JPS6049166B2 - Process for producing orthomethylated phenols - Google Patents

Description

[Detailed Description of the Invention] The present invention is directed to the use of alcohols such as phenol and cresol;
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■■■ This invention relates to a method for producing orthomethylated phenols such as 2,6-xylenol by reaction.

More specifically, the present invention relates to a method capable of selectively methylating the ortho position and suppressing the decomposition reaction of methanol. Orthomethylated phenols, such as xylenol, are used as raw materials for the production of polyphenylene oxide resins. Conventionally, these orthomethylated phenols have been produced by reacting phenols having ortho hydrogen with methanol in the presence of a catalyst, and various metal oxides are effective as catalysts. is proposed. For example, Japanese Patent Publication No. 42-6894 discloses a method of using magnesium oxide as a catalyst;
No. 11101 discloses a method using manganese oxide as a catalyst, and Japanese Patent Publication No. 52-47446 discloses a method using manganese oxide as a catalyst.
Publication No. 717588 and British Patent No. 717588 disclose a method using iron oxide as a catalyst. Among these metal fluoride catalysts, the method using magnesium oxide as a catalyst has high ortho-selectivity in the methylation reaction, but if the reaction is carried out at high temperature to increase the catalytic activity, the life of the catalyst will be shortened. There are disadvantages such as shortening of the catalyst, and inconvenience in handling since the catalyst is easily powdered. Therefore, in order to improve these drawbacks of magnesium oxide catalysts, methods using various multi-component catalysts consisting of magnesium oxide and other metal oxides have been proposed, but these methods have not yielded fully satisfactory results. It's hard to say that it is. In addition, in the method of using iron oxide as a catalyst, the iron oxide catalyst has the characteristic of showing high activity at lower temperatures than the magnesium oxide catalyst, but the ortho position selectivity of the methylation reaction is not sufficiently high. Another drawback is that methanol is often decomposed during the reaction. In order to improve these drawbacks of iron oxide catalysts, methods using various multicomponent catalysts consisting of iron oxide and other metal oxides have also been proposed (
For example, Special Publication No. 3781, Special Publication No. 47-
Publication No. 37943, Japanese Patent Publication No. 47-37944, Japanese Patent Publication No. 47-37945, Japanese Patent Publication No. 47-37946
No. Publication, Special Publication No. 47-702 @ Publication, Special Publication No. 50-56
Publication No. 96, Special Publication No. 51-10023, Special Publication No. 5
Publication No. 1-126■, Special Publication No. 52-47446,
Special Publication No. 52-1264, Special Publication No. 52-12690
Publication No. 12692/1983, Japanese Patent Application Publication No. 1972-12692
38936, JP 50-76032, JP 53-9024, JP 53-101318
Publications, etc.). However, even if these catalysts are used, the above objectives cannot be fully achieved. The present inventors have developed a method for producing orthomethylated phenols by the reaction of phenols having hydrogen at the ortho position with methanol, which has high activity and high ortho selectivity in the methylation reaction, As a result of searching for a long-life iron oxide-containing catalyst that can suppress the decomposition reaction of reached the method.

That is, the present invention provides a method for producing orthomethylated phenols by reacting phenols having at least one ortho-position hydrogen with 3-methanol in the presence of a catalyst, in which iron oxide (a) and at least one metal oxide (b) selected from the group consisting of tin oxide, zirconium oxide, molybdenum oxide, and tungsten oxide. This is a method for producing orthomethylated phenols, characterized in that the reaction is carried out in the presence of a catalyst containing.

The phenols used as raw materials in the process of the invention are those having at least one ortho hydrogen.

Specifically, phenols: cresols such as o-cresol, m-cresol, and p-cresol; xylenes such as 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, and 3,5-xylenol; 2,
Trimethylphenol such as 3,4-trimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, methyl having ortho hydrogen such as 2,3,4,5-tetramethylphenol Group-substituted phenols: Examples of hydrocarbon-substituted phenols in which at least one methyl group of these methyl-substituted phenols is substituted with a hydrocarbon group such as an ethyl group, a propyl group, a butyl group, a cyclohexyl group, or a phenyl group. can do. Among these phenols having hydrogen at the ortho position, it is preferable to apply the method of the present invention to phenol, o-cresol, or a mixture thereof.
In the method of the present invention, the ratio of methanol used is usually 1 mole to 1 mole of the phenol having ortho hydrogen.
The amount ranges from 1 to 10 moles, preferably from 3 to 6 moles.

The catalyst used in the process of the invention is iron oxide (a)
and a catalyst containing at least one metal oxide (b) selected from the group consisting of tin oxide, zirconium oxide, molybdenum oxide, and tungsten oxide.

The catalyst of the present invention includes, in addition to the catalyst consisting of the above two components, a catalyst consisting of the above two components and another metal oxide, a catalyst formed by adding various binders to the above two components, or catalyst components thereof. It can also be used in the form of a catalyst supported on various carriers. Iron oxide (a) as the first catalyst component
Specifically, ferric oxide, ferrous oxide, or a mixture thereof can be exemplified.

Among these iron oxide catalyst components, ferric oxide or a mixture of ferric oxide and ferrous oxide is preferred. These iron oxide catalyst components can be produced by calcining various ferrous compounds, ferric compounds, or mixtures thereof. In addition, the second catalyst component is tin oxide,
At least one metal oxide (b) selected from the group consisting of zirconium oxide, molybdenum oxide, and tungsten oxide.

More specifically, tin oxides such as stannic oxide, stannous oxide or mixtures thereof; zirconium oxides such as zirconium dioxide; molybdenum monoxide, dimolybdenum trioxide, molybdenum dioxide, dimolybdenum pentoxide, trioxide. Examples may include molybdenum oxides in different oxidation states, such as molybdenum or mixtures thereof; tungsten oxides in different oxidation states, such as tungsten dioxide, ditungsten pentoxide, tungsten trioxide, or mixtures thereof. These metal oxide catalyst components can also be used as a mixture of two or more. Among these metal oxide catalyst components, it is preferable to use zirconium oxide or tin oxide because the ortho-position selectivity of the methylation reaction and the effect of suppressing methanol decomposition are further improved.
These metal oxide catalyst components can be produced by firing at least one metal compound selected from the group consisting of tin, zirconium, molybdenum, and tungsten. The blending ratio of the metal oxide (b) in the catalyst used in the method of the present invention is usually 0.00% as the metal atom per gram atom of iron atom of iron oxide a.
003 to 0.30 gram atoms, preferably 0.01
It ranges from 0.15 to 0.15 gram atom. As a method for preparing the catalyst used in the method of the present invention, a method of blending the iron oxide (a) prepared by the above method, the metal oxide (b), and other catalyst components as necessary; A method of firing a mixture consisting of an iron compound that can become iron oxide a, the metal oxide that can similarly become the metal oxide (b) by firing, and other catalyst components as necessary, or an aqueous solution of the mixture. Examples include a method of firing after drying.

In the method of the present invention, when using a catalyst in which the iron oxide (a) and the metal oxide (b) are supported on a carrier, the method for preparing the catalyst includes an iron compound that can be converted into iron oxide by calcination, Similarly, a method can be exemplified in which a carrier is impregnated with an aqueous solution of a mixture consisting of the metal oxide which can be turned into the metal oxide by firing and, if necessary, other catalyst components, and then fired.

In the method of the present invention, orthomethylated phenols are produced by reacting phenols having at least one hydrogen at the ortho position with methanol under heating in the presence of the catalyst.

The reaction is usually carried out in the gas phase, but can also be carried out in the liquid phase. When the reaction is carried out in the gas phase, the reaction temperature is usually 250 to 450°C, preferably 300 to 400°C. During the reaction, it can be used as a fixed bed catalyst or as a fluidized bed catalyst. When the reaction is carried out in a fixed bed mode, the liquid hourly space velocity (L
HSV) is usually in the range of 0.1 to 10 hr-'', preferably 0.5 to 5 F1r-''. In addition, the reaction can usually be carried out under reduced pressure or increased pressure, but preferably 1-
It is carried out under pressure in the range of 30k9/C7lf-G.
After separating unreacted methanol from the mixture after completion of the reaction, orthomethylated phenols are obtained by processing according to conventional methods such as distillation, crystallization, and extraction. The recovered unreacted methanol and phenols having ortho-position hydrogen are recycled and reused in the reaction. Next, the method of the present invention will be specifically explained using examples.

The meaning of each term used below and the calculation method are as follows. Example 1 After dissolving 202.0 g of ferric nitrate nonahydrate and 4.87 g of zirconium tetrachloride in 21 distilled water, 25% aqueous ammonia was gradually added to adjust the pH of the liquid to 7.

The formed precipitate was washed with water, filtered, dried at 90°C for a day and night, and then calcined at 450°C for 3 hours to prepare a catalyst consisting of iron oxide and zirconium oxide. When the catalyst thus prepared was analyzed by atomic absorption spectroscopy, it was confirmed that the atomic ratio of iron:zirconium was 97:3. 6-10
20ml of the catalyst crushed into a mesh was filled into a Pyrex reaction tube with an internal diameter of 20TI1n, and then heated to 350°C.

After reaching a predetermined temperature, a mixture of methanol/phenol with a molar ratio of 5 was heated at 14 ml/Hr (LHSVO.7hr-
The reaction was carried out by feeding at the rate of 1). The results are shown in Table 1. Example 2 A catalyst consisting of iron oxide and zirconium oxide was prepared in the same manner as in Example 1 except that the atomic ratio of Fe/Zr was changed to 90/10.

A reaction was carried out in the same manner as in Example 1 using this catalyst. The results are shown in Table 1. Comparative Examples 1-2 Iron oxide catalyst prepared from only ferric nitrate nonahydrate in the same manner as in Example 1 (Comparative Example 1), zirconium oxide catalyst prepared only from zirconium chloride in the same manner (Comparative Example 2) was used to conduct a reaction in the same manner as in Example 1.

The results are shown in Table 1. Example 3 In the catalyst preparation method of Example 1, zirconium tetrachloride 4
．． A catalyst consisting of iron oxide and tin oxide was prepared in the same manner except that 87 g was replaced with 5.93 g of stannous chloride.

The reaction was carried out using the same three methods as in Example 1, except that this catalyst was used. The results are shown in Table 2. Comparative Example 3 A tin oxide catalyst was prepared using only stannous chloride in the same manner as in the catalyst preparation method of Example 1.

A reaction was carried out in the same manner as in Example 1 using the catalyst thus prepared. The results are shown in Table 2. Example 4 In the catalyst preparation method of Example 1, zirconium tetrachloride 4
．． 87g ammonium molybdate tetrahydrate 2.82g
A catalyst consisting of iron oxide and molybdenum oxide was prepared in the same manner except that the 25% ammonia water was replaced with a 1N aqueous sodium hydroxide solution.

Further, a reaction was carried out in the same manner as in Example 1 using the catalyst thus prepared. The results are shown in Table 2. Comparative Example 4 A reaction was carried out in the same manner as in Example 4 using molybdenum oxide obtained by thermally decomposing ammonium molybdate at 450° C. for 3 hours as a catalyst.

The results are shown in Table 2. Example 5 The catalyst was prepared in the same manner as in Example 1, except that 4.87 g of zirconium tetrachloride was changed to 2.81 g of ammonium tungstate, and the 25% aqueous ammonia was changed to 1N aqueous sodium hydroxide solution. A catalyst consisting of iron oxide and tungsten oxide was prepared.

A reaction was carried out in the same manner as in Example 1 using the catalyst thus prepared. The results are shown in Table 2. Comparative Example 5 A reaction was carried out in the same manner as in Example 5 using tungsten oxide obtained by thermally decomposing ammonium tungstate at 450° C. for 3 hours as a catalyst.

Claims (1)

[Claims] 1. A method for producing orthomethylated phenols by reacting phenols having at least one ortho-position hydrogen with methanol in the presence of a catalyst, wherein iron oxide a and oxidized tin, zirconium oxide,
A method for producing orthomethylated phenols, characterized in that the reaction is carried out in the presence of a catalyst containing at least one metal oxide (b) selected from the group consisting of molybdenum oxide and tungsten oxide. 2. The catalyst is a catalyst comprising iron oxide (a) and said metal oxide (b) in the range of 0.01 to 0.15 gram atom per gram atom of iron of said iron oxide. The method described in Section 1. 3 Claim 1 or 2 in which the reaction is carried out in a gas phase
The method described in section. 4. The method according to any one of claims 1 to 3, wherein the phenol having at least one hydrogen at the ortho position is phenol, o-cresol, or a mixture thereof. 5. The method according to any one of claims 1 to 4, wherein the reaction is carried out at 300 to 400°C.