JP2007039387A - Method for producing carbonate having alkyl group or aryl group by carbon dioxide fixation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an alkylene carbonate by using an ionic liquid as a medium. <P>SOLUTION: The method for producing the carbonate involves reacting an unsubstituted or substituted halogenated alkyl or halogenated aryl, and an alkyl alcohol or an aryl alcohol of substrate compounds with carbon dioxide in the presence of an alkali by using the ionic liquid as a medium to produce a dialkyl carbonate, a diaryl carbonate or an alkyl aryl carbonate. The method is carried out by not only using no dangerous phosgene but also using the safe carbon dioxide as a raw material, and by using a low environmental loading-type reaction system and reaction process, and yet has an extremely high reaction rate, yield and selectivity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a carbonate using an ionic liquid as a medium, and more specifically, by using an ionic liquid as a medium in the presence of an alkali, The present invention relates to a method for producing a target compound dialkyl carbonate, diaryl carbonate or alkylaryl carbonate by reacting alkyl alcohol or aryl alcohol with carbon dioxide.

  Alkylene carbonate is an important compound as a raw material for dialkyl carbonates and polycarbonates, but the conventional method does not use dangerous raw materials such as phosgene, and without using a catalyst, at a high reaction rate and low environmental impact. A method for producing carbonate by a loaded reaction system has not been established, and there has been a strong demand for its solution. In the present invention, an ionic liquid is used as a medium, an alkyl halide, an alkyl alcohol, or the like is used as a substrate compound, and this is reacted with carbon dioxide to produce carbonate at a high reaction rate and in a high yield. It has high technical significance as a new carbonate production technology that can replace the conventional method.

  Dialkyl carbonate, particularly dimethyl carbonate, is used as a methylating agent, a solvent, an electrolyte for a lithium ion battery, and the like, and is one of mass products boasting a production amount of 4 million tons per year. Further, diaryl carbonate, particularly diphenyl carbonate, is mainly used as a raw material of polycarbonate, and has various uses such as CD, bulletproof glass, and car light as an engineering plastic.

  Polycarbonate boasts a production volume of 1.2 million tons / year worldwide, half of which is synthesized from diphenyl carbonate. Thus, carbonate has become one of the compounds that must be industrially and in our living environment, and is an important compound. As a conventional technique for producing this dialkyl or diaryl carbonate, a method of obtaining alkylene carbonate by reacting phosgene and diol (phosgene method) or a method of obtaining alkylene carbonate by reacting epoxide and carbon dioxide is generally used. Are known.

  Among these, the phosgene method has been known for a long time, and there are many practical examples. In this method, since the activity of phosgene is very high, it easily reacts with alcohol or a compound having a hydroxyl group to easily produce a dialkyl carbonate, but at the same time, hydrochloric acid is generated. There are problems that neutralization is necessary, and there are many problems such as corrosion of the reactor due to the generated hydrochloric acid. Furthermore, the phosgene used itself is very toxic, and strict control is required to prevent it from being discharged to the outside world.

  A method for synthesizing alkylene carbonate using epoxide and carbon dioxide was discovered in 1956. In this case, the alkylene carbonate is converted to a dialkyl carbonate through a transesterification reaction with an alcohol, and further a diaryl carbonate is produced through a further transesterification with a phenol, and finally a polycarbonate is obtained from the diaryl carbonate and bisphenol A. Need to manufacture. In this method, dangerous phosgene is not used, and since safe carbon dioxide is used as a raw material, it is attracting attention as a production method friendly to the earth, but the reaction rate is slow and it is a step to make a final polycarbonate It has the disadvantage of a large number and has not been put into practical use until recently.

Regarding the production techniques of dialkyl carbonates and diaryl carbonates, many examples have been reported in the prior literature. As typical examples, for example, the following production techniques are disclosed. That is, (1) a method for producing a polycarbonate polyol by reacting a carbonyl component such as phosgene with a polyhydric alcohol containing a branched diol and a 4- to 6-valent alcohol has been proposed (see Patent Document 1). . In addition, (2) by bringing the active hydrogen-containing compound and CO ₂ synthon into contact in the presence of a catalyst such as a mixed metal oxide catalyst under conditions effective to produce a carboxylated compound, the carboxylated compound Has been proposed (see Patent Document 2).

In addition, (3) a method for continuously producing aromatic carbonates by efficiently recycling and reusing methanol and dimethyl carbonate as raw materials has been proposed (see Patent Document 3). In addition, a method for producing dialkyl carbonate from alkylene oxide, CO ₂ and alkanol is proposed in which (4) in the first stage, an alkylene carbonate is produced and then ester-converted with alkanol (see Patent Document 4). .

  Also, (5) a method of producing poly (alkylene carbonate) by reacting dialkyl carbonate and alkanediol in the presence of an enzyme under normal pressure to perform oligomerization, and then increasing the molecular weight under reduced pressure. It has been proposed (see Patent Document 5). Further, a method for producing urethane and carbonate by using an amine compound, an organic halide, carbon dioxide in a liquid or supercritical state as a raw material and a solvent, and capturing halogen liberated from the organic halogen. Is also known.

  However, the conventional method does not use dangerous phosgene, organic halides, or other raw materials, and does not use a catalyst, and at a high reaction rate, produces a carbonate with high efficiency by an environmentally low-load reaction system. A method has not been established, and there has been a strong demand in the art for the development of a new technology for such a carbonate production method.

JP-A-6-73173 JP-A-6-25103 JP-A-6-40616 JP-A-5-97774 JP 2000-80160 A

  Under such circumstances, the present inventors, in view of the above prior art, in the course of earnest research and development with the goal of developing a new technique related to the above-mentioned carbonate production method, As a result of various researches on the reaction mechanism and reaction selectivity between the substrate compound and carbon dioxide, high yields can be obtained by using alkyl halide or aryl halide and alkyl alcohol or aryl alcohol and carbon dioxide as raw materials. The present inventors have found that carbonates can be easily produced at a high reaction rate at a high rate and high selectivity, and further research has been made to complete the present invention.

  In the present invention, an ionic liquid is used as a medium, and a substrate compound and carbon dioxide different from those of the conventional method are used as raw materials. An object of the present invention is to provide a new production technique of carbonate that makes it possible to produce an aryl carbonate.

The present invention for solving the above-described problems comprises the following technical means.
(1) In the presence of an alkali, an ionic liquid is used as a medium, and a dialkyl is obtained by reacting an alkyl halide or aryl halide having an unsubstituted or substituted group of the substrate compound with an alkyl alcohol or an aryl alcohol and carbon dioxide. A method for producing carbonate, comprising producing carbonate, diaryl carbonate or alkylaryl carbonate.
(2) The method according to (1), wherein an alkali metal or alkaline earth metal hydroxide or carbonate is used as the alkali.
(3) The method according to (1) above, wherein an imidazole salt ionic liquid, a pyridinium salt ionic liquid, or an onium salt ionic liquid is used as the ionic liquid.
(4) The method according to (3) above, wherein an ionic liquid comprising an alkyl-substituted imidazolium salt, an alkyl ammonium salt, an alkyl-substituted pyridinium salt, or an alkylphosphonium salt derivative is used as the ionic liquid.
(5) The method according to (3), wherein a compound represented by the following general formula is used as the ionic liquid.

(In the formula, R _{1 to} R ₅ represent hydrogen, an unsubstituted or substituted alkyl group having 1 to 16 carbon atoms, or an unsubstituted or substituted aryl group, and A ⁻ represents an anionic species. To express.)

(6) The method as described in said (3) using the compound represented by the following general formula as an ionic liquid.

(However, wherein R ₆ to R ₁₁ is hydrogen, or unsubstituted or alkyl group having 1 to 16 carbon atoms having a substituent, or an aryl group having an unsubstituted or substituted, A ^- is the anion species To express.)

(7) The method as described in said (3) using the compound represented by the following general formula as an ionic liquid.

(However, in the formula, Q is N or P, and R _{12 to} R ₁₅ may be the same group, different groups, or groups which are bonded to each other to form a ring, hydrogen, unsubstituted or substituted, an alkyl group having a group, alkenyl group, alkynyl group, cycloalkyl group or aryl group, a ^- represents an anionic species).

(8) As the ionic liquid, 1-octyl-3-methylimidazolium tetrafluoroborate (OMI-BF ₄ ), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMI-BF ₄ ), 1-butyl- 3-methylimidazolium tetrafluoroborate _(BMI-BF 4), 1- ethyl-3-methylimidazolium tetrafluoroborate _(EMI-BF 4), 1- octyl-3-methylimidazolium chloride (OMI-Cl), 1-octyl-3-methylimidazolium bromide (OMI-Br), 1-octyl-3-methylimidazolium hexafluoroantimony (OMI-SbF ₆ ), 1-octyl-3-methylimidazolium hexafluorophosphate (OMI- PF _6), or 1-octyl - - The method according to (3) using methyl imidazolium trifluoromethane carbonate _{(OMI-CO 2 CF 3)} .
(9) Carbon dioxide is a mixed gas of at least one gas selected from hydrogen, helium, carbon dioxide, nitrogen, oxygen, argon, and air and carbon dioxide, and the partial pressure of carbon dioxide is 0 The method as described in said (1) using the gas or supercritical fluid which is 0.01 Mpa or more.
(10) The method according to (1) above, wherein the reaction temperature is in the range of 0 ° C. to 200 ° C., and the reaction pressure is normal pressure to 50 MPa.
(11) The method according to (1) above, wherein the reaction time is within 24 hours.
(12) The method according to (1), wherein the volume of the ionic liquid is 0.1 or more with respect to the volume 1 of the substrate.

Next, the present invention will be described in more detail.
The present invention uses an ionic liquid as a medium in the presence of an alkali and reacts an alkyl halide or aryl halide having an unsubstituted or substituted group of a substrate compound with an alkyl alcohol or aryl alcohol and carbon dioxide, The objective compound is characterized by producing a dialkyl carbonate, diaryl carbonate or alkylaryl carbonate.

  Here, the substituent is not particularly limited, and a substrate compound having an arbitrary substituent can be used as long as the reaction can be performed. For example, a methyl group, an ethyl group, a vinyl group, Alkyl having 1 to 16 carbon atoms such as ethynyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, cyclobutyl group, pentyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, etc. Group, alkenyl group, alkynyl group and other aliphatic substituents, or phenyl group, methylphenyl group, dimethylphenyl group, trimethylphenyl group, tetramethylphenyl group, pentaphenyl group, biphenyl group, hydroxyphenyl group, acetylphenyl group Alkyl group, alkenyl group, alkynyl group, alkoxy group, Examples include a phenyl group having a substituent such as a mil group, a carbonyl group, a carboxyl group, an alkoxycarbonyl group, a hydroxyl group, a mercapto group, a halogen, a sulfonyl group, and an amino group, a naphthyl group, an anthracene group, a phenalene group, and a naphthalacene group. Preferably, a methyl group, an ethyl group, a propyl group, a phenyl group, a hydroxyphenyl group, a methoxyphenyl group and the like are exemplified.

In the method of the present invention, as the alkali, for example, alkali metal, alkaline earth metal hydroxide, carbonate, for example, NaOH, KOH, LiOH, Na ₂ CO ₃ , NaHCO ₃ , K ₂ CO ₃ , KHCO ₃ , Li ₂ CO ₃ , CaCO ₃ , MgCO ₃ , BaCO _{3 and the} like are used. The alkali concentration in the reaction system is not particularly limited because it depends on the input amount of the substrate to be used, but is 0.1 to 1000 mol, preferably 0.1 to 1 mol of the substrate. The range of not less than 100 moles is preferable. However, the method of the present invention is not limited to these, and any alkali can be used at any concentration.

Next, in the present invention, an imidazole salt-based ionic liquid, a pyridinium salt-based ionic liquid, or an onium salt-based ionic liquid is used as the ionic liquid as a solvent. For example, an alkyl-substituted imidazolium salt, an alkylammonium salt Examples thereof include ionic liquids composed of salts, alkylpyridinium salts, and alkylphosphonium salt derivatives. In the present invention, it is particularly emphasized that the ionic liquid is an ionic liquid as a solvent. It is emphasized that even a compound similar to the ionic liquid used in the present invention is not an ionic liquid as used in the present invention if it is not a solvent. Furthermore, in the method of the present invention, as the ionic liquid, an imidazole salt-based ionic liquid represented by the following general formula (wherein R _{1 to} R ₅ have hydrogen, unsubstituted or substituted groups). Represents an alkyl group having 1 to 16 carbon atoms, or an aryl group having an unsubstituted or substituted group, and A ⁻ represents an anionic species).

In the method of the present invention, a pyridinium salt-based ionic liquid represented by the following general formula (wherein R _{6 to} R ₁₁ are hydrogen, or an unsubstituted or substituted alkyl having 1 to 16 carbon atoms). Represents an unsubstituted or substituted aryl group, and A ⁻ represents an anionic species).

Here, the anion species is not particularly limited, but preferably, for example, X ⁻ (X is halogen), N (CF ₃ SO ₂ ) ₂ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF _3. Examples include SO ₃ ⁻ , CF ₃ CO ₂ ⁻ , NO ₃ ⁻ , SCN ⁻ , ClO ₄ ⁻ , carbonate ion, benzoate anion or picrate anion. Further, as the above-mentioned substituent, for example, aryl group, alkyl group, alkenyl group, alkynyl group, alkoxy group, formyl group, carbonyl group, carboxyl group, alkoxycarbonyl group, hydroxyl group, mercapto group, halogen, sulfonyl A group or an amino group is exemplified.

In the method of the present invention, an onium salt-based ionic liquid represented by the following general formula (wherein Q is N or P, and R _{12 to} R ₁₅ may be the same or different groups). Or it may be a group which is bonded to each other to form a ring, and represents hydrogen or an unsubstituted or substituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group or aryl group, and A ⁻ represents an anionic species.) Is used.

Here, as the anion species, for example, X ⁻ (X is a halogen), N (CF ₃ SO ₂ ) ₂ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO _{^{2 -, NO 3 -, SCN}} -, ClO 4 -, carbonate ion, benzoate anion, or picric acid anion is exemplified. Further, as the above-mentioned substituent, for example, aryl group, alkyl group, alkenyl group, alkynyl group, alkoxy group, formyl group, carbonyl group, carboxyl group, alkoxycarbonyl group, hydroxyl group, mercapto group, halogen, sulfonyl A group or an amino group is exemplified.

In the present invention, for an ionic liquid, for example, in the counter cation, when R ₁ is an octyl group, R ₂ is hydrogen, R ₃ is a methyl group, and X is BF ₄ : OMI-BF ₄ , R ₁ Is a hexyl group: abbreviated as HMI-BF ₄ , and when R ₁ is a butyl group: BMI-BF ₄ , and when R ₁ is an ethyl group: EMI-BF ₄ . On the other hand, in the counter anion, in the case of Cl ⁻ : OMI-Cl, in the case of Br ⁻ : in the case of OMI-Br and SbF ₆ ⁻ : in the case of OMI-SbF ₆ and PF ₆ ⁻ : OMI-PF ₆ , CO ₂ CF ₃ ^- for: abbreviated as _OMI-CO 2 CF _3.

  In the present invention, an unsubstituted or substituted halogenated alkyl or aryl halide and an alkyl alcohol or aryl alcohol are used as a substrate compound and reacted with carbon dioxide. Examples of the substrate include a methyl group and an ethyl group. , Vinyl group, ethynyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, cyclobutyl group, pentyl group, isopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, etc. Halides having aliphatic substituents such as alkyl groups, alkenyl groups, alkynyl groups and alcohol or phenyl groups, methylphenyl groups, dimethylphenyl groups, trimethylphenyl groups, tetramethylphenyl groups, pentaphenyl groups, biphenyls Group, hydroxyph Substituents such as alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, formyl groups, carbonyl groups, carboxyl groups, alkoxycarbonyl groups, hydroxyl groups, mercapto groups, halogens, sulfonyl groups, amino groups, etc. Examples thereof include halogenated phenyl groups, naphthyl groups, anthracene groups, phenalene groups, and naphthalacene groups, and alcohols.

  More preferably, methanol, ethanol, propanol, isopropanol, phenol, naphthol, hydroxyanthracene, hydroxyphenalene, chloromethane, chloroethane, chloropropane, chloroisopropane, chlorobenzene, chloronaphthalene, chlorohydroxyanthracene, chlorohydroxyphenalene Etc. are exemplified. However, it is not limited thereto, and any substrate compound can be used in the method of the present invention as long as it produces carbonate in the above reaction system.

  In the present invention, since carbon dioxide is also one of the raw materials, it is basically sufficient to contain at least 1 mol of carbon dioxide with respect to 1 mol of the halogenated compound and alcohol of the substrate compound. As this carbon dioxide, for example, hydrogen, helium, carbon dioxide, nitrogen, oxygen, argon, and a mixed gas of at least one kind of gas and carbon dioxide can be used, preferably A gas or a supercritical fluid having a partial pressure of carbon dioxide of 0.01 MPa or more is used.

  In the method of the present invention, the reaction conditions are a temperature range of 0 ° C. or higher and 300 ° C. or lower, preferably a temperature range of 50 ° C. or higher and 200 ° C. or lower, and a reaction pressure of normal pressure or higher, preferably 0.1 MPa or higher and 50 MPa or lower. Range. When the temperature is 50 ° C. or lower, the reaction hardly proceeds, and when it is 0 ° C., the reaction hardly occurs. On the other hand, when the temperature is 200 ° C. or higher, the yield decreases, and when the temperature is 300 ° C. or higher, a complicated reaction occurs and it is difficult to obtain the target product.

  In addition, as for the influence on the pressure, the yield is better at the low pressure, and the pressure tends to decrease to 30 MPa by increasing the pressure. However, at a pressure higher than that, a tendency to increase is seen in the range of 40 to 50 MPa. In the case of a pressure higher than this, it is expected that the yield will be further improved, but considering that the yield at 1 MPa and the yield at 60 MPa are approximately the same, at 120 MPa, The yield is expected to be close to 100%. However, in practice, a pressure of 50 MPa or more is not so preferable in terms of apparatus cost.

  In the method of the present invention, the reaction time can be produced within 5 minutes to 24 hours, but more preferably 3 hours or more, a sufficient yield can be obtained. However, in the present invention, the reaction time can be arbitrarily set in consideration of the conversion rate, selectivity, yield, etc. of the target compound, depending on the substrate, the type of reaction system, temperature and pressure conditions, etc. .

  In the method of the present invention, the amount of the ionic liquid in the reaction system is preferably such that the volume of the ionic liquid is 0.1 or more with respect to the volume 1 of the substrate. Thereby, the yield of the target compound can be greatly increased. In the present invention, when an alkali (for example, NaOH) is added for each reaction, the yield decreases after the second time. However, for example, by separating the NaCl precipitated from the ionic liquid and adding a new alkali, the yield is reduced. Since the rate can be improved, it is possible to recycle the ionic liquid.

  Examples of the carbonate obtained by the method of the present invention include, for example, dimethyltyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, diisobutyl carbonate, di-t-butyl carbonate, dicyclobutyl carbonate, dipentyl carbonate, diisopentyl. Examples thereof include carbonates having aliphatic substituents such as dialkyl carbonates, dialkenyl carbonates, dialkynyl carbonates and the like having any of 1 to 16 carbon atoms such as carbonates, dicyclopentyl carbonates, dihexyl carbonates, dicyclohexyl carbonates.

  Furthermore, diphenyl carbonate, bis (methylphenyl) carbonate, bis (dimethylphenyl) carbonate, bis (trimethylphenyl) carbonate, bis (tetramethylphenyl) carbonate, bis (pentamethylphenyl) carbonate, bis (biphenyl) carbonate, bis ( Hydroxyphenyl) carbonate, bis (acetylphenyl) carbonate, alkyl group, alkenyl group, alkynyl group, alkoxy group, formyl group, carbonyl group, carboxyl group, alkoxycarbonyl group, hydroxyl group, mercapto group, halogen, sulfonyl group, amino group A phenyl group, a naphthyl group, an anthracene group, a phenalene group, a carbonate of a naphthalacene group having a substituent such as Bets are exemplified.

  Preferably, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, diphenyl carbonate, dinaphthyl carbonate, dianthryl carbonate and the like are exemplified. However, it is not limited to these.

  The method of the present invention is a new synthesis method of alkylene carbonate. (1) No dangerous phosgene is used as a raw material. (2) Safe carbon dioxide is used as a raw material. Since alcohol is used, it is environmentally friendly and can reduce production costs. (3) The reaction rate reaches 93% or more in about 3 hours. (4) Uses alkali and ionic liquids. Therefore, hydrochloric acid is neutralized in the reaction process, and there is no problem such as corrosion of the reactor due to the acid. (5) Yield, selectivity is nearly 100%, and high efficiency. (6) Ionic liquid is Because it can be used repeatedly, it has features such as minimizing waste discharge, and it is possible to reliably solve the problems of conventional methods. It is useful as a new method for the synthesis of Ren carbonate.

  According to the present invention, (1) a new method for synthesizing carbonate using an ionic liquid as a reaction medium can be provided. (2) Since the method of the present invention uses safe carbon dioxide as a raw material, it has a low environmental impact. It is useful as a type of reaction process. (3) Since high reaction rate, high yield, and high selectivity can be expected, it can be highly expected as a new production technology of carbonate that can be put to practical use. (4) Reaction Since the corrosion of the apparatus hardly occurs, the apparatus can be used for a long time. (5) Since the yield and selectivity can be close to 100%, the purification work such as impurity removal can be simplified as much as possible. (6) Since the discharge of waste can be suppressed as much as possible, the effect of being useful as an environmentally friendly and environmentally friendly process can be achieved.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples.

  In this example, the reaction was examined by the method shown by the following reaction formula.

  In an autoclave made of stainless steel with an internal volume of 25 ml, sodium carbonate (0.1 g) as an alkali, chloropropane (1.2 mL, 14 mmol) and propanol (1 mL, 13 mmol) as substrates and 5 mL of various ionic liquids are placed in an oil bath and 180 ml. After heating to 0 ° C., carbon dioxide was introduced with a high pressure pump to a pressure of 20 MPa. Thereafter, the mixture was stirred for 5 hours to react, then cooled on ice and then slowly depressurized. The obtained reaction product was extracted with ether and then analyzed by CG-MS / MS to obtain the reaction yield and selectivity. The obtained results are summarized in Table 1.

  As a result of performing the reaction under the above-mentioned conditions, the conversion rate was 100%, and the raw material was not recovered. Furthermore, the types of substituents of imidazole salts and the types of anions thereof in various ionic liquids, the types of pyridinium salt type anions, the substituents of ammonium salts, and ionic liquids of phosphonium salts are almost 90% carbonate. It was found that the above yield was obtained. Moreover, although it turned out that a trace amount dipropyl ether produces | generates as an impurity, it is thought that this side reaction shown by the following Reaction Formula was obtained at the stage heated to 180 degreeC at the beginning of reaction.

  Under the same conditions as in Example 1, the dependence of alkali species was examined. The results are summarized in Table 2. As a result, it was found that any of sodium hydroxide, sodium hydrogen carbonate, potassium carbonate and sodium carbonate can similarly obtain a carbonate with a yield of 99% or more.

The amount of sodium carbonate was examined under the same conditions as in Example 1 above. The results are summarized in Table 3. When the amount of sodium carbonate is 0.05 g with respect to propanol (13 mmol), the yield of carbonate is reduced to 67% in the case of EMI-SbF ₆ ionic liquid, but in the case of other ionic liquids In both cases, it was found that carbonate was obtained in a yield of 80% or more.

  Various alcohols and alkyl halides were examined under the same conditions as in Example 1 above. The results are summarized in Table 4. In the case where R and R ′ are different substituents, it was found that the target carbonate was produced, but at the same time, only R or R ′ carbonate was obtained. Furthermore, when phenol and chlorobenzene were used as raw materials, although some carbonates were produced, most of them were found to be diphenyl ether. In Table 4, a) represents the total yield of each carbonate: dipropyl: 9.6%, butyl propyl carbonate: 42.8%, dibutyl carbonate: 8.6%.

  Under the same conditions as in Example 1, the pressure dependence of the yield at 180 ° C. was examined using propanol and chloropropane as raw materials. The results are summarized in Table 5. FIG. 1 shows the graph. From these, it was found that when the reaction pressure was about 20 MPa, the yield was 99%, which was the highest, and the selectivity was also 99%. The remaining 1% was ether.

  Under the same conditions as in Example 1, propanol and chloropropane were used as raw materials, and the temperature dependence of the carbonate yield was examined under the conditions of 5 MPa and 5 hours. The results are summarized in Table 6. Moreover, the graph is shown in FIG. From these results, it was found that when the reaction temperature was about 160 ° C., the yield was the highest, 99%, and the selectivity was 99%. The remaining 1% was ether. In addition, when the temperature was high, the generation of impurities such as ether was particularly prominent, and the selectivity decreased.

  Under the same conditions as in Example 1, propanol and chloropropane were used as raw materials, and changes in carbonate yield over time were examined under the conditions of 180 ° C. and 20 MPa. The results are summarized in Table 7. Moreover, the graph is shown in FIG. From these, it was found that a yield of 93% was reached in about 3 hours and 99% or more after about 5 hours.

  As described above in detail, the present invention relates to a new carbonate production technique using an ionic liquid as a reaction medium, and according to the present invention, synthesis of a new carbonate using an ionic liquid and safe carbon dioxide as raw materials. A method can be provided. The present invention does not use dangerous phosgene, uses safe carbon dioxide as a raw material, uses a low environmental load type reaction system and reaction process, and has extremely high reaction rate, yield, and selectivity. It provides new carbonate production technology. The method of the present invention can be highly expected to be put to practical use as an industrial production technique that can replace the conventional method.

The relationship between the reaction pressure and carbonate yield in this invention is shown. The relationship of reaction temperature and carbonate yield in this invention is shown. The relationship between the reaction time and carbonate yield in this invention is shown.

Claims (12)

  In the presence of alkali, an ionic liquid is used as a medium, and an alkyl halide or aryl halide having an unsubstituted or substituted group of the substrate compound is reacted with alkyl alcohol or aryl alcohol with carbon dioxide, thereby dialkyl carbonate, diaryl. A method for producing carbonate, comprising producing carbonate or alkylaryl carbonate.   The method according to claim 1, wherein an alkali metal or alkaline earth metal hydroxide or carbonate is used as the alkali.   The method according to claim 1, wherein an imidazole salt ionic liquid, a pyridinium salt ionic liquid, or an onium salt ionic liquid is used as the ionic liquid.   The method according to claim 3, wherein an ionic liquid comprising an alkyl-substituted imidazolium salt, an alkyl ammonium salt, an alkyl-substituted pyridinium salt, or a derivative of an alkylphosphonium salt is used as the ionic liquid. The method according to claim 3, wherein a compound represented by the following general formula is used as the ionic liquid.

(In the formula, R _{1 to} R ₅ represent hydrogen, an unsubstituted or substituted alkyl group having 1 to 16 carbon atoms, or an unsubstituted or substituted aryl group, and A ⁻ represents an anionic species. To express.) The method according to claim 3, wherein a compound represented by the following general formula is used as the ionic liquid.

(In the formula, R _{6 to} R ₁₁ represent hydrogen, an unsubstituted or substituted alkyl group having 1 to 16 carbon atoms, or an unsubstituted or substituted aryl group, and A ⁻ represents an anionic species. To express.) The method according to claim 3, wherein a compound represented by the following general formula is used as the ionic liquid.

(However, in the formula, Q is N or P, and R _{12 to} R ₁₅ may be the same group, different groups, or groups which are bonded to each other to form a ring, hydrogen, unsubstituted or substituted, an alkyl group having a group, alkenyl group, alkynyl group, cycloalkyl group or aryl group, a ^- represents an anionic species). As the ionic liquid, 1-octyl-3-methylimidazolium tetrafluoroborate (OMI-BF ₄ ), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMI-BF ₄ ), 1-butyl-3-methyl tetrafluoroborate _(BMI-BF 4), 1- ethyl-3-methylimidazolium tetrafluoroborate _(EMI-BF 4), 1- octyl-3-methylimidazolium chloride (OMI-Cl), 1- octyl 3-methylimidazolium bromide (OMI-Br), 1- octyl-3-methylimidazolium hexafluoroantimonate _(OMI-SbF 6), 1- octyl-3-methylimidazolium hexafluorophosphate _(OMI-PF 6) Or 1-octyl-3-me The method of claim 3 using the Le imidazolium trifluoromethane carbonate _{(OMI-CO 2 CF 3)} .   Carbon dioxide is a mixed gas of at least one gas selected from hydrogen, helium, carbon dioxide, nitrogen, oxygen, argon, and air and carbon dioxide, and the partial pressure of carbon dioxide is 0.01 MPa or more. The method according to claim 1, wherein a gas or a supercritical fluid is used.   The method according to claim 1, wherein the reaction temperature is in the range of 0 ° C. to 200 ° C., and the reaction pressure is normal pressure to 50 MPa.   The process according to claim 1, wherein the reaction time is within 24 hours.   The method according to claim 1, wherein the volume of the ionic liquid is 0.1 or more with respect to the volume 1 of the substrate.

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