JPS6049167B2 - Process for producing orthomethylated phenols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing orthomethylated phenols such as 2,6-xylenol by reacting phenols having ortho hydrogen such as phenol and cresol with methanol.

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 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 no fully satisfactory results have been obtained. 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 that it shows high activity at a lower temperature 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, JP 46-37814, JP 47-37943, JP 47-37944, JP 47-37945, JP 47-37946.
No. Publication, Special Publication No. 47-702 x Publication, Special Publication No. 50-56
Publication No. 96, Special Publication No. 51-10023, Special Publication No. 5
Publication No. 1-1261'', Special Publication No. 52-47446,
Special Publication No. 52-126, Special Publication No. 52-12690
Publication No. 12692/1983, Japanese Patent Application Publication No. 1972-12692
38936, JP 50-76032, JP 53-9022 Wani, JP 53-101318
Publications, etc.). However, even if these catalysts are used, the above objectives cannot be fully achieved. The present inventors have discovered that a method for producing ortho-methylated phenols by the reaction of phenols having ortho hydrogen with methanol is highly active and has high ortho-selectivity in the methylation reaction, and that methanol As a result of searching for a long-life iron oxide-containing catalyst that can suppress decomposition reactions, we used a catalyst made of iron oxide and a specific metal oxide. The inventors have now discovered that the above object can be achieved, and have arrived at the method of the present invention.

That is, the present invention provides a method for producing orthomethylated phenols by reacting phenols having at least one ortho-position hydrogen with methanol in the presence of a catalyst, in which iron oxide (a) and Carrying out the reaction in the presence of a catalyst containing at least one metal oxide (b) selected from the group consisting of gallium oxide, germanium oxide, yttrium oxide, niobium oxide, hafnium oxide, tantalum oxide, and bismuth oxide. A method for producing orthomethylated phenols, characterized by:

The phenols used as raw materials in the process of the invention are those having at least one ortho hydrogen. Specifically, phenol; cresols such as o-cresol, m-cresol, and p-cresol;
2,3-xylenol, 2,4-xylenol, 2,5
-xylenol, 3,5-xylenol, etc., 2,3,4-trimethylphenol, 2,3,5
- trimethylphenol, such as trimethylphenol, 3,4,5-trimethylphenol, 2,)3,4,5
- Methyl group-substituted phenols having hydrogen at the ortho position such as tetramethylphenol: At least one of the methyl groups of these methyl group-substituted phenols is a hydrocarbon such as an ethyl group, propyl group, butyl group, cyclohexyl group, or phenyl group. Examples include hydrocarbon-substituted phenols. 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 proportion of methanol used is generally 1 to 10 mol, preferably 3 to 6 mol, per mol of the phenol having ortho hydrogen.

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 potassium oxide, germanium oxide, yttrium oxide, niobium oxide, hafnium oxide, tantalum oxide, and bismuth 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 a catalyst formed by adding various binders to the above two components, or a variety of these catalyst components. It can also be used in the form of a catalyst supported on a carrier. Specific examples of the iron oxide (a) of the first catalyst component include ferric oxide, ferrous oxide, or a mixture thereof. 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.
Further, the second catalyst component is at least one metal oxide (b) selected from the group consisting of gallium oxide, germanium oxide, yttrium oxide, niobium oxide, hafnium oxide, tantalum oxide, and bismuth oxide.

More specifically, gallium oxides such as gallous oxide, gallium oxide or mixtures thereof; germanium oxides such as germanium oxide, germanium oxide or mixtures thereof; ,．． ．． i). diolium oxide in various oxidation states such as niobium monoxide, diniobium trioxide, niobium dioxide, diniobium pentoxide or mixtures thereof; hafnium oxide such as hafnium dioxide; tantalum dioxide, ditantalum pentoxide or Examples include bismuth oxide in various oxidation states such as tantalum oxide, bismuth oxide, bismuth trioxide, bismuth pentoxide, and mixtures thereof. These metal oxide (b) catalyst components can be used as a mixture of two or more. Among these metal oxide (b) catalyst components, the use of at least one metal oxide selected from the group consisting of gallium oxide, germanium oxide, and hafnium oxide improves the ortho-position selectivity of the methylation reaction and improves the methanol This is preferable because the effect of suppressing the decomposition of is further improved. These metal oxide catalyst components include gallium,
It can be produced by firing at least one metal oxide selected from the group consisting of germanium, yttrium, niobium, hafnium, tantalum, and bismuth. The blending ratio of the metal oxide (b) in the catalyst used in the method of the present invention is usually 0.0 as the metal atom per gram atom of iron atom of iron oxide (a).
03 to 0.30 gram atoms, preferably 0.005
to 0.15 gram atom. A method for preparing the catalyst used in the method of the present invention is a method of blending the iron oxide (a) prepared by the above method, the metal oxide (b), and other catalyst components as necessary: by calcination. 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 calcination, and other catalyst components as necessary, or Examples include a method in which the aqueous solution is dried and then baked. In the method of the present invention, when using a catalyst on which the iron oxide (a) and the metal oxide (b) are supported, the method for preparing the catalyst includes iron compounds that can be converted into iron oxide by calcination, and the like. Examples include a method in which a carrier is impregnated with an aqueous solution of a mixture of the metal oxide, which can become the metal oxide upon firing, and optionally 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, the catalyst 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
HS■) usually ranges from 0.1 to 10 hr-1, preferably from 0.5 to 511 r-1. 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/Cli-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 five examples.

The meaning of each term used below and the calculation method are as follows. Example 1 After dissolving 202.0y of ferric nitrate nonahydrate in 2e of distilled water, 25% ammonia water was gradually added to adjust the pH of the liquid.
By setting 7 to 7, colloidal ferric hydroxide was generated.

This colloidal ferric hydroxide had particle sizes distributed in the range of 1 to 10p (average particle size of about 5μ). Wash the generated ferric hydroxide precipitate with water? passed. Add 0.55y of germanium dioxide to this and use an automatic mortar to
Kneaded for hours. This was dried at 90°C for a day and night, and then
The mixture was calcined at 50° C. for 3 hours to prepare a catalyst consisting of iron oxide and germanium oxide. When the catalyst thus prepared was analyzed by atomic absorption spectroscopy, it was confirmed that the atomic ratio of iron:germanium was 99:1. 20 mL of the catalyst pulverized to 6 to 10 mesh was filled into a Pyrex reaction tube with an inner diameter of 2'', and then heated to 350°C.

After reaching a predetermined temperature, a mixture of methanol/phenol with a molar ratio of 5 was heated to 14TrLt/Hr (LHS■0.7h
The reaction was carried out by feeding at a rate of r-1). The results are shown in Table 1. Examples 2 to 7 In the catalyst preparation method of Example 1, germanium dioxide 0
．． 55y and 4.08q of gallium nitrate octahydrate (Example 2
), hismuth nitrate pentahydrate 7.50y Example 3), yttrium oxide (■) 3.49g (Example 4), niobium oxide (■) 2.711g (Example 5), hafnium oxide (
■) 2.14q (Example 6), tantalum oxide (■
) 6.83y (Example 7) in the same manner except that iron oxide/gallium oxide, iron oxide/hismuth oxide, iron oxide/yttrium oxide, iron oxide/niobium oxide,
Catalysts were prepared from iron oxide/hub trinium oxide and iron oxide/tantalum oxide, respectively.

The reaction was carried out in the same manner as in Example 1 except that these catalysts were used. The results are shown in Table 1. Example 8 After dissolving 202.0y of ferric nitrate nonahydrate in 2e of distilled water, 25% ammonia water was gradually added while stirring,
The pH of the liquid was set to 7.

When the cofloid-like ferric hydroxide produced at this time was measured using a Coulter counter, it had a particle size distributed in the range of 1 to 10 μm (average particle size of about 3 μm). The precipitate of ferric hydroxide produced was washed with water and filtered. 1.62 y of germanium dioxide was added to this and kneaded for 1 hour using an automatic mortar. This was dried at 90°C for a day and night, and then calcined at 450°C for 5 hours to prepare an iron oxide/germanium oxide catalyst. Table 1 shows the results of a reaction using this catalyst in the same manner as in Example 1.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 using an iron oxide catalyst prepared from only ferric nitrate nonahydrate in the same manner as in Example 1.

The results are shown in Table 1. Comparative Examples 2 to 8 Germanium dioxide (Comparative Example 2), gallium nitrate octahydrate (Comparative Example 3), bismuth nitrate pentahydrate (Comparative Example 4),
Yttrium oxide (■) (Comparative Example 5), niobium oxide (■
) (Comparative Example 6), hafnium oxide (■) (Comparative Example 7), and tantalum oxide (■) (Comparative Example 8) were each calcined at 450°C for 3 hours in the same manner as in Example 1 to form germanium oxide catalyst, germanium oxide catalyst, Gallium, bismuth oxide, yttrium oxide, niobium oxide, hafnium oxide, and tantalum oxide catalysts were prepared.

Claims (1)

[Scope of 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 carrying out the reaction in the presence of a catalyst containing at least one metal oxide (b) selected from the group consisting of gallium oxide, germanium oxide, yttrium oxide, niobium oxide, hafnium oxide, tantalum oxide, and bismuth oxide. A method for producing orthomethylated phenols, characterized by: 2. The catalyst is a catalyst comprising iron oxide (a) and the metal oxide (b) in the range of 0.005 to 0.15 gram atom per gram atom of iron of the 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 ortho-position hydrogen 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.