High-purity 2-imidazolidinone and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of compounds, and discloses high-purity 2-imidazolidinone and a preparation method thereof. The preparation method of the high-purity 2-imidazolidinone comprises the following steps: reacting ethylenediamine, dimethyl carbonate and an ionic liquid catalyst to obtain primary 2-imidazolidinone; mixing the obtained primary 2-imidazolidinone with dimethyl carbonate, and filtering to obtain high-purity 2-imidazolidinone; the ionic liquid catalyst is chloridized 1-butyl-3-methylimidazole, brominated 1-butyl-3-methylimidazole, chloridized 1-ethyl-3-methylimidazole, brominated 1-ethyl-3-methylimidazole, 1-butyl-3-methylimidazole tetrafluoroborate or 1-ethyl-3-methylimidazole tetrafluoroborate, and the ionic liquid catalyst is an ionic liquid catalyst which is chloridized 1-butyl-3-methylimidazole, brominated 1-ethyl-3-methylimidazole, brominated 1-ethyl-3-methylimidazole tetrafluoroborate or 1-ethyl-3-methylimidazole tetrafluoroborate. According to the preparation method of the high-purity 2-imidazolidinone, a small amount of high-boiling-point byproducts such as MI and NMI and a dimethyl carbonate solution are further treated, and the target product MI with high purity is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of compound preparation, and particularly relates to a high-purity 2-imidazolidinone and a preparation 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 it can be 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, medicine, electronic chips, etc.

[0003] 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. After the crude product obtained by the existing synthesis process of 2-imidazolidinone (MI) separates and recovers the ionic liquid catalyst, in the remaining MI crude product, in addition to the main product MI, there are also a small amount of high-boiling by-products such as 1-methyl-2-imidazolidinone (NMI). It can be seen that the purity of MI prepared by the existing synthesis process of MI is relatively low.

[0004] Therefore, it is of great significance to study and obtain a 2-imidazolidinone with higher purity and its green, environmentally friendly and low-cost preparation method. Summary of the Invention

[0005] In view of this, the present invention provides a high-purity 2-imidazolidinone and a preparation method thereof, and the purpose is to solve the technical problems of more by-products and lower purity in the 2-imidazolidinone prepared by the existing preparation method.

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

[0007] The present invention provides a preparation method of high-purity 2-imidazolidinone, comprising the following steps:

[0008] 1) React ethylenediamine, dimethyl carbonate and an ionic liquid catalyst to obtain primary 2-imidazolidinone;

[0009] 2) Mix the obtained primary 2-imidazolidinone with dimethyl carbonate and then filter to obtain high-purity 2-imidazolidinone;

[0010] The ionic liquid catalyst in step 1) is 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0011] Preferably, in the step 1), the molar ratio of ethylenediamine, dimethyl carbonate and the ionic liquid catalyst is 1:1 to 1.5:0.08 to 0.15.

[0012] Preferably, in the step 1), the reaction temperature is 165 - 185 °C and the reaction time is 2 - 4 h.

[0013] Preferably, in the step 2), the molar ratio of primary 2 - imidazolidinone to dimethyl carbonate is 0.8 - 1.2:1.8 - 2.2.

[0014] Preferably, in the step 2), the mixing temperature is 70 - 80 °C and the mixing time is 20 - 40 min.

[0015] Preferably, in the step 1), after the reaction, distillation is carried out to obtain primary 2 - imidazolidinone; the distillation temperature is 150 - 200 °C and the distillation time is 1 - 3 h.

[0016] Preferably, in the step 2), after filtration, drying is carried out to obtain high - purity 2 - imidazolidinone; the drying temperature is 40 - 60 °C and the drying time is 7 - 9 h.

[0017] The present invention also provides the high - purity 2 - imidazolidinone prepared by the preparation method of the high - purity 2 - imidazolidinone. The purity of the high - purity 2 - imidazolidinone is 98.9 - 99.9%, and the yield of the high - purity 2 - imidazolidinone is 84.5 - 94%.

[0018] As can be seen from the above - mentioned technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a preparation method of high - purity 2 - imidazolidinone. The target product MI and a small amount of high - boiling - point by - products such as NMI are further processed with the dimethyl carbonate solution to obtain a target product MI with higher purity. The by - product NMI produced in the preparation of MI can continue to react to obtain DMI during the preparation of DMI. During the preparation of DMI, the methanol and carbon dioxide generated by side reactions are recycled to prepare dimethyl carbonate. The whole process is in a closed - loop cycle of raw materials and maximizes circular economy, which is a green and environmentally friendly synthesis process. Detailed Embodiments

[0020] The present invention provides a preparation method of high - purity 2 - imidazolidinone, which includes the following steps:

[0021] 1) React ethylenediamine, dimethyl carbonate and an ionic liquid catalyst to obtain primary 2 - imidazolidinone;

[0022] 2) Mix the obtained primary 2 - imidazolidinone with dimethyl carbonate and then filter to obtain high - purity 2 - imidazolidinone;

[0023] The ionic liquid catalysts described in step 1) are 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0024] In the present invention, in the said step 1), the molar ratio of ethylenediamine, dimethyl carbonate and the ionic liquid catalyst is preferably 1:1-1.5:0.08-0.15, more preferably 1:1.1-1.4:0.09-0.14, and still more preferably 1:1.2-1.3:0.1-0.12.

[0025] In the present invention, in the said step 1), the reaction temperature is preferably 165-185 °C, more preferably 170-180 °C, and still more preferably 175-178 °C; the reaction time is preferably 2-4 h, more preferably 2.5-3.5 h, and still more preferably 3 h.

[0026] In the present invention, the main reaction formula in the said step 1) is as shown in formula (I):

[0027]

[0028] The side reaction formula in the said step 1) is as shown in formula (II):

[0029]

[0030] In the present invention, in the said step 2), the molar ratio of primary 2-imidazolidinone to dimethyl carbonate is preferably 0.8-1.2:1.8-2.2, more preferably 0.9-1.1:1.9-2.1, and still more preferably 1:2.

[0031] In the present invention, in the said step 2), the mixing temperature is preferably 70-80 °C, more preferably 72-78 °C, and still more preferably 75-76 °C; the mixing time is preferably 20-40 min, more preferably 25-35 min, and still more preferably 30-32 min;

[0032] The heating method for the mixing is preferably oil bath heating.

[0033] In the present invention, in the said step 2), the filtration is preferably hot filtration.

[0034] In the present invention, in step 1), after the reaction, distillation is carried out to obtain primary 2-imidazolidinone; the distillation temperature is preferably 150-200 °C, more preferably 160-190 °C, still more preferably 170-180 °C, and the distillation time is preferably 1-3 h, more preferably 1.5-2.5 h, still more preferably 2 h;

[0035] The purpose of the distillation is to remove methanol in the product after the reaction.

[0036] In the present invention, in step 2), after filtration, drying is carried out to obtain high-purity 2-imidazolidinone; the drying temperature is preferably 40-60 °C, more preferably 45-55 °C, still more preferably 50-52 °C, and the drying time is preferably 7-9 h, more preferably 7.5-8.5 h, still more preferably 8 h;

[0037] The drying is preferably vacuum drying, and the vacuum degree of the vacuum drying is preferably -0.1 to -0.09 MPa, more preferably -0.098 to -0.092 MPa, still more preferably -0.095 to -0.094 MPa.

[0038] In the present invention, the treatment methods of the filtrate obtained after filtration in step 2) include Method 1 and Method 2:

[0039] Method 1: Distill to remove the solvent dimethyl carbonate in the filtrate, and then distill to remove the filtrate after dimethyl carbonate, and recrystallize and purify to obtain 2-imidazolidinone;

[0040] Method 2: Moderately concentrate the filtrate, and then use the remaining dimethyl carbonate in the filtrate as a solvent to recrystallize and purify the crude 2-imidazolidinone;

[0041] In the solvent screening for the separation and recovery of the catalyst in the present invention, it is found that at 75 °C, the solubility of MI in dimethyl carbonate is as high as 102.3 g / 100 g of solvent, while at a lower temperature (40 °C), the solubility of MI in dimethyl carbonate is only 3.6 g / 100 g of solvent. Therefore, dimethyl carbonate has the basic conditions for being used as a recrystallization solvent for MI (the solubility of the solute must have a significant difference at high and low temperatures), and using dimethyl carbonate as a solvent can simplify the MI recrystallization and purification process. Therefore, the second method (that is, moderately concentrating the filtrate and then directly recrystallizing) is selected to recrystallize and purify the crude MI after recovering the ionic liquid catalyst.

[0042] The present invention also provides high-purity 2-imidazolidinone prepared by the preparation method of the high-purity 2-imidazolidinone. The purity of the high-purity 2-imidazolidinone is preferably 98.9-99.9%, more preferably 99.2-99.8%, and still more preferably 99.5-99.7%. The yield of the high-purity 2-imidazolidinone is preferably 84.5-94%, more preferably 86-93%, and still more preferably 88-90%.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0044] Example 1

[0045] Ethylenediamine, dimethyl carbonate and 1-butyl-3-methylimidazolium bromide were mixed in a molar ratio of 1:1.2:0.1, reacted at 180°C for 2 h, and the reaction product was distilled at 180°C for 2 h to remove methanol in the reaction solution to obtain primary 2-imidazolidinone;

[0046] The primary 2-imidazolidinone and dimethyl carbonate were mixed in a molar ratio of 1:2 in an oil bath at 75°C for 30 min, filtered while hot, and the obtained filter cake was placed in a vacuum drying oven at 50°C (vacuum degree: -0.095 MPa) and dried for 8 h to obtain high-purity 2-imidazolidinone with a yield of 93.6%.

[0047] Example 2

[0048] Ethylenediamine, dimethyl carbonate and 1-ethyl-3-methylimidazolium chloride were mixed in a molar ratio of 1:1.2:0.1, reacted at 175°C for 2.5 h, and the reaction product was distilled at 180°C for 2 h to remove methanol in the reaction solution to obtain primary 2-imidazolidinone;

[0049] The primary 2-imidazolidinone and dimethyl carbonate were mixed in a molar ratio of 1:2 in an oil bath at 75°C for 30 min, filtered while hot, and the obtained filter cake was placed in a vacuum drying oven at 50°C (vacuum degree: -0.095 MPa) and dried for 8 h to obtain high-purity 2-imidazolidinone with a yield of 92.4%.

[0050] Example 3

[0051] Ethylenediamine, dimethyl carbonate and 1-butyl-3-methylimidazolium tetrafluoroborate were mixed in a molar ratio of 1:1.2:0.1, reacted at 170°C for 3 h, and the reaction product was distilled at 180°C for 2 h to remove methanol in the reaction solution to obtain primary 2-imidazolidinone;

[0052] The primary 2-imidazolidinone and dimethyl carbonate were mixed in a molar ratio of 1:2 in an oil bath at 75 °C for 30 min, filtered while it was hot, and the obtained filter cake was dried in a vacuum drying oven at 50 °C (vacuum degree: -0.095 MPa) for 8 h to obtain high-purity 2-imidazolidinone with a yield of 92.8%.

[0053] Pilot test: The purity of MI in the high-purity 2-imidazolidinone obtained in Examples 1 to 3 was analyzed by a gas chromatograph respectively, and the analysis results are shown in Table 1.

[0054] Table 1 Analysis results of the high-purity 2-imidazolidinone obtained in pilot test Examples 1 to 3

[0055] Example Example 1 Example 2 Example 3 Purity / % 98.9 99.4 99.8

[0056] As can be seen from Table 1, by using the preparation process of the high-purity 2-imidazolidinone described in the present invention, the purity of the obtained high-purity 2-imidazolidinone can reach more than 98.9%. After repeated experiments in multiple batches, this experimental result is stable and has achieved the expected goal.

[0057] Intermediate test: On the basis of the pilot test of the high-purity 2-imidazolidinone obtained in Examples 1 to 3, referring to the process shown in Example 1, a medium-scale amplification experiment was carried out. The yield of the product obtained from the medium-scale amplification experiment was calculated and the purity was analyzed. The test results are shown in Table 2.

[0058] Table 2 Analysis results of the high-purity 2-imidazolidinone obtained in intermediate test Examples 1 to 3

[0059]

[0060]

[0061] As can be seen from Table 2, although the product yield in the intermediate test results is lower than that in the pilot test results, the purity of the obtained high-purity 2-imidazolidinone is still higher than 99.4%. It can be seen that the purity of the 2-imidazolidinone prepared by the preparation method described in the present invention is relatively high.

[0062] 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 still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of high-purity 2-imidazolidinone, characterized in that, It includes the following steps: 1) React ethylenediamine, dimethyl carbonate and an ionic liquid catalyst to obtain primary 2-imidazolidinone; 2) Mix the obtained primary 2-imidazolidinone with dimethyl carbonate and then filter to obtain high-purity 2-imidazolidinone; The ionic liquid catalyst described in step 1) is 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium tetrafluoroborate or 1-ethyl-3-methylimidazolium tetrafluoroborate.

2. The preparation method of a high-purity 2-imidazolidinone according to claim 1, characterized in that, In step 1), the molar ratio of ethylenediamine, dimethyl carbonate and the ionic liquid catalyst is 1:1 - 1.5:0.08 - 0.

15.

3. The preparation method of a high-purity 2-imidazolidinone according to claim 2, characterized in that, In step 1), the reaction temperature is 165 - 185 °C and the reaction time is 2 - 4 h.

4. The preparation method of a high-purity 2-imidazolidinone according to claim 1 or 3, characterized in that, In step 2), the molar ratio of primary 2-imidazolidinone to dimethyl carbonate is 0.8 - 1.2:1.8 - 2.

2.

5. The preparation method of a high-purity 2-imidazolidinone according to claim 4, characterized in that, In step 2), the mixing temperature is 70 - 80 °C and the mixing time is 20 - 40 min.

6. The preparation method of a high-purity 2-imidazolidinone according to claim 2 or 3, characterized in that, In step 1), after the reaction, distillation is carried out to obtain primary 2-imidazolidinone; the distillation temperature is 150 - 200 °C and the distillation time is 1 - 3 h.

7. The preparation method of a high-purity 2-imidazolidinone according to claim 5, characterized in that, In step 2), after filtration, drying is carried out to obtain high-purity 2-imidazolidinone; the drying temperature is 40 - 60 °C and the drying time is 7 - 9 h. The high-purity 2-imidazolidinone prepared by the method for preparing high-purity 2-imidazolidinone according to any one of claims 1 to 7, characterized in that, The purity of the high-purity 2-imidazolidinone is 98.9 - 99.9%, and the yield of the high-purity 2-imidazolidinone is 84.5 - 94%.

Images