JP2005053808A - Method for producing organic compound with metallosilicate photocatalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for selectively converting a reactant having a specific molecular diameter into an objective substance in the presence of a metallosilicate having a specific average pore diameter in a liquid phase, concretely to provide a method for selectively converting an organic compound having approximately the same molecular diameter (minor axis) as the average pore diameter of the metallosilicate in the presence of the porous metallosilicate as a photocatalyst in a water-containing solvent into the compound having a smaller size. <P>SOLUTION: This method is characterized by adding a metallosilicate having approximately the same average molecular diameter (minor axis) as the average pore diameter to a solution of an organic compound in a water-containing solvent and irradiating the mixture with light. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photocatalytic reaction in which a porous metallosilicate having a specific pore size is used as a photocatalyst in a liquid phase, and an organic compound is selectively converted into a smaller size compound.

  Semiconductor photocatalysts typified by titanium oxide are widely used for decomposing harmful substances in water because of their strong oxidizing power. Since this semiconductor photocatalyst can react in a heterogeneous system, it has various merits such as easy recovery and reuse of the catalyst and complete decomposition of harmful organic compounds into water and carbon dioxide. Yes.

  In addition, research on applying these semiconductor photocatalysts to organic synthesis reactions has been actively conducted. However, due to its strong oxidizing power, it is difficult to control the reaction, and there is a demerit that it can be applied only to limited reactions.

  On the other hand, in recent years, titanosilicate has attracted attention as a solid catalyst containing titanium in its structure, as with titanium oxide. This titanosilicate has a structure containing titanium in a highly dispersed manner in the skeleton of porous silica, and has been found to exhibit an excellent function as a thermal catalyst (oxidation catalyst).

  However, studies using titanosilicate as a photocatalyst are mainly gas phase reactions, and few reports have been used for liquid phase reactions. Examples of the liquid phase reaction include a method of producing an aromatic hydroxy compound from an aromatic compound by irradiating light on a catalyst composed of titanosilicate and titanium dioxide (Patent Document 1), and a titanium silicalite-2 catalyst. Only a photodecomposition reaction such as 4-chlorophenol (Non-Patent Document 1) has been reported.

However, in the future, the photocatalytic reaction of metallosilicates such as titanosilicate will be used as a versatile tool for organic synthesis reactions, controlling reactivity and selectivity of target compounds. It is not satisfactory at all.
JP-A-9-208511 Chemistry Letters, 1999, 885

  An object of the present invention is to provide a method for selectively converting a reaction substrate having a specific molecular diameter into a target product using a metallosilicate having a specific average pore diameter as a photocatalyst in a liquid phase. Specifically, in a hydrous solvent, a porous metallosilicate is used as a photocatalyst, and an organic compound having a molecular diameter (short diameter) approximately equal to the average pore diameter of the metallosilicate is selectively selected as a smaller compound. It is to provide a way to convert. For example, there is a method of selectively converting an aromatic halide into an aromatic hydroxide.

  In order to solve the above problems, the inventors of the present invention firstly have a mechanism of a photolysis reaction using a titanium silicalite-2 (hereinafter also referred to as “TS-2”) catalyst described in Non-Patent Document 1. Was examined.

  According to Non-Patent Document 1, it is described that in a photolysis reaction of a substrate (such as 4-chlorophenol) in an aqueous solution, the decomposition rate of the substrate is larger as the substrate is more easily adsorbed on the surface of the TS-2 catalyst. That is, when the distribution ratio D of the substrate in the aqueous solution in the presence of TS-2 (easiness of adsorption of the substrate to the catalyst; see Example 1 (1)) is increased, the initial reaction rate is also increased. .

  However, the inventors of the present invention have examined the results of Non-Patent Document 1 in detail, and as a result, the ease of adsorption of the substrate on the titanosilicate surface is not the dominant factor of the ease of decomposition of the substrate. It was found that decomposition of the substrate was promoted when the pore shape (average pore size) of titanosilicate approximated the molecular size (short diameter) of the substrate. That is, it was found that titanosilicate having a specific pore diameter can recognize the molecular diameter of the substrate and promote the substrate-selective photocatalytic reaction.

  Based on this knowledge, further research has been developed to complete the present invention. That is, the present invention provides the following method.

  Item 1 By adding a metallosilicate to a solution in which an organic compound is dissolved in a water-containing solvent and irradiating with light, an organic compound having a molecular diameter (short diameter) comparable to the average pore diameter of the metallosilicate is reduced to a smaller size. A method for selectively producing a compound.

  Item 2 The method according to Item 1, wherein the molar ratio (Si / M) of silicon (Si) to the metal having photocatalytic activity (Si / M) in the metallosilicate is about 10 to 200.

  Item 3. The method according to Item 1, wherein the metallosilicate has an average pore size of about 0.4 to 10 nm.

  Item 4. The method according to Item 1, wherein the metallosilicate is titanosilicate.

  Item 5 The method according to Item 1, wherein the hydrous solvent contains water and an organic solvent miscible with water, and the content of water in the hydrous solvent is about 1 to 100% by volume.

  Item 6. The method according to any one of Items 1 to 5, wherein the organic compound is an aromatic halide.

  Item 7 A fragrance characterized by adding a metallosilicate having an average pore diameter comparable to the molecular diameter (short diameter) of an aromatic halide to a solution in which an aromatic halide is dissolved in a water-containing solvent and irradiating with light. A method for producing a group hydroxide.

  Item 8 The aromatic halide has, as a substituent, at least one halogen atom selected from the group consisting of a chlorine atom, a bromine atom and an iodine atom on an aromatic compound having 6 to 30 carbon atoms. The manufacturing method as described in.

Item 9 By adding a metallosilicate to a solution in which two or more kinds of substrates having different molecular diameters (short diameters) are dissolved in a water-containing solvent and irradiating with light, a molecular diameter comparable to the average pore diameter of the metallosilicate ( A method of selectively reacting a reactive substrate having a short diameter).

Hereinafter, the present invention will be described in detail.
I. Method of the present invention The present invention comprises adding a metallosilicate having an average pore diameter comparable to the molecular diameter (short diameter) of the organic compound to a solution obtained by dissolving an organic compound as a reaction substrate in a water-containing solvent, and irradiating with light. It is a photocatalytic reaction characterized by selectively converting an organic compound into a smaller size compound. Hereinafter, each component will be described in detail.

Metallosilicate The metallosilicate used in the present invention is a porous metallosilicate, which is a structure in which a part of silicon in the porous silica skeleton is replaced with a metal having photocatalytic activity.

  The metal having photocatalytic activity may be any metal that has a reduced valence when absorbing light and has reactivity with a substrate of an organic compound, such as a transition metal. Specific examples include transition metals such as titanium (Ti), chromium (Cr), iron (Fe), vanadium (V), niobium (Nb), cobalt (Co), manganese (Mn), and molybdenum (Mo). Is done. Of these, titanium, chromium, and iron are preferable, and titanium is particularly preferable. The metal having photocatalytic activity in these skeletons becomes an active site that can contribute to the photocatalytic reaction of the substrate. For example, FIG. 1 shows a schematic diagram when the metal having photocatalytic activity is titanium (titanosilicate).

  The content of metal (M) having photocatalytic activity incorporated into the skeleton is not particularly limited, but in order to obtain a desired photocatalytic activity, the metal content ratio (molar ratio) of Si / M is about 10 to 200. In particular, it is preferable to be about 30 to 100. In particular, when titanium is used as M, the Si / Ti metal content ratio (molar ratio) is about 20 to 150, preferably about 30 to 100.

  The pore morphology of the metallosilicate is not particularly limited, and any average pore diameter in a range that can be prepared, from microporous of about 4 to 20 mm, mesoporous of about 2 to 50 nm, and macroporous of about 50 to 200 nm. You may have. In the method of the present invention, since the average pore diameter of the metallosilicate and the molecular diameter (short diameter) of the substrate are the controlling factors of the reaction, the metallosilicate is preferably a metallosilicate having a substantially uniform pore diameter. In particular, the titanosilicate may have an average pore diameter in the range of about 4 to 10 nm. In the present invention, the average pore diameter is usually measured by a nitrogen adsorption method.

In addition, the larger the surface area in the pores of the metallosilicate, the higher the reaction rate of the substrate. Therefore, it is preferable that the specific surface area of the metallosilicate is large. That is, the specific surface area is preferably about 100 m ² / g or more, and particularly about 300 to 1500 m ² / g. The specific surface area of the metallosilicate is usually measured by the BET method.

  The above porous structure means a porous silicate. Examples of the zeolite type include silicalite-1 and silicalite-2, and examples of the non-zeolite type include mesoporous molecular sieves (M41S, MCM-41, MCM-48, etc.). The metallosilicate may contain other elements such as aluminum, phosphorus and boron in addition to silicon and metal having photocatalytic activity.

  Preferred metallosilicates include titanosilicate (TS-1, TS-2, Ti-β, Ti-MCM-41, Ti-MWW, etc.), chrome silicate (CrS-1, CrS-2, Cr-MCM-41) Etc.), ferric silicate (Fe-ZMS-5 etc.), manganese silicate, niobium silicate, molybdenum silicate and the like. Among these, titanosilicate (TS-1, TS-2) is more preferable.

  The porous metallosilicate used as the photocatalyst in the method of the present invention is prepared by a known synthesis method, and can be carried out, for example, according to JP-A-56-96720. A mixture of silica or a precursor thereof (eg, alkoxysilane) and / or water glass (sodium silicate concentrated solution) and a hydrolyzable metal compound (eg, alkoxide, chloride, etc.) as a metal oxide precursor. After hydrolyzing and precipitating a metal hydroxide on the hydrous silica, a heat treatment for crystallization is performed, followed by firing to prepare a porous metallosilicate.

  Examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, and tetra-n-butoxysilane, preferably tetraethoxysilane. Examples of the alkoxide of the hydrolyzable metal compound include tetramethoxy titanium, tetraethoxy titanium, tetraisopropoxy titanium, and tetra-n-butoxy titanium, preferably tetraisopropoxy titanium. Moreover, titanium tetrachloride is illustrated as a chloride of a hydrolysable metal compound.

Further, titanosilicate can be produced by changing the pore diameter, specific surface area, pore volume, and the like by a known method such as JP-A-10-330111.

Light source The light source for the photocatalytic reaction used in the method of the present invention is appropriately selected depending on the type of metal (M) having the photocatalytic activity of the metallosilicate. For example, metallosilicates with a light absorption wavelength of about 200 to 300 nm, such as titanosilicate, manganese silicate, niobium silicate, molybdenum silicate, etc. are usually high pressure mercury lamp, low pressure mercury lamp, black light, excimer laser, heavy Light sources centered on ultraviolet light such as hydrogen lamps, xenon lamps, and Hg-Zn-Pb lamps are used. From the viewpoint of ensuring practical reaction efficiency, a high-pressure mercury lamp (output: about 100 to 400 W) is preferable. In order to suppress the light itself from participating in the reaction and generating by-products, it is preferable to cover the light source with a Pyrex (registered trademark) filter that cuts a wavelength of 280 nm or less from the light source.

For metallosilicates having a light absorption wavelength of about 300 to 500 nm, such as chrome silicate and ferric silicate, a light source centering on visible light such as natural light or a fluorescent lamp is usually employed.

Reaction Solvent The reaction solvent used in the method of the present invention is not particularly limited as long as it is a solvent that does not adversely affect the photoreaction and contains water and is miscible with the substrate. Preferably, it is a solvent capable of dissolving the substrate, and further, the solvent itself is not decomposed by a photoreaction.

  Examples of such solvents include water, alcohols such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; nitriles such as acetonitrile, propionitrile, and butyronitrile; halogens such as chloroform and dichloromethane. And hydrocarbons. Solvents other than water may be used by mixing one or more of those exemplified above.

  The water content in the water-containing solvent used in the present invention is usually about 1 to 100% by volume, preferably about 10 to 100% by volume, more preferably 50 to 100%, based on the total amount of the water-containing solvent. It is about volume%. The water content can be appropriately selected from the above range in consideration of the solubility of the substrate.

  In the method of the present invention, water in the solvent plays an important role. For example, a case where titanosilicate is used as a photocatalyst will be described. Tetracoordinate titanium in titanosilicate is excited by absorbing light (ultraviolet light), and trivalent titanium species are generated by electron transfer from an adjacent oxygen ligand (ligand). This serves as an active species of the photocatalyst of the present reaction (see, for example, FIG. 6). However, it is known that the lifetime of this trivalent titanium species is very short in the presence of water and deactivates immediately (J. Phys. Chem. B 2001, 105, 8350). In the titanosilicate pores, the substrate molecules are constantly diffusing, but in order for the substrate to react, it is necessary to capture this short-lived active species. Since the substrate having a small molecular diameter relative to the pore diameter can smoothly diffuse in the pores, it is difficult to catch the above-mentioned short-lived active species and hardly react. On the other hand, a substrate having a molecular diameter larger than the pore diameter is difficult to react because it cannot enter the pores. A substrate having a molecular diameter substantially equal to the pore diameter cannot diffuse smoothly in the pores, and is temporarily trapped in the pores, so that it is easy to catch active sites and react easily. .

  In addition, titanosilicate has a very large surface area in the pores compared to the outer surface area, and most of the active sites are present in the pores.

Therefore, it is considered that the shape-selective reaction of titanosilicate is manifested by a combination of a decrease in active site lifetime due to the presence of water and a pore size.

Substrate The method of the present invention is characterized in that a substrate having a molecular diameter substantially equal to the average pore diameter of the porous metallosilicate can be selectively reacted to lead to the target compound.

  The reactive substrate means a substrate that is highly reactive to the photocatalytic reaction of metallosilicate. Examples of the reactive substrate include organic compounds having a molecular diameter that can enter into the pores of the metallosilicate and that can easily catch active sites in the pores (long residence time in the pores). . Specifically, it is an organic compound having a molecular diameter (preferably, a minor axis of the molecule) comparable to that of the metallosilicate. Here, the molecular diameter comparable to the pore diameter of the metallosilicate refers to an organic compound having a molecular diameter (short diameter) of about 70 to 130% with respect to the average pore diameter of the metallosilicate. Preferably, it has a molecular diameter of about 80 to 120%, more preferably about 90 to 110% with respect to the average pore diameter.

  In addition, the molecular diameter (minor axis) here may be a molecular diameter (minor axis) calculated by a semi-empirical molecular orbital method (PM3 method or the like).

  As described above, since the area inside the pores of titanosilicate is much larger than the outer surface area, it is considered that most of the active sites are present in the pores. Therefore, it is considered that a compound having a molecular diameter larger than that of the metallosilicate cannot enter the pores and thus is difficult to be decomposed. In addition, it is considered that a compound having a molecular diameter smaller than that of the metallosilicate pore is difficult to be decomposed because it hardly passes through the photocatalytic active site in the pore and passes through.

  In addition, the reactive substrate of the method of the present invention needs to have a molecular diameter of the reaction product obtained after the photocatalytic reaction smaller than the average pore diameter of the metallosilicate. When the molecular diameter of the reaction product is smaller than the molecular diameter of the reaction substrate, the reaction product can smoothly diffuse through the pores of the metallosilicate, making it difficult to capture the active sites present on the inner walls of the pores. This is because decomposition of the product by further photocatalytic reaction can be avoided. For example, a substrate in which the molecular diameter of the product is 0.1% or more smaller than the average pore diameter of the metallosilicate by conversion from a reactive substrate to a product is preferable, and a substrate in which the molecular diameter is 10% or more is more preferable. More preferably, the substrate is reduced by 30% or more.

  Furthermore, as the reactive substrate, a compound in which the molecular shape and the three-dimensional structure affecting the molecular diameter are not easily changed by the surrounding environment is suitably selected. Specifically, a compound having an aromatic ring or a heteroaromatic ring is preferably used.

  Preferred examples of the reactive substrate include aromatic halides and heteroaromatic halides. These substrates may have a substituent as long as they do not adversely affect the photoreaction. Examples of the halogen of the aromatic halide or heteroaromatic halide include chlorine, bromine and iodine, and the halogen atom in the substrate is converted into a hydroxyl group by the reaction of the present invention. Since the size of the halogen atom increases in the order of Cl <Br <I, aromatic iodides and aromatic bromides, which are considered to increase the difference in molecular diameter between the compounds before and after the reaction, are more preferable. is there.

  Examples of the aromatic halide include compounds having, as a substituent, at least one halogen atom selected from the group consisting of a chlorine atom, a bromine atom and an iodine atom on an aromatic compound having 6 to 30 carbon atoms. It is done. Examples of the aromatic compound having 6 to 30 carbon atoms include benzene, naphthalene, anthracene, phenanthrene, biphenyl, and pyrene.

  On the aromatic compound, in addition to a halogen atom, an alkyl group, a mono- or di-alkylamino group, an acyl group, a carboxyl group, a lower alkoxycarbonyl group, an optionally protected hydroxyl group, or an optionally protected group. It may have a substituent such as an amino group. These groups may be reactive to the reaction of the present invention.

  The alkyl group may be a linear or branched alkyl group having 1 to 10 carbon atoms, and a linear or branched alkyl group having 1 to 5 carbon atoms is particularly preferable. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl and the like.

  Examples of the alkyl of the mono- or di-alkylamino group are the same as those described above.

  Examples of the acyl group include formyl, acetyl, propionyl and the like.

  Examples of the alkoxy in the alkoxycarbonyl group include linear or branched alkoxy having 1 to 6 carbon atoms, specifically, methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, t-butyloxy and the like. Is exemplified.

  Examples of the hydroxyl protecting group include an acetyl group, a propionyl group, a benzyl group, and a t-butyldimethylsilyl group.

  Examples of the amino-protecting group include an acetyl group, a benzyl group, and a lower alkoxycarbonyl group. Examples of the lower alkoxy of the lower alkoxycarbonyl group include linear or branched alkoxy having 1 to 6 carbon atoms, specifically, methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, t- Examples include butyloxy and the like.

  Specific examples of aromatic halides include chlorobenzene, bromobenzene, iodobenzene, chlorophenol, bromophenol, iodophenol, dihydroxychlorobenzene, dihydroxyiodobenzene, dihydroxybromobenzene, chloronaphthalene, bromonaphthalene, iodonaphthalene, and hydroxychloro. Examples include naphthalene, hydroxybromonaphthalene, hydroxyiodonaphthalene, dihydroxychloronaphthalene, dihydroxyiodonaphthalene, dihydroxybromonaphthalene and the like.

  The heteroaromatic halide is at least one selected from the group consisting of a chlorine atom, a bromine atom and an iodine atom on a heteroaromatic compound containing at least one heteroatom selected from the group consisting of oxygen, nitrogen and sulfur. The compound which has a halogen atom of a kind as a substituent is mentioned. Heteroaromatic compounds such as thiophene, furan, pyrrole, imidazole, pyrazole, isoxazole, isothiazole, pyridine, pyrazine, pyrimidine, pyridazine, benzofuran, indole, isoindole, purine, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline , Carbazole, acridine and the like.

On the heteroaromatic compound, in addition to a halogen atom, a substituent such as an alkyl group, a mono- or di-alkylamino group, an acyl group, an optionally protected hydroxyl group, and an optionally protected amino group is added. You may have. These groups may be reactive to the reaction of the present invention.

The method of the present invention The method of the present invention is specifically carried out as follows. The reaction is carried out by adding a substrate, a water-containing solvent, and a metallosilicate to a reaction vessel (such as a Pyrex (registered trademark) tube) having light permeability and irradiating with light.

  The substrate, water-containing solvent, metallosilicate, and light source are as described above.

  The concentration of the substrate in a solution obtained by dissolving the substrate in a water-containing solvent is usually about 0.01 to 1000 mmol / L, preferably about 0.1 to 1000 mmol / L. If the concentration is too low, the reactivity decreases, and if the concentration is too high, the reaction takes time and side reactions increase, which is not preferable. The addition amount of the metallosilicate may be about 0.1 to 10 parts by weight, preferably about 1 to 10 parts by weight with respect to 100 parts by weight of the substrate.

  The reaction vessel used for the reaction is preferably stirred by adding a stirrer or the like in order to promote the reaction between the metallosilicate and the substrate. In addition, the shape of the metallosilicate to be subjected to the reaction is preferably a powder or fine powder that is easily diffused into the reaction solution, and the average particle size thereof is usually about 0.01 to 100 μm, preferably 0.1 to It may be about 10 μm.

  When the target reaction is an oxidation reaction, it is necessary to make the reaction vessel have an oxygen atmosphere. Under an oxygen atmosphere means that the reaction solution and the space have oxygen molecules necessary for the oxidation reaction, and usually a gas containing oxygen may be filled in the reaction vessel. Examples of other methods include a method of supplying air or oxygen continuously or intermittently into the reaction solution. When air or oxygen is continuously supplied into the sample water, the supply amount may be, for example, supplied at a rate of about 0.1 to 100 mL per minute with respect to 1 L of the reaction solution.

  In light irradiation, the entire reaction vessel is covered with an internal mirror, so that the irradiation efficiency of ultraviolet rays can be increased and the reaction can be promoted.

  The method of the present invention is a method capable of reacting at room temperature, but the reaction liquid may be heated when the reaction time is further shortened. The heating temperature may be in the range of 40 to 80 ° C., for example, although it may be related to the boiling point of the solvent. When heating, pay close attention to the sealing of the reaction vessel so that the measurement value is not affected by evaporation of the solvent or substrate.

  The reaction time varies depending on the reaction conditions such as the size of the reaction vessel, the concentration of the substrate in the solution, the amount of photocatalyst used, the ultraviolet light source, etc., but it proceeds in about 30 to 60 minutes.

After completion of the reaction, the metallosilicate is filtered off from the reaction solution, the solution is concentrated, and the desired product can be obtained through a known purification process. The metallosilicate filtered off can be reused after washing and drying.

II. Use of the method of the present invention As described above, the method of the present invention can obtain a target product by selectively reacting a reactive substrate having an equivalent molecular diameter with a metallosilicate having a specific average pore diameter. This method of the present invention is applied to the following fields, for example.

  (1) By using a metallosilicate having an average pore size corresponding to the molecular diameter of a reactive substrate (aromatic halide, etc.) as a photocatalyst, the desired product (aromatic hydroxide, etc.) is obtained in high yield. be able to. This reaction is greatly different from a photocatalyst having low substrate selectivity and a thorough oxidative decomposition reaction like a photocatalytic reaction of titanium oxide or the like. Further, it is different from Patent Document 1 (Japanese Patent Laid-Open No. 9-208511) that indiscriminately converts a hydrogen atom of an aromatic ring into a hydroxyl group in that a halogen atom on the aromatic ring can be selectively substituted with a hydroxyl group. To do.

  (2) A reactive substrate can be selectively reacted in a reaction system in which a reactive substrate and other substrates are mixed. That is, in a liquid phase in which a plurality of substrates having different molecular diameters are present, a reactive substrate having a molecular diameter equivalent to the pore diameter of the metallosilicate can be reacted with high selectivity. This is because the reactive substrate easily captures the active site of the metallosilicate and the reaction proceeds preferentially.

  Specifically, by adjusting the pore size of the metallosilicate, specific substances contained in the liquid phase (for example, harmful substances such as dioxin and PCB) can be decomposed with high selectivity. It can be converted into a compound with high added value such as hydroxides.

  According to the method of the present invention, a metallosilicate having a specific average pore diameter is used as a photocatalyst in a liquid phase, and a reaction substrate having a molecular diameter (short diameter) substantially equal to the average pore diameter is selectively used. It can be converted into a thing. Specifically, using a porous metallosilicate as a photocatalyst in a water-containing solvent, an organic compound having a molecular diameter (short diameter) approximately the same as the average pore diameter of the metallosilicate is selectively converted to a smaller compound. can do. More specifically, the aromatic halide can be selectively converted into an aromatic hydroxide.

  Therefore, by using the method of the present invention, a substrate having an equivalent molecular diameter can be reacted with high selectivity by controlling the average pore diameter of metallosilicates having different molecular diameters.

  Hereinafter, although the specific example (Example) of this invention is shown, this invention is not limited by this.

Example 1 (Verification of Non-Patent Document 1)
In order to verify the contents of Non-Patent Document 1 (Chemistry Letters, 1999, 885) described in the technical background section, the following experiment was performed. The following compounds 1 to 10 shown below were dissolved in distilled water (10 mmol / L). These aqueous solutions (15 mL) were put into a Pyrex (registered trademark) test tube (capacity 20 mL) together with a catalyst (0.01 g) and a stirrer, respectively. Table 1 shows literatures describing the physical property values and production methods of the photocatalyst used in this example. The test tube was sealed with a rubber stopper, and oxygen gas was passed through the test tube for 5 minutes through a stainless steel syringe (flow rate: 10 mL / min). Subsequently, as shown in FIG. 2, a test tube was placed beside a high-pressure mercury lamp (300 W, YHB-300 type manufactured by Eikoh), and irradiated with light from the bottom while being stirred by a magnetic stirrer. The light-emitting part of the high-pressure mercury lamp was covered with a Pyrex (registered trademark) filter so that only light with λ> 280 nm or more was irradiated onto the test tube. After 30 minutes of light irradiation, the reaction solution was filtered to recover the catalyst. The obtained solution was analyzed with a high performance liquid chromatograph (manufactured by Shimadzu Corporation, LC-6A) to determine the conversion rate of the compound.

(1) Table 2 shows the partition ratio D (see formula below for D) and the decomposition rate of the substrate when the compound is photolyzed using titanosilicate (TS-1, TS-2) and titanium oxide as catalysts. Show. According to the results of Table 2, in the compounds 6 to 10, TS-1 and TS-2 have a significantly lower decomposition rate than titanium oxide, although the distribution ratio D is larger (easily adsorbed) than titanium oxide. I understood that. Further, regarding TS-1 and TS-2, no proportional relationship was found between the distribution ratio D and the decomposition rate. Therefore, it was found that the ease of adsorption to the photocatalyst as described in Non-Patent Document 1 is not necessarily the controlling factor of the ease of decomposition.

  D = (Substrate concentration in initial solution−Substrate concentration in solution at equilibrium) / Substrate concentration in solution at equilibrium

(2) Next, in the decomposition reaction of titanosilicate, it was considered that the shape and size of the substrate molecule had an effect on the decomposition, and the relationship between the molecular size and the decomposition rate was examined as follows. FIG. 3 shows the calculation results of the molecular size of the compounds 2, 3 and 6 using the semi-empirical molecular orbital method (PM3 method). Molecular short diameter and decomposition when the decomposition reaction was performed using three types of catalysts ((a) TS-1, (b) TS-2, (c) titanium oxide (anatase)) (irradiation time 30 minutes) The relationship between the rates is shown in FIG. In addition, the wavy line in FIG. 4 shows the pore diameter of each catalyst. According to FIG. 4, when titanium oxide is used (c), there is no relationship between the molecular diameter and the decomposition rate, but in the case of TS-1 (a) and TS-2 (b) In both cases, small molecules are difficult to be decomposed, and are easily decomposed as the molecular diameter increases. It can be seen that the substrate is most easily decomposed when the molecular diameter is almost equal to the pore diameter (dashed line), and tends to be difficult to decompose when the molecular diameter is further increased. That is, in (a) and (b), titanosilicate decomposes a substrate having a molecular diameter smaller than the pore diameter as in Compound 6 or a substrate having a molecular diameter larger than the pore diameter as in Compound 3. On the other hand, it was found that a substrate having a molecular diameter almost equal to the pore diameter as in Compound 2 was selectively decomposed.

Example 2 (Mechanism of expression of shape selectivity)
(1) It was investigated as follows what the shape selective decomposition characteristic shown in Example 1 originates. First, titanosilicate (TS-1 and TS-2: pore diameter 0.6 nm), which is a 4-coordinate Ti species having micropores as a photocatalyst, using compound 2 (molecular minor axis 0.6341 nm) as a substrate , (Ii) a catalyst in which titanium oxide is impregnated with and supported by titanium oxide which is a 6-coordinated Ti species (pore diameter 0.6 nm), and (iii) a 4-coordinated titanium species having mesopores -MCM-41 (pore diameter 2.7 nm) was used. As a result, in the photocatalyst (i), the shape selective decomposition characteristics shown in FIG. 4 were observed, but in the photocatalysts (ii) and (iii), such shape selectivity was not observed at all. None (see FIG. 5). From this, it was found that the shape selectivity of titanosilicate with respect to compound 2 was a function that was first expressed by the combination of tetracoordinate titanium and micropores.

Therefore, the mechanism by which the titanosilicate shape selectivity is expressed can be explained as follows. The tetracoordinate titanium in the titanosilicate is excited by absorbing ultraviolet rays, and a trivalent titanium species is generated by electron transfer from an adjacent oxygen ligand, and this acts as an active species. However, the lifetime of this trivalent titanium active species is very short and deactivates quickly due to the presence of water (see, for example, FIG. 6). Since the inner surface area of titanosilicate is much larger than the outer surface area, it is considered that most of the active sites are present in the pores. In order for the substrate to be decomposed, it is necessary to capture this short-lived active species present in the pores. However, since a substrate having a small molecular diameter can diffuse smoothly in the pores, it is a short-lived trivalent. It is hard to catch active titanium species and to be decomposed. In addition, a substrate having a large molecular diameter is not decomposed because it cannot enter the pores. On the other hand, a substrate having a molecular diameter almost equal to the pore diameter can enter the pores, but cannot diffuse smoothly and is temporarily trapped in the pores. Easy (see FIG. 7). Therefore, it is considered that the shape selectivity of titanosilicate is expressed by the combination of the decrease in the lifetime of active sites due to the presence of water and the pore size.
(2) In order to verify the mechanism of (1) above, the following experiment was conducted. As the solvent for the photocatalytic reaction of titanosilicate, anhydrous acetonitrile (◯) and a solution obtained by adding 10% by volume of water to acetonitrile (●) were used to photolyze compounds 1 to 10 using TS-1. The reaction conditions are the same as in Example 1. FIG. 8 shows the relationship between the molecular diameter (minor axis) of the substrate and the decomposition rate obtained as a result. In addition, the wavy line in FIG. 8 shows the pore diameter of TS-1. According to FIG. 8, in anhydrous acetonitrile, since water does not exist, the lifetime of the trivalent titanium active species does not decrease, so there is no correlation between the molecular diameter and the decomposition rate. On the other hand, it was found that the decomposition rate depends on the molecular diameter in a solution obtained by adding 10% water to acetonitrile. This result strongly suggests the mechanism of the above (1), and it was found that the decrease in the lifetime of active sites due to the presence of water plays an important role in the shape selectivity of titanosilicate.

Example 3 (Application of shape selection type decomposition function)
Next, application of the shape selective decomposition reaction of titanosilicate shown in Examples 1 and 2 was attempted.

As reactive substrate, endocrine disrupting substance 2-chloro-1,4-dihydroxybenzene 10 mmol / L, titanium oxide (anatase type, manufactured by Wako Pure Chemical Industries, particle size 5 (m)
It was irradiated with light at 0.01 ° C., 15 mL of water and 30 ° C. for 0.5 hours in an oxygen atmosphere. The harmless 1,2,4-trihydroxybenzene in which the chlorine atom is replaced with a hydroxyl group is temporarily produced, but it is further decomposed into water and carbon dioxide, and the final 1,2,4-trihydroxy is obtained. The yield of benzene was about 1.3%. Although the decomposition rate of 2-chloro-1,4-dihydroxybenzene was high, it was found that the selectivity of 1,2,4-trihydroxybenzene was very low (see FIG. 9).

  Further, in the above reaction, the reaction was performed in the same manner except that 0.01 g of titanosilicate catalyst (TS-1, TS-2) was used instead of 0.01 g of titanium oxide. Since 2-chloro-1,4-dihydroxybenzene has a molecular diameter almost equal to the pore diameter of titanosilicate, the decomposition reaction proceeded efficiently. In addition, in this case, since the produced trihydroxybenzene is smaller than the pore size of titanosilicate, further decomposition reaction does not proceed, and in particular TS-2 has achieved a selectivity of nearly 100% (Fig. 9).

It is a schematic diagram of a titanosilicate (TS-2). 1 is a schematic view of an experimental apparatus used in Example 1. FIG. It is a figure which shows the molecular size of the compound 2,3,6 calculated | required by the semi-empirical molecular orbital method. It is a figure which shows the relationship between a molecular minor axis and a decomposition rate at the time of performing a decomposition reaction using three types of catalysts ((a) TS-1, (b) TS-2, (c) titanium oxide (anatase)) . It is a figure which shows the structure of the 3 types of photocatalyst in Example 2, and the presence or absence of the shape selectivity of a decomposition reaction using the same. It is a figure which shows the influence of trivalent titanium active species and water in titanosilicate. It is a schematic diagram of the mechanism of shape selectivity in the decomposition reaction using titanosilicate. It is a figure which shows the relationship between the molecular diameter (short diameter) of a substrate, and the decomposition rate in the presence or absence of the water in a solvent. This is an application example of a shape selective decomposition reaction using titanosilicate.

Claims (9)

By adding a metallosilicate to a solution in which an organic compound is dissolved in a water-containing solvent and irradiating with light, a compound having a smaller size is obtained from an organic compound having a molecular diameter (short diameter) similar to the average pore diameter of the metallosilicate. Selective manufacturing method. The method according to claim 1, wherein the molar ratio (Si / M) of silicon (Si) to metal (M) having photocatalytic activity in the metallosilicate is about 10 to 200. The method according to claim 1, wherein the metallosilicate has an average pore diameter of about 0.4 to 10 nm. The method of claim 1, wherein the metallosilicate is titanosilicate. The method according to claim 1, wherein the hydrous solvent contains water and an organic solvent miscible with water, and the water content in the hydrous solvent is about 1 to 100% by volume. The method according to claim 1, wherein the organic compound is an aromatic halide. Aromatic water characterized by adding a metallosilicate having an average pore diameter comparable to the molecular diameter (short diameter) of the aromatic halide to a solution in which the aromatic halide is dissolved in a water-containing solvent and irradiating with light. Production method of oxide. The aromatic halide has, as a substituent, at least one halogen atom selected from the group consisting of a chlorine atom, a bromine atom and an iodine atom on an aromatic compound having 6 to 30 carbon atoms. The manufacturing method as described. By adding a metallosilicate to a solution in which two or more substrates having different molecular diameters (minor axis) are dissolved in a water-containing solvent and irradiating with light, the molecular diameter (minor axis) is about the same as the average pore size of the metallosilicate. And a reactive substrate having a selective reaction.