CN-121974856-A - Synthesis method of 1, 3-dimethyl-2-imidazolidinone by one-pot method

Abstract

The invention provides a one-pot synthesis method of 1, 3-dimethyl-2-imidazolidinone, which comprises the steps of mixing an alkaline catalyst, ionic liquid and methanol, adding ethylenediamine to synthesize 2-imidazolidinone at low temperature, and raising the temperature to enable the 2-imidazolidinone and methyl carbonate to undergo an N-methylation reaction. According to the synthesis method, ionic liquid is used as a catalyst, so that on one hand, the acid binding effect of an acid binding agent is enhanced by using the ionic liquid as a phase transfer catalyst, and on the other hand, the acid binding effect of the acid binding agent is enhanced by using the ionic liquid as a carbene catalyst to activate dimethyl carbonate, so that the acylation and methylation reaction efficiency is improved.

Inventors

• LI WEIPENG
• GAO YUXI
• ZHANG XIAOYU
• CHEN HONGLIANG

Assignees

• 南京大学

Dates

Publication Date

20260505

Application Date

20260330

Claims (7)

1. 1. The one-pot synthesis method of 1, 3-dimethyl-2-imidazolone is characterized by comprising the following steps: mixing an alkaline catalyst, an ionic liquid and methanol, adding ethylenediamine, synthesizing 2-imidazolidone at low temperature, and raising the temperature to enable the 2-imidazolidone and dimethyl carbonate to undergo an N-methylation reaction.
2. 2. The synthesis method according to claim 1, wherein the ionic liquid is one or a mixture of more of imidazole ionic liquid, imidazolidine ionic liquid and 1,2, 4-triazolidine ionic liquid.
3. 3. The method of claim 1, wherein the ionic liquid is an imidazole type ionic liquid; preferably, the imidazole type ionic liquid is one or a mixture of more of (1-butyl-3-methylimidazole) chloride, (1-methyl-3-methylimidazole) chloride, (1-butyl-3-butylimidazole) chloride and (1-butyl-3-butylimidazole) bromide.
4. 4. The synthesis method according to claim 1, wherein the imidazole type ionic liquid is (1-butyl-3-methylimidazole) chloride and (1-butyl-3-butylimidazole) chloride, and the mass ratio between the two is (2-4): 1.
5. 5. The synthetic method according to any one of claims 1 to 4, wherein the mass parts of the respective substances are compounded according to the following amounts of 1 to 20 parts of alkaline catalyst, 1 to 20 parts of ionic liquid, 10 to 100 parts of methanol, 80 to 120 parts of ethylenediamine and 300 to 900 parts of dimethyl carbonate.
6. 6. The synthetic method according to any one of claims 1 to 4, characterized in that the reaction temperature under low temperature conditions is 60-160 ℃, the reaction time is 1-6h, preferably the reaction temperature is 130-160 ℃.
7. 7. The synthetic method according to any one of claims 1to 4, characterized in that the reaction temperature after the elevated temperature is 140-200 ℃, the reaction time is 3-6h, preferably the reaction temperature is 150-190 ℃.

Description

Synthesis method of 1, 3-dimethyl-2-imidazolidinone by one-pot method Technical Field The invention relates to the field of preparation of 1, 3-dimethyl-2-imidazolone, in particular to a one-pot synthesis method of 1, 3-dimethyl-2-imidazolone. Background 1,3-Dimethyl-2-imidazolidinone (1, 3-Dimethyl-2-imidazolidinone, abbreviated as DMI) is an important high-polarity aprotic solvent and an organic synthesis intermediate, and has excellent solubility, thermal stability and chemical inertness. In recent years, the lithium ion battery has wide application in the fields of lithium batteries, electronic chemicals, medicines, green chemical industry and the like. At present, ethylenediamine and urea are used as raw materials in industry, 2-imidazolidinone is synthesized firstly, formaldehyde and formic acid are used as solvents and methylating agents, and N-methylation reaction is carried out on the 2-imidazolidinone to prepare 1, 3-dimethyl-2-imidazolidinone. The formic acid is difficult to recover, the wastewater discharge amount is large, the production efficiency is low, the comprehensive cost is high, and the development trend of green chemical industry is difficult to meet. In Chinese patent application (application number: 202510405850.8), a process route for synthesizing 1, 3-dimethyl-2-imidazolidinone by using a carbon dioxide method is disclosed. The process comprises three main steps of 1) taking carbon dioxide and ethylenediamine as raw materials, reacting at 180-250 ℃ and about 5MPa to synthesize 2-imidazolidinone, 2) reacting the carbon dioxide with methanol at 9-MPa high pressure to generate dimethyl carbonate, and 3) reacting the 2-imidazolidinone with the dimethyl carbonate at 180 ℃ and 5-6 MPa to obtain the target product 1, 3-dimethyl-2-imidazolidinone. As described in the patent, the whole process still involves high-temperature and high-pressure conditions, the flow is complex, the mass ratio of the dimethyl carbonate to the 2-imidazolidone exceeds 40, and the comprehensive production efficiency is low. The carbonate synthesis method is to use carbonate compounds as the donors of carbonyl and methyl simultaneously to react with ethylenediamine to synthesize DMI, and has the advantages of simple reaction flow and equipment, outstanding environmental protection advantages and the like, and is focused by scientific researchers. The Xiamen university Mao Chenlu et al (development of efficient clean production process of 1, 3-dimethylimidazolidinone, mao Chenlu, xiamen university's master graduation paper 2020) reported a synthetic method of synthesizing 2-imidazolidinone from dimethyl carbonate and ethylenediamine, and synthesizing 1, 3-dimethyl-2-imidazolidinone from 2-imidazolidinone and dimethyl carbonate. But the total reaction time of the two steps exceeds 12 hours, the comprehensive yield is low, the purification and treatment processes are complex, the mass ratio of the dimethyl carbonate to the ethylenediamine exceeds 15, the cost advantage is avoided, and the industrial production value is not realized. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a one-pot synthesis method of 1, 3-dimethyl-2-imidazolidinone, which is characterized in that ionic liquid is added to the synthesis method to serve as a phase transfer catalyst to enhance the acid binding effect of an acid binding agent and serve as a carbene catalyst to activate dimethyl carbonate to improve the acylation and methylation reaction efficiency. The strategy not only remarkably reduces the dosage of the dimethyl carbonate, thereby reducing the cost, but also realizes a simplified one-pot production process, effectively improves the economic feasibility of the process, and improves the reaction efficiency and the comprehensive production efficiency. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: the invention provides a synthesis method of 1, 3-dimethyl-2-imidazolone by a one-pot method, which comprises the following steps: mixing an alkaline catalyst, an ionic liquid and methanol, adding ethylenediamine, synthesizing 2-imidazolidone at low temperature, and raising the temperature to enable the 2-imidazolidone and dimethyl carbonate to undergo an N-methylation reaction. Preferably, as a further implementable embodiment, the ionic liquid is one or a mixture of more of imidazole ionic liquid, imidazolidine ionic liquid and 1,2, 4-triazolidine ionic liquid. Compared with the prior art, the synthesis method of the invention does not need to add carbon dioxide like a carbon dioxide method, and the condition of high temperature and high pressure is avoided, and the carbon dioxide method has the defects that the carbon dioxide is used as a raw material, the 2-imidazolidinone is produced at high temperature and high pressure, and then the 2-imidazolidinone and the methyl carbonate (the dosage is more t