JP5747409B2 - Cyclic organic compound oxidation method and cyclic organic compound oxidation apparatus - Google Patents

Description

  The present invention relates to a method for oxidizing a cyclic organic compound and an apparatus for oxidizing a cyclic organic compound.

  Cyclic organic compounds have a cyclic structure based on a carbon skeleton, and there are a wide variety of substances such as monocyclic compounds such as benzene and phenol, condensed ring compounds such as naphthalene, and these are industrially important raw materials. Etc. are used.

  For example, phenol is an industrially important raw material, and phenol is generally produced by the cumene method. The cumene method is a chemical synthesis method in which acetone and phenol are obtained by oxidizing cumene (isopropylbenzene). Cumene is produced by the addition reaction of benzene and propene by Friedel-Crafts reaction to produce cumene. Acetone and phenol can be produced by rearranging this with an acid. The cumene method requires a three-step process and includes a process requiring a high temperature as high as 250 ° C. Furthermore, the phenol yield is 5% or less in terms of benzene, and many by-products are produced. For this reason, the method of manufacturing a phenol more simply and with sufficient yield is desired.

  In recent years, methods for oxidizing benzene and converting it directly to phenol have been studied. For example, in Non-Patent Document 1, a palladium catalyst is used and benzene is converted to phenol under 200 ° C. conditions. In Non-Patent Document 2, titanium oxide having a controlled pore size is used as a photocatalyst, and benzene is converted to phenol by irradiation with ultraviolet rays.

Niwa S, Eswaramorty M, Nair J, Raj A, Itoh N, Shoji H, Namba T, Mizukami F; Science, 2002, 295, 105-107 Shirai Y, Saito N, Hirai T; Am. Chem. Soc. 2005, 127, 12820-12822

  In Non-Patent Document 1, since a high temperature of 200 ° C. is required, there is a problem that corresponding equipment and heat supply are necessary, and the manufacturing cost is high. Moreover, although the selectivity of the produced | generated phenol (ratio of the produced | generated phenol with respect to the reacted benzene) is favorable, there exists a problem that a yield (ratio of the produced | generated phenol with respect to the added benzene) is low.

  In Non-Patent Document 2, although the yield of the produced phenol is high, its selectivity is low. That is, phenol is further oxidized and oxidized to polyhydric phenols such as dihydric phenols such as hydroquinone and catechol, and trihydric phenols such as 1,2,4-trihydroxylbenzene. For this reason, the separation operation of phenol after production becomes complicated. Moreover, if the ultraviolet light which is a light absorption region of titanium oxide is irradiated, and if it is attempted to irradiate it with sunlight, the yield and the selectivity will be lowered.

  The present invention has been made in view of the above-mentioned matters, and an object of the present invention is to provide a ring capable of suppressing the formation of a sequential oxide of a cyclic organic compound and selectively obtaining a target compound. An object of the present invention is to provide an oxidation method for a cyclic organic compound and an oxidation apparatus for a cyclic organic compound.

The method for oxidizing a cyclic organic compound according to the first aspect of the present invention includes:
Interposing a photocatalyst and a solution in which benzene is dissolved in a solvent capable of generating active oxygen by the action of the photocatalyst,
While irradiating light in an inert gas atmosphere with a partial pressure of 200 kPa to 300 kPa to oxidize the benzene , the generation of oxides is sequentially suppressed by the inert gas, and phenol is selectively obtained.
It is characterized by that.

The method for oxidizing a cyclic organic compound according to the second aspect of the present invention includes:
Interposing a photocatalyst, a solution in which benzene is dissolved in a solvent, and a gas capable of generating active oxygen by the action of the photocatalyst,
While irradiating light in an inert gas atmosphere with a partial pressure of 200 kPa to 300 kPa to oxidize the benzene , the generation of oxides is sequentially suppressed by the inert gas, and phenol is selectively obtained.
It is characterized by that.

Further, the inert gas may be a CO _2.

  Further, the photocatalyst in which gold fine particles are supported on titanium oxide may be used.

  The solvent may be water.

An apparatus for oxidizing a cyclic organic compound according to the third aspect of the present invention provides:
A chamber filled with a photocatalyst, a solvent capable of generating active oxygen by the action of the photocatalyst, benzene and an inert gas, having a light transmission window capable of transmitting light at least in part;
A pressure sensor for detecting the atmospheric pressure in the chamber;
An inert gas tank filled with the inert gas supplied into the chamber;
A control device for controlling the supply of the inert gas based on the atmospheric pressure detected by the pressure sensor so that the partial pressure of the inert gas is 200 kPa to 300 kPa ,
It is characterized by that.

The cyclic organic compound oxidation apparatus according to the fourth aspect of the present invention provides:
A chamber filled with a photocatalyst, a gas capable of generating active oxygen by the action of the photocatalyst, a solvent, benzene, and an inert gas;
A pressure sensor for detecting the atmospheric pressure in the chamber;
An inert gas tank filled with the inert gas supplied into the chamber;
A control device for controlling the supply of the inert gas based on the atmospheric pressure detected by the pressure sensor so that the partial pressure of the inert gas is 200 kPa to 300 kPa ,
It is characterized by that.

In the method for oxidizing a cyclic organic compound according to the present invention, a cyclic organic compound dissolved in a solvent is oxidized by a catalytic action of a photocatalyst in an inert gas atmosphere such as CO ₂ gas. When the cyclic organic compound is oxidized, it eventually becomes CO ₂ , but is reacted in an inert gas atmosphere, and the inert gas functions to suppress the CO ₂ generation mechanism. For this reason, since generation | occurrence | production of a sequential oxide is suppressed, the target predetermined compound can be obtained selectively.

It is a schematic block diagram of the oxidation method of a cyclic organic compound. It is a schematic block diagram of the oxidation apparatus of a cyclic organic compound. It is a schematic block diagram of the oxidation apparatus of the cyclic organic compound which concerns on another form. It is a TEM photograph of Au @ P25. It is an ultraviolet-visible diffuse reflection spectrum of P25 and Au @ P25. It is a powder X-ray diffraction pattern of P25 and Au @ P25. It is a high-performance liquid chromatogram of the solution before and after the reaction. CO ₂ partial pressure and benzene addition rate is a graph showing the relationship between phenol yield and selectivity.

(Embodiment 1)
In the method for oxidizing a cyclic organic compound according to the first embodiment, a photocatalyst and a solution in which the cyclic organic compound is dissolved in a solvent capable of generating active oxygen by the action of the photocatalyst are interposed, under an inert gas atmosphere. In this method, the cyclic organic compound is oxidized by irradiating light, and the formation of the oxide is sequentially suppressed by an inert gas to selectively obtain a desired predetermined compound.

  Hereinafter, a case where phenol is selectively produced by oxidizing benzene will be described in detail.

First, as shown in the schematic diagram of FIG. 1, a predetermined amount of benzene, a solvent capable of generating active oxygen, and a photocatalyst are placed in a reaction vessel. Then, the gas phase in the reaction vessel is filled with CO ₂ gas, and the reaction vessel is sealed.

Here, water is used as a solvent capable of generating active oxygen. Water is rich in OH ^{− which} is a source of hydroxy radicals (.OH) as active oxygen. An aqueous benzene solution in which benzene is dissolved in water is added to the reaction vessel. The amount of benzene added is such that it dissolves in water so that the reaction with the generated hydroxy radical occurs promptly. Since the maximum amount of benzene dissolved in water is about 800 ppm, an aqueous benzene solution of about 800 ppm may be added to the reaction vessel.

  In addition, titanium oxide supporting gold fine particles is used as a photocatalyst. Titanium oxide is excited by ultraviolet rays (light having a wavelength of 400 nm or less) and exhibits a catalytic function. However, since ultraviolet rays contained in sunlight are several percent, sunlight cannot be used efficiently, and the reaction time becomes long. By supporting gold fine particles on titanium oxide, visible light response is exhibited, sunlight is efficiently used, and the catalytic function is enhanced. For example, when the gold fine particles to be carried are spherical, light having a wavelength around 520 to 550 nm is absorbed and excited. Thereby, even if the light to irradiate is natural light, such as sunlight, a hydroxyl radical is produced | generated efficiently and shortening of the reaction time when benzene is converted into phenol is implement | achieved.

  Then, light is irradiated. Since titanium oxide supporting gold fine particles is used as the photocatalyst, the light to be irradiated may be natural light such as sunlight. By irradiation with light, hydroxy radicals are generated from water by the action of the photocatalyst. Hydroxyl radicals are very reactive and react with benzene to produce phenol.

More specifically, when light strikes the photocatalyst, the photocatalyst is excited and electrons are ejected from the surface. At this time, the hole (hole) from which the electron has escaped has a positive charge. Holes have strong oxidizing power and take electrons from OH ⁻ (hydroxide ions) in water. For this reason, OH ⁻ deprived of electrons becomes a hydroxy radical in a very unstable state.

  Hydroxy radicals have strong oxidizing power, so they take electrons from nearby benzene and try to stabilize themselves. For this reason, benzene is deprived of electrons and converted to phenol.

Hydroxy radicals are further generated as long as OH ⁻ is present and the photocatalyst is irradiated with light. The generated phenol is further oxidized by the excessively generated hydroxy radicals to produce dihydric phenols such as catechol and hydroquinone, and trihydric phenols such as 1,2,3-trihydroxybenzene, and finally organic compounds. It is thought that the bond of is divided into carbon dioxide.

However, since the gas phase in the reaction vessel is filled with CO ₂ gas, the target phenol can be selectively obtained, and the yield and selectivity of phenol can be increased.

Although the mechanism is not clear, it is considered as follows. First, it acts to suppress the carbon dioxide production mechanism by the mechanical equilibrium between the gas phase (filled CO ₂ gas) and the liquid phase (benzene aqueous solution). That is, it is thought that it suppresses that a phenol is oxidized sequentially and a carbon dioxide is produced | generated.

Moreover, the produced phenol is easily desorbed from the catalyst due to repulsion with the photocatalyst. When the photocatalyst is composed of titanium oxide, the isoelectric point of titanium oxide is about pH = 5, and when pH is 5 or less, it is electrically neutral and repels phenol. That is, carbon dioxide in the liquid phase increases and pH decreases according to the CO ₂ filling amount, and the generated phenol repels and desorbs from the photocatalyst, so that the sequential oxidation of phenol is suppressed without being affected by the photocatalyst. It is thought that.

In the case CO ₂ gas is small to be filled, hydroxyl radical is an oxidizing agent, there is a possibility that is consumed prior to reaction with the adsorbed benzene. That is, a part of CO ₂ is dissolved in the aqueous solution to become HCO ₃ ⁻ . This reacts with a hydroxy radical to become peroxocarbonate (HO ₃ C—CO ₃ ), and CO ₂ and O ₂ . Thereby, oxidation of benzene may be delayed. On the other hand, when there is too much CO ₂ gas to be filled, the production of phenol may be suppressed as a result of suppressing the oxidation of benzene. For this reason, it is preferable that the pressure (partial pressure) of the CO ₂ gas to be filled is set within a predetermined range as follows.

  After the production of phenol, the photocatalyst is separated by filtration or the like, and water is evaporated to obtain high-purity phenol.

In order to selectively obtain phenol by oxidizing benzene in an aqueous solution of benzene as described above, the partial pressure of CO ₂ in the reaction vessel is preferably 200 kPa or more and 300 kPa or less from the examples described later. Oxidation of benzene with the partial pressure of CO _{2 in} the above pressure range improves the yield and selectivity of phenol as compared with the case where CO ₂ gas is not charged. More preferably, the partial pressure of CO ₂ is 220 kPa or more and 270 kPa or less.

The filling of the CO ₂ gas may be performed by any method as long as the partial pressure of CO ₂ in the gas phase in the reaction vessel becomes a predetermined pressure. CO ₂ gas may be sealed directly in the reaction vessel, or dry ice may be put in the reaction vessel and vaporized. Further, it may be in the form of introducing a constant CO ₂ gas into the reaction vessel.

  In the above, titanium oxide supporting gold fine particles was used as the photocatalyst, but the photocatalyst is not limited to this as long as it can generate active oxygen by light irradiation. It is also possible to use titanium oxide as it is. Moreover, although the example which carried | supported the granular gold microparticles | fine-particles was demonstrated above, if it is gold microparticles which have anisotropy, such as a rod-shaped particle, since it absorbs and excites a wide range light of visible light-a near infrared region, Sunlight can be used more efficiently and reactivity can be enhanced. In addition, it is also possible to use a semiconductor (titanium oxide or zinc oxide) sensitized with zinc oxide or an organic dye.

In the above description, CO ₂ gas is used as the inert gas, but the present invention is not limited to this. For example, if it is a gas that is difficult to dissolve in the solvent used, such as nitrogen, neon, or argon, it brings about a mechanical equilibrium between the liquid phase and the gas phase, and suppresses the above-mentioned carbon dioxide production mechanism to suppress the generation of sequential oxides. And the desired compound is selectively obtained.

  As an example, the method for selectively obtaining phenol by oxidizing benzene using benzene as the cyclic organic compound has been described. However, various cyclic organic compounds are oxidized and the generation of sequential oxides is suppressed. And can be applied to a method for selectively obtaining a target compound.

(Embodiment 2)
The method for oxidizing a cyclic organic compound according to Embodiment 2 includes a photocatalyst, a solution in which a cyclic organic compound is dissolved in a solvent, and a gas capable of generating active oxygen by the action of the photocatalyst, and an inert gas. In this method, the cyclic organic compound is oxidized by irradiating light in an atmosphere, and the generation of oxides is sequentially suppressed by an inert gas, thereby selectively obtaining a predetermined compound.

  The difference from Embodiment 1 described above is that the medium that generates active oxygen is not a solvent but a gas.

As a gas capable of generating active oxygen, hydrogen or oxygen in which a hydroxyl radical or a superoxide anion (.O ₂ ⁻ ) is generated by the action of a photocatalyst may be introduced into the reaction vessel. Hydrogen and oxygen may be introduced into the liquid phase (a solution in which a cyclic organic compound is dissolved in a solvent) by bubbling or the like. These gases may be introduced according to the type of cyclic organic compound to be oxidized.

  For example, the case where cyclohexanone is selectively obtained by oxidizing cyclohexane will be described as an example.

A photocatalyst and a solution obtained by dissolving cyclohexane in an organic solvent such as acetonitrile are placed in a reaction solution, and filled with an inert gas such as CO ₂ gas. Furthermore, oxygen is interposed in the liquid phase by bubbling as a gas capable of generating active oxygen.

By irradiating with light, the photocatalyst is excited, electrons are ejected from the surface, and the electrons are supplied to oxygen to produce a superoxide anion. Since the superoxide anion is unstable and has strong oxidizing power, cyclohexane is oxidized to produce cyclohexanone. Since the CO ₂ gas suppresses further oxidation of cyclohexanone as described in Embodiment 1, it is possible to selectively obtain cyclohexanone.

  Similarly, naphthalene can be oxidized to selectively obtain 1,4-naphthoquinone useful as an intermediate for pharmaceuticals and agricultural chemical raw materials. In addition, phenanthrene can be oxidized to selectively obtain 6H-benzo [C] chromen-6-ol useful as an intermediate for drugs and fluorescent dyes.

  In this embodiment, when a cyclic organic compound that is insoluble in a solvent capable of generating active oxygen such as water is oxidized to obtain a desired compound, the cyclic organic compound is used as a general-purpose organic solvent. This is effective in that it can be dissolved and oxidized. Others are the same as those in the first embodiment, and thus the description thereof is omitted.

(Embodiment 3)
Subsequently, an apparatus for oxidizing a cyclic organic compound will be described. Here, as an example of an apparatus for oxidizing a cyclic organic compound that can be dissolved in a solvent capable of generating active oxygen such as water, an apparatus for oxidizing a cyclic organic compound that selectively produces phenol by oxidizing benzene will be described. To do.

  As shown in the schematic configuration diagram of FIG. 2, the cyclic organic compound oxidation apparatus 1 includes a chamber 10, a pressure sensor 12, an inert gas tank 20, a solvent tank 30, a cyclic organic compound tank 40, and a control. The apparatus 50, the light source 60, the catalyst separator 70, the target compound separator 71, and the impurity separator 72 are provided.

The chamber 10 is a sealable reaction vessel that is filled with a solvent, benzene, a photocatalyst, and CO ₂ gas, and oxidizes benzene inside to selectively generate phenol. A light transmission window 11 is provided in the upper part of the chamber 10. The light transmission window 11 is made of colorless glass or resin having a high light transmittance. Light is irradiated into the chamber 10 through the light transmission window 11. The chamber 10 is made of a material that has chemical stability and can withstand internal pressure, such as stainless steel. As long as it has chemical stability and high mechanical strength, it may be glass or resin having high light transmission. In this case, the light transmission window 11 may not be provided.

  The chamber 10 is provided with a pressure sensor 12 for detecting the pressure of the gas phase in the chamber 10.

  The solvent tank 30 and the cyclic organic compound tank 40 are filled with water and benzene, respectively. The chambers 10 are filled with a predetermined amount of water and benzene by opening and closing the valves 31 and 41 and a pump (not shown).

  The inert gas tank 20 is a tank filled with an inert gas such as carbon dioxide. The inert gas tank 20 and the chamber 10 are connected via an inert gas introduction path 22, and a valve 21 is installed in the inert gas introduction path 22. The valve 21 is a solenoid valve or the like and opens and closes based on a command from the control device 50.

  The control device 50 is electrically connected to the pressure sensor 12 and the valve 21, respectively. The control device 50 opens and closes the valve 21 based on the information on the pressure of the gas phase in the chamber 10 sent from the pressure sensor 12. That is, when the pressure of the gas phase in the chamber 10 is lower than a predetermined pressure, the control device 50 opens the valve 21 and controls to introduce carbon dioxide from the inert gas tank 20 into the chamber 10. On the other hand, when the pressure of the gas phase in the chamber 10 is higher than a predetermined pressure, the control device 50 controls to close the valve 21 and stop introducing carbon dioxide from the inert gas tank 20 to the chamber 10.

  As the light source 60, various known light-emitting devices such as a fluorescent lamp, an incandescent bulb, and simulated sunlight are used.

  The catalyst separator 70 is a device that separates and recovers the photocatalyst from the solution after the reaction. As the catalyst separator 70, in addition to a filter such as a filter and a centrifugal separator, a known separator capable of separating and recovering a solid photocatalyst is used.

  The target compound separator 71 is a device that separates phenol, which is the target compound, from the solution after the reaction, and a known device that can separate phenol is used. Examples of the target compound separator 71 include liquid chromatography.

  The impurity separator 72 is a device that separates impurities (products other than phenol) and a benzene aqueous solution, and a known device capable of separating the benzene aqueous solution is used.

According to the above configuration, since the CO ₂ gas is controlled to be supplied so that the pressure of the gas phase in the chamber 10 (partial pressure of the CO ₂ gas) becomes the pressure described above, a good yield and Phenol can be produced with selectivity.

  In addition, when making it react with sunlight, the light source 60 does not need to be provided. In the above description, the case where phenol is selectively obtained by oxidizing benzene has been described as an example. However, not only benzene but also various cyclic organic compounds that can be dissolved in a solvent capable of generating active oxygen such as water are oxidized. In addition, the present invention can also be applied appropriately when a desired compound is selectively obtained.

  In the above, an example of an apparatus effective for oxidizing a cyclic organic compound that can be dissolved in a solvent capable of generating active oxygen such as water has been described. However, the apparatus is insoluble in a solvent capable of generating active oxygen such as water. In the case of oxidizing a cyclic organic compound, as shown in FIG. 3, a gas capable of generating active oxygen by a photocatalyst may be supplied by bubbling.

  The cyclic organic compound oxidation apparatus 2 shown in FIG. 3 includes a gas tank 80 filled with a gas capable of generating active oxygen such as oxygen and hydrogen. The gas tank 80 is connected to the chamber 10 via a gas supply path 82. Connected. The tip of the gas supply path 82 on the chamber 10 side extends to the vicinity of the bottom surface of the chamber 10. A valve 81 is installed in the gas supply path 82, and by opening the valve 81, gas is supplied to a solution in which a cyclic organic compound is dissolved in an organic solvent or the like.

  When cyclohexane is obtained by oxidizing cyclohexane as the cyclic organic compound, the cyclic organic compound tank 40 is filled with cyclohexane, and the solvent tank 30 is filled with an organic solvent such as acetonitrile. The target compound separator 71 is a known apparatus that can separate the target compound cyclohexanone from the solution after the reaction. The impurity separator 72 is a known device that can separate impurities (products other than cyclohexanone) and unreacted cyclohexane and acetonitrile. Furthermore, a separator capable of separating cyclohexanone and acetonitrile may be installed. Further, the present invention is not limited to cyclohexanone, and can be appropriately applied to the case where various cyclic organic compounds insoluble in a solvent capable of generating active oxygen such as water are oxidized to selectively obtain a target compound.

  About another structure, since it is the same as that of the oxidation apparatus 1 of the cyclic organic compound mentioned above, description is abbreviate | omitted.

  Using the prepared photocatalyst, benzene was oxidized by light irradiation and phenol was produced.

(Adjustment of photo-oxidation catalyst)
Titanium oxide powder (P25, manufactured by Degussa) (1.0 g) and HAuCl ₄ .3H ₂ O (0.5 g) were added to dehydrated ethanol (30 mL), and the mixture was stirred at room temperature for 1 day.
NaBH ₄ (0.24 g) was added and stirred at room temperature for 4 hours.
The supernatant obtained by removing the black precipitate by decantation was centrifuged (3500 rpm, 15 min), and the reddish purple precipitate was washed with ethanol and dried at 70 ° C. for 1 day. Thus, a photocatalyst (hereinafter referred to as Au @ P25) in which gold fine particles were supported on titanium oxide was obtained.

  FIG. 4 shows a TEM (Transmission Electron Microscope) photograph of Au @ P25, FIG. 5 shows an ultraviolet-visible diffuse reflection spectrum of P25 and Au @ P25, and FIG. 6 shows a powder X-ray diffraction pattern. When FIG. 4 is seen, the black spot which is a gold fine particle can be confirmed on a titanium oxide particle. Moreover, when FIG. 5 is seen, the peak peculiar to gold which does not appear in P25 near 550 nm can be confirmed. In addition, referring to FIG. 6, a gold peak appears at 45 (2θ / °). Therefore, it was confirmed that gold fine particles were supported on titanium oxide.

(Production of phenol)
An aqueous benzene solution (20 mL, 800 ppm), Au @ P25 (60 mg), CO ₂ and a stir bar were sealed in a stainless steel sealed container with a glass (pyrex (registered trademark)) window having an internal volume of 50 mL. CO ₂ was gasified in the vessel by adding dry ice.

  While stirring the benzene aqueous solution with a stirrer, simulated sunlight was irradiated from a glass window for 24 hours to oxidize benzene to produce phenol.

Incidentally, the addition amount of dry ice 0 mg, 40 mg, 80 mg, 120 mg, and 200mg, the CO ₂ partial pressure in the container 0 kPa, 75 kPa, 150 kPa, 230 kPa, performs various as 380 kPa, phenol by partial pressure of CO ₂ The effect of yield and selectivity was evaluated. The value of each CO ₂ partial pressure is a value converted from the gas equation of state (PV = nRT) assuming that dry ice is all gasified into the gas phase in the container.

FIG. 7 shows high-performance liquid chromatogram spectra of the benzene aqueous solution before the reaction and the solutions after the reaction of the dry ice added amounts of 0 mg, 80 mg and 120 mg, respectively. Further, Table 1 shows the conversion rate (conversion) of benzene, the yield (Yield) and selectivity (selectivity) of the produced phenol at each CO ₂ partial pressure. The conversion rate is the ratio of the reacted benzene to the added benzene, the yield is the ratio of the generated phenol to the added benzene, and the selectivity is the ratio of the generated phenol to the ratio of the reacted benzene.

When FIG. 7 is seen, in the solution after reaction, while the peak of benzene decreases, the peak of phenol appears, and it can confirm that all have produced | generated phenol. In addition, the peak of the oxide gradually decreases as the CO ₂ partial pressure increases. It can be seen that the phenol is further oxidized to suppress the formation of sequential phenol oxides such as dihydric phenol and trihydric phenol.

Incidentally, CO ₂ partial pressure is more than 230 kPa, yield and selectivity are decreased. This, CO ₂ is considered to have also suppress the oxidation of benzene. Therefore, it is considered desirable to have an appropriate CO ₂ partial pressure.

Moreover, the graph which plotted the yield and selectivity of Table 1 in FIG. 8 is shown. From FIG. 8, when the partial pressure of CO ₂ is 200 kPa to 300 kPa, the yield and selectivity of phenol are better than when CO ₂ is not added. Moreover, when it is 220 kPa to 270 kPa, the selectivity for phenol is about 80% or more, which is better.

As mentioned above, although the oxidation method of the cyclic organic compound was demonstrated based on the Example, this invention is not limited to the said Example. That is, the cyclic organic compound is oxidized under an inert gas atmosphere such as CO ₂ gas, and the mechanical equilibrium in the gas phase liquid phase between the inert gas and the solution obtained by dissolving the cyclic organic compound in a solvent is utilized. It is widely interpreted as a method for selectively obtaining a desired compound by suppressing the CO ₂ production mechanism.

  It can be used when a desired compound such as phenol is selectively obtained from a cyclic organic compound such as benzene.

DESCRIPTION OF SYMBOLS 1 Cyclic compound oxidizing device 2 Cyclic compound oxidizing device 10 Chamber 11 Light transmission window 12 Pressure sensor 20 Inert gas tank 21 Valve 22 Inert gas introduction path 30 Solvent tank 31 Valve 40 Cyclic organic compound tank 41 Valve 50 Control Equipment 60 Light source 70 Catalyst separator 71 Target compound separator 72 Impurity separator 80 Gas tank 81 Valve 82 Gas supply path

Claims (7)

Interposing a photocatalyst and a solution in which benzene is dissolved in a solvent capable of generating active oxygen by the action of the photocatalyst,
While irradiating light in an inert gas atmosphere with a partial pressure of 200 kPa to 300 kPa to oxidize the benzene , the generation of oxides is sequentially suppressed by the inert gas, and phenol is selectively obtained.
And a method for oxidizing a cyclic organic compound. Interposing a photocatalyst, a solution in which benzene is dissolved in a solvent, and a gas capable of generating active oxygen by the action of the photocatalyst,
While irradiating light in an inert gas atmosphere with a partial pressure of 200 kPa to 300 kPa to oxidize the benzene , the generation of oxides is sequentially suppressed by the inert gas, and phenol is selectively obtained.
And a method for oxidizing a cyclic organic compound. The inert gas is CO ₂ ;
The method for oxidizing a cyclic organic compound according to claim 1 or 2. Using the photocatalyst in which gold fine particles are supported on titanium oxide,
The method for oxidizing a cyclic organic compound according to any one of claims 1 to 3 . The solvent is water;
The method for oxidizing a cyclic organic compound according to any one of claims 1 to 4 . A chamber filled with a photocatalyst, a solvent capable of generating active oxygen by the action of the photocatalyst, benzene and an inert gas, having a light transmission window capable of transmitting light at least in part;
A pressure sensor for detecting the atmospheric pressure in the chamber;
An inert gas tank filled with the inert gas supplied into the chamber;
A control device for controlling the supply of the inert gas based on the atmospheric pressure detected by the pressure sensor so that the partial pressure of the inert gas is 200 kPa to 300 kPa ,
An apparatus for oxidizing a cyclic organic compound, characterized in that: At least partially permeable light transmitting window light, a chamber photocatalyst gas capable of generating active oxygen by the action of the photocatalyst, solvents, benzene and inert gas is filled,
A pressure sensor for detecting the atmospheric pressure in the chamber;
An inert gas tank filled with the inert gas supplied into the chamber;
A control device for controlling the supply of the inert gas based on the atmospheric pressure detected by the pressure sensor so that the partial pressure of the inert gas is 200 kPa to 300 kPa ,
An apparatus for oxidizing a cyclic organic compound, characterized in that: