JPH0640977A - Production of dihydric phenols - Google Patents

Abstract

PURPOSE:To provide a process for the production of a dihydric phenol by the reaction of a phenol with hydrogen peroxide, achieving extremely high para- selectivity compared with conventional process and giving high yield based on hydrogen peroxide. CONSTITUTION:Phenols are made to react with hydrogen peroxide in a polar solvent in the presence of a cyclic ether (e.g. dioxane) and a crystalline aluminotitanosilicate catalyst.

Description

Detailed Description of the Invention

[0001]

The present invention relates to various industrial chemicals and pharmaceuticals,
The present invention relates to a method for producing dihydric phenols such as hydroquinone and catechol, which are useful as raw materials for agricultural chemicals and fragrances.

[0002]

2. Description of the Related Art Conventionally, many catalyst systems have been studied for a method of producing dihydric phenols such as hydroquinone and catechol by oxidizing phenols with hydrogen peroxide. For example, a method of oxidizing phenol in the presence of ketones such as 4-methyl-2-pentanone and methyl phenyl ketone and a sulfate such as aluminum sulfate (JP-A-
130727), a method of oxidizing in the presence of a strong mineral acid such as perchloric acid (Japanese Patent Publication No. 56-47891), a method known as the Fenton method of oxidizing in the presence of iron or cobalt salts (US Pat. No. 3,914,323), titanium. A method for oxidizing a synthetic zeolite containing atoms as a catalyst (British Patent No. 2116974, European Patent No. 314582)
No.) or a method using a layered acidic clay as a catalyst (European Patent No. 299893) and the like can be mentioned as known methods.

[0003]

The above-mentioned methods are all excellent in the yield of dihydric phenols relative to hydrogen peroxide, and for example, when phenol is oxidized with hydrogen peroxide, hydroquinone and catechol are combined. It has the biggest problem of producing. That is, the para- ortho isomer ratio (P / O) of the dihydric phenol produced by any of the above-mentioned ketone peroxide catalyst system, mineral acid catalyst system and Fenton reaction is 0.4 to 0. 7 and the ortho body, which is in low demand, is produced in a large amount with respect to the para body,
It has a drawback that the production amount and manufacturing cost are greatly affected by the ortho body, for example, the catechol market. European Patent No. 314582 discloses that the use of a titanosilicate catalyst having the same crystal structure as the ZSM-5 type zeolite improves the paraselectivity, but in that case also P / O The ratio is almost 1. When using layered clay (European Patent No. 299893)
No.) and an example in which the P / O ratio is improved to 1.86, but the conversion rate of hydrogen peroxide is low and not practical. There is also a report that the P / O ratio is improved to 12.5 when a strong acid type ion exchange resin containing a transition metal cation such as Ti or V is used as a catalyst (European Patent No. 1322783). The yield of dihydric phenols was low and not satisfactory. Recently, a method for obtaining a para form in high yield by utilizing the shape selectivity of H-ZSM-5 type zeolite has been disclosed (US Pat. No. 4,578,521). The present inventors tried hydroxylation of phenol by the method described in the above-mentioned U.S. Patent, but it was not possible to obtain a satisfactory yield and selectivity, and the reproducibility was poor.

[0004]

In view of the above problems, the inventors of the present invention have earnestly studied in order to produce dihydric phenols in which two hydroxyl groups are in a para position with each other in high yield and selectivity. As a result of repeated studies, in the hydroxylation reaction of phenols with hydrogen peroxide using crystalline aluminotitanosilicate as a catalyst, it was found that the objective can be easily achieved by making the cyclic ethers coexist in the reaction system. The invention has been completed.

The present invention will be described in more detail below. In the present invention, the composition of the catalyst is xM ^+.
AlO ₂ · yTiO ₂ · SiO ₂ (where M ⁺ is H ⁺
Alternatively, it represents a monovalent alkali metal, and the ranges of x and y are 0.0001 <x <0.05 and 0.0001, respectively.
<Y <0.5, more preferably 0.001 <x <0.0
2, a crystalline alumino titanosilicate represented by 0.001 <y <0.1) is used.

As its production method, a reaction mixture consisting of a silicon source, a titanium source, an aluminum source, a nitrogen-containing compound and water is prepared and obtained by hydrothermal synthesis (JP-A-58-7).
4521, JP-A-62-162617), or ZSM-
A method for synthesizing a crystal skeleton of aluminosilicate such as 5 by substituting titanium atoms for the synthesis (JP-A-2-302314)
Etc. are known. Here, the former synthesis method will be described in detail. Tetraalkyl orthosilicate as a silicon source,
Colloidal silica or the like can be used. Tetraethyl orthosilicate is preferably used as the tetraalkyl orthosilicate. As the titanium source, tetraalkyl orthotitanate or a hydrolyzable titanium halide compound such as TiOCl ₂ can be used. Tetraethyl orthotitanate and tetrabutyl orthotitanate are preferably used as the tetraalkyl orthotitanate. As the aluminum source, aluminum alkoxide, aluminum salt or the like can be used. Specific examples of the aluminum source include triethoxyaluminum, triisopropoxyaluminum, sodium aluminate and the like, and any of them is preferably used. As the nitrogen-containing compound, tetraalkylammonium ion, preferably tetrapropylammonium hydroxide, tetrabutylammonium hydroxide can be used. As a nitrogen-containing compound,
Choline, triethanolamine, diethanolamine,
Titanium-containing zeolites having various crystal forms can also be synthesized by using amines that are generally used for preparing zeolite catalysts such as piperidine. In the present invention, crystalline titanium-containing zeolite, which has a crystal structure similar to ZSM-5 or ZSM-11 and is generally referred to as pentasil type, is particularly preferably used.

When preparing the alumino titanosilicate used in the present invention, the starting molar ratio of the raw materials is Si / Ti = 5.
~50, Si / Al = 50~1000, H 2 O / Si =
10 to 100 and nitrogen-containing compound / Si = 0.05 to 1. The reaction mixture obtained by mixing the above raw materials was mixed with an autoclave at 100 to 220 ° C. for 1 hour.
After hydrothermally synthesizing for ~ 1000 hours, the resulting solid is washed with ion-exchanged water and dried, and then in air at 400-600 ° C for 1 hour.
A crystalline alumino titanosilicate catalyst can be obtained by firing for 10 hours. When tetrapropylammonium hydroxide is used as the nitrogen-containing compound, a titanium-containing zeolite having a silicalite-1 type structure is obtained, and when tetrabutylammonium hydroxide is used, a titanium-containing zeolite having a silicalite-2 structure is obtained. To be

The amount of the alumino titanosilicate catalyst used is in the range of 0.001 to 1.0 g, preferably 0.02 to 0.5 g, per 1 g of phenols. When it is less than this range, the reaction rate becomes small, and when it is more than that range, no adverse effect is exerted, but it is not economical. Therefore, the above range is practical.

As the phenols used in the present invention, phenol, anisole, cresol, xylenol and the like can be used, but phenol is particularly preferably used.

The concentration of hydrogen peroxide used in the present invention is not particularly limited, but it is industrially easily available.
A 0-60 wt% aqueous solution is preferably used. The amount of hydrogen peroxide used is preferably 0.5 mol or less relative to 1 mol of phenols, and more preferably 0.30 mol or less in order to suppress the contribution of side reactions.
Hydrogen peroxide can be added all at once to a reaction system consisting of phenols, titanium-containing zeolite, cyclic ethers and, in some cases, a solvent. It is desirable to add it continuously or continuously.

As described above, the characteristic feature of the method for producing dihydric phenols of the present invention is that cyclic ethers are allowed to coexist when the phenols are hydroxylated with crystalline aluminotitanosilicate as a catalyst. The cyclic ethers used in the present invention include 1,3-dioxolane,
Tetrahydrofuran, tetrahydropyran, 1,3-dioxane, 1,4-dioxane, 1,3,5-trioxane and the like can be mentioned. Especially among them, 1,4
-Dioxane is preferred.

The amount of the cyclic ether used is 0.04 to 1.2 mol, preferably 0.1 to 0.8 mol, per 1 mol of the phenol. If it is less than this range, a sufficient addition effect cannot be obtained and the P / O ratio becomes small, and if it is more than this range, the yield of dihydric phenols decreases, which is not preferable.

The reaction temperature is in the range of 50 to 150 ° C, preferably 60 to 120 ° C. If the temperature is lower than this, the reaction rate will be slow, and if it is higher than this, the decomposition of hydrogen peroxide or the contribution of by-products of high-boiling substances will be large and the yield of dihydric phenols will be low. Not preferable.

Although the above reaction can be carried out without solvent,
It is preferable to use a solvent in order to increase the yield of dihydric phenols. As the solvent, for example, polar solvents such as methanol, ethanol, acetonitrile, acetone and water can be used. Among them, water is particularly preferable. The amount of the solvent added is not limited, but if used in excess, the concentration of the reaction product will decrease and the reaction rate will decrease, so it is generally preferable that the amount is within 1 times the weight of the phenols. Also, P
The / O ratio can be adjusted within a certain range by changing the ratio of phenols to cyclic ethers, and can be arbitrarily selected depending on the ratio of demands of hydroquinone and catechol, for example. . The method of the present invention can be preferably carried out by either a batch system or a continuous system.

[0015]

INDUSTRIAL APPLICABILITY The present invention is a method for producing dihydric phenols, which comprises reacting phenols with hydrogen peroxide in the presence of a cyclic ether using a crystalline aluminotitanosilicate catalyst. It has a significantly higher para-selectivity than that of, and at the same time has a high yield with respect to hydrogen peroxide, which has an important industrial significance.

[0016]

EXAMPLES Next, the method of the present invention will be described more specifically by way of examples, but the following examples do not limit the method of the present invention. The conversion rate of hydrogen peroxide and the yield of dihydric phenols in the following Examples and Comparative Examples are defined by the following equations. Conversion rate of hydrogen peroxide (%) = [(mol number of hydrogen peroxide supplied-mol number of unreacted hydrogen peroxide) / (mol number of supplied hydrogen peroxide)] x 100 of dihydric phenols Yield (%) = [(number of moles of dihydric phenol produced) / (number of moles of converted hydrogen peroxide)] × 100

(Catalyst preparation) In a four-necked flask having an inner volume of 500 ml, 0.43 g of triisopropoxyaluminum was dissolved in 76 g of a 20% aqueous tetrapropylammonium hydroxide solution under a nitrogen stream. In another container, 3.6 g of tetraethyl orthotitanate and 62.6 g of tetraethyl orthosilicate were premixed, and the mixed solution was slowly added dropwise to the previously prepared solution while stirring. This mixed solution was stirred at room temperature for 1 hour for hydrolysis, further heated to 80 ° C. in an oil bath, and stirred for 5 hours while distilling off the produced ethanol to complete the reaction. After adding 150 ml of ion-exchanged water to the obtained reaction mixture, it was filled in a stainless steel autoclave having an internal volume of 300 ml,
Hydrothermal synthesis was carried out at 170 ° C. for 38 hours under autogenous pressure. The produced white crystals were centrifuged from the mother liquor, thoroughly washed with ion-exchanged water, and dried at 90 ° C for 6 hours. After sufficiently dried, a crystalline alumino titanosilicate was obtained by heat treatment in air at 550 ° C. for 6 hours (hereinafter, this catalyst is abbreviated as ATS-1). From the X-ray fluorescence analysis, the Si / Ti ratio in the crystal was 21, and the Si / Al ratio was 1.
It was 03. The X-ray diffraction of this crystal is ZSM-5.
And a diffraction peak similar to The specific surface area and pore volume measured by the nitrogen adsorption method were 354 m ^{2 /} g and 0.46, respectively.
It was 5 ml / g.

Example 1 A four-necked flask having an internal volume of 100 ml was placed in a stirrer, a cooling tube,
Equipped with a thermometer, 25.0 g of phenol, 1,
4-Dioxane (4.1 g), water (15.0 g) and ATS-1 catalyst (0.64 g) prepared by the above method were added, and the mixture was heated to 80 ° C. in an oil bath. After the mixture reached 80 ° C,
7.3 g of 31 wt% hydrogen peroxide solution was added dropwise by a metering pump over 4.6 hours. After the dropping was completed, stirring was continued for another 20 minutes. The reaction solution was analyzed by liquid chromatography and gas chromatography to determine the conversion rate of hydrogen peroxide and the yields of hydroquinone and catechol,
Hydrogen peroxide was consumed 100%, the yield of dihydric phenol was 71%, and the hydroquinone / catechol ratio was 4.0.

Comparative Example 1 The same experiment as in Example 1 was carried out except that 4.1 g of 1,4-dioxane in Example 1 was not added, and the hydrogen peroxide conversion rate was 100% and the dihydric phenol yield was 100%. Rate = 70
%, Hydroquinone / catechol ratio = 1.1.

Example 2 The amount of 1,4-dioxane added in Example 1 was 7.4 g.
When the same operation as in Example 1 was performed except that
The yield of dihydric phenol was 63%, and the hydroquinone / catechol ratio was 4.9.

Example 3 The same operation as in Example 1 was carried out except that tetrahydrofuran was used instead of 1,4-dioxane in Example 1, and hydrogen peroxide conversion rate = 100%, dihydric phenol. Yield = 20%, hydroquinone / catechol ratio =
It was 2.5.

Example 4 25 g of anisole, 4.4 g of 1,4-dioxane, 15.0 g of water and 0.65 g of ATS-1 catalyst were placed in the same apparatus as in Example 1 and heated to 80 ° C. in an oil bath. After the mixture reached 80 ° C., 7.3 g of 31 wt% hydrogen peroxide solution was added dropwise by a metering pump over 4.2 hours. After the dropping was completed, stirring was continued for another 2 hours. After the reaction was completed, the reaction solution was still separated into two layers, but guaiacol and paramethoxyphenol (PMP) in the water layer and the oil layer were quantified by gas chromatography, and the conversion rate of hydrogen peroxide was 9
5%, the yield of guaiacol and PMP with respect to hydrogen peroxide was 17%, and the PMP / guaiacol ratio was 4.7.

Claims (6)

[Claims] 1. A process for producing a dihydric phenol, which comprises reacting a phenol with hydrogen peroxide in the presence of a crystalline aluminotitanosilicate and a cyclic ether. 2. The method for producing a dihydric phenol according to claim 1, wherein the crystalline aluminotitanosilicate is a zeolite having a pentasil type structure. 3. The method for producing a dihydric phenol according to claim 1, wherein the cyclic ether is 1,4-dioxane. 4. The method for producing a dihydric phenol according to claim 1, wherein the reaction is carried out in a polar solvent containing cyclic ethers. 5. The polar solvent is water, acetone, methanol,
5. A selected from the group consisting of acetonitrile and ethanol.
A method for producing the dihydric phenols described. 6. The method for producing a dihydric phenol according to claim 4, wherein the polar solvent is water.