inexpensively, except for a disadvantage of a low yield in a conventional method. SOLUTION: At least one compound selected from the group consisting of 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol and trimethylhydroquinone diacetate is used in the presence of a catalyst. A method for producing trimethylhydroquinone, comprising hydrolyzing below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing trimethylhydroquinone from trimethylhydroquinones. Trimethylhydroquinone is a useful substance as an intermediate in vitamin E synthesis.

[0002]

2. Description of the Related Art A method for producing trimethylhydroquinone from trimethylhydroquinone diacetate is disclosed in, for example, JP-A-47-7632. In this method, trimethylhydroquinone diacetate obtained by isomerizing 4-oxoisophorone in the presence of a large excess of acid anhydride or acetic acid is hydrolyzed to trimethylhydroquinone using sulfuric acid or p-toluenesulfonic acid as a catalyst. Things. A large excess of acid anhydride or acetic acid is directly subjected to hydrolysis. However, this method does not have a high hydrolysis yield of about 63%. Further, in this method, a coexisting large excess of an acid anhydride or the like is simultaneously hydrolyzed and consumed, and as a result, it is impossible to reuse the acid anhydride or the like. Since acid anhydrides are generally expensive, this method is very costly.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing trimethylhydroquinone inexpensively and in large quantities at low cost, except for the disadvantage that the yield of trimethylhydroquinone in the conventional method is low. Things.

[0004]

That is, the first aspect of the present invention is as follows.
Reacts at least one compound selected from the group consisting of 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol and trimethylhydroquinone diacetate in the presence of a catalyst. The present invention relates to a method for producing trimethylhydroquinone, which is characterized by hydrolysis. The second aspect of the present invention is
The first aspect of the present invention relates to a method for producing trimethylhydroquinone, wherein the hydrolysis is performed in an atmosphere of an inert gas. A third aspect of the present invention relates to the method for producing trimethylhydroquinone according to the first aspect of the present invention, wherein the hydrolysis is performed in a nitrogen atmosphere. A fourth aspect of the present invention relates to the method for producing trimethylhydroquinone according to the first aspect of the present invention, wherein the catalyst is an acid catalyst. The fifth of the present invention
Relates to a method for producing trimethylhydroquinone in which the catalyst is a protonic acid in the first aspect of the present invention. A sixth aspect of the present invention relates to the method for producing trimethylhydroquinone of the first aspect of the present invention, wherein the catalyst is sulfuric acid. Seventh of the present invention
The production method of trimethylhydroquinone according to the first aspect of the present invention, wherein the catalyst is a synthetic solid acid catalyst, a natural clay-based solid acid catalyst, or a solid acid catalyst in which an inorganic acid is supported on a porous inorganic substance. About the law. Eighth of the invention
The first aspect of the present invention relates to a method for producing trimethylhydroquinone, wherein the catalyst is silica-alumina, Y-type zeolite, USY-type zeolite, mordenite or ZSM-5. A ninth aspect of the present invention relates to the method for producing trimethylhydroquinone according to the first aspect of the present invention, wherein the hydrolysis is performed at a temperature of 0 to 600 ° C. A tenth aspect of the present invention is the method according to the first aspect, wherein the hydrolysis is carried out in a gas phase in a continuous flow system at 0.00.
The present invention relates to a method for producing trimethylhydroquinone, which is performed for a contact time of 1 to 100 seconds. Eleventh of the present invention
The first aspect of the present invention relates to a process for producing trimethylhydroquinone, wherein the hydrolysis is carried out in a gas phase by a continuous flow system at a pressure of 1 MPa or less. A twelfth aspect of the present invention is the first aspect of the present invention, wherein 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-
At least one of the compounds selected from the group consisting of 2,3,5-trimethylphenol and trimethylhydroquinone diacetate is produced by contacting 4-oxoisophorone and a carboxylic acid in the gas phase in the presence of a solid acid catalyst. And a method for producing trimethylhydroquinone.

The inventors of the present invention have conducted intensive studies on a method for producing trimethylhydroquinone from an acetate of trimethylhydroquinone. As a result, the low yield in the conventional method is due to the fact that trimethylhydroquinone and its ester are very easily oxidized. For this reason, it was speculated that the oxidation was partially oxidized to trimethylbenzoquinone. Therefore, in the present invention, hydrolysis is performed in a system substantially free of oxygen, for example, in an atmosphere of an inert gas in the presence of a catalyst. According to the present invention, oxidation of trimethylhydroquinone and its ester can be prevented, so that trimethylhydroquinone can be produced with a very high yield.

[0006]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, at least one of 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol and trimethylhydroquinone diacetate is used. Hydrolysis in the presence of a catalyst produces trimethylhydroquinone.

A catalyst is used for hydrolyzing 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol, trimethylhydroquinone diacetate or a mixture thereof. As the catalyst, any of an acid catalyst and a base catalyst can be used. Acid catalysts include proton acids, Lewis acids,
A solid acid or the like is used. Examples of the protic acid include carboxylic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, perchloric acid, formic acid, and acetic acid, and adipic acid. Particularly preferred is sulfuric acid. Examples of the Lewis acid include aluminum chloride, boron trifluoride, boron trifluoride ether complex, iron chloride, zinc chloride and the like. As a solid acid catalyst, silica-
Examples include synthetic solid acid catalysts such as alumina, alumina, silica and zeolite, and natural clay minerals such as acid clay and activated clay. When using zeolite as a solid acid catalyst,
What contains hydrogen zeolite, such as HX type zeolite, HY type zeolite, or hydrogen faujasite, can be used. Preferably, HY type zeolite, USY type zeolite, mordenite, ZSM-5 or the like is used. Further, for the purpose of reducing the amount of carbon adhering to the catalyst, an alkali metal such as sodium or potassium can be supported on these solid acid catalysts. In addition, inorganic acids such as phosphoric acid or phosphotungstic acid, heteropolyacids such as silicotungstic acid or silicomolybdic acid may be used alone or in combination, or by appropriately supporting them on a porous inorganic substance. it can. A specific example is a supported acid catalyst in which an inorganic acid is supported on a porous inorganic substance such as alumina, magnesia, silica, and activated carbon. Among the above solid acid catalysts, synthetic solid acid catalysts, particularly silica-alumina, HY-type zeolite, USY-type zeolite, mordenite, ZSM-5, and the like are preferably used in terms of catalyst stability.

On the other hand, examples of the base catalyst include inorganic salts such as sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium methoxide, sodium ethoxy. Examples thereof include alkoxides such as chloride, amines such as triethylamine and pyridine, and ammonia.

In the present invention, the hydrolysis reaction is carried out in a system substantially free of oxygen. This prevents oxidation of trimethylhydroquinone and its esters, especially trimethylhydroquinone produced by hydrolysis. The hydrolysis is performed in an atmosphere of an inert gas to make the atmosphere substantially free of oxygen. When oxygen is already dissolved in the hydrolysis raw material, oxygen is sufficiently removed in advance by an appropriate deoxidation operation, for example, distillation or bubbling of an inert gas. When the hydrolysis temperature is high, the oxidation is apt to proceed, so the effect of protection by an inert gas is particularly large. Industrially, nitrogen gas is preferred as the inert gas.

The type of hydrolysis may be a batch type or a flow type. The use of a solid acid as a catalyst facilitates the reaction in a flow-through manner. In general, steam is often used as a medium for the flow reaction system. Since steam is inexpensive and condenses when cooled, it is easy to recover the product when used as a medium.

The reaction temperature ranges from 0 to 600 depending on the type of catalyst, the contact time between the catalyst and the raw material, the dilution ratio between the raw material and the medium, and the like.
° C, preferably 50 to 300 ° C, more preferably 10 ° C.
It can be selected from the range of 0 to 250 ° C. When the reaction temperature is higher than 600 ° C., side reactions increase,
It is not preferable because coking of the catalyst becomes remarkable and selectivity is remarkably reduced. When the reaction temperature is lower than 0 ° C.,
The desired rate of the reaction decreases, which is economically undesirable.

In the reaction of the present invention, if the catalyst is used for a long time, the activity gradually decreases due to coking or the like.
For example, by performing decoking with air or the like at a high temperature of about 500 ° C., the initial activity can be recovered.

In the case of a flow type, the reaction pressure is not particularly limited as long as the raw material or the product can be in a gaseous phase, but is usually 1 MPa or less, preferably 0.5 MPa or less, more preferably 0.2 MPa or less. It is.

The contact time between the raw material and the catalyst is 0.001 to 100 seconds, preferably 0.0, in the case of a flow type in a gas phase.
It is 1 to 10 seconds, more preferably 0.05 to 5 seconds.
If the contact time is shorter than 0.001 seconds, the conversion will decrease.
If the time is longer than 100 seconds, side reactions such as polymerization of the generated trimethylhydroquinone increase. In the case of a batch type, the range is 10 minutes to 10 hours.

In the case of the flow type, the gas discharged from the reactor is immediately cooled and liquefied. If necessary, the above gas may be recovered by passing through an absorbing liquid such as a hydrocarbon. After hydrolysis, the desired product of high purity can be obtained from the reaction solution by distillation, molecular distillation, sublimation, crystallization, recrystallization, pressure crystallization, or the like, if necessary. In the case of crystallization or recrystallization, hexane is preferably used as a solvent. High purity and colorless crystals are obtained by using hexane.

[0016]

The present invention will be further described by way of examples. The percentages described below indicate% by weight. <Example 1> 8.64% of trimethylhydroquinone diacetate, 6.24% of total amount of 4-acetoxy-2,3,6-trimethylphenol and 4-acetoxy-2,3,5-trimethylphenol, and 4 10.0 g of a raw material containing 75.7% of oxoisophorone was placed in a 500 ml flask, and the atmosphere in the flask was replaced with nitrogen. Add 50.0 g of water, 9
1.0 g of 7% sulfuric acid and 11.3 g of acetic acid were added, and 100
The mixture was stirred at 0 ° C under atmospheric pressure for 2 hours. The reaction solution was cooled to room temperature, 30 ml of hexane was added, and the precipitated crystals were filtered,
0.941 g of trimethylhydroquinone was obtained (yield 9).
0.0%). When the crystals were analyzed by gas chromatography, the purity was 100%. The fact that the crystal was trimethylhydroquinone was confirmed by the fact that the results of the retention time, IR absorption and MS analysis in gas chromatography agreed with the standard sample. The production of trimethylbenzoquinone, an oxidation product, was not confirmed.

<Comparative Example 1> An experiment was performed in the same manner as in Example 1 except that nitrogen substitution was not performed. As a result, 0.627 g of trimethylhydroquinone (60.0% yield, 100% conversion of trimethylhydroquinone acetates) was obtained. 0.410 g (yield 39.8%) of trimethylbenzoquinone was confirmed as a by-product resulting from the oxidation product.

Example 2 The particle size of a silica-alumina catalyst (trade name: N633L, manufactured by JGC Chemicals, Inc.) was 16 to 20.
The mesh was adjusted, and 15 ml thereof was filled into a stainless steel tube having an inner diameter of 12 mm and a length of 1 m. After the atmosphere in the system was replaced with nitrogen, 10.5 g of a 33% by weight solution of trimethylhydroquinone diacetate in toluene was added at a flow rate of 10.5 ml / h, and water was added at a flow rate of 30 ml / h via a preheating tube. At a reaction temperature of 200 ° C. under atmospheric pressure (contact time with the catalyst 0.5 second). Cool the reaction,
As a result of analysis by gas chromatography, the conversion of the raw material was 100%, and the selectivity for trimethylhydroquinone was 95%.

<Comparative Example 2> An experiment was performed in the same manner as in Example 2 except that nitrogen substitution was not performed. The reaction was cooled and analyzed by gas chromatography to find that the conversion of the starting material was 100% and the selectivity for trimethylhydroquinone was 90%. Trimethylbenzoquinone was confirmed as a by-product, and the selectivity was 10%.

[0020]

According to the method of the present invention, oxidation as a side reaction is prevented by performing hydrolysis in a system substantially free of oxygen, for example, in the presence of a catalyst in an atmosphere of an inert gas. As a result, trimethylhydroquinone useful as an intermediate in organic synthesis can be produced from inexpensive raw materials in a simple reaction step in a high yield.

Claims (12)

[Claims] 1. A catalyst comprising at least one compound selected from the group consisting of 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol and trimethylhydroquinone diacetate. A method for producing trimethylhydroquinone, comprising hydrolyzing in the presence of trimethylhydroquinone. 2. The method according to claim 1, wherein the hydrolysis is performed in an atmosphere of an inert gas. 3. The method according to claim 1, wherein the hydrolysis is performed in a nitrogen atmosphere. 4. The method according to claim 1, wherein the catalyst is an acid catalyst. 5. The method according to claim 1, wherein the catalyst is a protonic acid.
Production method described in 1. 6. The method according to claim 1, wherein the catalyst is sulfuric acid. 7. The process according to claim 1, wherein the catalyst is a synthetic solid acid catalyst, a natural clay-based solid acid catalyst, or a solid acid catalyst in which an inorganic acid is supported on a porous inorganic substance. Law. 8. The catalyst according to claim 1, wherein the catalyst is silica-alumina, Y-type zeolite, USY-type zeolite, mordenite or Z-type.
The method according to claim 1, wherein the method is SM-5. 9. The method according to claim 1, wherein the hydrolysis is performed at a temperature of 0 to 600 ° C. 10. The method according to claim 1, wherein the hydrolysis is carried out in a gas phase by a continuous flow method with a contact time of 0.001 to 100 seconds. 11. The method according to claim 1, wherein the hydrolysis is performed in a gas phase by a continuous flow system at a pressure of 1 MPa or less. 12. At least one compound selected from the group consisting of 4-acetoxy-2,3,6-trimethylphenol, 4-acetoxy-2,3,5-trimethylphenol and trimethylhydroquinone diacetate,
2. The method according to claim 1, wherein the compound is produced by reacting 4-oxoisophorone and a carboxylic acid in the gas phase in the presence of a solid acid catalyst.