JPH10182526A - Production of phenol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce phenol by irradiating a mixed liquid of benzene and a saturated fatty acid or alcohol with ultraviolet light in the presence of oxygen to easily hydroxylating the benzene. SOLUTION: A reaction vessel equipped with a ball filter for oxygen gas bubbling, condenser tube and a quartz inner tube for ultraviolet irradiation is charged with a mixed liquid composed of 100mL of a 2-6C saturated fatty acid such as acetic acid or 1-2C alcohol such as methanol and 2-200g of benzene followed by agitating the mixture while bubbling an oxygen gas via the above- mentioned ball filter. Subsequently, the mixture is irradiated with ultraviolet light for 30min or longer while keeping the mixture at 10-40 deg.C to directly hydroxylating the benzene, thus producing the objective phenol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing phenol by hydroxylation of benzene, and more particularly to a method for producing phenol by irradiating benzene with ultraviolet light in the presence of oxygen.

[0002]

2. Description of the Related Art A cumene method is conventionally known as a method for producing phenol using oxygen gas as an oxidizing agent and benzene as a raw material. However, according to this method, since a by-product of phenol and an equimolar amount of acetone is produced, various direct benzene hydroxylation methods that do not produce by-products such as acetone have been developed.

For example, Japanese Patent Application Laid-Open No. 7-223984 discloses a method for producing phenol from benzene using oxygen gas as an oxidizing agent in the presence of sulfuric acid and a CuCl catalyst.

Japanese Patent Application Laid-Open No. Hei 7-238042 discloses that benzene is converted from benzene by performing a reaction in the presence of CO—O ₂ gas using a catalyst in which Pd or Rh and V are supported on a carrier such as silica. A method for producing phenol is disclosed.

Further, JP-A-6-192150 discloses that P
It discloses a method for oxidizing benzene using oxygen gas in the presence of h ₃ P and H ₂ O or an acid catalyst.

However, in JP-A-7-232984, sulfuric acid and CuCl are added, and
In No. 150, Ph ₃ P was added,
The reaction system is complicated, and the operation of purifying and recovering phenol, which is the final treatment step, is complicated. Further, in Japanese Patent Application Laid-Open No. Hei 7-238042, it is necessary to allow a CO gas to coexist in the reaction system, but this has a problem that the reaction apparatus and the reaction operation are complicated.

From an industrial point of view, a production method using only oxygen gas as an oxidizing agent and not using any special additives or catalysts is desirable. Therefore, it is desired to develop such a direct hydroxylation method of benzene. is there.

[0008]

SUMMARY OF THE INVENTION The present inventors have made intensive studies to develop an excellent direct benzene hydroxylation method capable of solving the above-mentioned problems. It was found that irradiating ultraviolet light on benzene easily oxidized benzene without adding catalysts and other additives that were difficult to separate in the subsequent steps to the reaction system, and completed the present invention. The objective is to produce phenol by directly hydroxylating benzene under mild conditions without adding any catalyst or the like that makes separation from the reaction system difficult. Is to provide.

[0009]

In order to achieve the above object, the present invention proposes a method for producing phenol, which comprises irradiating benzene with ultraviolet light in the presence of oxygen. Is benzene in the presence of oxygen,
The present invention proposes a method for producing phenol, which comprises irradiating a mixture of a saturated fatty acid having 2 to 6 carbon atoms or an alcohol having 1 to 2 carbon atoms with ultraviolet rays.

Hereinafter, the present invention will be described in detail.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing phenol by irradiating ultraviolet light to benzene alone, a mixture of benzene and saturated fatty acids, or a mixture of benzene and alcohol in the presence of oxygen.

The above reaction proceeds with benzene alone to produce phenol. However, when saturated fatty acids or alcohols coexist with benzene, the reaction rate is remarkably accelerated.

The mixing ratio of the saturated fatty acid or alcohol and benzene is 100 m
It is preferable that benzene is used in an amount of 2 to 200 g based on 1.

The saturated fatty acid is preferably a liquid having 2 to 8 carbon atoms and in a liquid state at normal temperature. Particularly, acetic acid is preferable because it has a high effect of accelerating the reaction rate and also facilitates the recovery of phenol after completion of the reaction. Things.

As the alcohol, methanol having 1 carbon atom and ethanol having 2 carbon atoms are preferable for the same reason as the above-mentioned saturated fatty acids, and particularly, methanol is industrially preferable.

The ultraviolet rays to be irradiated may be those having any wavelength in the wavelength range of 150 to 400 nm, and those having a single wavelength peak or those having a plurality of wavelength peaks in the above wavelength range may be used. And may further include visible light. There is no particular limitation on the irradiation amount of the ultraviolet ray, but the reaction time can be shortened as the irradiation amount increases. Therefore, it is preferable to increase the irradiation amount within a practically feasible range. A commercially available ultraviolet irradiation device can be appropriately used.

The reaction temperature may be room temperature, specifically, preferably 10 to 40 ° C. When the reaction temperature is lower than 10 ° C., the saturated fatty acid may coagulate, and in this case, the reaction rate tends to decrease. When the reaction temperature is higher than 40 ° C., the amount of dissolved oxygen in benzene or the above-mentioned mixed solution decreases, and therefore, the reaction rate tends to decrease.

The reaction is carried out in the presence of oxygen.
As a method for supplying oxygen to benzene or the mixed solution, a method of blowing oxygen gas or a gas containing oxygen into benzene or the mixed solution by bubbling, a method of performing a reaction in a closed system under an oxygen atmosphere (additional method). Pressure state). In view of the oxygen gas dissolution efficiency and the simplicity of the apparatus, a method of bubbling is generally preferred.
The reaction proceeds more rapidly as the oxygen concentration in benzene or in the mixture increases. Therefore, it is preferable that the oxygen concentration be close to the saturation concentration.

Examples of the gas containing oxygen include a mixed gas of an inert gas such as a nitrogen gas and an oxygen gas, and air.

The reaction time is not particularly limited, but is usually preferably 30 minutes or more. If the reaction time is short, the yield of phenol is small, and even if the reaction is performed indefinitely for a long period of time, the yield of phenol does not increase in proportion to the reaction time.

The phenol produced by the above reaction is
When benzene, alcohol, or saturated fatty acid as a raw material is allowed to coexist, they are separated and recovered.
In the separation method, it is preferable that these benzenes and the like be distilled off by a conventional method.

Hereinafter, the present invention will be described specifically with reference to examples. The present invention is not limited to these examples.

[0023]

【Example】

Example 1 A reaction vessel equipped with a ball filter for oxygen gas bubbling, a cooling tube, and an inner tube for ultraviolet irradiation made of quartz,
300 ml of a mixture of 60 g of benzene and 250 ml of acetic acid was added. Next, the mixture was stirred while bubbling oxygen gas into the mixture at a flow rate of 100 ml / min from the ball filter.

A 200 W high-pressure mercury lamp (manufactured by Ishii Rika Kikai, Ltd.) was attached to the inner tube, and irradiation with ultraviolet light was started. After the photoreaction was continued for 3 hours while maintaining the temperature of the mixture at 20 ° C., stirring, ultraviolet irradiation, and bubbling were stopped. A part of the obtained reaction solution was injected into a gas chromatograph (GC-14A, manufactured by Shimadzu Corporation), and the amount of phenol produced was measured. Phenol production is 20
It was 4 mg. Then, benzene and acetic acid were distilled off under reduced pressure to isolate phenol.

Example 2 Phenol was produced in the same manner as in Example 1 except that the reaction time was changed to 1 hour. 82 m of phenol is produced
g.

Example 3 Phenol was produced in the same manner as in Example 1 except that the reaction time was changed to 6 hours. The amount of phenol produced is 306
mg.

Example 4 Mixed solution 3 prepared by mixing 180 g of benzene and 120 ml of acetic acid
Phenol was produced in the same manner as in Example 1 except that 00 ml was used. The amount of phenol produced was 366 mg.

Example 5 A mixed solution 300 obtained by mixing 6 g of benzene and 300 ml of acetic acid
Phenol was produced in the same manner as in Example 1 except that ml was used. The amount of phenol produced was 43 mg.

Example 6 Phenol was produced in the same manner as in Example 1 except that 300 ml of a mixed solution obtained by mixing 60 g of benzene and 250 ml of methanol was used. Phenol production is 41mg
Met.

Example 7 Except that 300 ml of benzene was used instead of the mixture,
Phenol was produced in the same manner as in Example 1. The amount of phenol produced was 32 mg.

Example 8 Phenol was produced in the same manner as in Example 1 except that the gas to be bubbled was air instead of oxygen gas.
The amount of phenol produced was 71 mg.

Comparative Example 1 The same operation as in Example 1 was performed. However, ultraviolet irradiation was not performed. The amount of phenol produced was measured in the same manner as in Example 1, but no phenol was detected.

Comparative Example 2 Phenol was produced in the same manner as in Example 1 except that 300 ml of a mixed solution obtained by mixing 60 g of benzene and 250 ml of n-heptane was used. The amount of phenol produced is 1mg
It was below.

[0034]

According to the method for producing phenol of the present invention, since benzene is irradiated with ultraviolet rays in the presence of oxygen, benzene can be easily subjected to direct hydroxylation under mild conditions. . Since this reaction does not require the addition of various catalysts or additives that are difficult to remove from the reaction system, the separation and recovery of phenol after the completion of the reaction becomes extremely simple. Therefore, the method for producing the present phenol is a very industrially advantageous method. Furthermore, when alcohols or saturated fatty acids are added to benzene, the hydroxylation reaction proceeds more rapidly. Further, it has features such that separation of phenol from alcohol or fatty acid after the reaction is completed can be performed by a simple operation.

Claims (2)

[Claims] 1. A method for producing phenol, comprising irradiating benzene with ultraviolet light in the presence of oxygen. 2. In the presence of oxygen, benzene and C 2 -C 2
A method for producing phenol, comprising irradiating a mixture of a saturated fatty acid of 6 or an alcohol having 1 to 2 carbon atoms with ultraviolet light.