JPS6049168B2 - 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 that can selectively methylate the ortho position and suppress the decomposition reaction of methanol, and particularly provides a long-life catalyst for the reaction. orthomethylated phenols,
For example, xylenol is conveniently used as a raw material for manufacturing polyphelene oxide resins.

Traditionally, these ortho-methylated phenols have been produced by reacting phenols with ortho hydrogen with methanol in the presence of a catalyst, and various metal oxides have been effective as catalysts. It is proposed that. For example, Japanese Patent Publication No. 42-6894 discloses a method using magnesium oxide as a catalyst, Japanese Patent Publication No. 51-11101 discloses a method using manganese oxide as a catalyst, and Japanese Patent Publication No. 52-47446 and British Patent No. 717
No. 588 discloses a method using iron oxide as a catalyst. Among these metal oxide catalysts, a method using magnesium oxide as a catalyst is common. On the other hand, the following method has been conventionally known for producing thiophenecarboxylic acid.

(1) Oxidation of acetylthiophene [H. D. HartO
ngtl&L. G. Conley; J. A. C. S. ，
? , 3096 (1947)] (2) Carbonation reaction of thenyllithium [H. Gilman&D. ．． A. Shirly
J. A. C. S. , Kawa, 1870 (1949)] (3)
Oxidation of methylthiophene [L. Friedman, D.
L. Fishland Schechter, J. ()
Rg, Chem. ，? , 1453 (1965)] (4)
Oxidation of thiophene aldehyde [Ya. L. Goldfa
rb. Yu. B. ■01kenstejnandB. ■
．． Fat PatinZh. O? Hch. Khlm,? -,9
59 (1964)] All of these methods have various disadvantages such as long and complicated steps, industrially difficult preparation of raw materials, and high costs.

In view of these circumstances, the present inventors have conducted intensive studies on shortening and streamlining the process, and as a result, have discovered that thiophene carbonyl chloride can be efficiently obtained by directly chlorinating thiophene aldehyde without going through thiophenecarphonic acid. Heading The present invention has been arrived at. That is, the gist of the present invention is to react thiophene aldehyde represented by the general formula [shi,6,,''-0H0 with chlorine in the presence of a catalyst containing a radical initiator or under ultraviolet irradiation to obtain a compound of the general formula This is a method for producing thiophene carbonyl chloride represented by 00C1, and its purpose is to produce thiophene carbonyl chloride from thiophene aldehyde via thiophene carboxylic acid, which is an improved method of producing thiophene carbonyl chloride without passing through thiophene carboxylic acid. An innovative method for directly producing thiophene carbonyl chloride in high yield is provided.

When chlorinating thiophene aldehyde in the method of the present invention, no special chlorinating agent is required; gaseous or liquid chlorine is sufficient.

The reaction proceeds without a catalyst, but the reaction rate is slow and the yield is low.

Therefore, in the present invention, preferable results can be obtained when the reaction is carried out in the presence of a catalyst as a radical initiator or under ultraviolet irradiation, since the reaction rate is increased and the yield is improved. When a catalyst is used as a radical initiator, the reaction temperature ranges from room temperature to 200°C, preferably from 50'C to 140°C.

If the temperature is too low, the reaction rate will be slow, and if the temperature is too high, the selectivity will decrease. l The reaction can be carried out in either gas phase or liquid phase. In the case of liquid phase, it can be carried out without solvent, but it can be carried out with halogenated hydrocarbons such as carbon tetrachloride, chloroform, benzene, monochlorobenzene, oxygen Use of a solvent that is inert to the adhesive actant and the product, such as a benzene-based solvent such as chlorobenzene, has the advantage of making it easier to control the reaction rate, remove reaction heat, etc.

For example, as the solvent, carbon tetrachloride, benzene, Monokucho lebenzene, O-dichlorobenzene, etc. are used.

In addition, the molar ratio of CI2/thiophene aldehyde was 0.
．． 7 to W, preferably 1 to 3 gives a good yield. Catalysts that are radical initiators used in the present invention include inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide;
Organic peroxides such as benzoyl peroxide, di-t-butyl peroxide, t-butyl hydroxyperoxide, azobisisobutyronitrile, 2,2″-azubis(2,4-dimethylvaleronitrile), N,N In addition to azo compounds such as ``-azobis(2-cyanopentanoic acid) and azobis(cyclohexanecarbonitrile), diazo compounds are also effective.

The catalyst concentration was 0.0% relative to thiophene aldehyde.
A range of 0.05 to 10% by weight, preferably 0.5 to 5% by weight is suitable.

When it is too small, the reaction rate is slow, and when it is too large, there is no significant effect.

When thiophene aldehyde and chlorine are reacted in the presence of a catalyst, the selectivity can be maintained at approximately 100%, the reaction rate can be increased, and production can therefore be advantageously carried out industrially. Next, carrying out the reaction of the present invention as a photoreaction under ultraviolet irradiation is effective in improving the reaction rate and selectivity.

The reaction temperature when carrying out this without a solvent or in a solvent, C
l. /thiophenealde As the first catalyst component (a), ferric oxide, ferrous oxide, or a mixture thereof can be specifically 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. 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; yttrium oxides such as diyttrium trioxide; Niobium monoxide, diniobium trioxide,
Niobium oxides in various oxidation states such as niobium dioxide, diniobium pentoxide or mixtures thereof; hafnium oxides such as hafnium dioxide; tantalum oxides such as tantalum dioxide, tantalum pentoxide or mixtures thereof; bismuth monoxide, bismuth trioxide Examples include bismuth oxide in various oxidation states such as bismuth pentoxide, bismuth pentoxide, and mixtures thereof. These metal oxide (b) catalyst components can also 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 can be produced by firing at least one metal oxide selected from the group consisting of gallium, germanium, yttrium, niobium, hafnium, tantalum, and bismuth. The third catalyst component is chromium oxide (C).

Specific examples of chromium oxide include chromium monoxide, dichromium trioxide, chromium dioxide, dichromium pentoxide, chromium trioxide, and mixtures thereof. Among these chromium oxides, it is preferable to use dichromium trioxide or a mixture of dichromium trioxide and chromium trioxide. These chromium oxide catalyst components can be produced by calcining various chromium compounds or mixtures thereof. The proportion of the metal oxide (b) in the catalyst used in the method of the present invention is usually 0.003 to 0.30 gram atoms per gram of iron atom of iron oxide (a); Preferably it is in the range of 0.005 to 0.15 gram atom.

The proportion of chromium oxide (c) in the catalyst is usually 0.0001 to 0.1 gram atom, preferably 0.0001 to 0.1 chromium atom per gram atom of iron in iron oxide (a).
001 to 0.05 gram atom. As a method for preparing the catalyst used in the method of the present invention, the iron oxide (a) prepared by the above method, the metal oxide (b), the chromium oxide (c), and other catalyst components as necessary are blended. A method of converting an iron compound which can be turned into iron oxide (a) by firing; a metal compound which can be turned into the metal oxide (b) by firing;
) A method of calcining a mixture consisting of the chromium compound and optionally other catalyst components, which can become After that, the metal. A method of blending and firing the oxide (b) or the metal compound that can become the metal oxide (b) and other catalyst components as necessary, the iron compound, the chromium compound, the metal oxide (b), ) and, if necessary, add a base to a solution of the mixture containing the metal compound that can be used as another catalyst component to coprecipitate a mixture of hydroxides,
Examples include a method in which this mixture is fired, or a method in which an aqueous solution of the mixture is dried and then fired.

In the method of the present invention, when using a catalyst in which the iron oxide (a), the metal oxide pentoxide (b) and the chromium oxide (c) are supported on a carrier, the catalyst may be prepared by calcination. An iron compound that can be turned into iron oxide (a) when fired, a metal compound that can be turned into the metal oxide (b) when fired, and a chromium compound that can be turned into the chromium oxide (c) when fired. Examples include a method in which a carrier is impregnated with an aqueous solution of a mixture of the compound and, if necessary, other catalyst components, and then calcined.

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,
It can also be carried out in the liquid phase. When the reaction is carried out in a gas phase, the reaction temperature is usually 250 to 450°C, preferably 300°C.
The catalyst can be used as a fixed bed catalyst or as a fluidized bed catalyst in the reaction at temperatures between 400°C and 400°C. When the reaction is carried out in a fixed bed mode, the liquid hourly space velocity (LHSV) of the feedstock is usually between 0.1 and 1.
011 r-'', preferably in the range of 0.5 to 511 r-''. Further, the reaction can usually be carried out under reduced pressure or increased pressure, but preferably 1 to 30 k9/c! It is carried out under pressures in the range i-G. After separating unreacted methanol from the mixture at the end 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 in 2e distilled water, 25% ammonia water was gradually added to adjust the pH of the liquid.
was set as 7.

The generated precipitate was washed with water and filtered. To this, 0.97 g of germanium dioxide and 2.47 g of chromium nitrate nonahydrate were added and kneaded for 1 hour using an automatic mortar. This was dried at 90°C for a day and night, then fired at 450°C for 3 hours to form iron oxide.
A ternary catalyst consisting of germanium oxide and chromium oxide was prepared. The catalyst prepared in this way was analyzed by atomic absorption method,
The atomic ratio of iron: germanium nichrome is 97:1.8:1
．． I confirmed that it was 2. 21 mt of catalyst crushed to 6-10 mesh with an inner diameter of 20 m! ! After filling a Pyrex reaction tube with a diameter of 355 mm and reaching a predetermined temperature, the molar ratio of phenol ni methanol di H2O is 1.
:5:2 mixed solution was supplied at a rate of 12 ml/Alr to carry out the reaction.

Table 1 shows the results after 50F1r and after 45011r of reaction initiation. Example 2 In the catalyst preparation of Example 1, 0.97 g of germanium dioxide was replaced with 1.95 g of hafnium oxide.
A catalyst consisting of iron oxide, hafnium oxide, and chromium oxide was prepared in the same manner except for changing to g.

The reaction was carried out under the same conditions as in Example 1 except that this catalyst was used. Table 1 shows the results 50 hours and 200 hours after the start of the reaction. Comparative Example 1 An iron oxide/germanium oxide catalyst was prepared in the same manner as in Example 1 from 202.0 g of ferric nitrate nonahydrate and 0.97 g of germanium dioxide.

Using this catalyst, a reaction was carried out under the same conditions as in Example 1.
Table 1 shows the results after 3011r and 20011r from the start of the reaction. Comparative Examples 2-3 In the catalyst preparation of Comparative Example 1, 0.97 g of germanium dioxide was mixed with 1.9 g of hafnium oxide.
An iron oxide/hafnium oxide catalyst and an iron oxide/chromium oxide catalyst were prepared in the same manner as in Comparative Example 1 except that 95 g or 2.47 g of chromium nitrate nonahydrate was used. A reaction was carried out under the same conditions as in Example 1 using these catalysts. Table 1 shows the results after 20F1r and 10011r of reaction initiation. Examples 3-7 In the catalyst preparation of Example 1, germanium dioxide 0.
3.71 g of gallium nitrate octahydrate instead of 97 g (
Example 3), 1.23 g of niobium oxide (■) (Example 4)
, 1.83 g of yttrium oxide (■) (Example 5), 2.05 g of tantalum oxide (■) (Example 6), and 4.50 g of bismuth nitrate pentahydrate (Example 7) were used. The catalyst was prepared using the method described in .

A reaction was carried out in the same manner as in Example 1 using these catalysts. The results are shown in Table 2. Comparative Examples 4 to 8 In the catalyst preparation of Comparative Example 1, germanium dioxide 0.
Instead of 97 g, 3.71 g of gallium nitrate octahydrate (Comparative example 4), 1.23 g of niobium (V) oxide (Comparative example 5), 1.83 g of yttrium oxide (■) (Comparative example 6), tantalum oxide (V ) (Comparative Example 7) and 4.50 g of bismuth oxalate pentahydrate (Comparative Example 8) were used respectively.

Claims (1)

[Claims] 1. A method for producing orthomethylated phenols by reacting a phenol having at least one ortho hydrogen with methanol in the presence of a catalyst under heating, comprising: iron oxide (a); In the presence of a catalyst consisting of 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 and chromium oxide (c) A method for producing orthomethylated phenols, characterized by carrying out the reaction. 2. The method according to claim 1, wherein the catalyst contains the metal oxide (b) in an amount of 0.005 gram atom per gram atom of iron of the iron oxide (a). . 3. The catalyst is a catalyst containing the chromium (c) oxide in an amount of 0.001 to 0.05 gram atom per gram atom of iron of the iron oxide (a). The method described in Section 2. 4 Claims 1 to 3 in which the reaction is carried out in a gas phase
Any of the methods described in section. 5. The method according to any one of claims 1 to 4, wherein the phenol having at least one hydrogen at the ortho position is phenol, o-cresol, or a mixture thereof. 6. The method according to any one of claims 1 to 5, wherein the reaction is carried out at 300 to 400°C.