JP2003055306A - Method for dialkyl carbonate production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a dialkyl carbonate by industrially advantageously transesterifying an alkylene carbonate with an alcohol. SOLUTION: This method for dialkyl carbonate production is characterized in that the dialkyl carbonate is obtained in high selectivity in a high yield by transesterifying an alkylene carbonate with an alcohol by using 3-octahedral smectite as a catalyst.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a dialkyl carbonate. For more details,
The present invention relates to a method for producing a dialkyl carbonate represented by the general formula (3) by transesterifying an alkylene carbonate represented by the general formula (1) and an alcohol represented by the general formula (2) in the presence of a catalyst. In this transesterification reaction, an alkylene glycol represented by the general formula (4) is also produced in addition to the desired dialkyl carbonate.

[Chemical 4] (1) (2) (3) (4) (In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl. Represents a group or an alkoxy group, R ⁵ represents an alkyl group, an alkenyl group, an arylalkyl group, a cycloalkyl group or an alkoxyalkyl group having 1 to 20 carbon atoms) Dialkyl carbonate is used for a solvent, a gasoline additive, etc. It is a compound that is expected to grow in demand as a highly safe and easy-to-handle carbonated agent and alkylating agent that can substitute for highly toxic phosgene, dimethylsulfate, methyl chloride and the like.

[0002]

2. Description of the Related Art As a method for producing a dialkyl carbonate, various methods for transesterifying an alkylene carbonate and an alcohol have been proposed. The basic technology lies in transesterification catalysts and is classified into homogeneous catalysts and heterogeneous catalysts.

Examples of homogeneous catalysts include alkali metals or alkali metal derivatives (US Pat. No. 3,642,428).
58, Japanese Patent Publication No. 61-16267) and the like. These methods using a homogeneous catalyst have the advantage that high catalytic activity can be obtained with a small amount of addition,
It is difficult to separate the catalyst from the reaction solution. This transesterification reaction is an equilibrium reaction, and when trying to separate the target dialkyl carbonate by distilling the reaction solution in the presence of a catalyst, the equilibrium shifts during the distillation and the reverse reaction occurs, and the dialkyl carbonate once produced is alkylene. Return to carbonate. Further, since the catalyst is present, decomposition, polymerization reaction and the like occur simultaneously, resulting in poor efficiency in the purification step, which is not preferable in the process.

On the other hand, in the case of a heterogeneous catalyst, it is easy to separate the catalyst from the reaction solution, and the above problems found in the homogeneous catalyst are solved. As a heterogeneous catalyst, there has been proposed a method using an ion exchange resin, particularly a solid strong basic anion exchange resin having a quaternary ammonium group as an exchange group (JP-A-64-31737, JP-A-63-63).
238043). Although these methods exhibit relatively high catalytic activity, they have problems in heat resistance and durability for industrial use, and in particular, decomposition of nitrogen-containing compounds from quaternary ammonium groups occurs at high temperatures, There was a problem that the catalyst component was dissolved in the reaction solution.

Further, as a heterogeneous catalyst, silica-titania solid acid (Japanese Patent Publication No. 61-5467); silica carrying silicate of alkali metal or alkaline earth metal, ammonium exchanged zeolite (JP-A-64-31737).
No.); oxides of zirconium, titanium and tin.
3-41432); lead compounds (JP-A-4-93356)
No.) and other inorganic solid catalysts have been proposed. These methods have low catalytic activity as a whole and are not suitable for practical use.

Furthermore, in recent years, MgO and A have been used as heterogeneous catalysts.
A method using a hydrotalcite compound containing l ₂ O ₃ (JP-A-3-43354) and a method using a composite oxide (European Patent Publication No. 478073) have been proposed. Although these methods have improved catalytic activity over the above methods, they are not yet satisfactory, and it takes a long time for the transesterification reaction to reach equilibrium,
There are still problems such as the need for high reaction temperatures.

The 3-octahedral smectite is a known substance, and is classified into hectorite, saponite, and stevensite represented by the following formulas (5) to (7).
W Brindley and G Brown (GWBr
indley and G. Brown), Mineralogica Society Monograph Number Five (Mineralogica)
l Society Monograph No.5), page 170, Mineralogical Societ
y), 1980].

[0008]

Embedded image Hectorite: (M ⁺ _y · nH ₂ O) (Mg _3-y Li _y ) Si ₄ O ₁₀ (OH) ₂ (5)

[0009]

Embedded image saponite ^{_{:( M + xy · nH 2 O}} ) [Mg 3-y (Al, Fe) y]] (Si 4-x Al x) O 10 (OH) 2 (6)

[0010]

[Chemical Formula 7] Stephen Sight: (M ⁺ _2y・ nH ₂ O) (Mg _3-y □ _y ) Si ₄ O ₁₀ (OH) ₂ (7)

[In the above formulas (5) to (7), M, □
And n represent the number of water molecules between the alkali metal, the atom deficiency and the layer, respectively. In hectorite, the divalent magnesium in the octahedral sheet is replaced with monovalent lithium to develop a negative charge in the silicate layer, and in stevensite, the divalent magnesium in the octahedral sheet is converted to monovalent lithium. It is considered that the lack of a part causes a negative charge, and that in saponite, the negative charge is expressed by replacing silicon in the tetrahedral sheet with aluminum. In these 3-octahedral smectites, a cation such as an alkali metal enters between the layers to supplement the negative charge of the silicate layer, and the structure maintains electrical neutrality. Further, the value of y in the formula (5) is usually 0.2 to 0.5, and is 0.
33, and the value of y in equation (6) is usually
When the value of y is 0, the value of x is 0.2 to 0.
5, the ideal composition is set to 0.33, and the value of y in the formula (7) is usually 0.1 to 0.3.
The ideal composition is 0.17.

It is also known that a synthetic porous body or porous material made of a 3-octahedral smectite containing divalent heavy metal ions or Mg ions in an octahedral sheet can be produced.

However, no conventional technique has been known in which a synthetic porous body composed of the above-mentioned 3-octahedral smectite and / or 3-octahedral smectite is used as a catalyst in the production of dialkyl carbonate.

[0014]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
In a method for producing a dialkyl carbonate by transesterifying an alkylene carbonate and an alcohol, to solve the problems of the conventional techniques, to provide a method for producing an industrially advantageous dialkyl carbonate having excellent catalytic activity. is there.

[0015]

Means for Solving the Problems The present inventors have
As a result of intensive studies on a method for producing a dialkyl carbonate by transesterifying an alkylene carbonate and an alcohol, a synthetic porous body composed of a 3-octahedral smectite and / or a 3-octahedral smectite has a high catalytic activity. The present invention has been completed by finding out what is shown.

That is, in the present invention, the dialkyl carbonate represented by the general formula (3) is obtained by transesterifying the alkylene carbonate represented by the general formula (1) and the alcohol represented by the general formula (2) in the presence of a catalyst. In the method for producing a dialkyl carbonate, a method for producing a dialkyl carbonate is characterized in that a 3-octahedral smectite and / or a porous body composed of a 3-octahedral smectite is used as a catalyst. The present invention will be described in detail below.

Examples of the alkylene carbonate represented by the general formula (1) used as a raw material in the present invention include ethylene carbonate, propylene carbonate,
1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, styrene carbonate, 3-methoxy-1,2-propylene carbonate, 3-ethoxy-1,2-propylene carbonate and the like can be mentioned. However, even a mixture of these may be used. Among these, ethylene carbonate and propylene carbonate are mainly industrially useful because they are industrially easily available and the by-product of the alkylene glycol represented by the general formula (4) is highly useful.

The alcohol represented by the general formula (2) used as the other raw material in the present invention is, for example, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, t-butyl alcohol, pentyl. Alcohol, hexyl alcohol, octyl alcohol, 2-ethylhexyl alcohol, decyl alcohol, dodecyl alcohol, tetradecyl alcohol,
Hexadecyl alcohol, octadecyl alcohol, allyl alcohol, benzyl alcohol, cyclohexyl alcohol, ethylene glycol monomethyl ether,
Examples thereof include ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and mixtures thereof may be used. Among these, methyl alcohol is industrially useful because dimethyl carbonate is in great demand as a dialkyl carbonate produced. By combining the alkylene carbonate and the alcohol as the raw materials, the dialkyl carbonate represented by the general formula (3) and the alkylene glycol represented by the general formula (4) are produced according to the above reaction formula.

3 used as a catalyst in the present invention
-The synthetic porous body composed of octahedral smectite and / or 3-octahedral smectite is a known substance as described above, and the hectorite represented by the formulas (5) to (7),
Saponite and stevensite can be exemplified.

[0020]

Embedded image Hectorite: (M ⁺ _y · nH ₂ O) (Mg _3-y Li _y ) Si ₄ O ₁₀ (OH) ₂ (5)

[0021]

Embedded image saponite ^{_{:( M + xy · nH 2 O}} ) [Mg 3-y (Al, Fe) y]] (Si 4-x Al x) O 10 (OH) 2 (6)

[0022]

[Chemical formula 7] Steven site: (M ⁺ _2y・ nH ₂ O) (Mg _3-y □ _y ) Si ₄ O ₁₀ (OH) ₂ (7)

[In the above formulas (5) to (7), M,
□ and n represent the number of water molecules between the alkali metal, the atom deficiency and the layer, respectively. In hectorite, the divalent magnesium in the octahedron sheet is replaced with monovalent lithium to develop a negative charge in the silicate layer, and in stevensite, the divalent magnesium in the octahedron sheet is replaced by monovalent lithium. It is considered that the lack of a part causes a negative charge, and in saponite, the negative charge is expressed by replacing tetravalent silicon in the tetrahedral sheet with trivalent aluminum. In these 3-octahedral smectites, a cation such as an alkali metal enters between the layers to supplement the negative charge of the silicate layer, and the structure maintains electrical neutrality. The value of y in the equation (5) is usually 0.
It is 2 to 0.5, and is set to 0.33 in the ideal composition, and the value of y in the formula (6) is usually around 0, and when the value of y is 0, the value of x is 0. .2 to 0.5, and 0.33 in the ideal composition. Further, the value of y in the formula (7) is usually 0.1 to 0.3, and in the ideal composition, it is 0. It is said to be 17.

In the above formulas (5) to (7), some or all of Mg in the octahedral sheet is Ni, Co, Fe, Zn, C.
A 3-octahedral smectite substituted with at least one heavy metal ion selected from divalent heavy metal ions such as u, Mn, Pb and Cd can also be synthesized and can be used in the catalyst of the present invention.

The 3-octahedral smectite used as a catalyst in the present invention can be produced by hydrothermal photosynthesis. For example, hectorite can be produced by the method disclosed in Japanese Patent Publication No. Sho 61-12848, and saponite can be produced in Japanese Examined Patent Publication No.
According to the method of the official gazette, and also for the Steven site
It can be manufactured by the method described in JP-A-3-6485. Furthermore,
Compounds obtained by substituting the hydroxyl groups of the compounds of formulas (5) to (7) with fluorine have also been synthesized. These synthetic products, hectorite, saponite and stevensite are water-based paints,
It is also known that it can be used for cosmetics, pharmaceuticals, boring mud, etc.

In the formulas (5) to (7), Ni, Co, Fe, Zn and C are used instead of magnesium in the octahedral sheet.
A 3-octahedral smectite in which at least one heavy metal ion selected from divalent heavy metal ions such as u, Mn, Pb, and Cd is partially or wholly substituted is also synthesized. Patent No. 1841
No. 413 and Japanese Patent No. 1841414 can be exemplified.

The above-mentioned synthetic porous body made of 3-octahedral smectite is produced by a method such as hydrothermal synthesis.
No. 1,250,54 and US Patent 5,559,070, a synthetic porous material produced by the method, Patent No. 170.
Porous Material Produced by 8281, Patent No. 20
Synthetic porous body manufactured by 36082, Patent No. 2
Any of the synthetic porous materials produced by 667978 can be used as the catalyst of the present invention.

The 3-octahedral smectite or the 3-octahedral smectite in the synthetic porous body can be identified by an X-ray diffraction method. The value of d (06) is 1.51
It is in the range of ~ 1.54Å, and when iron is contained, the d value tends to increase. In the case of 3-octahedral smectite, broad (001) reflection is often observed around 15Å, but in the case of a synthetic porous body, it is often unclear due to delamination. In the hk reflection, the (02,11) peak is observed in the vicinity of 4.5 to 4.6Å, and the (13,20) peak is observed in the vicinity of 2.6Å.

The 3-octahedral smectite or the synthetic porous body composed of 3-octahedral smectite used in the present catalyst is insoluble in organic compounds such as alcohol, alkylene carbonate, dialkyl carbonate, alkylene glycol and organic solvents, Further, it is an inorganic substance which does not directly react with these organic compounds to form a complex. Therefore, the present catalyst can be easily separated from the above-mentioned organic compounds and organic solvents, and can be suitably used for the production of the dialkyl carbonate of the present invention.

In the present invention, the shape of the catalyst is not particularly limited, but it is preferable that the catalyst is molded in order to facilitate liquid permeability during the reaction and separation of the catalyst after the reaction. The form may be a fine powder having a size of about 100 μm or may be formed by a general method such as granulation or tableting.

In preparing the catalyst used in the present invention, a suitable binder may be used. The binder is used for the purpose of binding solids to enhance the mechanical strength of the catalyst, and any inorganic or organic substance can be used as long as it does not inhibit the reaction according to the present invention or the catalytic activity. . Further, the binder is not particularly limited as long as it exhibits catalytic activity to the reaction to some extent. Specific examples of the binder used in the present invention include kibushi clay, kaolin, talc, bentonite, silica sol, alumina sol, zirconia sol, and organic polymer.

In preparing the catalyst used in the present invention, a suitable carrier can be used. The carrier is used for the purpose of dispersing catalytic active points on the surface thereof to form a catalyst having a high surface area and increasing the mechanical strength of the catalyst. The carrier is not particularly limited as long as it does not inhibit the reaction or the catalytic activity, and a carrier that exhibits some catalytic activity to the reaction can also be used.

The catalyst used in the present invention is preferably porous and has a large specific surface area because high catalytic activity can be obtained. A catalyst having a specific surface area of usually 5 to 800 m ² / g, more preferably 10 to 500 m ² / g is used. When the specific surface area is less than 5 m ² / g, sufficient catalytic activity cannot be obtained, which is not preferable. On the other hand, if the specific surface area exceeds 800 m2 / g, the strength of the catalyst will decrease and problems will occur in terms of durability, such being undesirable.

The catalyst used in the present invention is preferably activated by heat treatment in a gas stream of hydrogen, nitrogen or the like for the purpose of removing surface adsorbates such as water and organic substances before use. The processing temperature at that time is 80 ° C to 700 ° C.
C. range, more preferably 100 to 600.degree. C. and most preferably 100 to 400.degree. When the treatment temperature is lower than 80 ° C, desorption of the adsorbed substance becomes insufficient, which is not preferable. Further, if the treatment temperature exceeds 700 ° C., the structure of the 3-octahedral smectite contained in the catalyst is broken and the surface area is reduced, which is not preferable. The activation treatment time is not particularly limited as it depends on the amount of adsorbed substances on the surface and the treatment temperature, but is usually in the range of 1 to 100 hours.

The theoretical composition ratio of the alkylene carbonate and alcohol used as the raw material in the present invention is 2, but it is not particularly limited to this value, and it can be used in a wide range in accordance with the production process. You can Since the reaction is an equilibrium reaction, it is generally preferable to increase the ratio of alcohol in order to improve the conversion rate of alkylene carbonate. Usually, the molar ratio of alcohol to alkylene carbonate is preferably 1 to 20, and more preferably 2 The range is from -10.

In the present invention, the reaction temperature has a different adaptable range depending on the type of raw material and the activity of the catalyst, but is generally 3
It is in the range of 0 to 300 ° C, and more preferably 50 to 200 ° C. At that time, the pressure is regulated by the vapor pressure of the reaction solution, and there is no particular limitation, and the effect on the transesterification reaction is small, but there is no problem in applying the pressure, and carbon dioxide and nitrogen are used as atmospheric gases. The reaction proceeds even when argon, helium, hydrogen, oxygen, air, etc. are used.

In the present invention, the method for transesterifying the alkylene carbonate and alcohol in the presence of a catalyst may be a batch reaction or a flow reaction, and is not particularly limited.

The amount of the catalytic reaction catalyst used in the batch reaction is 0.1 to 30% by weight, more preferably 1 to 15% by weight, and most preferably 1 to 10% by weight based on the raw materials.
It is in the range of% by weight. A batch reactor is charged with a predetermined amount of the catalyst of the present invention and raw materials, and the transesterification reaction is carried out at a predetermined temperature with stirring, whereby a desired reaction liquid mixture containing a dialkyl carbonate is obtained.
At that time, the reaction time varies depending on the reaction temperature and the amount of the catalyst used, but is generally 0.1 to 100 hours, more preferably 0.1 to 30 hours, and most preferably 0.1 to 15 hours. . From the reaction solution containing the catalyst thus obtained, the catalyst can be easily separated by a method such as filtration or centrifugation, and dialkyl carbonate or by-produced alkylene glycol, unreacted alkylene carbonate or alcohol is generally obtained from the reaction solution obtained by separating the catalyst. By distillation,
In some cases, it can be recovered by a method such as extraction or recrystallization.

When a flow-through reaction is carried out, a fixed bed system,
Either a fluidized bed system or a stirring tank system can be used. The liquid passing conditions at this time are, when expressed as a liquid hourly space velocity (LHSV) with respect to the catalyst, a range of 0.1 to 50 / hr, more preferably 0.2 to 10 / hr can be used.

[0040]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0041]

Example 1 86 g of No. 3 water glass was dissolved in 200 ml of distilled water, and 160 ml of a 2N aqueous sodium hydroxide solution was added to obtain an alkaline solution A. An acidic solution B was prepared by dissolving 64.2 g of nickel chloride hexahydrate primary reagent in 300 ml of distilled water. While stirring Solution B in Solution A, 5
The mixture was added dropwise over 1 minute and stirred for 1 hour. The obtained reaction complex precipitate was filtered, washed thoroughly with water, transferred to a beaker, and 20 ml of water in which 0.72 g of lithium hydroxide primary reagent was dissolved was added to obtain a slurry. This slurry was transferred to an autoclave having an internal volume of 1 liter, and the slurry was 1.66 MPa,
The reaction was carried out at 200 ° C. for 2 hours. After cooling, the reaction product was taken out, dried at 80 ° C., and then pulverized to obtain Ni-containing hectorite. The chemical composition obtained from the chemical analysis values is Si-Ni-Li-Na.
= 8-5.66-0.34-0.61. The amount of methylene blue adsorbed was 0.68 meq / g. The value of the cation exchange capacity calculated from the amount of methylene blue adsorbed in this sample is S
It is 0.63 for i = 8, which is in good agreement with the value Na of the chemical composition value of 0.61. Also, the X-ray powder diffraction pattern is similar to the pattern of normal hectorite, and (3
The d value of the 5,06) reflection peak was 1.522Å.
This sample dispersed in water to form a thixotropic green translucent solid gel. This sample is placed in a dryer for 110
It was dried at ℃ for 15 hours to obtain a catalyst. The specific surface area of the catalyst obtained from the nitrogen adsorption measurement was 365 m ² / g. Using this catalyst, an attempt was made to synthesize dimethyl carbonate from ethylene carbonate under the following conditions. In a glass flask equipped with a stirrer, a condenser, and a thermometer, 25 mmol (2.2 g) of ethylene carbonate, 0.2 mol (6.4 g) of methyl alcohol, 0.5 g of catalyst (5.
5% by weight) was charged and heated, and a transesterification reaction was carried out at a reaction temperature of 150 ° C. for 4 hours. After completion of the reaction, the reaction solution was sampled and analyzed for composition of the reaction solution by high performance liquid chromatography. The composition of the reaction solution is ethylene carbonate 12.3.
Mmol, 11.2 mmol dimethyl carbonate and 10.4 mmol ethylene glycol. Therefore, the conversion of ethylene carbonate was 50.8%, the selectivity of dimethyl carbonate was 88.2%, and the yield of dimethyl carbonate was 46.4%. The selectivity of ethylene glycol was 81.9%, and its yield was 41.6%.

[0042]

Example 2 A hydrophilic smectite product SWN manufactured by Corp Chemical was dried in a dryer at 110 ° C. for 15 hours and used as a catalyst. The value of specific surface area obtained from the nitrogen adsorption measurement was 131 m ² / g. The SWN product gives a methylene blue adsorption amount of 1.01 meq / g, and the chemical composition determined from the chemical analysis value is Si-Mg-Li-Na = 8-5.41-
It was 0.59-0.63. Using this catalyst, an attempt was made to synthesize dimethyl carbonate from ethylene carbonate under the same conditions as in the examples. The liquid composition after the reaction was ethylene carbonate 9.8 mmol, dimethyl carbonate 13.
It was 5 mmol and 14.6 mmol of ethylene glycol. The conversion of ethylene carbonate was 60.8%, the selectivity of dimethyl carbonate was high at 88.8%, and the yield of dimethyl carbonate was 54.0%. The selectivity of ethylene glycol is 96.1%.
And the yield was 58.4%.

[0043]

Example 3 A synthetic porous body containing nickel was prepared according to Japanese Patent No. 2125054. 200 ml of distilled water
86 g of No. 3 water glass was dissolved in the solution, and 90 ml of a 4N aqueous sodium hydroxide solution was added to obtain a solution A. Distilled water 30
Liquid B was obtained by dissolving 71.3 g of nickel chloride hexahydrate primary reagent in 0 ml. The solution B was added dropwise to the solution A with stirring for 10 minutes and further stirred for 1 hour. The obtained reaction complex precipitate was filtered, washed thoroughly with water, transferred to a beaker, and 20 ml of water was added to form a slurry. Transfer this slurry to an autoclave with an internal volume of 1 liter,
The reaction was carried out at 1.66 MPa and 200 ° C. for 2 hours. After cooling
The reaction product was taken out, dried at 80 ° C., and then pulverized to obtain a Ni-containing synthetic porous body. The chemical composition obtained from the chemical analysis values is Si
-Ni-Na = 8-5.93-0.40, and the X-ray powder diffraction diagram is around 2θ = 20 °, 35 ° and 60 ° when measured using a copper tube and a nickel filter. Broad diffraction was observed. These were similar to the diffraction pattern of smectite having a similar composition, but the diffraction line of 001 reflection observed in smectite was not observed, and it was recognized as a low crystalline smectite-like substance. Considering the chemical composition together, it is considered to be a synthetic porous body composed of a Ni-containing stevensite-like substance. The pore characteristics obtained from nitrogen adsorption have a specific surface area of 456 m ² / g and a pore volume of 0.304 ml.
And the average pore diameter was 2.7 nm. The methylene blue adsorption amount of this sample was 0.42 meq / g, and it was not dispersed in water at all. This synthetic porous body is placed in a drier 110
A catalyst was obtained by drying at 15 ° C for 15 hours. Using this catalyst, an attempt was made to synthesize dimethyl carbonate from ethylene carbonate under the same conditions as in Example 1. The liquid composition after the reaction was 17.1 mmol of ethylene carbonate, 6.3 mmol of dimethyl carbonate and 5.9 mmol of ethylene glycol. The conversion rate of ethylene carbonate calculated from these values was 31.6%, the selectivity of dimethyl carbonate was 79.7%, and the yield of dimethyl carbonate was 25.2%. The ethylene glycol selectivity was 74.7%, and the yield was 23.6%.

[0044]

Comparative Example 1 Synthesis of dimethyl carbonate from ethylene carbonate was carried out in the same manner as in Example 1 except that a hydrotalside compound (compositional formula: Mg ₅ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O) was used as a catalyst. I tried. The specific surface area of this catalyst is 8
It was 3 m ² / g. The liquid composition after the reaction was ethylene carbonate 14.3 mmol, dimethyl carbonate 3.0 mmol and ethylene glycol 3.2 mmol.
The conversion rate of ethylene carbonate calculated from these values was 42.8%, the selectivity of dimethyl carbonate was as low as 28.0%, and the yield of dimethyl carbonate was 12.0%. The selectivity of ethylene glycol was 29.9% and its yield was 12.8%.

[0045]

EFFECTS OF THE INVENTION According to the method of the present invention, a transesterification reaction of an alkylene carbonate and an alcohol to a dialkyl carbonate rapidly proceeds, and a catalyst composed of 3-octahedral smectite and / or 3-octahedral smectite is synthesized. Since the porous material is insoluble in the reaction solution, it is easy to separate the reaction solution from the catalyst, preventing the yield reduction due to the reverse reaction, decomposition, polymerization reaction, etc. due to the residual catalyst in the distillation step that is seen with homogeneous catalysts. it can. Therefore, industrially important dialkyl carbonate can be efficiently produced,
It contributes to the development of industry.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Balchandra Mahadeo Banague             Hokkaido, Sapporo, Kita-ku, Kita 13-jo Nishi 8-chome, Hokkaido             Department of Materials Engineering, Graduate School of Engineering, University (72) Inventor Masayuki Shirai             3-16-10, Saiwaicho, Miyagino-ku, Sendai City, Miyagi Prefecture             No. 103 (72) Inventor Kazuo Torii             1-19-13 Nishi-Nakada, Taihaku-ku, Sendai City, Miyagi Prefecture F-term (reference) 4H006 AA02 AC48 BA68 BA85 KA58                 4H039 CA66 CD90

Claims (4)

[Claims] 1. A compound represented by the general formula (1): (In the formula, R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom,
An alkylene carbonate represented by an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group, an alkoxyalkyl group or an alkoxy group) and a general formula (2): R ⁵ OH (2) (wherein R ⁵ Represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an arylalkyl group, a cycloalkyl group or an alkoxyalkyl group), and undergoes a transesterification reaction with an alcohol represented by the general formula (3): In the method for producing a dialkyl carbonate represented by the formula (wherein R ⁵ is the same as above), a 3-octahedral smectite is used as a catalyst. 2. The method according to claim 1, wherein hectorite and / or stimbunsite is used as a catalyst as the 3-octahedral smectite. 3. The method according to claim 1, wherein a synthetic porous body made of 3-octahedral smectite is used as a catalyst. 4. A part or all of magnesium in the octahedral sheet is replaced with at least one heavy metal selected from divalent heavy metal ions such as Ni, Co, Fe, Zn, Cu, Mn, Pb and Cd. -Octahedral smectite and / or 3 above
-The production method according to any one of claims 1 to 3, wherein a porous body composed of octahedral smectite is used as a catalyst.