Development Of High Efficient And Clean Production Process Of 1,3-dimethyl-2-imidazolinone

1,3-Dimethyl-2-imidazolidinone(DMI)as a strong polar aprotic solvent with high boiling point,high flash point and low melting point,has strong solvency.It has the advantages of acid and alkali resistance,good thermal stability and low toxicity,so it is widely used as the solvent in the fields of chemical synthesis and industrial product production and processing.The known synthesis processes of DMI still have many shortcomings,such as serious environmental pollution,high cost and high toxicity of raw materials,and severe reaction conditions.Therefore,a more efficient,clean and low-cost process of producting DMI needs to be developed.(1)Optimization of high efficiency production process of 2-imidazolidinone(MI)and pilot test of it.Based on the previous research in our research group,this paper further explored the process of preparing 2-imidazolidinone with ethylenediamine and dimethyl carbonate as raw materials.The preferred process preparation conditions were as follows:Cl and C2 as catalysts,the reaction temperature and time were 170? and 2 h respectively.Under this condition,the yield was about 93.6%.Then the catalyst separation and recovery and product recrystallization purification process were explored.It was determined that dimethyl carbonate could be used as a more suitable solvent for recovery of catalyst and recrystallization to purify MI.After purification,the product purity could reach more than 99.0%.Finally,a pilot test was successfully conducted on the production process of preparing MI using ethylenediamine and dimethyl carbonate as raw materials.The product yield was about 85%and the purity of the product after purification could reach more than 99.5%,meeting the requirements of industrial production.(2)Study of clean production process of DMI.Using 2-imidazolidinone and dimethyl carbonate as raw materials,the synthesis process of DMI was explored.By optimizing the catalyst,catalyst dosage,material ratio,reaction temperature,reaction time and so on,the optimal process preparation conditions was determined as follows:C3 as the catalyst,the catalyst dosage was 3.2 mol%,the material molar ratio was 10.2:1(DMC:MI),the reaction temperature and time were 205? and 10 h respectively.Under this condition,the yield could reach more than 70%.(3)Optimization of clean production process of DMI and pilot test of it.On the basis of the above research,the synthesis of DMI with Cl and C2 system was explored to achieve the "one-pot" synthesis of DMI.By optimizing the material ratio,reaction temperature,reaction time and so on,the preferred process preparation conditions were determined as follows:2-imidazolidinone and dimethyl carbonate as raw materials,Cl as catalyst and C2 as cocatalyst,the material molar ratio was 10.2:1(DMC:MI),the reaction temperature and time were 205? and 15 h respectively.Under this condition,the yield could reach more than 73%.The pilot test was successfully carried out at last and the product yield was about 70%.Compared with the traditional synthesis process,the new process of DMI developed in this paper was more efficient,cleaner and safer.Furthermore no water participated or was generated in the reaction and the product had better performance.So this route had extremely high industrial competitiveness.(4)Engineering calculation of clean production process of DMI.Finally,engineering calculation was conducted for a set of production equipment with an annual output of 500 tons of DMI with drawing out the process flow charts,and the process date of material balance,energy balance,main equipments for each process and public utility was calculated to support for and serve the industrial production of DMI.