JPH0466546A - Production of armatic hydroxy compound - Google Patents

Abstract

PURPOSE:To efficiently produce the subject compound by hydroxylating phenols and/or alkoxybenzenes with H2O2 using a crystalline substance containing silicon oxide and titanium oxide having a specific crystallite size as a catalyst. CONSTITUTION:Phenols and/or alkoxybenzenes are hydroxylated by using a crystalline substance, containing silicon oxide and titanium oxide and having a crystallite size within the range of <10,000 Angstrom as a catalyst to afford aromatic hydroxyl compounds, i.e. aromatic dihydroxy compounds or alkoxyphenols. The hydroxylation can be efficiently carried out and advanced at a high reaction rate by the aforementioned method to industrially and advantageously produce the subject compound. The resultant compound is useful as various organic synthetic intermediates or raw material substances and further in the field of reducing agents, rubber chemicals, dyes, medicines, perfumes, polymerization inhibitors, oxidation inhibitors, etc.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing aromatic hydroxy compounds, specifically a method for producing hydroxy compounds by hydroxylating phenols and/or alkoxybenzenes with hydrogen peroxide. Regarding improvements.

The hydroxy compounds obtained by the method of the present invention are, for example,
Para-methoxophenol, hydroquinone, catechol, etc., which are useful as various organic synthesis intermediates or raw materials, reducing agents, rubber drugs, dyes, pharmaceuticals, etc.
Used in fields such as fragrances, polymerization inhibitors, oxidation inhibitors, and rubber drugs.

[Conventional technology]

For the hydroxylation of phenols using hydrogen peroxide, divalent iron ions (Fenton's reagent) have long been used.
A method of electrophilic substitution reaction in the presence of a strong acid such as sulfuric acid INature, 165
, 401(+950)], or a method using hydrofluoric acid [J, Org, Chem, 35.4028(1
970)], a method using cobalt salts [Chem,
8 bst,, 80133015g 肚, 151787k
The first prize is known.

In these methods, because the catalyst is homogeneous, it is complicated to separate the catalyst from the reaction product and isolate the desired product, and there are problems with post-treatment with highly corrosive acids. There was a problem.

Subsequently, a method using a crystalline substance containing silicon oxide and titanium oxide, a heterogeneous catalyst that can easily separate the catalyst from the reaction system, was developed (GB2083.816.2
, 116, 974], in this method, since the catalyst is heterogeneous, it is only necessary to mechanically separate the catalyst from the product after the reaction, and it is an industrially advantageous method. However, methods using crystalline silicon oxide and titanium oxide compounds as catalysts have drawbacks such as insufficient activity of the catalysts used and the catalytic activity varying depending on the catalyst preparation method.

[Problem B to be solved by the invention] As mentioned above, the hydroxylation of phenols with hydrogen peroxide using crystalline silicon oxide and titanium oxide compounds as catalysts has insufficient catalyst activity. There are problems such as variations in catalyst activity depending on the production hatch.

An object of the present invention is to provide a highly efficient method for producing aromatic hydroquino compounds that does not have the problems of conventional methods.

[Means to solve the problem]

In order to solve these problems, the inventors of the present invention conducted various studies on the production method of aromatic dihydrophenols or alkokephenols using phenols and hydrogen peroxide, and in particular on the catalysts used in the hydroxylation reaction. As a result, regarding the hydroxylation reaction of phenols with hydrogen peroxide, using a crystalline substance containing silicon oxide and titanium oxide with a specific microcrystalline size as a catalyst, which has never been reported, can efficiently achieve the desired purpose. The present invention was completed based on the discovery that a product can be obtained.

That is, the present invention provides a method for producing an aromatic hydrogen hydroxy compound by hydroxylating phenols and/or alkoxybenzenes with hydrogen peroxide in the presence of a crystalline substance containing silicon oxide and titanium oxide. and crystalline containing titanium oxide! ! This is a method for producing an aromatic hydroxy compound, characterized in that a compound having a crystallite size of less than 10,000 particles is used.

According to the present invention, aromatic dihydroxy compounds or alcoquine phenols are produced.

The definition of the crystallite size of the catalyst used in the method of the present invention is the value according to the method described below. That is,
By observing the size of the secondary electron image of a normal scanning electron microscope and directly measuring the crystallite size 6 Normally, the crystallite size of a crystal is determined by the half value of powder X-ray diffraction [↑
Calculated from J, the crystalline compound according to the method of the present invention has a relatively large microcrystal size of about 5,000 or less. Therefore, in normal powder X-ray diffraction,
For the purpose of sample pretreatment, it is necessary to grind the sample in a mortar or the like.

If the microcrystal size is about 1,000 or less, the microcrystal size will hardly change even after grinding, but in the method of the present invention, there is a risk that the microcrystal size may change due to the grinding process using a mortar or the like depending on the case. Therefore, instead of using the half-width method of powder X-ray diffraction, a microcrystal size measurement method using a scanning electron microscope is used. Scanning electron micrographs showing the size of microcrystals on the glue body side are shown in Examples and Comparative Examples.

A crystalline material containing silicon oxide and titanium oxide having a microcrystal size of less than 10,000 is prepared, for example, by the following method.

■Alcoholic or aqueous solutions of titanium salts, titanium tetrachloride, titanic acid, titanium sulfide, or titanium alkoxides such as titanium isopropoxide as titanium sources,■
An alcoholic or aqueous solution of water glass, colloidal silica sol or ethyl silicate as a silica source, and (1) an aqueous quaternary ammonium salt solution are mixed while adjusting the pH appropriately to obtain a gel-like precipitate. This precipitate was heated at 100 to 250°C.
Hydrothermal synthesis under heating yields a crystalline compound.

As for the bond strength and titanium ratio of the crystalline material used in the method of the present invention, Si/Ti=20 to 200 (atomic ratio) is usually used.

In addition, a catalyst consisting of a crystalline silicon and titanium oxide can be used regardless of the manufacturing method or starting materials, as long as its microcrystal size falls within the range of the method of the present invention.

In the method of the present invention, alkoxybenzenes or phenols are reacted with or without a solvent in the presence of a crystalline compound having a microcrystalline size of -6. When a solvent is used, methanol or tertiary -Alcohols such as butyl alcohol are often used, and 5 to 50-t% of alkoxybenzenes and phenols as substrates are added to the solvent for reaction. As alkoxybenzenes, anisole, ethoxyphenol, etc. are used, and as phenols, phenol, ortho-
Alkylphenols such as cresol and meta-cresol are used.

The appropriate amount of the catalyst, a crystalline compound consisting of titania and silica, is in the range of 0.1 to 30-t% based on the substrate, taking the case of the Hatchi reaction as an example.

One of the features of the present invention is that an aqueous solution of hydrogen peroxide can be used as the hydrogen peroxide, and there is no need to use anhydrous hydrogen peroxide, so there is no risk of explosion or the like. Usually 30
~60-t% aqueous hydrogen peroxide solution is used.

The amount of hydrogen peroxide to be used is 0.3 to equimolar to the phenol that is the substrate. That is, the reaction conditions are set so as to keep the residual hydrogen peroxide concentration in the reaction-completed liquid sufficiently low.

The reaction temperature is often in the range of 40 to 100°C, particularly 50 to 90°C. The time required for the reaction is in the range of 1 to 10 hours, taking the Hutch reaction as an example.

〔Example〕

The present invention will be explained below with reference to Examples and Comparative Examples.

(Example 1) In a 200 mR flask, 342 g of tetraethoxy silicon (164 mmol) and 1.9 #If under nitrogen atmosphere
! of tetraisopropoxytitanium (6.4 mmol) was added and mixed. To this, 38.9 g of 25% aqueous tetrapropylammonium hydroxide solution was gradually added dropwise while stirring. By stirring at 90°C for 3 hours, 30 d of ethanol was distilled off. The residue was transferred to a chikun-lined autoclave and an additional 800 d of deionized water was added. Heated at 175° C. under autogenous pressure for 7 hours with gentle stirring.

After cooling the autoclave, the contents were taken out, centrifuged, the supernatant was taken out, water washing and centrifugation were repeated several times, and the precipitate was washed and dried at 110°C for 4 hours. Next, the temperature was gradually raised to 500°C under air circulation and baked at 500°C for 5 hours. The powder chi-ray diffraction pattern of the product was in good agreement with that of crystalline titanosilicate. A scanning electron micrograph showed that the microcrystal size was 3000 (Fig. 1).

0.4g and 15g of the powdered crystalline titanosilicate obtained by the above method in a 30rrl flask equipped with a cooling tube.
of tert-butyl alcohol, phenol 1.5g
was added and stirred while heating to 85°C. To this, 1.5 g of a 30% aqueous hydrogen peroxide solution was added dropwise over a period of 30 minutes.

Thereafter, stirring was continued at 90°C for another 2 hours to carry out the hydroxylation reaction.

After the reaction was completed, the flask was centrifuged, and the supernatant was collected and analyzed by gas chromatography. The yield of hydroquine was 28%, the yield of catechol was 26%, and the total yield of dihydroxy compounds was 54%, based on hydrogen peroxide.

(Comparative Example-1) Tiz(SQ,)i-8HzO1.07g, NaCl
3.60g, tetrapropylammonium promer (F
72 g of H2SO4 and 1.82 g of deionized water 17.
4g and mixed (liquid A). 22.1 g of JIS-3 water glass and 14.5 g of deionized water were mixed (liquid B). 112.2 g of NaC, 0.7 g of tetrapropylammonium bromide, 112.2 g of NaCl (0.72 g, NZ
60 g of SO4 was mixed with 62.0 g of deionized water (
C liquid).

The above-mentioned liquids A and B were simultaneously injected into liquid C using micrometer metering pumps. During this time, the C solution is sufficiently stirred and the pH of the C solution is
The injection speeds of both solutions A and B were adjusted so as to maintain the value in the range of 10 to 105. The time required for injection was 20-30 minutes. A gel-like precipitate was formed by injection, but 3 more
Stirring was continued for 0 minutes to carry out ripening. The mother liquor containing the precipitated gel was then treated with a homogenizer to homogenize it, and then filled into a hydrothermal synthesis autoclave. The autoclave used was constructed of alkali-resistant glass and lined to prevent the contents from coming into contact with metal.

The autoclave was heated while stirring at 2-3 revolutions/second, and the temperature was raised to 150°C over 2 hours, and then to 210°C over 3 hours. Stirring was continued for an additional 3 hours at 210'C, then the apparatus was allowed to cool.

The resulting autoclave contents were washed with deionized water;
After drying, the temperature was raised to 550°C under air circulation and baked for 4 hours. Then, after ion exchange treatment with (Nl(-1hcO+) aqueous solution, it was calcined at 450°C for 3 hours and used as a catalyst.

The X-ray diffraction pattern of the obtained catalyst was in good agreement with that of crystalline titanosilicate. Observation using a scanning electron microscope revealed that the average size of microcrystals was 30,000 (second time).

The same reaction as in Example 1 was carried out using this catalyst. The yield of unobtained hydro-1-non was 0.7 based on hydrogen peroxide.
%, the yield of catechol was 0.6%, and the yield of catechol was 0.6%.
The yield of noodles was 1.3%.

(Examples 2 to 4, Comparative Examples 2 to 3) Using a compound consisting of crystalline silica and titania with different microcrystal sizes as a catalyst, the hydroxyl of anisole was treated using the same method and reaction conditions as in Example 1. implemented. The obtained crystals are shown in the following table.

C Effects of the Invention] According to the method of the present invention, hydroxylation of phenols and alkoxyphenols with hydrogen peroxide can proceed efficiently and at a high reaction rate, and it is industrially advantageous to hydroxylate dihydroxyphenols and alkoxyphenols. and alcoquine phenols can be obtained.

[Brief explanation of drawings]

The first panel is a scanning electron micrograph showing the crystal structure of the catalyst used in Example 1. 2nd 1 is a scanning electron micrograph showing the crystal structure of the catalyst used in Comparative Example 1. Patent applicant Mitsui Toatsu Chemical Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) When producing an aromatic hydroxy compound by hydroxylating phenols and/or alkoxybenzenes with hydrogen peroxide in the presence of a crystalline substance containing silicon oxide and titanium oxide, silicon oxide and titanium oxide are added. A method for producing an aromatic hydroxy compound, characterized in that a crystalline substance having a microcrystal size of less than 10,000 Å is used.