JP3010793B2 - Method for oxidizing substituted aromatic compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for oxidizing a substituted aromatic compound, and more particularly to a method for producing phenols and quinones useful in the organic chemical industry.

[0002]

2. Description of the Related Art In the synthesis of phenols and quinones, which are oxidation products of aromatic compounds, obtaining these by a one-step reaction by oxidizing an aromatic nucleus is difficult because the carbon atom of the aromatic ring has poor reactivity. It is known that under strong oxidizing conditions, side chain oxidation, dimerization, aromatic ring cleavage and the like occur, which is difficult.

As an example of directly oxidizing an aromatic compound to synthesize phenols and quinones, a method of reacting an aromatic compound with an organic peroxide in the presence of a Lewis acid (Bull. Chem. Soc) Jpn., 43, p
293 (1970)) and a method of reacting an aromatic compound with hydrogen peroxide in the presence of crystalline titanosilicate (St)
ud. Surf. Sci. Catal. 37, p41
3) is known. Also, acetic acid first in acetic acid solution
A method of obtaining phenol by oxidizing benzene with oxygen using copper as a catalyst has also been proposed (US Pat. No. 371).
No. 8629). However, in these methods, expensive raw materials such as peracids and peroxides must be used, the selectivity of the resulting oxide is as low as about 90%, or the catalytic activity is too low or the reaction is substantially not carried out. In general, it is a stoichiometric reaction of the catalyst component, and there has been a problem that a long-term continuous reaction cannot be realized.

[0004] In order to solve these problems, a continuous direct oxidation method of an aromatic compound which reacts with an aromatic compound in the presence of oxygen and hydrogen using palladium-supported silica as a catalyst has been proposed (Catal. Lett. , 4 (2)
139 (1990)). However, the above-described method has a problem that the oxidation reaction does not occur depending on the substituent of the aromatic compound, for example, phenols cannot be oxidized.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has as its object to provide a method for oxidizing a substituted aromatic compound in a highly selective and continuous manner from inexpensive raw materials. To provide.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by using a catalyst comprising a metal of group VIII in the periodic table and crystalline titanosilicate, the substitution has been carried out. The present inventors have found that the oxidation reaction of an aromatic compound can be performed with high selectivity and continuously, and have completed the present invention.

[0007] That is, the present invention relates to the VII.
A method for oxidizing a substituted aromatic compound, comprising reacting a substituted aromatic compound with a gas containing hydrogen and oxygen using a catalyst comprising a group I metal and crystalline titanosilicate.

Hereinafter, the method of the present invention will be specifically described.

In the process of the present invention, a catalyst comprising a metal of Group VIII in the periodic table and crystalline titanosilicate is used. What is titanosilicate here?
In "silicalite" (crystalline zeolite type structure with SiO ₂ of, disclosed by E.M.Flanigen et. (Nature, vol271, p512
(1978)) obtained by substituting part of silicon forming the crystal lattice with titanium.

The titanosilicate may be synthesized by any method, and an example of the synthesis is disclosed in JP-A-56-97720. Further, the amount of titanium contained in the titanosilicate can be defined as a silica / titania ratio (molar ratio),
Silica of titanosilicate used in the present invention /
The titania ratio is about 5 to 200. The components contained in the titanosilicate are not limited to titania and silica, and may contain one or more elements such as boron, aluminum, phosphorus, vanadium, chromium, manganese, iron, gallium, and zirconium.

In the present invention, the titanosilicate may be used as it is, or may be used after molding. When molded and used, a binder is generally used, but the type of the binder is not particularly limited, and for example, silica, alumina, or the like is used.

In the method of the present invention, a catalyst comprising a metal of Group VIII in the periodic table and the above-mentioned crystalline titanosilicate is used.
There is no particular limitation, and any Group VIII metal may be used. Typically, palladium, platinum, iridium, rhodium, ruthenium and the like can be used, and among them, palladium is particularly preferable.

The Group VIII metal may be supported on crystalline titanosilicate or used on silica, alumina, activated carbon or the like, and then mixed with titanosilicate. When a Group VIII metal is supported and used, the raw material to be supported is not particularly limited. For example, in the case of palladium, palladium (II) chloride, tetraammine palladium (II) chloride, palladium (II) acetate, or the like is used. Can be. Further, the method of supporting these metals on titanosilicate is not particularly limited, but an impregnation method or the like is used.

[0014] In the present invention, the VIIth of the periodic table
The content of the Group I metal relative to titanosilicate is preferably 0.1 to 5% by weight as a metal atom.
If it is less than 0.1%, the effect may be reduced, while if it exceeds 5%, it is disadvantageous from an economic viewpoint.

Further, when a Group VIII metal in the periodic table is supported on titanosilicate by a method such as an impregnation method, these can be calcined and / or reduced as necessary to be used as a catalyst. The calcination can be carried out under an inert gas or an oxygen-containing gas flow. The calcination temperature and time are not particularly limited. For example, the calcination is performed at 100 to 700 ° C. for about 30 minutes to 24 hours. I just need.

The catalyst obtained as described above may be used as it is, or may be used in the reaction by adding a diluent such as silica or alumina. Further, before use in the reaction, it may be used by reducing it under a stream of a hydrogen-containing gas.

In the method of the present invention, a monocyclic substituted aromatic compound whose substituent is an alkyl group, a hydroxyl group, a nitro group, or the like is used as a reaction raw material.
Examples thereof include alkylbenzenes such as ethylbenzene and styrene, phenols such as phenol, catechol, resorcin and cresol, and nitrobenzene.
When performing the reaction, a solvent may be used as necessary. As the solvent, an alcohol having 6 or less carbon atoms,
Polar solvents such as water, ketones, glycols and carboxylic acids are preferably used.

The reaction method may be any of a continuous flow system, a semi-batch system and a batch system. The reaction temperature is from 0 to 150 ° C., particularly from 10 to 100 from the viewpoint of reaction efficiency.
It is preferably set to ° C. When using a solvent, if the reaction temperature exceeds the boiling point of the solvent, the reaction can be performed under pressure, and the reaction pressure is not particularly limited,
Usually, it is carried out in a range from normal pressure to about 100 atm.

In the method of the present invention, oxygen is used as one component of the reaction raw material, but an oxygen-containing gas such as air can be used as the oxygen source.

The content of each raw material in the supplied gas is not particularly limited, but from the viewpoint of safety, the content of each raw material is
Preferably, it is outside the explosion range, for example, H ₂
2 to 60% by volume of O ₂ and 5 to 30% by volume of O ₂ , and a gas diluted with an inert gas such as nitrogen is used.

The amount of catalyst used in the reaction is
Group III metal / titanium ratio (molar ratio) of 0.001 to 1
0, the titanium / substituted aromatic compound ratio (molar ratio) is 0.00
It is preferably set to 0001 to 0.1.

The contact time of the gas used depends on the content of H ₂ and O ₂ in the gas. However, if the gas described above is used, the gas space velocity (total volume of gas supplied per hour / unit of catalyst) Volume; hereinafter abbreviated as GHSV)
It is performed in a range of about 1000 to 40000 hr ^{- 1} (20 ° C). When the reaction is carried out by continuously supplying the substituted aromatic compound, the contact time of the compound is determined by the weight hourly space velocity (weight of the supplied aromatic compound / hour).
Unit catalyst weight; hereinafter abbreviated as WHSV), 0.1
This is performed in the range of about 10 to 10 hr ^-1 .

[0023]

According to the present invention, the Vth in the periodic table
By using a catalyst composed of a group III metal and crystalline titanosilicate, phenols and quinones can be selectively selected without using expensive raw materials such as hydrogen peroxide in the reaction of the substituted aromatic compound with hydrogen and oxygen. Can be obtained, and furthermore, the catalyst life is longer than that of a conventionally used catalyst, so that the reaction can be continued for a long time, which is significant from an industrial point of view.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 197.5 g of tetraethylorthosilicate and 41.9 g of tetraethylorthotitanate were added to a 1000 ml three-necked flask in a nitrogen atmosphere, and 346 g of a 25% aqueous solution of tetrapropylammonium hydroxide was added in a few minutes with vigorous stirring. It was dropped. Two hours later, ethanol was distilled off, and water was added so that the total amount of water was 297 g.
This was transferred to a 500 ml autoclave and 164
After heating at 50 ° C for 50 hours, the resulting white precipitate was washed with water and dried, and then calcined in air at 550 ° C for 6 hours to prepare titanosilicate.

The silica / titania ratio of the prepared titanosilicate was 67 (measured by ICP emission analysis).

An aqueous solution of tetraammine palladium (II) chloride was added to the prepared titanosilicate so that the weight of palladium atoms was 0.5% by weight based on the titanosilicate, and the mixture was stirred for 1 hour. After evaporation to dryness, 150 ° C
For 1 hour to obtain a catalyst.

Next, 1.0 g of the above-mentioned catalyst was placed in a normal pressure, liquid phase, semi-batch reactor, and suspended in 60 ml of toluene. Further, the supply amounts of H ₂ and O ₂ are set to 60 and 20 mm, respectively.
ol / hr, diluted with nitrogen, and GHSV = 28
The reaction was performed at 80 hr- ¹ (20.0C). The reaction was started at a reaction temperature of 45 ° C, and the reaction temperature was set to 65 ° C 2.5 hours after the start of the reaction. The reaction products were analyzed by high performance liquid chromatography. As a result, it was confirmed that the product of toluene conversion was cresol only.
Table 1 shows the results up to 4.5 hours after the start of the reaction.

[0029]

[Table 1] Example 2 Example 1 except that the substituted aromatic compound was phenol.
The reaction was carried out in the same manner as described above. As a result of analyzing the reaction product by gas chromatography, it was confirmed that the product of phenol conversion was p-benzoquinone alone. Table 2 shows the results up to 4.5 hours after the start of the reaction.

[0030]

[Table 2] Comparative Example 1 An aqueous tetraamminepalladium (II) chloride solution was added to silica gel such that the weight of palladium atoms became 0.5% by weight with respect to the silica gel, and the mixture was stirred and mixed for 1 hour.
After evaporating to dryness, hydrogen reduction was carried out at 150 ° C. for 1 hour to obtain a catalyst.

The reaction was carried out in exactly the same manner as in Example 1 except that the catalyst was palladium-supported silica prepared by the above method, and the substituted aromatic compound was phenol. As a result of the reaction, no oxidation products such as hydroquinone and benzoquinone were obtained at all.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI C07C 46/08 C07C 46/08 50/04 50/04 (58) Investigated field (Int.Cl. ⁷ , DB name) C07B 33 / 00 C07B 41/02 C07B 41/06 C07C 37/58 C07C 46/06

Claims (1)

(57) [Claims] 1. A method comprising reacting a monocyclic substituted aromatic compound with a gas containing hydrogen and oxygen using a catalyst comprising a group VIII metal in the periodic table and crystalline titanosilicate. A method for oxidizing a substituted aromatic compound.