Method for synthesizing dimethyl carbonate through in-situ self-activation homogeneous catalysis transesterification

Abstract

The invention relates to the technical field of organic synthesis, in particular to a method for synthesizing dimethyl carbonate by in-situ self-activation homogeneous catalysis transesterification, which comprises the following steps: uniformly mixing organic sulfonate serving as a homogeneous catalyst with cyclic carbonate and methanol, stirring and refluxing at 55-80 DEG C to react for 1-8 hours, and cooling to room temperature; and carrying out atmospheric distillation on the reaction materials, and collecting fractions at 64-91 DEG C to obtain a mixture consisting of methanol and dimethyl carbonate. The organic sulfonate catalyst disclosed by the invention can keep high catalytic activity and excellent solubility in multiple times of recycling, has the characteristics of self-activation and super water resistance, and can solve many problems of a sodium alkoxide catalyst.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate. Background Technology

[0002] Dimethyl carbonate (DMC) is widely used as a raw material in organic synthesis reactions and as an environmentally friendly solvent. Compared with other synthetic routes, the synthesis of DMC by transesterification of cyclic carbonates such as propylene carbonate (PC) or ethylene carbonate (EC) with methanol (MeOH) has advantages such as mild conditions, low equipment investment costs, high economy, and high safety, making it the mainstream process for industrial DMC synthesis.

[0003] The direct transesterification reaction between cyclic carbonates and MeOH is extremely slow, requiring a catalyst to accelerate it for practical application. Catalysts accelerate the reaction rate by altering the reaction pathway and lowering the energy barrier. During long-term operation or cyclic reactions, most chemical catalysts are inevitably affected by factors such as reactants, impurities, heat, and oxygen, resulting in irreversible activity decay and changes in physical properties (such as solubility). For existing homogeneous transesterification catalysts, this manifests as a decrease in catalytic activity and a deterioration in solubility in reactants with increasing cycles, making it extremely difficult to observe an automatic increase in catalytic activity during use.

[0004] In the industrial production of DMC via transesterification of cyclic carbonates and methanol, sodium methoxide is typically used as a homogeneous catalyst. While sodium methoxide exhibits high catalytic activity for transesterification, it suffers from several major problems in practical applications: its low solubility in the reaction mixture leads to easy crystallization; and it readily reacts with moisture and organic carbonates in the feedstock to form sodium carbonate solid, which has even lower solubility in the system. These issues easily cause blockages in pipelines and reactors, necessitating frequent equipment maintenance and periodic catalyst replacement; they not only reduce catalytic efficiency but also result in feedstock waste and decreased production efficiency. Therefore, developing novel homogeneous catalytic DMC synthesis processes has significant industrial application value.

[0005] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of poor compatibility, water resistance and cycle stability of existing sodium alkoxide catalysts, and to provide an in-situ self-activated homogeneous catalytic transesterification method for the synthesis of dimethyl carbonate.

[0007] To achieve the above objectives, this invention discloses an in-situ self-activated homogeneous catalytic transesterification method for synthesizing dimethyl carbonate, comprising the following steps:

[0008] S1, using organic sulfonate as a homogeneous catalyst, is mixed evenly with cyclic carbonate and methanol, and stirred and refluxed at 55-80°C for 1-8 hours, then cooled to room temperature;

[0009] S2, the material obtained in step S1 is subjected to atmospheric distillation to collect a mixed fraction consisting of methanol and the target product dimethyl carbonate in the range of 64℃~91℃.

[0010] In step S1, the organic sulfonate is an organic sulfonate metal salt that exhibits good solubility in a mixture of cyclic carbonates and methanol, and its structural formula is: Where R is H or an alkyl group, m is a natural number from 0 to 2; n is a positive integer from 1 to 3, satisfying the relationship m + n = 3; x is a positive integer from 2 to 4, Me x+ These are +2 to +4 valence metal ions with empty orbitals.

[0011] In the structural formula, Me x+ For Mn 2+ Fe 2+ Ni 2+ Cu 2+ Zn 2+ ,Sc 3+ Cr 3+ Mn 3+ Co 3+ Fe 3+ Ti 4+ Any one of them.

[0012] In step S1, the organic sulfonate is an organic zinc sulfonate.

[0013] In step S1, the organic sulfonate is a metal salt of trifluoromethanesulfonate.

[0014] In step S1, the organic sulfonate is zinc trifluoromethanesulfonate.

[0015] In step S1, the cyclic carbonate is any one or a mixture of two of ethylene carbonate and propylene carbonate.

[0016] In step S1, the molar ratio of methanol to cyclic carbonate is 3 to 15:1, and the amount of organic sulfonate catalyst used is 0.5 to 12% of the total mass of cyclic carbonate and methanol.

[0017] Organic sulfonic acids are strong acids, and the salts formed by their anions and metal ions are ionic compounds. The structure and combination of the anions and cations of organic sulfonates have a decisive influence on their solubility in different solvents. Organometallic salts with good solubility in mixtures of cyclic carbonates and methanol can be screened as candidate catalysts for transesterification of cyclic carbonates and methanol based on solubility parameters or the principle of like dissolves like. The polarity and bond energy of the CF bond are higher than those of the C-C bond, and the bond length of the CF bond decreases and the bond energy increases with the increase of fluorine atoms on the same carbon atom. Therefore, when the organic substituent of the sulfonate anion contains multiple fluorine atoms, it not only improves the solubility of the organic sulfonate in polar solvents but also enhances its thermal stability, providing a structural basis for its use as a highly stable and long-lived catalyst. Experiments have shown that the zinc trifluoromethanesulfonate in this invention has good solubility in mixtures of cyclic carbonates and methanol and can serve as a highly efficient homogeneous catalyst for transesterification reactions. The acid radical anion and zinc cation contained in this substance can catalyze the transesterification reaction between cyclic carbonates and methanol in a synergistic effect: the negatively charged oxygen atom in the trifluoromethanesulfonate ion (acting as a hydrogen bond acceptor) can form a hydrogen bond with the hydroxyl hydrogen atom in the methanol molecule (acting as a hydrogen bond donor). This increases the negative charge density and nucleophilicity of the oxygen atom in the methoxy group, thus activating the methanol molecule. Zinc ions, as Lewis acids, can coordinate with the carbonyl oxygen of cyclic carbonates, increasing the positive charge density and electrophilicity of the carbonyl carbon atom, thereby activating the cyclic carbonate molecule. This allows the transesterification reaction to proceed with low activation energy and high reaction rate to yield dimethyl carbonate. From the above analysis, it is clear that the dissolution and subsequent dissociation of organic sulfonates in the transesterification system are essential for their catalytic activity.

[0018] Organic sulfonic acid metal salts activate cyclic carbonate and methanol molecules in a synergistic and homogeneous catalytic manner, enabling the transesterification reaction between the two to proceed with a lower activation energy and a higher reaction rate. This ensures that the transesterification reaction yields a high dimethyl carbonate yield under relatively mild reaction conditions.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. Organic sulfonic acid metal salts can efficiently catalyze the transesterification of cyclic carbonates with methanol to synthesize dimethyl carbonate. They exhibit excellent solubility, ensuring that the transesterification reaction and distillation separation process always proceed in a homogeneous manner. This avoids a series of problems caused by the poor solubility of traditional sodium alkoxide catalysts, such as easy crystallization and precipitation, scaling on the reactor wall, which leads to reduced catalytic efficiency and increased energy consumption.

[0021] 2. Organic sulfonic acid metal salts do not react chemically with the materials in the reaction system. They can maintain high catalytic activity and excellent solubility during multiple cycles of use, enabling the raw materials to be continuously converted into the target product of dimethyl carbonate at a high conversion rate, exhibiting excellent chemical stability. This solves the problem of sodium alkoxide catalysts reacting irreversibly with carbonates to precipitate as solid sodium carbonate, requiring frequent catalyst replacement during production. It can effectively ensure the stability and continuity of chemical production and reduce production costs.

[0022] 3. The more prominent advantage of the homogeneous catalyst of organic sulfonic acid metal salt is that it has the characteristics of "self-activation" and "super water resistance": (1) After the first use, the homogeneous catalyst can exhibit higher catalytic activity in subsequent continuous cycles than when it was first used, showing the characteristic of "self-activation"; (2) After multiple cycles with water, the catalyst does not suffer any damage to its activity, and after anhydrous cycles, its activity and solubility will not change, showing super water resistance. Detailed Implementation

[0023] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the embodiments.

[0024] Example 1

[0025] A method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate includes the following steps:

[0026] Step 1: Take 12 parts by weight of methanol (MeOH), 1 part by weight of ethylene carbonate (EC), and 10.0% by weight of zinc trifluoromethanesulfonate (based on the total mass of methanol and ethylene carbonate) and add them to a three-necked flask equipped with a reflux reflux device. Mix well. Stir and reflux the mixture at 60°C for 7 hours. Stop heating and cool to room temperature.

[0027] Step 2: Distill the mixture after reaction at atmospheric pressure, collect the fraction at 64-91℃, weigh the collected fraction and perform gas chromatography analysis.

[0028] Example 2

[0029] A method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate includes the following steps:

[0030] Step 1: Take 9 parts by weight of methanol, 1 part by weight of ethylene carbonate, and 1.0% by weight of zinc trifluoromethanesulfonate (based on the total mass of methanol and ethylene carbonate) and add them to a three-necked flask equipped with a reflux reflux device. Mix them thoroughly. Stir and reflux the mixture at 68°C for 2 hours. Stop heating and cool to room temperature.

[0031] Step 2: Distill the mixture after reaction at atmospheric pressure, collect the fraction at 64-91℃, weigh the collected fraction and perform gas chromatography analysis.

[0032] Example 3

[0033] A method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate includes the following steps:

[0034] Step 1: Take 4 parts by weight of methanol, 1 part by weight of ethylene carbonate, and 3.0% by weight of zinc trifluoromethanesulfonate (based on the total mass of methanol and ethylene carbonate) and add them to a three-necked flask equipped with a reflux reflux device. Mix them thoroughly. Stir and reflux the mixture at 70°C for 7 hours. Stop heating and cool to room temperature.

[0035] Step 2: Distill the mixture after reaction at atmospheric pressure, collect the fraction at 64-91℃, weigh the collected fraction and perform gas chromatography analysis.

[0036] Example 4

[0037] A method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate includes the following steps:

[0038] Step 1: Take 9 parts by weight of methanol, 1 part by weight of ethylene carbonate, and 10.0% by weight of zinc trifluoromethanesulfonate (based on the total mass of methanol and ethylene carbonate) and add them to a three-necked flask equipped with a reflux reflux device. Mix them thoroughly. Stir and reflux the mixture at 72°C for 7 hours. Stop heating and cool to room temperature.

[0039] Step 2: Distill the mixture after reaction at atmospheric pressure, collect the fraction at 64-91℃, weigh the collected fraction and perform gas chromatography analysis.

[0040] Example 5

[0041] A method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate includes the following steps:

[0042] Step 1: Take 9 parts by weight of methanol, 1 part by weight of ethylene carbonate, and 7.0% by weight of zinc trifluoromethanesulfonate (based on the total mass of methanol and ethylene carbonate) and add them to a three-necked flask equipped with a reflux reflux device. Mix them thoroughly. Stir and reflux the mixture at 70°C for 7 hours. Stop heating and cool to room temperature.

[0043] Step 2: Distill the mixture after reaction at atmospheric pressure, collect the fraction at 64-91℃, weigh the collected fraction and perform gas chromatography analysis.

[0044] In Examples 1-5, the material systems in the transesterification and distillation processes were homogeneous, with no precipitation or scaling on the flask walls, indicating that the organic sulfonate catalyst has good compatibility with the alcohol-ester reaction system.

[0045] The composition of the fractions collected by atmospheric distillation in each embodiment and comparative example was analyzed using a GC-2010 Pro gas chromatograph. The quantitative method was the area normalization method with proportionality factor correction. Test conditions: N2 as carrier gas; SH-Rtx-1701 capillary column; injection port temperature 200℃; column oven temperature programmed: 50℃ for 2.5 minutes, then increased to 125℃ at a rate of 25℃ / min; FID detector, temperature 250℃. The mass of the fractions collected by atmospheric distillation in each embodiment is represented by m. The mass percentages of dimethyl carbonate and methanol in the fractions determined by gas chromatography are represented by a and b, respectively. The mass of ethylene carbonate used in the transesterification formulations of each embodiment is represented by m. This indicates the yield Y of the corresponding product, dimethyl carbonate. DMC Calculate using the following formula:

[0046] ;

[0047] In the formula , The numbers represent the relative molecular masses of dimethyl carbonate and ethylene carbonate, respectively.

[0048] The specific schemes and dimethyl carbonate yields of Examples 1-5 are shown in Table 1 below:

[0049] Table 1. Synthesis of dimethyl carbonate and its yield from homogeneous catalytic transesterification reactions in Examples 1-5

[0050]

[0051] As can be seen from Table 1, even under conditions of lower methanol dosage, lower reaction temperature, and shorter reaction time, the DMC yield of the catalyst of the present invention can still reach 22-25%, indicating that the catalyst has high catalytic activity.

[0052] Example 6

[0053] The homogeneous catalyst zinc trifluoromethanesulfonate was used in 10 cycles. In each cycle, the same mass of methanol and ethylene carbonate were used at a molar ratio of 10:1, and the mixture was stirred and refluxed at 68°C for 7.0 hours. In the first cycle, 5.5% (by mass of the total mass of methanol and ethylene carbonate) of zinc trifluoromethanesulfonate was added to the reaction system. After each reaction, the reactants were subjected to atmospheric distillation and vacuum distillation sequentially. Atmospheric distillation was performed according to step 2 in Example 1. The undistilled mixture was transferred to a rotary evaporator and evaporated under reduced pressure at 150–160°C for 2 hours. The remaining mixture (composed of the catalyst and a small amount of undistilled ethylene glycol and ethylene carbonate) was cooled to room temperature and then entered the next transesterification cycle. The methanol and dimethyl carbonate contents in the fraction collected during atmospheric distillation were analyzed using the gas chromatography method and conditions described above, and the dimethyl carbonate yield in each cycle was calculated. The dimethyl carbonate yield, transesterification reaction process, and material system state during atmospheric distillation for each cycle are listed in Table 2.

[0054] Table 2. Dimethyl carbonate yield, reactants, and atmospheric distillation system status in the zinc trifluoromethanesulfonate cyclic test.

[0055]

[0056] Table 2 shows that, under the same formulation and reaction conditions, the DMC yield of zinc trifluoromethanesulfonate was 34.4% in the first use, while the dimethyl carbonate yield in the second to tenth uses was around 60%, significantly higher than the first use. This indicates that zinc trifluoromethanesulfonate underwent self-activation in the first use, and this activated catalytic activity was stably maintained. Furthermore, the materials in both the transesterification reaction system and the atmospheric distillation system remained homogeneous in each cycle, demonstrating that zinc trifluoromethanesulfonate maintains good solubility in the transesterification reaction system.

[0057] Example 7

[0058] Zinc trifluoromethanesulfonate was used as a homogeneous catalyst in two cycles to verify its "self-activation" phenomenon during use. In each cycle, equal masses of methanol and ethylene carbonate were used at a molar ratio of 9:1, and the mixture was stirred and refluxed at 70°C for 7.0 hours. In the first cycle, 5% (by mass) of zinc trifluoromethanesulfonate was added to the reaction system. After the first reaction, atmospheric distillation was performed, and the fraction collected at 64–91°C was distilled. The undistilled mixture was transferred to a rotary evaporator and evaporated under reduced pressure at 150–160°C for 2 hours. The remaining mixture (composed of the catalyst and a small amount of undistilled ethylene glycol and ethylene carbonate) was cooled to room temperature before being used in the second cycle. The contents of methanol and dimethyl carbonate in the fractions collected by atmospheric distillation were analyzed according to the gas chromatography method and conditions described above, and the dimethyl carbonate yield in the two cycles was calculated. The dimethyl carbonate yield, transesterification reaction process and material system state of the atmospheric distillation process in each cycle are listed in Table 3.

[0059] Table 3. Dimethyl carbonate yield, reactants, and atmospheric distillation system status in the homogeneous catalytic transesterification cycle test of zinc trifluoromethanesulfonate.

[0060]

[0061] As shown in Table 3, under the same formulation and reaction conditions, the DMC yield was 39.60% in the first use of zinc trifluoromethanesulfonate, and the dimethyl carbonate yield increased to 67.62% in the second use, which was much higher than the first cycle. This indicates that zinc trifluoromethanesulfonate produced a "self-activation" phenomenon in the first use.

[0062] Example 8

[0063] Zinc trifluoromethanesulfonate was dried at 80–160 °C for 2 hours using both atmospheric and vacuum drying methods. The weight loss rate was calculated by the ratio of the weight difference before and after drying to the original weight. Simultaneously, with a methanol to ethylene carbonate molar ratio of 9:1 and zinc trifluoromethanesulfonate comprising 5% of the mass of methanol and ethylene carbonate after drying, the mixture was stirred and refluxed at 70 °C for 7 hours. After the reaction was complete, atmospheric distillation was performed, and the fractions from 64–91 °C were collected. Gas chromatography was used to analyze the fractions and calculate the DMC yield. The weight loss rate and DMC yield of zinc trifluoromethanesulfonate under different drying conditions are shown in Table 4.

[0064] Table 4. Weight loss and DMC yield of zinc trifluoromethanesulfonate under different drying conditions

[0065]

[0066] As shown in Table 4, under the same material ratio, dosage, and reaction conditions, the DMC yield of zinc trifluoromethanesulfonate under different drying conditions was improved to some extent compared with the undried condition (Table 3, Example 7, first cycle, 39.6%), but it was still much lower than the 67.62% in the second cycle of Example 7. Especially at 140 and 160°C, the weight loss rate of zinc trifluoromethanesulfonate was almost the same regardless of whether it was dried at atmospheric pressure or under vacuum, indicating that the zinc trifluoromethanesulfonate raw material was completely dehydrated. However, the DMC yield under these conditions was much lower than that in the second cycle of Example 7, which fully demonstrates that the "activation" of zinc trifluoromethanesulfonate in Examples 6 and 7 was not due to the removal of its chemically or physically adsorbed water by drying. This "activation" occurred in situ during the transesterification reaction.

[0067] Example 9

[0068] Zinc trifluoromethanesulfonate was subjected to six cycles with water and three cycles without water to verify its water resistance. In each cycle, the same mass of methanol and ethylene carbonate were used at a molar ratio of 9:1. In cycles 1-6, 1% (by mass of methanol and ethylene carbonate) of deionized water was added at the initial feed, and the mixture was stirred and refluxed at 70°C for 7.0 hours. In the first cycle, 5% (by mass of methanol and ethylene carbonate) of zinc trifluoromethanesulfonate was added to the reaction system. After each reaction, the reactants were subjected to atmospheric distillation and vacuum distillation sequentially. Atmospheric distillation was performed according to step 2 in Example 1. The undistilled mixture was transferred to a rotary evaporator and evaporated under reduced pressure at 150-160°C for 2 hours. The remaining mixture (composed of catalyst and a small amount of undistilled ethylene glycol and ethylene carbonate) was cooled to room temperature before entering the next transesterification cycle. After completing the first six cycles with water, three more anhydrous cycles were performed using the rotary distillation residue mixture containing zinc trifluoromethanesulfonate catalyst (without adding deionized water). The amounts of methanol and ethylene carbonate, reaction conditions, and cycling methods were exactly the same as the first six cycles. The contents of methanol and dimethyl carbonate in the fractions collected during atmospheric distillation were analyzed using the gas chromatography method and conditions described above, and the yield of dimethyl carbonate in each cycle was calculated. The dimethyl carbonate yield, transesterification reaction process, and material system state during the atmospheric distillation process for each cycle are listed in Table 5.

[0069] Table 5. DMC yield of zinc trifluoromethanesulfonate via water circulation test

[0070]

[0071] As shown in Table 5, the DMC yield decreased to some extent during the aqueous cycle, but the DMC yield in the subsequent anhydrous cycle increased back to its "self-activation" level, even slightly higher than the DMC yield in cycles 2-10 of Example 6. This indicates that moisture only inhibits the catalytic activity of zinc trifluoromethanesulfonate to a certain extent, but does not irreversibly damage the catalyst. Furthermore, in all aqueous and anhydrous cycles of this example, the material systems of the transesterification reaction and atmospheric distillation processes were homogeneous, demonstrating that the presence of moisture had no adverse effect on the solubility of zinc trifluoromethanesulfonate, indicating that the zinc trifluoromethanesulfonate catalyst has excellent water resistance.

[0072] Comparative Example 1

[0073] A cyclic test was conducted using sodium methoxide. In each cycle, the same mass of 78.4 parts methanol and 21.6 parts ethylene carbonate (molar ratio 10:1) were reacted at 70℃ for 7.0 hours. In the first cycle, 1.66 parts sodium methoxide were added. After each reaction, atmospheric distillation was performed, collecting the fraction between 64℃ and 91℃. The undistilled mixture was transferred to a rotary evaporator and evaporated under reduced pressure at 150–160℃ for 2 hours. The remaining mixture (composed of catalyst and a small amount of undistilled ethylene glycol and ethylene carbonate) was cooled to room temperature and then entered the next transesterification cycle. The methanol and dimethyl carbonate contents in the fractions collected from atmospheric distillation in each cycle were tested using the gas chromatography method and conditions described above, and the dimethyl carbonate yield was calculated. The dimethyl carbonate yield and the material states during each cycle are shown in Table 6. As can be seen from Table 6, although the catalytic activity of sodium methoxide does not decrease during the cycle, its solubility deteriorates with the increase of the number of cycles.

[0074] Table 6 Sodium methoxide recycling test

[0075]

[0076] Comparative Example 2

[0077] Seven cycles with water and one cycle without water were conducted using sodium methoxide. In each cycle with water, the same mass of 78.4 parts methanol, 21.6 parts ethylene carbonate (molar ratio 10:1), and 1 part water were added to a three-necked flask equipped with a reflux condenser and subjected to transesterification at 70°C for 7 hours. For the first cycle, 1.63 parts sodium methoxide were added. After each transesterification reaction, the reactants were first distilled at atmospheric pressure, collecting a mixed fraction consisting of methanol and the target product dimethyl carbonate within the temperature range of 64°C–91°C. The undistilled mixture was then transferred to a rotary evaporator and evaporated under reduced pressure at 150–160°C for 2 hours. The remaining mixture (composed of catalyst and a small amount of undistilled ethylene glycol and EC) was cooled to room temperature and directly introduced into the next transesterification cycle. After the first seven cycles with water, a third anhydrous cycle (without adding deionized water) was performed using the rotary distillation residue mixture containing sodium methoxide catalyst. The amounts of methanol and ethylene carbonate, reaction conditions, and distillation method were exactly the same as in the first seven cycles. The contents of methanol and dimethyl carbonate in the fractions collected during atmospheric distillation were analyzed using the gas chromatography method and conditions described above, and the yield of dimethyl carbonate in each cycle was calculated. The dimethyl carbonate yield, transesterification reaction process, and material system state during atmospheric distillation for each cycle are listed in Table 7. As can be seen from Table 7, the DMC yield decreased in the water-containing cycle experiment, indicating that the catalytic activity of sodium methoxide was also inhibited by water; and in the eighth cycle without adding deionized water, the DMC yield decreased significantly, indicating that sodium methoxide has poor water resistance.

[0078] Table 7. DMC yield and reaction system states with sodium methoxide catalyst and water circulation

[0079]

[0080] In summary, the organic sulfonate catalytic transesterification synthesis of dimethyl carbonate provided by this invention enables transesterification to proceed in a homogeneous manner in multiple cycles. The catalyst in this technology has high catalytic activity and stability, and possesses in-situ "self-activation" and "super water resistance" characteristics. It can solve many problems of traditional catalysts, such as insufficient solubility and blockage of pipelines and towers caused by reactions with water and organic carbonates, requiring frequent equipment maintenance, catalyst replacement or addition.

[0081] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate, characterized in that, Includes the following steps: S1, using organic sulfonate as a homogeneous catalyst, is mixed evenly with cyclic carbonate and methanol, and stirred and refluxed at 55-80°C for 1-8 hours, then cooled to room temperature; S2, the material obtained in step S1 is subjected to atmospheric distillation to collect a mixed fraction consisting of methanol and the target product dimethyl carbonate in the range of 64℃~91℃.

2. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 1, characterized in that, In step S1, the organic sulfonate is an organic sulfonate metal salt that exhibits good solubility in a mixture of cyclic carbonates and methanol, and its structural formula is: Where R is H or an alkyl group, m is a natural number from 0 to 2; n is a positive integer from 1 to 3, satisfying the relationship m + n = 3; x is a positive integer from 2 to 4, Me x+ These are +2 to +4 valence metal ions with empty orbitals.

3. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 2, characterized in that, In the structural formula, Me x+ For Mn 2+ Fe 2+ Ni 2+ Cu 2+ Zn 2+ ,Sc 3+ Cr 3+ Mn 3+ Co 3+ Fe 3+ Ti 4+ Any one of them.

4. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 1, characterized in that, In step S1, the organic sulfonate is an organic zinc sulfonate.

5. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 1, characterized in that, In step S1, the organic sulfonate is a metal salt of trifluoromethanesulfonate.

6. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 1, characterized in that, In step S1, the organic zinc sulfonate salt is zinc trifluoromethanesulfonate.

7. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 1, characterized in that, In step S1, the cyclic carbonate is any one or a mixture of two of ethylene carbonate and propylene carbonate.

8. The method for in-situ self-activated homogeneous catalytic transesterification synthesis of dimethyl carbonate as described in claim 1, characterized in that, In step S1, the molar ratio of methanol to cyclic carbonate is 3 to 15:1, and the amount of organic sulfonate catalyst used is 0.5 to 12% of the total mass of cyclic carbonate and methanol.

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