JP4714924B2 - Method for producing carbonate ester - Google Patents

Description

  The present invention relates to a method for producing a carbonate ester, and more particularly to a method for producing a carbonate ester by reacting alcohol and carbon dioxide in the presence of a specific inorganic metal oxide and an acidic compound.

  Carbonates are used as raw materials for polycarbonate production, lithium battery electrolytes, gasoline additives for improving octane number, diesel fuel additives for reducing particulates in exhaust gas, alkylating agents, carbonylating agents, solvents, etc. It is a useful compound.

  As a conventional method for producing a carbonic acid ester, first, a method of reacting phosgene with an alcohol as a carbonylating agent is used. In this method, phosgene having extremely toxicity and corrosivity is used. Care was required in handling, and it was very expensive to maintain and manage production facilities, dispose of waste, and ensure the safety of workers. Also known is an oxidative carbonylation method in which carbon monoxide is reacted with alcohol and oxygen as a carbonylating agent. In this method, too, the use of highly toxic carbon monoxide at high pressure ensures the safety of workers. In addition, there is a drawback in that side reactions such as the formation of carbon dioxide by oxidation of carbon monoxide occur.

  For this reason, development of the method of manufacturing carbonate ester more safely and cheaply is requested | required, and the method of making it react with alcohol by using a carbon dioxide as a carbonylating agent was proposed (nonpatent literature 1-2). However, since the equilibrium of the reaction between the alcohol and carbon dioxide is greatly biased toward the original system, this method has a very low carbonate ester yield regardless of whether a homogeneous system or a heterogeneous system is used. There was a problem.

  Moreover, although the method of manufacturing carbonate ester from reaction of a carbon dioxide and carboxylic acid orthoester is also proposed (patent document 1), the raw material used is expensive, yield is not enough, and it is for industrial implementation. There was a problem.

  In contrast, the present inventors have proposed a method for producing a carbonic ester by reacting carbon dioxide with an acetal compound in the presence of a catalyst such as a metal alkoxide (Patent Documents 2 to 5). This method uses carbon dioxide, which is not toxic and corrosive and can be obtained at a very low cost, as a carbonylating agent. There was a problem such as.

For synthesis of dimethyl carbonate from methanol and carbon dioxide in the presence of an acetal compound, a solid solution of cerium oxide and zirconium oxide is known as a catalyst (Non-patent Document 3), but it is not sufficient in terms of catalytic activity. In addition, there is a problem that it is necessary to add an expensive rare earth metal oxide as a second component to zirconium oxide, and zirconium oxide having a BET surface area of 10 m ² / g does not exhibit any activity itself. It was said.

  On the other hand, the present inventors have found that when a high surface area zirconium oxide is used as a catalyst, the carbonate ester yield is improved (Patent Document 6).

Japanese Patent Laid-Open No. 7-2224011 Japanese Patent No. 2852418 Japanese Patent No. 3005684 Japanese Patent No. 3128576 Japanese Patent No. 3385359 Japanese Patent Application No. 2005-293462 Collection of Czechoslovak Chemical Communications, 1995, 60, 687 Catalysis Letters, 1999, 58, 225 AppliedCatalysis A: General, 2002, 237, 103

  The present invention develops and improves the invention of the above-mentioned Patent Document 6, and uses carbon dioxide, which is not toxic and corrosive and is obtained at a very low cost, as a carbonylating agent, and alcohol as a reactive agent. An object of the present invention is to provide an industrially advantageous method for producing a carbonate ester that can be produced.

As a result of intensive studies to solve the problems of the conventional methods, the present inventors have found that when a specific inorganic metal oxide and an acidic compound are present in the reaction system, a carbonic acid ester is efficiently produced from carbon dioxide and alcohol. As a result, the present invention was completed.
That is, according to this application, the following invention is provided.
(1) A method for producing a carbonate ester comprising reacting an alcohol and carbon dioxide in the presence of (i) an inorganic metal oxide and (ii) an acidic compound.
(2) The method for producing a carbonate ester according to the above (1), wherein the inorganic metal oxide is an oxide containing at least one element selected from the group consisting of Group IVA and Group IVB.
(3) The method for producing a carbonate ester according to (1) or (2), wherein the group consisting of Group IVA and Group IVB is zirconium, titanium, or tin.
(4) The method for producing a carbonate ester according to any one of (1) to (3), wherein the acidic compound is a Lewis acid.
(5) The method for producing a carbonate ester according to any one of (1) to (3), wherein the acidic compound is a Bronsted acid.
(6) The method for producing a carbonate ester according to any one of (1) to (5) above, wherein the reaction is carried out in the presence of a dehydrating agent.

According to the method of the present invention, a carbonate ester can be obtained in a high yield by reacting alcohol and carbon dioxide in the presence of (i) an inorganic metal oxide and (ii) an acidic compound.
That is, the method of the present invention uses carbon dioxide which is alcohol and non-toxic and corrosive as raw materials in the presence of the above (i) inorganic metal oxide and (ii) acidic compound, and uses a safe and simple facility for carbonation. Since the ester can be obtained with a high yield (based on alcohol), it can be said to be a very advantageous method industrially.

The carbonate ester production method of the present invention is characterized in that the reaction between alcohol and carbon dioxide is carried out in the presence of (i) an inorganic metal oxide and (ii) an acidic compound.
This reaction can be represented by the following formula.
R ¹ OH + CO ₂ + (dehydrating agent)
→ R ¹ O (CO) OR ¹ + (dehydrating agent + H ₂ O)
(In the formula, R ¹ represents an alkyl group or an aralkyl group.)

Examples of the alcohol represented by R ¹ OH include methanol, ethanol, n-propanol, n-butanol, methylcyclohexanol, cyclohexanol, and benzyl alcohol.
In the present invention, a polyhydric alcohol such as a diol may be used in addition to the monohydric alcohol.

  The reaction in the present invention is carried out in the presence of (i) an inorganic metal oxide and (ii) an acidic compound.

  The metal element of the inorganic metal oxide (i) is not particularly limited, but is preferably an oxide containing at least one element selected from the group consisting of Group IVA and Group IVB, more preferably zirconium. , An oxide containing at least one element selected from titanium and tin, and more preferably an oxide containing zirconium. The inorganic metal oxide may be a so-called single oxide containing one kind of metal element or a complex oxide containing two or more kinds of metal elements. The structure of the inorganic metal oxide is not particularly limited in the present invention, and may be polycrystalline or amorphous. The inorganic metal oxides may be used alone or as a mixture of two or more.

  The inorganic metal oxide is generally easily available. In addition, it is easily produced by firing an oxo acid salt such as a metal hydroxide, metal nitrate or metal carbonate, or an organic acid salt such as metal acetate or metal oxalate, but the production method is particularly limited. It is not something.

  In the present invention, the inorganic metal oxide supported on an arbitrary carrier may be used. Examples of such a carrier include, but are not limited to, silica, alumina, magnesia and the like.

  Although there is no restriction | limiting in particular in the form of the said inorganic metal oxide, Usually, it is suitable that it is a fine powder form, a spherical, columnar, or ring-shaped particle | grain with an average particle diameter of about 0.1-10 mm.

The reaction in the present invention requires that the acidic compound (ii) is present in the reaction system together with the (i) inorganic metal oxide. When the inorganic metal oxide (i) is used alone, it is difficult to obtain a carbonate ester in a high yield as seen in Comparative Examples described later.
The acidic compound (ii) is not particularly limited, but Lewis acid or Bronsted acid is preferably used. Examples of Lewis acids include the following metal triflates, metal halides, and Lewis acidic metal oxides. Examples of Bronsted acids include the following ammonium triflates, organic sulfonic acids, heteropoly acids, ion exchange resins, and Bronsted acid. A metal oxide etc. are mentioned.
[Examples of Lewis acid]

  In the above formula, THF represents tetrahydrofuran, Me represents a methyl group, and Ph represents a phenyl group.

  Moreover, in the reaction of the present invention, an additive is not particularly required. However, by adding an additive, the carbonate yield can be improved by increasing the solubility of the acidic compound. Examples of such additives include polar solvents such as tetrahydrofuran, dimethylformamide, and propylene carbonate.

The reaction in the present invention is preferably performed in the presence of an organic or inorganic dehydrating agent. No particular restriction on the organic dehydrating agent, but acetals represented by the general formula ^{{R 2 R 3 C (OR} 1) 2} is preferred. Although there is no restriction | limiting in particular in the quantity of an organic dehydrating agent, About 0.5-2 times is preferable by molar ratio with respect to alcohol.
(In the formula, the alkyl group represented by R ¹ , R ² and R ³ is preferably a lower alkyl group, more preferably 1 to 4 carbon atoms.)

When an acetal compound is used as the organic dehydrating agent, unreacted acetal can be recovered from the reaction system and reused. In addition, when an acetal compound is used as a dehydrating agent, a ketone or an aldehyde is produced together with a carbonate ester, but the ketone and the aldehyde can be easily converted into an acetal compound by reaction with an alcohol, and thus can be recovered and reused. . From the viewpoint of recovery and reuse of the co-product ketone and aldehyde, the groups R ¹ in the alcohol represented by the general formula and the acetal compound represented by the general formula are preferably the same group.

  More specific examples of such acetal compounds include benzaldehyde dimethyl acetal, acetaldehyde dimethyl acetal, formaldehyde dimethyl acetal, acetone dimethyl acetal, acetone diethyl acetal, acetone dibenzyl acetal, diethyl ketone dimethyl acetal, benzophenone dimethyl acetal, benzyl phenyl Examples thereof include ketone dimethyl acetal, cyclohexanone dimethyl acetal, acetophenone dimethyl acetal, 2,2-dimethoxy-2-phenylacetophenone, 4,4-dimethoxy-2,5-cyclohexadien-1-one acetal, dimethylacetamide diethyl acetal, and the like.

  The inorganic dehydrating agent used in the reaction in the present invention is not particularly limited. Examples of the inorganic dehydrating agent include zeolites such as molecular sieve (3A) and molecular sieve (4A), calcium chloride (anhydrous), calcium sulfate (anhydrous ), Magnesium chloride (anhydrous), magnesium sulfate (anhydrous), potassium carbonate (anhydrous), potassium sulfide (anhydrous), potassium sulfite (anhydrous), sodium sulfate (anhydrous), sodium sulfite (anhydrous), copper sulfate (anhydrous) Inorganic anhydrous salts such as

  As a reaction mode in the present invention, generally used methods such as a stirring method and a fixed bed method can be used, and any of a batch method, a semi-batch method, a continuous flow method and the like can be carried out. When manufacturing by a batch type, it carries out as follows, for example. An autoclave equipped with a stirrer is charged with alcohol, an inorganic metal oxide, an acidic compound and an organic dehydrating agent, and then filled with carbon dioxide and sealed. Thereafter, the inside of the autoclave is heated to a predetermined temperature while stirring, and further filled with carbon dioxide to adjust the internal pressure to a predetermined pressure, and after reacting for a predetermined time, the produced carbonate is separated by a desired means.

  When manufacturing by a fixed bed type continuous flow type, for example, it is performed as follows. Desirable carbonic acid ester to be produced after flowing a reaction liquid containing alcohol, acidic compound, organic dehydrating agent and carbon dioxide pressurized to a predetermined pressure through a reaction tube filled with an inorganic metal oxide and heated to a predetermined temperature. Isolate by means of When the acidic compound is a solid, the carbonate ester can be efficiently produced also by circulating alcohol, an organic dehydrating agent and carbon dioxide through a reaction tube filled with the inorganic metal oxide and the acidic compound. .

Moreover, when manufacturing using an inorganic dehydrating agent, it can implement according to the method of patent 3385359, for example. Specifically, a reaction liquid containing alcohol, an acidic compound, and carbon dioxide pressurized to a predetermined pressure is filled with an inorganic metal oxide and heated to a predetermined temperature, and filled with an inorganic dehydrating agent and cooled with a cooling device. After circulating for a predetermined time with a dehydrating tower cooled to a predetermined temperature, the produced carbonate is separated by a desired means.
Furthermore, it can be carried out in combination with a dehydration step such as distillation or membrane separation.

  In carrying out the present invention, the reaction temperature is not particularly limited, but is preferably room temperature (20 ° C.) to 300 ° C., more preferably 80 to 200 ° C. The reaction pressure is not particularly limited and is determined by the production cost of the pressure device used for the reaction, but it is preferably performed under high pressure from the viewpoint of improving the yield.

  Use amount of inorganic metal oxide and acidic compound, reaction time, type of inorganic metal oxide and acidic compound used, form of reactor, type of alcohol as raw material, type of organic or inorganic dehydrating agent, reaction temperature, reaction Depending on various conditions such as pressure and desired productivity, for example, when carried out using a batch reactor, the amount of inorganic metal oxide, the amount of acidic compound, and the reaction time are not particularly limited. However, the amount of the inorganic metal oxide is usually 0.001 to 3, preferably 0.01 to 2, in weight ratio to the alcohol, and the amount of the acidic compound is usually 0.000001 in weight ratio to the inorganic metal oxide. The reaction time is usually 0.1 to 100 hours, preferably 1 to 50 hours.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited by these Examples.

Example 1
As the inorganic metal oxide, zirconium oxide (ZrO2-300) calcined at 300 ° C. was used. ZrO2-300 was prepared by calcining zirconium hydroxide (manufactured by Daiichi Rare Element Chemical Industry, purity of 98% or more) in air at 300 ° C. for 3 hours. The BET surface area determined from the nitrogen adsorption amount of ZrO2-300 was 188 m ² / g.
As the acidic compound, Sc (OSO ₂ CF ₃ ) ₃ (manufactured by Sigma-Aldrich, purity 99.99% or more) was used.
In a 20 ml autoclave equipped with a stirrer, ZrO2-300 (0.5 g), Sc (OSO ₂ CF ₃ ) ₃ (1 μmol), methanol (4 ml, 100 mmol) and acetone dimethyl acetal (as organic dehydrating agent) 50 mmol), liquefied carbon dioxide was charged from a cylinder (60 atm) and sealed. Thereafter, the inside of the autoclave was heated to 180 ° C. with stirring, and further charged with carbon dioxide, thereby increasing the internal pressure to 300 atm and allowing the reaction to proceed for 24 hours. After cooling, the remaining carbon dioxide was released and the reaction mixture was analyzed by gas chromatography. The dimethyl carbonate yield based on methanol was 24.0%.

Example 2
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that Sc (OSO ₂ CF ₃ ) ₃ (4 μmol) was used as the acidic compound. The dimethyl carbonate yield based on methanol was 40.5%.

Example 3
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that Sc (OSO ₂ CF ₃ ) ₃ (13 μmol) was used as the acidic compound. The dimethyl carbonate yield based on methanol was 18.7%.

Example 4
Dimethyl carbonate was synthesized in the same manner as in Example 2 except that the reaction time was 6 hours. The dimethyl carbonate yield based on methanol was 17.3%.

Example 5
In a 20 ml autoclave equipped with a stirrer, ZrO2-300 (0.5 g), Sc (OSO ₂ CF ₃ ) ₃ (4 μmol), methanol (4 ml, 100 mmol) and acetone dimethyl acetal (50 mmol) as an organic dehydrating agent. Then, liquefied carbon dioxide was filled from a cylinder (60 atm) and sealed. Then, it heated to 180 degreeC, stirring the inside of an autoclave, and was made to react for 24 hours. The internal pressure at this time was 80 atmospheres. After cooling, the remaining carbon dioxide was released and the reaction mixture was analyzed by gas chromatography. The dimethyl carbonate yield based on methanol was 20.3%.

Example 6
Zirconium oxide (abbreviated as ZrO2-500) was prepared by calcining zirconium hydroxide in air at 500 ° C. for 3 hours. The BET surface area determined from the nitrogen adsorption amount of ZrO2-500 was 72 m ² / g.
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that ZrO2-500 (0.5 g) was used as the inorganic metal oxide and Sc (OSO ₂ CF ₃ ) ₃ (5 μmol) was used as the acidic compound. did. The dimethyl carbonate yield based on methanol was 32.2%.

Example 7
Zirconium hydroxide (abbreviated as ZrO2-700) was prepared by firing zirconium hydroxide in air at 700 ° C. for 3 hours. The BET surface area determined from the nitrogen adsorption amount of ZrO2-700 was 23 m ² / g.
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that ZrO2-700 (0.5 g) was used as the inorganic metal oxide and Sc (OSO ₂ CF ₃ ) ₃ (1 μmol) was used as the acidic compound. did. The dimethyl carbonate yield based on methanol was 15.0%.

Example 8
As the acidic _{^{compound, Ph 2 N + H 2 ·}} - other using OSO 2 _CF 3 (5μmol) was synthesized dimethyl carbonate in the same manner as in Example 1. The yield of dimethyl carbonate based on methanol was 32.7%.

Example 9
As the acidic ^{_{compound, C 6 F 5 N + H}} 3 · - other using OSO 2 _CF 3 (5μmol) was synthesized dimethyl carbonate in the same manner as in Example 1. The yield of dimethyl carbonate based on methanol was 32.6%.

Example 10
H ₃ PW ₁₂ O ₄₀ · xH ₂ O (manufactured by Merck, for analysis) was evacuated at 150 ° C. for 1 hour to obtain H ₃ PW ₁₂ O ₄₀ .
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that the above H ₃ PW ₁₂ O ₄₀ (5 μmol) was used as the acidic compound. The dimethyl carbonate yield based on methanol was 14.5%.

Example 11

Example 12

Example 13
Zirconium hydroxide (2.0 g) was impregnated with 1N sulfuric acid (30 ml), dried at 100 ° C. overnight, and then calcined in air at 650 ° C. for 3 hours to prepare SO ₄ ²⁻ / ZrO ₂ . The BET surface area determined from the nitrogen adsorption amount of SO ₄ ²⁻ / ZrO ₂ was 42 m ² / g.
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that the above SO ₄ ²⁻ / ZrO ₂ (11 mg) was used as the acidic compound. The dimethyl carbonate yield based on methanol was 15.3%.

Example 14
Example 1 except that tin oxide (manufactured by Kanto Chemical Co., Inc., purity 98% or more, 37 m ² / g) was used as the inorganic metal oxide, and Sc (OSO ₂ CF ₃ ) ₃ (5 μmol) was used as the acidic compound. Similarly, dimethyl carbonate was synthesized. The yield of dimethyl carbonate based on methanol was 6.8%.

Example 15
Implementation was performed except that titanium oxide (manufactured by Rhone-Poulenc, G5, 296 m ^{2 /} g) (0.5 g) was used as the inorganic metal oxide, and Sc (OSO ₂ CF ₃ ) ₃ (17 μmol) was used as the acidic compound. In the same manner as in Example 1, dimethyl carbonate was synthesized. The yield of dimethyl carbonate based on methanol was 4.2%.

Comparative Example 1
Dimethyl carbonate was synthesized in the same manner as in Example 1 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The dimethyl carbonate yield based on methanol was 7.5%.

Comparative Example 2
Dimethyl carbonate was synthesized in the same manner as in Example 4 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The yield of dimethyl carbonate based on methanol was 4.6%.

Comparative Example 3
Dimethyl carbonate was synthesized in the same manner as in Example 5 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The yield of dimethyl carbonate based on methanol was 2.8%.

Comparative Example 4
Dimethyl carbonate was synthesized in the same manner as in Example 6 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The yield of dimethyl carbonate based on methanol was 6.2%.

Comparative Example 5
Dimethyl carbonate was synthesized in the same manner as in Example 7 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The dimethyl carbonate yield based on methanol was 4.0%.

Comparative Example 6
Dimethyl carbonate was synthesized in the same manner as in Example 14 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The yield of dimethyl carbonate based on methanol was 6.1%.

Comparative Example 7
Dimethyl carbonate was synthesized in the same manner as in Example 15 except that Sc (OSO ₂ CF ₃ ) ₃ was not used. The dimethyl carbonate yield based on methanol was 1.0%.

Comparative Example 8
Dimethyl carbonate was synthesized in the same manner as in Example 6 except that ZrO2-500 was not used. The dimethyl carbonate yield based on methanol was 0%.

Claims (4)

(I) reacting an alcohol and carbon dioxide in the presence of an inorganic metal oxide containing at least one element selected from zirconium, titanium and tin , and (ii) an acidic compound selected from Lewis acid or Bronsted acid. A process for producing a carbonic ester characterized by the above. The method for producing a carbonate ester according to claim 1, wherein the acidic compound is a Lewis acid. The method for producing a carbonate ester according to claim 1, wherein the acidic compound is a Bronsted acid. Method for producing a carbonic ester according to any one of claims 1 to 3, characterized in that the reaction is carried out in the presence of a dehydrating agent.