1, 3-dimethyl-2-imidazolinone and green synthesis method thereof

Abstract

The invention belongs to the technical field of organic matter preparation, and discloses 1, 3-dimethyl-2-imidazolinone and a green synthesis method thereof. The synthesis method comprises the following steps: in a carbon dioxide atmosphere, mixing methanol with a catalyst, reacting to obtain dimethyl carbonate, mixing cesium carbonate, ethylenediamine and methanol, introducing carbon dioxide, reacting to obtain 2-imidazolidinone, and reacting dimethyl carbonate, 2-imidazolidinone and the catalyst to obtain 1, 3-dimethyl-2-imidazolidinone. The raw materials in the whole technological process are in closed circulation, circular economy is achieved to the maximum extent, and the method is a green and environment-friendly synthesis process.

Description

Technical Field

[0001] The present invention relates to the technical field of organic matter preparation, and particularly relates to 1,3-dimethyl-2-imidazolidinone and a green synthesis method thereof. Background Art

[0002] 1,3-Dimethyl-2-imidazolidinone (DMI) is a transparent and colorless polar aprotic solvent. Its excellent solubility can dissolve many polar organic and inorganic substances and is miscible with water in any proportion. It has the characteristics of low toxicity, safety, and stability, and is widely used in the fields of petrochemical industry, pharmaceuticals, electronic chips, etc.

[0003] Existing DMI synthesis methods include carbon dioxide method, phosgene method, trichloroacetyl chloride method, urea method, and 2-imidazolidinone methylation method. Currently, in industrial production of DMI, urea and ethylenediamine are mainly used as raw materials to first synthesize 2-imidazolidinone, and then N-methylation of 2-imidazolidinone is carried out to obtain the product DMI. The methylation of 2-imidazolidinone is commonly carried out by the "formic acid method" and the "hydrogenation method". Among them, the "formic acid method" is the commonly used method in current production. Its production cost is relatively low, but there are problems such as acid corrosion of equipment, environmental pollution, poor product quality, and difficulty in refining. The traditional reaction kettle type "hydrogenation method" has problems such as low production efficiency, low purity of the prepared product, and high production cost.

[0004] Therefore, it is of great significance to research and obtain a synthesis method of 1,3-dimethyl-2-imidazolidinone with circular economy and environmental friendliness. Summary of the Invention

[0005] In view of this, the present invention provides 1,3-dimethyl-2-imidazolidinone and a green synthesis method thereof, aiming to solve the problems of low production efficiency, high production cost, environmental impact, and low purity of the prepared product existing in the existing DMI synthesis methods.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a green synthesis method of 1,3-dimethyl-2-imidazolidinone, including the following steps:

[0008] 1) Under a carbon dioxide atmosphere, methanol is mixed with a catalyst, and after reaction, dimethyl carbonate (DMC) is obtained;

[0009] 2) Cesium carbonate, ethylenediamine, and methanol are mixed and carbon dioxide is introduced, and after reaction, 2-imidazolidinone (MI) is obtained;

[0010] 3) After reaction of dimethyl carbonate, 2-imidazolidinone, and a catalyst, 1,3-dimethyl-2-imidazolidinone (DMI) is obtained;

[0011] Steps 1) and 2) are not in a specific sequence.

[0012] Preferably, in step 1), the molar ratio of methanol to the catalyst is 20 - 30:1;

[0013] The catalyst is nickel acetate tetrahydrate.

[0014] Preferably, in step 1), the reaction temperature is 30 - 35°C, the reaction pressure is 9 - 9.5 MPa, and the reaction time is 100 - 150 min.

[0015] Preferably, in step 2), the dosage ratio of cesium carbonate, ethylenediamine and methanol is 2 g: 90 - 120 mL: 180 - 220 mL;

[0016] The amount of carbon dioxide introduced is such that the pressure of the reaction in step 2) is 4.3 - 4.7 MPa.

[0017] Preferably, in step 2), the reaction temperature is 170 - 180°C, and the reaction time is 2 - 8 h.

[0018] Preferably, in step 3), the molar ratio of dimethyl carbonate to 2 - imidazolidinone is 1.5 - 2.5:1.

[0019] Preferably, in step 3), the catalyst is cetyltrimethylammonium bromide or tetrabutylammonium bromide;

[0020] The mass ratio of the sum of the masses of dimethyl carbonate and 2 - imidazolidinone to the mass of the catalyst is 100: 2 - 6.4.

[0021] Preferably, in step 3), the reaction temperature is 180 - 250°C, the reaction time is 10 - 15 h, and the reaction pressure is 5 - 6 MPa.

[0022] The present invention also provides 1,3 - dimethyl - 2 - imidazolidinone prepared by the green synthesis method of 1,3 - dimethyl - 2 - imidazolidinone.

[0023] Through the above - mentioned technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0024] In the synthesis method of the present invention, dimethyl carbonate is prepared by catalytic reaction of methanol and carbon dioxide; 2 - imidazolidinone is prepared by catalytic reaction of ethylenediamine and carbon dioxide; finally, dimethyl carbonate and 2 - imidazolidinone are reacted to prepare 1,3 - dimethyl - 2 - imidazolidinone, and the by - product methanol and carbon dioxide are recycled to prepare dimethyl carbonate. The whole process has raw materials in a closed - loop cycle, and maximizes the realization of circular economy, which is a green and environmentally friendly synthesis process. Detailed implementation mode

[0025] The present invention provides a green synthesis method of 1,3-dimethyl-2-imidazolidinone, which comprises the following steps:

[0026] 1) Under a carbon dioxide atmosphere, methanol and a catalyst are mixed, and after reaction, dimethyl carbonate is obtained;

[0027] 2) Cesium carbonate, ethylenediamine and methanol are mixed and then carbon dioxide is introduced, and after reaction, 2-imidazolidinone is obtained;

[0028] 3) After dimethyl carbonate, 2-imidazolidinone and a catalyst react, 1,3-dimethyl-2-imidazolidinone is obtained;

[0029] Steps 1) and 2) are not in a specific order.

[0030] In the present invention, in step 1), the molar ratio of methanol to the catalyst is preferably 20-30:1, more preferably 22-28:1, and even more preferably 25-26:1;

[0031] The catalyst is preferably nickel acetate tetrahydrate.

[0032] In the present invention, in step 1), the reaction temperature is preferably 30-35°C, more preferably 31-34°C, and even more preferably 32-33°C; the reaction pressure is preferably 9-9.5 MPa, more preferably 9.1-9.4 MPa, and even more preferably 9.2-9.3 MPa; the reaction time is preferably 100-150 min, more preferably 110-140 min, and even more preferably 120-130 min.

[0033] In the present invention, in step 1), the mixing is preferably carried out under stirring, and the stirring is preferably magnetic stirring. The rotation speed of the magnetic stirring is preferably 250-350 rpm, more preferably 270-330 rpm, and even more preferably 280-300 rpm;

[0034] The heating rate for raising the temperature to the reaction temperature is preferably 0.1-0.3°C / min, more preferably 0.15-0.25°C / min, and even more preferably 0.18-0.2°C / min; the pressure increasing rate for increasing the pressure to the reaction pressure is preferably 0.008-0.013 MPa / min, more preferably 0.009-0.012 MPa / min, and even more preferably 0.01-0.011 MPa / min.

[0035] In the present invention, in step 1), after the reaction, centrifugation and rectification are successively carried out to obtain dimethyl carbonate;

[0036] The rotation speed of centrifugation is preferably 1200 - 1800 rpm, more preferably 1300 - 1700 rpm, and even more preferably 1500 - 1600 rpm. The time of centrifugation is preferably 3 - 7 min, more preferably 4 - 6 min, and even more preferably 5 min.

[0037] In the present invention, the reaction formula of step 1) is shown as formula (I):

[0038]

[0039] In the present invention, in step 2), the dosage ratio of cesium carbonate, ethylenediamine and methanol is preferably 2 g: 90 - 120 mL: 180 - 220 mL, more preferably 2 g: 95 - 110 mL: 190 - 210 mL, and even more preferably 2 g: 100 - 105 mL: 200 - 205 mL;

[0040] The amount of carbon dioxide introduced is such that the pressure of the reaction in step 2) is preferably 4.3 - 4.7 MPa, more preferably 4.4 - 4.6 MPa, and even more preferably 4.5 MPa.

[0041] In the present invention, in step 2), the reaction temperature is preferably 170 - 180 °C, more preferably 172 - 178 °C, and even more preferably 174 - 175 °C. The reaction time is preferably 2 - 8 h, more preferably 3 - 7 h, and even more preferably 4 - 5 h; After the reaction, rectification separation is carried out.

[0042] In the present invention, step 2) is carried out under stirring, and the stirring rate is preferably 280 - 320 rpm, more preferably 290 - 310 rpm, and even more preferably 300 rpm.

[0043] In the present invention, the reaction formula of step 2) is shown as formula (II):

[0044]

[0045] In the present invention, in step 3), the molar ratio of dimethyl carbonate to 2 - imidazolidinone is preferably 1.5 - 2.5:1, more preferably 1.7 - 2.3:1, and even more preferably 1.8 - 2:1.

[0046] In the present invention, in step 3), the catalyst is preferably cetyltrimethylammonium bromide or tetrabutylammonium bromide;

[0047] The mass ratio of the sum of the masses of dimethyl carbonate and 2 - imidazolidinone to the mass of the catalyst is preferably 100:2 - 6.4, more preferably 100:2.3 - 6, and even more preferably 100:3.3 - 5.

[0048] In the present invention, in step 3), the reaction temperature is preferably 180 - 250 °C, more preferably 190 - 240 °C, and even more preferably 200 - 220 °C; the reaction time is preferably 10 - 15 h, more preferably 11 - 14 h, and even more preferably 12 - 13 h; the reaction pressure is preferably 5 - 6 MPa, more preferably 5.2 - 5.8 MPa, and even more preferably 5.5 - 5.6 MPa.

[0049] In the present invention, in step 3), the reaction is preferably carried out under stirring, and the stirring speed is preferably 150 - 200 rpm, more preferably 160 - 190 rpm, and even more preferably 170 - 180 rpm; after the reaction, atmospheric distillation is carried out to remove unreacted dimethyl carbonate, methanol and low-boiling compounds.

[0050] In the present invention, the reaction formula of step 3) is shown as formula (III):

[0051]

[0052] In the present invention, the methanol and carbon dioxide generated during the preparation of 1,3-dimethyl-2-imidazolidinone are returned to step 1) for recycling in the preparation of dimethyl carbonate.

[0053] The present invention also provides 1,3-dimethyl-2-imidazolidinone prepared by the green synthesis method of 1,3-dimethyl-2-imidazolidinone.

[0054] The technical solutions provided by the present invention are described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

[0055] In the examples of the present invention, the yields are all detected by gas chromatography.

[0056] Example 1

[0057] Under a continuously introduced carbon dioxide atmosphere, methanol and nickel acetate tetrahydrate were magnetically stirred at a molar ratio of 25:1 at a speed of 300 rpm, and heated to 32 °C at a heating rate of 0.2 °C / min and pressurized to 9.3 MPa at a pressurization rate of 0.01 MPa / min. After reacting for 120 min, it was cooled and the residual gas was released. After centrifuging at a speed of 1500 rpm for 5 min, the reaction solution was subjected to distillation separation to obtain dimethyl carbonate with a yield of 63.7%;

[0058] Into a high-pressure reactor with a stirring speed of 300 rpm, cesium carbonate, ethylenediamine and methanol were added according to the dosage ratio of 2 g:100 mL:200 mL. After mixing, carbon dioxide was continuously introduced until the pressure in the high-pressure reactor remained at 4.5 MPa, and the reaction was carried out at 180 °C for 2 h. When the pressure in the high-pressure reactor remained unchanged for 30 min, the heating was stopped. After cooling to room temperature, the gas outlet valve of the high-pressure reactor was opened, and the obtained reaction solution was subjected to vacuum distillation to remove methanol, obtaining 2-imidazolidinone. The obtained 2-imidazolidinone contained 5.6% of by-products, and the yield of 2-imidazolidinone was 93.6%;

[0059] Dimethyl carbonate, 2-imidazolidinone and tetrabutylammonium bromide were added into a high-pressure reactor with a stirring speed of 180 rpm (the molar ratio of dimethyl carbonate to 2-imidazolidinone was 2:1, and the mass ratio of the sum of the masses of dimethyl carbonate and 2-imidazolidinone to the mass of tetrabutylammonium bromide was 100:3.3). The reaction was carried out at 210 °C for 15 h under a pressure of 6 MPa, and then cooled to room temperature. The reactor was emptied and depressurized, and then atmospheric distillation was carried out to remove unreacted dimethyl carbonate, methanol and low-boiling compounds, obtaining 1,3-dimethyl-2-imidazolidinone with a yield of 73%.

[0060] Example 2

[0061] Under a continuously introduced carbon dioxide atmosphere, methanol and nickel acetate tetrahydrate were magnetically stirred at a speed of 300 rpm according to a molar ratio of 25:1, and heated to 32 °C at a heating rate of 0.2 °C / min and pressurized to 9.3 MPa at a pressure increase rate of 0.01 MPa / min. After reacting for 120 min, it was cooled and the residual gas was released. After centrifuging at a speed of 1500 rpm for 5 min, the reaction solution was subjected to distillation separation to obtain dimethyl carbonate with a yield of 63.7%;

[0062] Into a high-pressure reactor with a stirring speed of 300 rpm, cesium carbonate, ethylenediamine and methanol were added according to the dosage ratio of 2 g:100 mL:200 mL. After mixing, carbon dioxide was continuously introduced until the pressure in the high-pressure reactor remained at 4.5 MPa, and the reaction was carried out at 170 °C for 3 h. When the pressure in the high-pressure reactor remained unchanged for 30 min, the heating was stopped. After cooling to room temperature, the gas outlet valve of the high-pressure reactor was opened, and the obtained reaction solution was subjected to vacuum distillation to remove methanol, obtaining 2-imidazolidinone. The obtained 2-imidazolidinone contained 7.5% of by-products, and the yield of 2-imidazolidinone was 89.9%;

[0063] Dimethyl carbonate, 2-imidazolidinone and tetrabutylammonium bromide were added to a high-pressure reactor with a stirring speed of 180 rpm (the molar ratio of dimethyl carbonate to 2-imidazolidinone was 2:1, and the mass ratio of the sum of the masses of dimethyl carbonate and 2-imidazolidinone to the mass of tetrabutylammonium bromide was 100:3.3). The reaction was carried out at 205 °C for 12 h under a pressure of 5 MPa and then cooled to room temperature. The reactor was emptied and depressurized, and then atmospheric distillation was carried out to remove unreacted dimethyl carbonate, methanol and low-boiling compounds, obtaining 1,3-dimethyl-2-imidazolidinone with a yield of 72%.

[0064] Example 3

[0065] Under a continuously introduced carbon dioxide atmosphere, methanol and nickel acetate tetrahydrate were magnetically stirred at a speed of 300 rpm according to a molar ratio of 25:1, and heated at a heating rate of 0.2 °C / min to 32 °C and pressurized at a pressure increasing rate of 0.01 MPa / min to 9.3 MPa. After reacting for 120 min, it was cooled and the residual gas was released. After centrifuging at a speed of 1500 rpm for 5 min, the reaction solution was subjected to distillation separation to obtain dimethyl carbonate with a yield of 63.7%;

[0066] Cesium carbonate, ethylenediamine and methanol were added to a high-pressure reactor with a stirring speed of 180 rpm according to a dosage ratio of 2 g:100 mL:200 mL. After mixing, carbon dioxide was continuously introduced until the pressure in the high-pressure reactor remained at 4.5 MPa, and the reaction was carried out at 170 °C for 5 h. When the pressure in the high-pressure reactor remained unchanged for 30 min, heating was stopped. After cooling to room temperature, the outlet valve of the high-pressure reactor was opened, and the obtained reaction solution was subjected to vacuum distillation to remove methanol, obtaining 2-imidazolidinone. The obtained 2-imidazolidinone contained 10.9% of by-products, and the yield of 2-imidazolidinone was 84.3%;

[0067] Dimethyl carbonate, 2-imidazolidinone and tetrabutylammonium bromide were added to a high-pressure reactor with a stirring speed of 180 rpm (the molar ratio of dimethyl carbonate to 2-imidazolidinone was 2:1, and the mass ratio of the sum of the masses of dimethyl carbonate and 2-imidazolidinone to the mass of tetrabutylammonium bromide was 100:3.3). The reaction was carried out at 205 °C for 10 h under a pressure of 5.5 MPa and then cooled to room temperature. The reactor was emptied and depressurized, and then atmospheric distillation was carried out to remove unreacted dimethyl carbonate, methanol and low-boiling compounds, obtaining 1,3-dimethyl-2-imidazolidinone with a yield of 70%.

[0068] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A green synthesis method of 1,3-dimethyl-2-imidazolidinone, characterized in that, It includes the following steps: 1) Under a carbon dioxide atmosphere, methanol is mixed with a catalyst, and dimethyl carbonate is obtained after the reaction; 2) Cesium carbonate, ethylenediamine and methanol are mixed and carbon dioxide is introduced, and 2-imidazolidinone is obtained after the reaction; 3) After dimethyl carbonate, 2-imidazolidinone and a catalyst react, 1,3-dimethyl-2-imidazolinone is obtained; Steps 1) and 2) are not in a specific order.

2. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 1, wherein In step 1), the molar ratio of methanol to the catalyst is 20-30:1; The catalyst is nickel acetate tetrahydrate.

3. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 2, characterized in that, In step 1), the reaction temperature is 30-35 °C, the reaction pressure is 9-9.5 MPa, and the reaction time is 100-150 min.

4. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 1 or 3, characterized in that, In step 2), the dosage ratio of cesium carbonate, ethylenediamine and methanol is 2 g: 90-120 mL: 180-220 mL; The amount of carbon dioxide introduced is such that the pressure of the reaction in step 2) is 4.3-4.7 MPa.

5. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 4, wherein In step 2), the reaction temperature is 170-180 °C, and the reaction time is 2-8 h.

6. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 5, wherein In step 3), the molar ratio of dimethyl carbonate to 2-imidazolidinone is 1.5-2.5:

1.

7. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 6, wherein, In step 3), the catalyst is cetyltrimethylammonium bromide or tetrabutylammonium bromide; The mass ratio of the sum of the masses of dimethyl carbonate and 2-imidazolidinone to the mass of the catalyst is 100: 2-6.

4.

8. The green synthesis method of 1,3-dimethyl-2-imidazolidinone according to claim 6 or 7, characterized in that, In step 3), the reaction temperature is 180-250 °C, the reaction time is 10-15 h, and the reaction pressure is 5-6 MPa.

9. 1,3-Dimethyl-2-imidazolinone prepared by the green synthesis method of 1,3-dimethyl-2-imidazolinone according to any one of claims 1-8.

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