JP2011184772A - Electrolytic reaction apparatus and method for producing carbonic acid diester using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide and electrolytic reaction apparatus for obtaining carbonic acid diester and hydrogen by carrying efficient electrolytic reaction of an alkoxy compound with carbon monoxide. <P>SOLUTION: The electrolytic reaction apparatus includes an anode 4 and a cathode 2A in a reaction vessel 1 and a means 9 dispose outside the reaction vessel 1 and for applying voltage between the anode 4 and the cathode 2A. The reaction vessel 1 is separated into a first chamber 2 having a counter electrode (cathode 2A) and a second chamber 3 having no counter electrode by a porous action electrode (anode 4). The carbonic acid diester is produced while efficiently bringing gaseous carbon monoxide into contact with the liquid alkoxy compound in a gap in the porous action electrode 4, while hydrogen is generated in the counter electrode 2A. The carbonic acid diester is produced in the first chamber 2 while taking out unreacted carbon monoxide from the second chamber 3 and by-produced hydrogen from the first chamber 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrolytic reaction apparatus for efficiently obtaining an electrolytic reaction between an alkoxy compound and carbon monoxide to obtain a carbonic acid diester, and a method for producing the carbonic acid diester using the electrolytic reaction apparatus.

  The oxidation-reduction reaction by transfer of electrons at the electrode is generally called an electrolytic reaction. This reaction requires an anode for receiving electrons from the material, a cathode for supplying electrons to the material, and means for applying a voltage between the two electrodes to move the electrons from the anode to the cathode. That is, an oxidation reaction occurs simultaneously at the anode and a reduction reaction occurs simultaneously at the cathode.

  There are many examples of research on the synthesis of organic compounds by electrolytic reaction, but those that are used industrially are very limited. As an example of practical use, a process for producing adiponitrile from acrylonitrile is known. In this electrolytic cell using nickel steel as the anode and Cd or Cd / Pb alloy as the cathode, the following formulas (1) and (2) are reacted with each electrode. As a result, the following formula (3) A product is obtained by reaction (Non-patent Document 1).

Anode: 2CH ₂ ═CH—CN + 2e ⁻ + 2H ⁺ → NC— (CH ₂ ) ₄ —CN (1)
Cathode: H ₂ O → 0.5 O ₂ + 2H ⁺ + 2e ⁻ (2)
_{2CH 2 = CH-CN + H} 2 O → 0.5O 2 + NC- (CH 2) 4 -CN (3)

  In this reaction, since the raw material is a uniform liquid, the working electrode and the counter electrode can be placed in the same reaction space.

  On the other hand, when there are two or more raw materials and they are gases and liquids, or when they are not miscible with each other like a hydrophilic liquid and a hydrophobic liquid and form a two-liquid phase, the contact between the raw materials is limited. For this reason, the efficiency of the electrolytic reaction is reduced. In a normal reaction, a method of blowing a gas into a liquid is generally used for gas-liquid contact, and a method of stirring and dispersing droplets is used for liquid-liquid contact. For this reason, it is not easy to increase the efficiency of the reaction.

  In order to solve this problem, a three-phase interfacial electrolysis method has been devised (Non-Patent Document 2). This is a method of using a unit membrane in which a porous membrane anode and a porous membrane cathode and an electrolyte membrane are integrated. This unit membrane is used as a diaphragm, and the reactor is divided into two chambers. The electrolytic reaction can be performed while supplying two raw materials, for example, a hydrophilic raw material and a hydrophobic raw material separately from both sides of the unit film. The electrolytic reaction is considered to proceed at the three-phase interface (liquid phase A or gas phase / electrode (solid) / liquid phase B) formed in the porous membrane.

  Conventionally, as an electrolytic reaction by this three-phase interfacial electrolysis method, for example, the following electrolytic synthesis examples have been reported.

(1) Reaction of synthesizing cyclohexanone in the anolyte by reacting while supplying hydrophobic cyclohexane from the anode side of the unit film and water from the cathode side (Non-patent Document 2)
cy-C ₆ H ₁₂ + H ₂ O → cy-C ₆ H ₁₀ O + 4H ⁺ + 4e ⁻
(2) Gas phase carbon monoxide is supplied from the anode side of the unit membrane, and liquid phase methanol is supplied into the electrolyte of the unit membrane, and reaction is performed while extracting by-product hydrogen from the porous membrane cathode to the outside (in the gas phase). Reaction to synthesize dimethyl carbonate in the electrolyte of the unit membrane (Non-patent Document 2)
2CH ₃ OH + CO → (CH ₃ ) ₂ CO + 2H ⁺ + 2e ⁻
(3) Reaction of synthesizing acetaldehyde in the anolyte by reacting while supplying an ethylene aqueous solution from the anode side of the unit film and oxygen from the cathode side (Non-patent Document 3)
C ₂ H ₄ + H ₂ O + 1 / 2O ₂ → CH ₃ CHO + H ₂ O

  As an electrolytic reactor used for the said use, there exist some which were described in the below-mentioned patent document 1, for example.

  Carbonic diesters are widely used as solvents such as electrolytes, synthetic raw materials such as alkylating agents and carbonylating agents, additives for gasoline and diesel fuel, and raw materials for polycarbonate and polyurethane.

Conventionally, phosgene methods, oxidative carbonylation methods, transesterification methods, and the like are known as methods for producing carbonic acid diesters, and among these, methods that do not use phosgene, which is a harmful substance, are required.
For this reason, dialkyl carbonate, which is increasing in demand as an electrolyte solvent, has been manufactured by the phosgene method in the past, but in recent years, it has been increasingly manufactured by an oxidative carbonylation method or a transesterification method.

  On the other hand, some attempts to produce a carbonic acid diester by an electrolytic reaction are also known. For example, a method of obtaining dimethyl carbonate and ethylene carbonate by electrolytic reaction of a monovalent or dihydric alcohol and carbon monoxide in the presence of an electrolyte containing halogen (excluding fluorine) is disclosed (Patent Document 2). ). Also disclosed is a method of obtaining dimethyl carbonate by electrolytic reaction of alcohol and carbon monoxide in the presence of a periodic table group VIII catalyst and an electrolyte containing chlorine, bromine or iodine (Patent Document 3). Furthermore, there is disclosed a method for producing a carbonate ester and a formate ester simultaneously by subjecting an alcohol and carbon monoxide to an electrolytic reaction using an anode containing a platinum group element in the presence of a supporting electrolyte (Patent Document 4). .

  In addition, using a reactor in which the reactor is partitioned into two reaction spaces on the anode side and the cathode side by a diaphragm in which an anode and a cathode are formed via a proton conducting membrane, alcohol and alcohol are added to the reaction space on the anode side. Carbon monoxide is supplied, oxygen is supplied to the reaction space on the cathode side, and a voltage is applied to the anode and the cathode to perform an electrolytic oxidation-reduction reaction, thereby generating carbonic acid diester on the anode side and water on the cathode side. (Patent Document 5). In this method, contact between the catalyst supported on the cathode and water and formation of an explosive gas mixture can be prevented.

  Furthermore, an organic electrolysis reaction apparatus for electrolytic oxidation of a system containing a substrate and a reducing substance, comprising a casing, an anode active material, an ion conductive or active species conductive anode, a cathode active material, and an ion Including a cathode that is conductive or active species conductive, and means for applying a voltage between the anode and the anode provided outside the casing and connected to the cathode, the anode And the cathode are spaced apart in the casing, and the inside of the casing is divided into an intermediate chamber formed between the inside of the anode and the inside of the cathode, and an anode chamber outside the anode. It is disclosed to synthesize dimethyl carbonate from methanol and carbon monoxide using an organic electrolysis reactor characterized by being partitioned. (Patent Document 1).

  However, in the conventional electrolytic reaction, an aliphatic organic hydroxy compound having 2 or more carbon atoms, an alicyclic organic hydroxy compound having 5 or more carbon atoms or an aromatic organic hydroxy compound, specifically, phenol or the like and carbon monoxide. The reaction with did not proceed efficiently, and the carbonic acid diester was not produced at all, or even when produced, the yield and selectivity were very low, which was not satisfactory.

  As a result of diligent studies to solve the above-mentioned problems, the present inventors have efficiently converted a reaction with carbon monoxide by converting an organic hydroxy compound into an alkoxy anion, which can be produced by a conventional method. It has been found that a carbonic acid diester can be obtained from a chain aliphatic organic hydroxy compound having 2 or more carbon atoms, an alicyclic organic hydroxy compound having 5 or more carbon atoms and an aromatic organic hydroxy compound (Patent Document 6). .

  Although the improvement regarding the synthesis reaction of carbonic acid diester has been achieved by the above invention, further problems remain from the aspect of the synthesis process of carbonic acid diester. One of them relates to separation of unreacted carbon monoxide and hydrogen produced as a reaction byproduct.

  That is, the inventors of the present invention disclosed in Patent Document 6 that the electrolytic synthesis of a carbonic acid diester is performed as shown in FIG. 3 and a two-chamber cell in which a working electrode and a counter electrode are separated by an ion-permeable membrane as shown in FIG. It has been shown that this can be achieved with any one-chamber cell in which a working electrode and a counter electrode are installed in the same space. However, in any cell, as shown below, further improvements are required for industrial practical use. is necessary.

  In FIG. 2, reference numeral 10 denotes a reaction vessel (electrolysis cell), in which a bottomed cylindrical container part constituting the anode chamber 11 and a bottomed cylindrical container part constituting the cathode chamber 12 are cylindrical communication parts. 13 connected to each other. A conductive solid electrode containing the aforementioned platinum group element-supported catalyst is provided as the anode 11A at the bottom of the anode chamber 11, and a cathode 12A is provided in the cathode chamber 12. The anode 11A and the cathode 12A are connected to the power source 19. Has been. In addition, the communication part 13 is provided with an ion-permeable diaphragm 14. 11B and 12B are stoppers for covering the upper part of each electrode chamber. Reference numeral 15 denotes a gas supply pipe for supplying carbon monoxide to the reaction solution in the anode chamber 11. The gas supply pipe also serves as a gas supply pipe for circulating an inert gas such as He. Reference numeral 16 denotes a gas supply pipe for circulating an inert gas such as He. Reference numerals 17 and 18 denote degassing pipes that also serve as gas sampling pipes.

  In this electrolytic reaction apparatus, a reaction solution containing an organic hydroxy compound and a basic substance or an alkoxy compound is introduced into the anode chamber 11, and a reaction solution containing the organic hydroxy compound is introduced into the cathode chamber 12, and monoxide is obtained from the gas supply pipe 15. When carbon is supplied and the anode 19A is energized between the anode 11A and the cathode 12A by the power source 19, in the presence of the platinum group element supported catalyst contained in the carbon electrode of the anode 11A in the anode chamber 11, the organic hydroxy compound and the basic substance The alkoxy compound produced by the above reaction and carbon monoxide undergo an electrolytic reaction to produce a carbonic acid diester. At the same time, carbon dioxide may be generated by the oxidation of carbon monoxide. On the other hand, in the cathode chamber 12, hydrogen ions are reduced and hydrogen gas is generated.

  In FIG. 3, reference numeral 20 denotes a reaction vessel (electrolysis cell) having a bottomed cylindrical vessel portion 20A and a stopper 20B for covering the upper opening. The aforementioned carbon electrode is provided as the anode 21 at the bottom of the container 20A. Further, the cathode 22 is inserted from the stopper 20B to an intermediate position in the height direction in the container portion 20A. These anode 21 and cathode 22 are connected to a power source 23. Reference numeral 24 denotes a current collector that conducts the power source 23 and the anode 21. Reference numeral 25 denotes a gas supply pipe for supplying carbon monoxide to the reaction solution in the container 20A. The gas supply pipe 25 also serves as a gas supply pipe for circulating an inert gas such as He. A gas vent pipe 26 also serves as a gas sampling pipe.

  In this electrolytic reaction apparatus, a reaction liquid containing an organic hydroxy compound and a basic substance or an alkoxy compound is introduced into a container portion 20A, carbon monoxide is supplied from a gas supply pipe 25, and an anode 21 and a cathode 22 are supplied from a power source 23. In the presence of the platinum group element-supported catalyst contained in the carbon electrode of the anode 21 in the container portion 20A, the alkoxy compound and carbon monoxide produced by the reaction between the organic hydroxy compound and the basic substance are produced. Electrolytic reaction produces carbonic acid diester. On the other hand, in the vicinity of the cathode 22, hydrogen ions are reduced and hydrogen gas is generated.

2 and 3 using the two-chamber cell of FIG. 2, unreacted carbon monoxide can be taken out from the anode (working electrode) side, and by-product hydrogen can be taken out from the cathode (counter electrode) side. Although advantageous in terms, the structure in which the diaphragm is sandwiched between the two electrodes increases the resistance between the two electrodes, resulting in high power consumption.
On the other hand, the one-chamber cell shown in FIG. 3 is advantageous in that the resistance between the two electrodes can be reduced and the structure is simple, but unreacted carbon monoxide and by-product hydrogen are mixed. Therefore, it is necessary to separate them externally.
Thus, the electrolytic reaction apparatus disclosed in Patent Document 6 requires further improvement for industrial practical use.

  The electrolytic reaction described in Patent Document 6 is applied to the reactor described in Patent Document 1, and unreacted carbon monoxide is extracted from the reaction space on the anode side, and byproduct hydrogen is extracted from the reaction space on the cathode side from the intermediate chamber. Although it is possible to obtain a carbonic acid diester, the reactor has a complicated structure and is difficult to apply to an actual plant.

Japanese Patent No. 4201703 U.S. Pat. No. 4,131,521 U.S. Pat. No. 4,310,393 JP-A-6-173057 JP-A-6-73582 Japanese Patent Application No. 2009-028581

Kirk Othmer, Encyclopedia of Chemical Technology vol.8,710-713 Catalyst, 46_4 (2004) 313-319 Res.Chem.Intermed., 32_3-4 (2006) 373-385 Applied Catalysis, A: General, 254 (2003) 5-25

  In view of the above-mentioned problems, the present invention provides an electrolytic reaction apparatus for obtaining a carbonic acid diester by electrolytically reacting an alkoxy compound and carbon monoxide in an efficient and industrially advantageous manner, and a carbonic acid diester using the same. It is an object to provide a manufacturing method.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have a reaction vessel having an anode and a cathode inside and means for applying a voltage between the anode and the cathode, and the reaction vessel has a cathode. And a second chamber having a structure capable of holding a gas containing carbon monoxide, and a first chamber having a structure in which the cathode and the reaction liquid containing the alkoxy compound can come into contact with each other. It has been found that the above problem can be solved by using a reaction vessel in which two chambers are separated by a porous anode containing a platinum group element.

  That is, in the electrolytic reaction in which carbon monoxide and an alkoxy compound react with each other in the presence of a platinum group element to form a carbonic acid diester, by using the reaction vessel, the gaseous carbon monoxide in the second chamber and the first Carbonate is produced while efficiently contacting an indoor liquid alkoxy compound in the void in the porous working electrode of the anode, while hydrogen is generated at the counter electrode (cathode) to generate unreacted carbon monoxide. While taking out from two chambers, it discovered that a carbonic acid diester could be manufactured in a 1st chamber, taking out byproduct hydrogen from a 1st chamber, and came to complete this invention.

  That is, the gist of the present invention is as follows.

[1] An electrolytic reaction apparatus for obtaining a carbonic acid diester by electrolytic reaction of an alkoxy compound and carbon monoxide in the presence of a platinum group element, a reaction vessel, and an anode and a cathode provided in the reaction vessel And means for applying a voltage between the anode and the cathode provided outside the reaction vessel, the reaction vessel has a cathode, and the cathode and the reaction liquid containing the alkoxy compound are in contact with each other in the room. A porous anode having a first chamber having a structure capable of holding and a second chamber having a structure capable of holding a gas containing carbon monoxide, wherein the first chamber and the second chamber contain a platinum group element. An electrolytic reaction apparatus characterized by being separated by

[2] The anode is a porous electrode including a platinum group element-supported catalyst in which a platinum group element is supported on a support made of conductive carbon having a primary particle diameter of 100 nm or less [1] ] The electrolytic reaction apparatus of description.

[3] The anode is a porous electrode including a platinum group element-supported catalyst in which a platinum group element is supported on a support made of conductive carbon having a BET specific surface area of 100 m ² / g or more. The electrolytic reaction apparatus according to [1] or [2].

[4] The anode is a porous electrode including a platinum group element-supported catalyst in which a platinum group element is supported on a carrier made of conductive carbon, and the conductive carbon is carbon black. [1] The electrolytic reaction apparatus according to any one of [3].

[5] The anode is formed by mixing a platinum group element-supported catalyst in which a platinum group element is supported on a carrier made of conductive carbon and a conductive auxiliary agent [1] Thru | or the electrolytic reaction apparatus in any one of [4].

[6] The electrolytic reaction apparatus according to any one of [1] to [5], wherein the platinum group element is palladium.

[7] A reaction liquid containing an alkoxy compound is supplied to the first chamber of the reaction vessel of the electrolytic reaction apparatus according to any one of [1] to [6], and a gas containing carbon monoxide is supplied to the second chamber. And producing a carbonic acid diester by an electrolytic reaction.

[8] The carbonic acid diester according to [7], wherein the alkoxy compound is produced in the reaction solution by containing an organic hydroxy compound and a basic substance in the reaction solution. Method.

[9] The method for producing a carbonic acid diester according to [7] or [8], wherein the alkoxy compound is a phenoxy compound, and the carbonic acid diester is diphenyl carbonate.

[10] A method for producing an aromatic polycarbonate, characterized in that diphenyl carbonate produced by the method according to [9] is used as a raw material.

  According to the present invention, a carbonic acid diester can be produced by electrolytically reacting an alkoxy compound and carbon monoxide efficiently and in an industrially advantageous manner.

That is, in the electrolytic reaction according to the present invention, an oxidation reaction of an alkoxy compound and carbon monoxide proceeds on the anode side to generate a carbonic acid diester, and hydrogen ions are reduced on the cathode side to generate hydrogen gas. When unreacted carbon monoxide and by-product hydrogen gas are taken out in a mixed state, it is difficult to separate them. Therefore, it is preferable that the gas supply field containing carbon monoxide and the hydrogen generation field are separated. In the electrolytic reaction apparatus of the present invention, since the second chamber to which the gas containing carbon monoxide as a raw material is supplied is separated from the first chamber in which hydrogen is generated, it is necessary to separate these gases. Not efficient.
Further, the separation of the first chamber and the second chamber is performed by a porous anode containing a platinum group element as a catalyst, so that the liquid material is efficiently contacted from the first chamber side and the gas material is efficiently contacted from the second chamber side. In addition, since the resistance between the anode and the cathode can be reduced, the power consumption can be reduced.
The electrolytic reaction apparatus of the present invention has the effect of enabling production of a carbonic acid diester by an industrially advantageous electrolytic reaction in terms of the above points.

It is a block diagram which shows the electrolytic reaction apparatus which concerns on embodiment of this invention. It is a block diagram which shows the two-chamber type | mold electrolytic reaction apparatus disclosed by patent document 6. FIG. It is a block diagram which shows the one-chamber type | mold electrolytic reaction apparatus disclosed by patent document 6. FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

[Electrolytic reactor]
The electrolytic reaction apparatus of the present invention has an anode and a cathode inside the reaction vessel, and means for applying a voltage between the anode and the cathode outside the reaction vessel, the reaction vessel has a cathode, and the cathode And a reaction chamber containing a reaction solution containing an alkoxy compound and a second chamber having a structure capable of holding a gas containing carbon monoxide, wherein the first chamber and the second chamber are platinum group elements. It is separated by a porous anode containing This electrolytic reaction apparatus is used to obtain an carbonic acid diester by electrolytically reacting an alkoxy compound and carbon monoxide in the presence of a platinum group element (hereinafter sometimes referred to as “electrolytic reaction of the present invention”).

  The reaction vessel according to the present invention is not particularly limited as long as it has a structure capable of holding a reaction liquid containing an alkoxy compound which is a raw material for performing the electrolytic reaction of the present invention and a gas containing carbon monoxide, The shape, volume and the like can be appropriately selected depending on the scale and conditions of the electrolytic reaction of the present invention performed in the reaction vessel. Specifically, resin, glass, metal, or the like is used as the material for the container, and the first chamber and the second chamber may have a bottomed cylindrical shape, a bottomed rectangular tube shape, a rectangular parallelepiped shape, or the like. The first chamber and the second chamber may be different in shape, volume, and material.

  The first chamber preferably has a supply port for the reaction solution in order to hold the reaction solution containing the alkoxy compound as a raw material. When the reaction solution is circulated, the reaction solution may have a supply port, a discharge port, a circulation pump, a solution tank, and the like outside.

  The cathode material of the cathode installed in the first chamber is not limited in shape and material as long as it can be used for a normal electrolytic reaction, but preferably has a low hydrogen overvoltage. Specifically, carbon, platinum, cadmium, lead, gold, an alloy containing them, or the like can be used.

  The place where the cathode is installed may be any place where an electrolytic reaction can occur in the first chamber, but it is preferable to place it as close to the anode as possible in order to reduce the interelectrode resistance. In that case, you may install the separator for preventing the short circuit between both poles.

  On the other hand, in order to hold | maintain the gas containing carbon monoxide which is a raw material similarly, it is preferable that the 2nd chamber is equipped with the supply port of this gas, the exit of excess gas, etc.

The first chamber and the second chamber are separated by a porous anode containing a platinum group element. Here, “separated by the anode” means that both the reaction liquid in the first chamber and the carbon monoxide in the second chamber can contact the anode so that the electrolytic reaction can be sufficiently performed. It means that the substance held in both chambers and the substance generated by the electrolytic reaction are not mixed with each other.
Specifically, for example, a form in which a plate-like anode is present as a wall separating the first chamber and the second chamber (FIG. 1 described later) can be cited, but all of the walls separating the two chambers Need not be the anode.

  As an anode, a normal conductive solid electrode manufactured from a porous material (hereinafter, sometimes referred to as “conductive porous solid electrode”) containing a platinum group element is used. Can do.

  As described above, in general, when a product is obtained by reacting two or more kinds of raw materials that are not originally miscible, such as a gas raw material and a liquid raw material, or a hydrophobic liquid raw material and a hydrophilic liquid raw material, It is necessary that the raw material separated into two phases and the catalyst come into efficient contact. For this purpose, a device has been devised to make the particle size of bubbles or droplets as small as possible (that is, to make the contact area of gas-liquid or liquid-liquid as large as possible). In the electrolytic synthesis reaction, it is necessary to reduce the particle size of bubbles or droplets to increase the contact area, but the electrode is solid and the reaction proceeds by transferring electrons on the surface, It is necessary to increase the contact efficiency at the gas / solid / liquid or liquid / solid / liquid three-phase interface.

  Therefore, in the electrolytic reaction apparatus of the present invention, the problem of contact efficiency at the three-phase interface is solved by using a conductive porous solid electrode for the anode. The conductive porous solid electrode referred to here is an electrode having a fine gap inside the electrode, and a liquid raw material or a gas raw material permeates into the gap portion to make a three-phase contact. If the inner diameter of the void (hole) of the conductive porous solid electrode is too small, the raw material cannot penetrate into the electrode, and conversely, if it is too large, the raw material leaks to the different phase side and does not serve as a diaphragm. Therefore, the pore diameter of the conductive porous solid electrode needs to be not less than the molecular diameter of the raw material alkoxy compound, carbon monoxide and the product carbonic acid diester. On the other hand, the maximum diameter is affected by the thickness of the electrode, the material, and the reaction conditions, so a design corresponding to the situation is required.

  From such a viewpoint, the diameter of the void (porous pore diameter) of the conductive porous solid electrode of the anode is generally 1 nm to 1000 nm, preferably 5 nm to 500 nm, and more preferably 10 nm to 100 nm.

  Such a conductive porous solid electrode can be produced, for example, by kneading a conductive powder mainly composed of carbon or metal and a binder powder such as polytetrafluoroethylene, followed by rolling. In producing the conductive porous solid electrode, for example, by mixing one or more of the platinum group elements described below in the kneaded material for producing the conductive porous solid electrode, A porous anode containing a platinum group element used in the electrolytic reaction apparatus of the present invention can be produced by containing a platinum group element in the porous porous solid electrode.

  A platinum group element is supported on the surface of a conductive material constituting the conductive porous solid electrode (hereinafter sometimes referred to as “support”) (hereinafter referred to as “platinum group element supported catalyst”). In some cases, the carrier is preferably conductive carbon, that is, conductive carbon fine particles. Furthermore, as the conductive carbon, it is preferable to use conductive carbon fine particles having a primary particle diameter of 100 nm or less, preferably 50 nm or less, or an aggregate thereof.

  Here, the primary particle diameter means an average value of individual particle diameters observed from a photograph of a plurality of particles dispersed using an electron microscope such as a transmission electron microscope. When calculating the particle size, if the shape of the particle observed from the photograph is columnar or the like and the aspect ratio is large, the short side length is used as the particle size, and the number of particles used when calculating the average value Although there is no particular limitation, it is preferable to observe as many particles as possible. Specifically, it is preferable to observe 100 or more particles, more preferably 1000 or more particles, for example, 5000 to 10000 particles. In calculating the average value, commercially available software for particle size measurement may be used.

  By using ultrafine particles of conductive carbon with a primary particle diameter of 100 nm or less as a carrier, the volume resistivity of the carrier is reduced and the electrical conductivity is improved, thereby improving the catalyst and electrode performance. Thus, it can be considered that the reaction efficiency is improved.

Further, as the conductive carbon, use of a conductive carbon having a BET specific surface area of 100 m ² / g or more, particularly 200 m ² / g or more and a large specific surface area increases the reaction point per unit weight of the catalyst. This is preferable.

Here, the BET specific surface area of the conductive carbon may be measured by any of the commonly used methods. Specifically, for example, it is measured as follows.
First, the sample is put into a sample tube (adsorption cell), evacuated while being heated, and the sample weight after degassing is measured. Next, a change in the amount of adsorption with respect to a change in pressure is plotted while feeding nitrogen gas into the cell and adsorbing nitrogen gas on the sample surface. From this graph, the adsorption amount of gas molecules adsorbed only on the sample surface is obtained from the BET adsorption isotherm. Since the nitrogen occupancy area is known in advance, the surface area of the sample can be measured from the gas adsorption amount.

There is no particular limitation on the lower limit of the primary particle diameter and the upper limit of the BET specific surface area of the conductive carbon used in this embodiment. However, the primary particles of the conductive carbon are usually limited due to limitations in the manufacturing method and mechanical strength. The diameter is 10 nm or more, and the BET specific surface area is 10000 m ² / g or less.

  Although there is no restriction | limiting in particular as a carbon raw material of electroconductive carbon, Preferably, carbon black, a graphite, fullerene, a carbon nanotube, a graphene, activated carbon fiber, etc. are mentioned. These may be used alone or in combination of two or more. Among these, carbon black is preferable from the viewpoints of availability as a carrier and price.

  On the other hand, examples of the platinum group element used in the present invention include ruthenium, rhodium, palladium, osmium, iridium, platinum and the like, and these may be used alone or in combination of two or more. . Of these, palladium is preferred because the desired reaction proceeds efficiently.

  The production method of the platinum group element supported catalyst using conductive carbon is not particularly limited, but a predetermined amount of an aqueous solution in which a platinum group element salt is dissolved is dropped into water in which conductive carbon is dispersed, and evaporated to dryness. The method etc. are mentioned. The platinum group element supported catalyst in which the platinum group metal is supported on the conductive carbon as a simple substance by reducing the platinum group element salt on the support by further heating to about 60 to 500 ° C. in a hydrogen stream. Can be obtained.

  The supported amount of platinum group element in the platinum group element-supported catalyst thus obtained is usually about 0.01 to 75% by weight, preferably 0.1 to 50% by weight, based on the conductive carbon. . If the supported amount is too small, the catalytic effect is insufficient due to a decrease in the platinum group element content of the anode produced using this, and if it is too large, it is detached from the anode and inactivated, which is not economical.

  The platinum group element-supported catalyst thus obtained is molded by adding a binder such as polytetrafluoroethylene (PTFE) to form a conductive porous material containing the platinum group element-supported catalyst suitable for the electrolytic reaction apparatus of the present invention. The anode of a solid electrode can be manufactured. Alternatively, the anode can also be produced by kneading and forming a platinum group element-supported catalyst together with the binder and the conductive auxiliary agent not supporting the platinum group element.

  The conductive auxiliary agent used here may be the same as or different from the conductive carbon used as the platinum group element support of the platinum group element-supported catalyst. It is preferable to use a conductive material having a body resistivity of 0.5 Ω · cm or less, preferably 0.25 Ω · cm or less. The combined use of the conductive auxiliary has the effect of suppressing the internal resistance of the electrode, but when the powder resistivity of the conductive auxiliary used exceeds 0.5 Ω · cm, the resistance in the electrode is reduced. Increases and current efficiency decreases. The lower limit of the powder resistivity of the conductive auxiliary agent is not particularly limited, but is usually about 0.01 Ω · cm.

  The powder resistivity is determined by placing four needle-shaped electrodes (four-probe probes) on a sample in a straight line, passing a constant current between the two outer probes, and the potential difference between the two inner probes. It can be obtained by measurement (four-probe method).

  Specific examples of conductive assistants used in the production of the anode include carbon powders such as carbon black, carbon-based materials such as carbon fibers, carbon flakes, and carbon ultrashort fibers (carbon nanotubes), silver, nickel, copper, Zinc, aluminum, iron, stainless steel, brass powders, metal materials in the form of flakes, fibers, metal oxide materials doped with metal oxide fine particles with metal, electroless plating, tin oxide coated powders and fibers Examples thereof include conductive coating materials such as. These may be used alone or in combination of two or more. Among these, in consideration of performance as a conductive material and availability, a carbon-based material and a metal-based material are preferable, and a carbon-based material is more preferable.

  There are no particular restrictions on the size (particle size, fiber diameter, etc.) of these conductive auxiliaries, but if they are excessively large, the moldability will be poor, and if they are excessively small, conductive paths will not be formed unless they are introduced in large quantities. When introduced in a large amount, the structure becomes dense and the porosity is lost. Therefore, if it is a granular conductive aid, the primary particle diameter is about 10 nm to 100 μm, and if it is a fibrous conductive aid, An average fiber diameter of 5 nm to 50 μm and an average fiber length of about 0.1 to 1000 μm are preferable.

If the amount of the white metal element contained in the anode composed of the conductive porous solid electrode containing such a platinum group element-supported catalyst is small, the reaction rate decreases, and if it is too large, it is desorbed from the anode and inactivated, so it is economical. Not. Therefore, the content of the white metal element in the anode can be appropriately selected according to the reaction system using the anode. For example, the content of the white metal element per electrode area (geometric area) of the anode is 0. .1μmol / cm ² or more is preferable, 1 [mu] mol / cm ² or more is more preferable. Further preferably 20 [mu] mol / cm ² or less, more preferably 15 micromol / cm ² or less.

  Therefore, the binder and conductive auxiliary agent used in forming the anode are appropriately adjusted so that the amount of the platinum group element supported per electrode area of the obtained anode is within the above range, and the platinum group element supported catalyst. Used in combination with.

  Below, with reference to FIG. 1 which shows an example of embodiment of the electrolytic reaction apparatus of this invention, the apparatus structure of the electrolytic reaction apparatus of this invention is demonstrated more concretely.

  In FIG. 1, 1 is a reaction vessel (electrolysis cell), 2 is a first chamber in which a cathode 2A is installed, 3 is a second chamber, and the first chamber 2 and the second chamber 3 carry platinum group elements. They are separated by an anode 4 which is a conductive porous solid electrode containing a catalyst. The anode 4 and the cathode 2A are connected to a power source 9 installed outside the reaction vessel. 2B and 3B are stoppers for covering the upper portions of the first chamber 2 and the second chamber 3, respectively. Reference numeral 5 denotes a carbon monoxide supply pipe for supplying carbon monoxide to the second chamber 3. The carbon monoxide supply pipe 5 also serves as a gas supply pipe for circulating an inert gas such as He. Reference numeral 6 denotes a helium gas supply pipe for circulating an inert gas such as helium into the first chamber 2. 7 is a degassing pipe for extracting excess unreacted carbon monoxide, and 8 is a degassing pipe also serving as a gas sampling pipe.

  In this electrolytic reaction apparatus, a reaction liquid containing an alkoxy compound (may be a reaction liquid containing an organic hydroxy compound and a basic substance as described later) is supplied to the first chamber 2 of the reaction vessel 1. When a gas containing carbon monoxide is supplied to the second chamber 3 from the carbon monoxide supply pipe 5 and energized between the anode 4 and the cathode 2A by the power source 9, the presence of a platinum group element catalyst in the gap of the anode 4 The alkoxy compound (which may be an alkoxy compound produced by the reaction of an organic hydroxy compound and a basic substance) and carbon monoxide undergo an electrolytic reaction to produce a carbonic acid diester. The produced carbonic acid diester diffuses into the liquid in the first chamber 2. On the other hand, on the cathode 2A installed in the first chamber 2, hydrogen ions are reduced to generate hydrogen gas. Prior to the reaction, the amount of water in the reaction system can be reduced by flowing an inert gas such as helium from the carbon monoxide or helium gas supply pipes 5 and 6 to the first chamber 2 and the second chamber 3. it can.

  In the electrolytic reaction apparatus of FIG. 1, the first chamber 2 and the second chamber 3 have a bottomed cylindrical container shape, which are connected by a cylindrical communication portion 4A, and a platinum group element is connected to the communication portion 4A. The first chamber 2 and the second chamber 3 are separated by the provision of the anode 4 made of a conductive porous solid electrode including a supported catalyst. However, the present invention is not limited to this form.

  The electrolytic reaction device of FIG. 2 disclosed in Patent Document 6 described above and the electrolytic reaction device of the present invention are different in the installation position of the anode. Due to this difference, the apparatus of FIG. 2 has a large resistance between the two electrodes, but the electrolytic reaction apparatus of the present invention has a small resistance between the two electrodes and can increase the reaction efficiency. It is practical because it is not necessary.

  3 differs from the electrolytic reaction device of FIG. 3 in that the reaction vessel is divided into a first chamber and a second chamber. As described above, in the reaction vessel of FIG. 3, it is necessary to separate unreacted carbon monoxide and by-product hydrogen outside the reaction vessel. However, in the electrolytic reaction apparatus of the present invention, a gas containing carbon monoxide as a raw material is used. Since the first chamber supplied with hydrogen and the second chamber in which hydrogen is generated are separated, it is not necessary to separate these gases, which is efficient.

[Method for producing carbonic acid diester]
The method for producing a carbonic acid diester of the present invention comprises a reaction solution containing an alkoxy compound in the first chamber of the reaction vessel of the electrolytic reaction device of the present invention described above (as described later, a reaction solution containing an organic hydroxy compound and a basic substance). And a gas containing carbon monoxide is supplied to the second chamber, and an alkoxy compound (an alkoxy compound generated by a reaction between an organic hydroxy compound and a basic substance may be used). And carbon monoxide are electrolyzed in the presence of a catalyst containing a platinum group element to produce a carbonic acid diester.
Specifically, the electrolytic reaction of the present invention is a reaction between an alkoxy compound represented by the following formula (1) and carbon monoxide, and produces a carbonic acid diester according to the following reaction formula (2).

RO ^- X ⁺ (1)
(R represents an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, and these hydrocarbon groups may have a substituent. X ⁺ represents RO ^- showing the cationic species constituting the salt, however, ^{X +} is not a hydrogen ion ^{(H +))..
2RO - X + + CO → RO} -C (= O) -OR + 2e - + 2X + (2)

  In the present specification, “alkoxy” means “in the general organic chemical nomenclature in which R in the above formula (1) is an aliphatic (that is, chain) hydrocarbon group or alicyclic hydrocarbon group. It includes not only “alkoxy” but also “aryloxy” in which R is an aromatic hydrocarbon group.

In addition, the method of the present invention is not limited to a method of producing a carbonic acid diester (RO—C (═O) —OR) using one kind of alkoxy compound, and using two or more kinds of alkoxy compounds, method of producing a different carbonic diester, for example, alkoxy compound ^{(R 1 O} - ^{X +)} and alkoxy compound - using ^{(2 O} R ^{X +)} and carbonate diester ^{(R 1 O-C (=} O) -OR ² ) is also included (wherein R ¹ and R ² have the same meanings as R and R ¹ ≠ R ² ).

The alkoxy compound used in the reaction is reacted with an organic hydroxy compound (that is, an organic hydroxy compound represented by the following formula (4)) and a basic substance in an electrolytic reaction apparatus, as described later, to form an organic hydroxy compound. In the case of producing by desorbing the hydrogen ions of the compound, X ⁺ produced by the formula (2) produces the alkoxy compound (1) by the following formula (3), and the H ⁺ produced at that time is reduced at the cathode. It becomes hydrogen gas.

ROH + X ⁺ → RO ⁻ X ⁺ + H ⁺ (3)
(R and X ⁺ have the same meanings as in formula (1).)

Therefore, in this reaction, hydrogen gas is by-produced together with the carbonic acid diester.
As described above, since the carbon monoxide and hydrogen are mixed when the electrolytic reaction is performed in the one-chamber cell shown in FIG. 3, a complicated operation for separating them is required.
In addition, since the carbon monoxide supply field and the hydrogen generation field can be separated in the two-chamber cell shown in FIG. 2, an operation for separating them is not necessary. However, in the two-chamber cell in FIG. In addition to increasing the distance, resistance by the diaphragm is added, so that a large applied voltage is required, and the efficiency of the electrolytic reaction is reduced.

<Alkoxy compound>
In the present invention, the alkoxy compound used as a raw material is represented by the formula (1). In the formula (1), R is a saturated or unsaturated aliphatic hydrocarbon group, saturated or An unsaturated alicyclic hydrocarbon group or an aromatic hydrocarbon group may be mentioned. In addition, examples of the substituent that these hydrocarbon groups may have include an alkyl group, a hydroxy group, an aryl group, a halogen atom, a nitro group, a sulfonic acid group, a sulfone group, and an amino group.

  More specifically, R is an ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group. A saturated or unsaturated, linear or branched aliphatic hydrocarbon group such as an allyl group or a crotyl group, preferably a linear or branched alkyl group or alkenyl having 2 or more carbon atoms, more preferably 2 to 10 carbon atoms. Group: a saturated or unsaturated alicyclic hydrocarbon group such as cyclopentyl group, cyclohexyl group, cycloheptyl group, methylcyclohexyl group, cyclohexenyl group, preferably a cyclohexane having 5 or more carbon atoms, more preferably 5 to 10 carbon atoms. Alkyl group or cycloalkenyl group; aralkyl group such as benzyl group and α-phenylethyl group; phenyl group, methylphenyl group, di- Aryl group or substituted aryl group such as tilphenyl group, naphthyl group, anthracenyl group, or derivatives thereof (hydrogen atom is substituted with alkyl group, aryl group, halogen atom, nitro group, sulfonic acid group, sulfone group, amino group, etc. And an aromatic hydrocarbon group having 6 or more carbon atoms which may have a substituent.

Among these, as R, in particular, a chain aliphatic hydrocarbon group having 2 or more carbon atoms, preferably 2 to 10 carbon atoms, an alicyclic hydrocarbon group having 5 or more carbon atoms, preferably 5 to 10 carbon atoms, An aromatic hydrocarbon group having 6 or more carbon atoms, preferably 6 to 14 carbon atoms, such as an aromatic hydrocarbon group, and particularly a phenyl group is preferable. The carbonic acid diester having it can be synthesized industrially advantageously. Here, the “carbon number” is the carbon number including the carbon number of the substituent when the group has a substituent. RO ⁻ represents an anion species formed by combining R and an oxygen atom, and may be an anion having a valence of 2 or more depending on the corresponding cation species. These may be used individually by 1 type and may use 2 or more types together. X ⁺ represents a cationic species that forms a salt with RO ^−, and X ⁺ represents an alkali metal ion such as lithium, sodium, or potassium, or an alkaline earth metal ion such as magnesium or calcium, trimethylammonium, triethylammonium, or tributyl. Tertiary ammonium cations such as ammonium, triphenylammonium, dimethylanilinium, pyridinium, secondary ammonium cations such as diisopropylammonium, primary ammonium cations such as methylammonium, ethylammonium, propylammonium, butylammonium, benzylammonium, NH ₄ Examples include ammonium cation represented by ⁺ , quaternary ammonium cation such as tetramethylammonium and tetraethylammonium. X ⁺ may be not only a monovalent cation but also a divalent or higher cation. These may be used individually by 1 type and may use 2 or more types together.
Examples of the phenoxide compound represented by RO ^- X ⁺ include sodium phenoxide, lithium phenoxide, potassium phenoxide and the like.

  The alkoxy compound used for the reaction is produced by reacting an organic hydroxy compound (that is, an organic hydroxy compound represented by the following formula (4)) with a basic substance to desorb hydrogen ions of the organic hydroxy compound. May be. This alkoxy compound may be synthesized simultaneously with the electrolytic reaction in the electrolytic reaction apparatus, or may be synthesized separately.

R-OH (4)
(R has the same meaning as in formula (1).)

  Specific examples of the organic hydroxy compound used for the preparation of the alkoxy compound include ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, n-hexanol, and n-heptanol. , Saturated or unsaturated, linear or branched aliphatic alcohols such as allyl alcohol, crotyl alcohol, etc., preferably linear or branched saturated or unsaturated fats having 2 or more carbon atoms, more preferably 2 to 10 carbon atoms Saturated or unsaturated alicyclic alcohols such as aromatic alcohol, cyclopentanol, cyclohexanol, cycloheptanol, methylcyclohexanol, 3-hydroxy-1-cyclohexene, 4-hydroxy-1-cyclohexene, preferably 5 or more carbon atoms , More preferably 5 carbon atoms 10 saturated or unsaturated alicyclic alcohols, aryl-substituted alcohols such as benzyl alcohol, hydroxybenzyl alcohol, diphenylcarbinol, aromatic organic hydroxy compounds such as phenol, cresol, xylenol, naphthol, hydroxyanthracene or derivatives thereof (aromatic Ring hydrogen atoms are substituted with alkyl groups, aryl groups, halogen atoms, nitro groups, sulfonic acid groups, amino groups, etc.).

  The basic substance used for the preparation of the alkoxy compound must be selected according to the reactivity with the organic hydroxy compound, but alkali metals such as metallic lithium, metallic sodium and metallic potassium or alkaline such as metallic calcium and metallic magnesium. Alkali metals such as earth metals, lithium hydroxide, sodium hydroxide and potassium hydroxide, or hydroxides of alkaline earth metals such as calcium hydroxide and magnesium hydroxide, alkali metals such as lithium hydride and sodium hydride, or calcium hydride Alkaline earth metal hydrides such as magnesium hydride, alkali metal or alkaline earth metal acetates such as sodium acetate and potassium carbonate, weak acid salts such as carbonates, trimethylamine, triethylamine, tributylamine, triphenyl Amine, diisopropylamine, dimethylaniline, amines such as pyridine, manufactured by Mitsubishi Chemical Corporation, Diaion (registered trademark) basic ion exchange resin such as SA10A can be mentioned. These may be used alone or in combination of two or more.

  The usage-amount of a basic substance should just be more than the reaction equivalent which can produce | generate an alkoxy compound from an organic hydroxy compound. In addition to supplying the necessary amount of the basic substance prior to the electrolytic reaction, the basic substance can be dividedly supplied in a plurality of times or continuously supplied during the electrolytic reaction.

<Supporting electrolyte>
In the electrolytic reaction of the present invention, a supporting electrolyte can be used to accelerate the reaction.

  Examples of supporting electrolytes include alkali metal halides such as sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, lithium chloride, lithium bromide and lithium iodide; potassium hypochlorite Alkaline metal hypohalites such as lithium hypochlorite, potassium hypoiodite, lithium hypoiodite; alkali metal halides such as potassium chlorate, lithium chlorate; sodium perchlorate, Perhalogenates of alkali metals such as sodium periodate; tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, tetrabutylammonium chloride, Tetrabu bromide Examples thereof include halides of alkyl quaternary ammonium such as til ammonium ammonium and tetrabutyl ammonium iodide; perhalogenates of alkyl quaternary ammonium such as tetrabutyl ammonium perchlorate and tetramethyl ammonium perchlorate. These may be used alone or in combination of two or more.

  However, in some cases, the above-described alkoxy compound or the basic substance added to produce the alkoxy compound functions as an electrolyte, and it is not necessary to add a supporting electrolyte separately. If the supporting electrolyte is not added, a separation operation between the target product after the reaction and the supporting electrolyte becomes unnecessary, which is industrially advantageous.

<Solvent>
In the electrolytic reaction of the present invention, a solvent may or may not be used. When a solvent is used, it is necessary to select a solvent that is inert to the electrolytic reaction (high oxidation potential). Examples of such a solvent include acetonitrile, carbon tetrachloride, dichloromethane (methylene chloride), N, N-dimethylformamide, N-methylpyrrolidone and the like. These may be used alone or in combination of two or more.

  When preparing an alkoxy compound as a reaction substrate by adding a basic substance to a reaction solution containing an organic hydroxy compound as a raw material, the organic hydroxy compound must be dissolved in the solvent. it can. Although the density | concentration of the organic hydroxy compound in a solvent can be selected in arbitrary ranges, 0.01 mol / L or more is preferable and 0.1 mol / L or more is further more preferable. The upper limit of the concentration depends on the solubility of the supporting electrolyte in the organic hydroxy compound, and can be selected as appropriate. However, if the solubility of the supporting electrolyte in the organic hydroxy compound is low, the concentration of the organic hydroxy compound needs to be kept low. There is. When the organic hydroxy compound dissolves the supporting electrolyte well or when the supporting electrolyte is not used, it is not always necessary to use a solvent. When no solvent is used, the separation of the target product and the solvent after the reaction is unnecessary, which is industrially advantageous.

<Moisture content>
In the electrolytic reaction of the present invention, the reaction tends to be inhibited by the water in the reaction solution, and therefore the water content in the reaction solution is preferably 5% by weight by using a raw material or a solvent having a low water content. Hereinafter, it is more preferably 1 wt% or less, further preferably 1000 wt ppm or less, and most preferably 800 wt ppm or less. The smaller the amount of water in the reaction solution, the more advantageous in terms of reaction efficiency. However, it is difficult to operate to make the amount of water in the reaction solution less than 0.1 ppm by weight, which is economically disadvantageous. Usually, the water content in the reaction solution is 0.1 ppm by weight or more.

  The amount of water in the reaction solution indicates the amount of water contained in the reaction solution in the first chamber of the reaction vessel of the electrolytic reaction apparatus of the present invention. Specifically, when the electrolytic reaction is carried out batchwise, the water content of the reaction liquid before the start of the reaction is shown, and when the electrolytic reaction is carried out continuously, the water quantity in the reaction liquid supplied to the first chamber is shown. Examples of the method for measuring the amount of water in the reaction solution include a method of sampling the reaction solution and measuring it with a Karl Fischer moisture meter or the like.

  In order to bring the amount of water in the reaction solution into the above range, a method of removing water from the raw material and the solvent is used, and as this specific method, any of the commonly used water removal methods can be used. For example, dehydration by distillation, adsorption dehydration by a moisture adsorbent such as molecular sieve, dehydration by membrane separation, etc. may be mentioned.

  It is also effective to remove residual moisture and oxygen by circulating an inert gas such as nitrogen or helium in the reaction solution prior to the reaction. Furthermore, the reaction rate at the initial stage of the reaction can be improved by increasing the concentration of carbon monoxide dissolved in the reaction solution by circulating carbon monoxide in the reaction solution prior to the reaction.

<Carbon monoxide>
In the present invention, the gas containing carbon monoxide to be reacted with the alkoxy compound is supplied in a gaseous state to the second chamber separated by the anode and not provided with a counter electrode in the electrolytic reaction apparatus of the present invention. This carbon monoxide comes into contact with the reaction solution containing the alkoxy compound in the gap of the anode. The concentration of carbon monoxide in the liquid cannot exceed the saturation solubility, and it takes a certain amount of time to reach the saturation solubility. However, microscopically, the concentration of gas components in the liquid is near the gas-liquid interface. Since the concentration becomes the highest, the electrolytic reaction can be efficiently advanced by this method.

  The gas containing carbon monoxide supplied to the second chamber of the reaction vessel of the electrolytic reaction apparatus of the present invention may be carbon monoxide alone or a plurality of gas mixtures containing carbon monoxide. As a gas mixed with carbon monoxide, one or more of nitrogen, helium, argon, carbon dioxide, methane, ethane, propane and the like can be used in any ratio as necessary.

<Reaction conditions>
In the electrolytic reaction of the present invention, the reaction temperature can be freely set as long as the reaction substrate does not solidify. Preferably it is 0 degreeC-200 degreeC, More preferably, it is 20 degreeC-100 degreeC, but generally it implements at about room temperature (for example, about 20-30 degreeC). In order to lower the reaction temperature, equipment for cooling is required, which is economically disadvantageous. Further, when the reaction temperature is increased, it is necessary to apply pressure in order to suppress evaporation of the reaction substrate, and reactions such as thermal decomposition of raw materials are likely to occur.

  Although the reaction pressure can be reduced, it can usually be carried out at normal pressure or under pressure. Preferably it is 1-15 atmospheres. If the pressure is lower than 1 atm, the concentration of CO dissolved in the reaction solution in the anode of the conductive porous solid electrode is lowered and the reaction rate is lowered, and it is not preferable, and if it exceeds 15 atm, the equipment cost becomes expensive.

  The electrolytic reaction of the present invention can be either constant potential electrolysis or constant current electrolysis. In the case of constant potential electrolysis, if the potential is low, the reaction does not proceed, and if it is high, the oxidation of the basic substance added to produce the alkoxy compound proceeds and the reaction does not proceed. A preferred potential is 0.01 V (vs. Ag / AgCl) or more, more preferably 0.1 V (vs. Ag / AgCl) or more. Further, it is preferably 5 V (vs. Ag / AgCl) or less, more preferably 2 V (vs. Ag / AgCl) or less.

  In the case of constant current electrolysis, if the current density is low, the reaction does not proceed. If the current density is high, the electrolysis potential increases depending on the resistance of the electrolysis reactor, and the direct oxidation of the organic hydroxy compound or basic substance proceeds. The rate drops. Since the preferred current density depends on the resistance value, it is preferable to make the resistance value as low as possible so that the current density and the electrolytic potential are in the preferred ranges.

  The electrolytic reaction time is appropriately selected. In the case of a batch system, it is, for example, about 0.1 to 24 hours.

The electrolytic reaction of the present invention may be carried out batchwise, but is preferably carried out continuously.
Note that the above-described electrolytic reaction apparatus of the present invention does not have to be constituted by a single reaction vessel, and may be constituted by connecting a plurality of reaction vessels in series or in parallel. When the electrolytic reaction apparatus of the present invention is composed of a plurality of reaction vessels, the raw materials such as unreacted organic hydroxy compound, alkoxy compound, basic substance, carbon monoxide, etc. contained in the reaction product from the recovery line are the same or You may circulate to the supply line of a different reaction container.

<Recovery of carbonic acid diester>
The carbonic acid diester produced by the electrolytic reaction of the present invention is recovered by an ordinary method known per se. Examples of the recovery method include a method by distillation, extraction, or crystallization.

<Uses of carbonic acid diester>
The diphenyl carbonate produced by the electrolytic reaction of the present invention can be used in the same applications as diphenyl carbonate produced by a known method. For example, when an aromatic polycarbonate is produced by transesterification with a dihydroxy compound. Can be used as raw material. The method for producing the aromatic polycarbonate is also included in the scope of the present invention.
In addition, the carbonic acid diester produced according to the present invention is useful for a wide range of applications, such as solvents such as electrolytes, synthetic raw materials such as alkylating agents and carbonylating agents, gasoline and diesel fuel additives, and polyurethane raw materials. is there.

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

[Example 1]
(1) Preparation of platinum group element-supported catalyst In a 200 mL beaker, carbon black having a primary particle diameter of 40 nm and a BET specific surface area of 800 m ² / g as a conductive carbon carrier (made by Ketjen Black International Co., Ltd. “ “Carbon ECP”, hereinafter abbreviated as “ECP”.) 650 mg was added, and 4.19 mL of 0.03 mo1 / L aqueous solution of chloropalladium acid (H ₂ PdCl ₄ ) was added dropwise while stirring with a magnetic stirrer. After all the solutions had been dropped, a beaker containing the solution was placed on a hot plate heated to 100 ° C., and evaporated to dryness until there was no moisture, thereby obtaining a black powder. This black powder contained 2.06% by weight of palladium chloride (PdCl ₂ ) based on the Pd metal. By treating this at 150 ° C. for 1 hour and then at 300 ° C. for 2 hours in a hydrogen stream (20 mL / min), the supported Pd ²⁺ becomes Pd ⁰ by hydrogen reduction, and Pd becomes a conductive carbon support. A supported platinum group element-supported catalyst of a black powder was obtained. The amount of Pd supported by this platinum group element supported catalyst is 2.06% by weight with respect to the conductive carbon.

(2) Preparation of porous electrode (anode) containing platinum group element-supported catalyst Polytetrafluoroethylene powder as a binder to 155 mg (Pd content 30 μmol) of platinum group element-supported catalyst obtained in (1) above 40 mg (Daikin, F-104) was added and kneaded in an agate mortar. It is rolled on a hot plate at 120 ° C., formed into a round sheet, and has an electrode area of 2 cm ² (geometric area) and a conductive porous solid electrode containing a platinum group element-supported catalyst having a thickness of about 1.6 mm. (Anode) was produced. The amount of Pd supported per electrode area of the conductive porous solid electrode containing this platinum group element-supported catalyst is 6 μmol / cm ² . The diameter of the void (porous pore diameter) is 10 to 10,000 nm.

(3) Electrolytic Reaction Constant current electrolysis was performed using the electrolytic reaction apparatus shown in FIG. 1 in which a conductive porous solid electrode containing a platinum group element-supported catalyst prepared by the above method was provided as the anode 4.
A platinum wire was used as the cathode 2A. In the reaction solution of the first chamber 2, 40 mL of acetonitrile (made by Wako Pure Chemicals, for organic synthesis) as a reaction solvent, 30 mmol of phenol (made by Wako Pure Chemicals, special grade) as an organic hydroxy compound, and anhydrous as an alkoxy compound Sodium phenoxide (Alfa
0.5 mmol of Aeser) and 0.78 mmol of lithium chloride (manufactured by Wako Pure Chemicals, special grade) as a supporting electrolyte were used. About 5 g of molecular sieves 3A (manufactured by Wako Pure Chemical Industries, Ltd., for chemical use) calcined at 300 ° C. for 10 hours in advance was added to the solvent acetonitrile, and dehydrated by placing it for 12 hours or more with occasional shaking.

Oxygen and water dissolved in the reaction liquid in the first chamber 2 by circulating helium (manufactured by Japan Helium Center, purity 99.9995%) from the gas supply pipes 5 and 6 at 900 mL / Hr for 10 minutes, After removing the air and moisture in the second chamber 3, the current density of the second chamber 3 is set to 0. 0 while flowing a gas containing carbon monoxide (manufactured by Nippon Oxygen Co., Ltd., purity 99.95%) at 900 mL / Hr. Constant current electrolysis was performed at ² mA / cm ² for 3 hours at room temperature (about 25 ° C.) and normal pressure.

  The electrolytic reaction solution in the first chamber 2 is sampled in a timely manner, and gas chromatography (detector: FID, column GC-2010 manufactured by Shimadzu Corporation, ZB-1 capillary column, φ0.25 mm × 30 m, analysis condition: injection temperature 220) (In the case of analysis, phenanthrene (manufactured by Wako Pure Chemicals, special grade)) was added so as to be 0.004%. ).

  The reaction product after completion of the reaction was analyzed in the same manner, and carbon dioxide in the sampling gas from the gas sampling tube 8 was analyzed by gas chromatography (detector: TCD, GC-8A manufactured by Shimadzu Corp., Hydrogen was analyzed by gas chromatography (detector: TCD, GC-8A manufactured by Shimadzu Corp., activated carbon column (4 mm × 2 m), 120 ° C. constant temperature analysis) using a PorapakQ packed column, 70 ° C. constant temperature analysis).

  As a result, the amount of diphenyl carbonate (hereinafter DPC) produced was 7.8 μmol, and the current efficiency of DPC production was about 35%. An amount of hydrogen corresponding to a current efficiency of about 61% was detected in the sampling gas. The turnover number (hereinafter referred to as TON) of the catalyst when reacted for 3 hours was 0.65 mol-DPC / mol-Pd. A summary of the results is shown in Table 1.

[Comparative Example 1]
Diphenyl carbonate was produced by an electrolytic reaction in the same manner as in Example 1 except that the electrolytic reaction was performed in the two-chamber cell shown in FIG. As the anode 11A and the cathode 12A, those similar to those in Example 1 were used. A glass filter was used as the diaphragm 14. In addition, the same reaction solution as that used in Example 1 was added to the anode chamber 11, and the same reaction solution as that in Example 1 was added to the cathode chamber 12 except that anhydrous sodium phenoxide was not added. In the same manner as in No. 1, constant current electrolysis was performed for 3 hours with a current density of 0.2 mA / cm ² while circulating carbon monoxide.

  As a result of analysis using the same procedure as in Example 1, the amount of diphenyl carbonate (hereinafter DPC) produced was 7.2 μmol, and the current efficiency of DPC production was about 32%. An amount of hydrogen corresponding to a current efficiency of about 68% was detected in the sampling gas. The TON of the catalyst when reacted for 3 hours was 0.60 mol-DPC / mol-Pd.

[Comparative Example 2]
Diphenyl carbonate was produced by an electrolytic reaction in the same manner as in Example 1 except that the electrolytic reaction was performed in the one-chamber cell shown in FIG. As the anode 21 and the cathode 22, the same ones as in Example 1 were used. The same reaction liquid as that used in Example 1 was supplied to the reaction vessel 20, and constant current electrolysis was performed at a current density of 0.2 mA / cm ² for 3 hours while circulating carbon monoxide as in Example 1. went.

  As a result of analysis in the same procedure as in Example 1, the amount of diphenyl carbonate (hereinafter referred to as DPC) produced was 6.4 μmol, and the current efficiency of DPC production was about 29%. An amount of hydrogen corresponding to a current efficiency of about 82% was detected in the sampling gas. The TON of the catalyst when reacted for 3 hours was 0.53 mol-DPC / mol-Pd.

  The results of Example 1 and Comparative Examples 1 and 2 are summarized in Table 1.

  Table 1 shows that according to the electrolytic reaction apparatus of the present invention, the carbonic acid diester can be efficiently produced with high current efficiency. In addition, in this electrolytic reaction apparatus, the second chamber to which the gas containing carbon monoxide as a raw material is supplied is separated from the first chamber in which hydrogen is generated. It is not necessary to perform separation and is efficient.

  The present invention relates to an electrolytic reaction apparatus and a carbonic acid which efficiently produce carbonic acid diesters such as diphenyl carbonate, which are useful as raw materials for electrolytic solutions and polycarbonates, without using toxic substances such as phosgene, so that they can be industrially put into practical use. A method for producing a diester is provided.

1 reaction vessel (electrolysis cell)
2 1st chamber 2A Cathode 2B plug 3 2nd chamber 3B plug 4 Anode 4A Communication part 5 Carbon monoxide supply pipe 6 Helium gas supply pipe 7 Gas vent pipe 8 Gas vent pipe 9 Power supply 10 Reaction vessel (electrolysis cell)
DESCRIPTION OF SYMBOLS 11 Anode chamber 11A Anode 11B Plug 12 Cathode chamber 12A Cathode 12B Plug 13 Communication part 14 Diaphragm 15 Gas supply pipe 16 Gas supply pipe 17 Degassing pipe 18 Degassing pipe 19 Power supply 20 Reaction container (electrolysis cell)
20A Container part 20B Plug 21 Anode 22 Cathode 23 Power supply 24 Current collector 25 Gas supply pipe 26 Gas vent pipe

Claims (10)

An electrolytic reaction apparatus for electrolytically reacting an alkoxy compound and carbon monoxide in the presence of a platinum group element to obtain a carbonic acid diester,
A reaction vessel, an anode and a cathode provided in the reaction vessel, and means for applying a voltage between the anode and cathode provided outside the reaction vessel,
The reaction vessel is
A first chamber having a cathode and having a structure in which the cathode and a reaction liquid containing an alkoxy compound can come into contact with the chamber;
A second chamber having a structure capable of holding a gas containing carbon monoxide,
The electrolytic reaction apparatus, wherein the first chamber and the second chamber are separated by a porous anode containing a platinum group element.   The anode according to claim 1, wherein the anode is a porous electrode including a platinum group element-supported catalyst in which a platinum group element is supported on a support made of conductive carbon having a primary particle size of 100 nm or less. Electrolytic reaction device. ^{2. The} porous electrode including a platinum group element-supported catalyst in which a platinum group element is supported on a support made of conductive carbon having a BET specific surface area of 100 m ² / g or more. Or the electrolytic reaction apparatus of 2.   The anode is a porous electrode including a platinum group element-supported catalyst in which a platinum group element is supported on a carrier made of conductive carbon, and the conductive carbon is carbon black. 4. The electrolytic reaction apparatus according to any one of items 3 to 3.   5. The anode according to claim 1, wherein the anode is formed by mixing a platinum group element-supported catalyst in which a platinum group element is supported on a carrier made of conductive carbon and a conductive auxiliary agent. The electrolytic reaction apparatus in any one.   6. The electrolytic reaction apparatus according to claim 1, wherein the platinum group element is palladium.   A reaction liquid containing an alkoxy compound is supplied to the first chamber of the reaction vessel of the electrolytic reaction apparatus according to any one of claims 1 to 6, and a gas containing carbon monoxide is supplied to the second chamber to produce carbonic acid by an electrolytic reaction. A process for producing a carbonic acid diester, characterized in that a diester is produced.   The method for producing a carbonic acid diester according to claim 7, wherein the alkoxy compound is produced in the reaction solution by containing an organic hydroxy compound and a basic substance in the reaction solution.   The method for producing a carbonic acid diester according to claim 7 or 8, wherein the alkoxy compound is a phenoxy compound, and the carbonic acid diester is diphenyl carbonate.   The manufacturing method of the aromatic polycarbonate characterized by using the diphenyl carbonate manufactured by the method of Claim 9 as a raw material.

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