Imidazole Salt And N-heterocyclic Carbenes Catalyzde The Synthesis Of DMF

N,N-Dimethylformamide(DMF)as an important chemical raw material and solvent has been widely used in dye stuff,medicine,pesticide,electronic and etc.The general way to produce DMF is use the method of CO and NH(CH3)2 in the presence of CH3ONa as a catalyst.CH3ONa can react with the impurity easily,like H20,O2,CO2 and generate sodium formate,sodium carbonate crystals.The crystals can block the pipes and cause a great deal of pollution.Therefore,to find a new method for the synthesis of DMF was highly demanded.This paper introduced the methods for the synthesis of DMF,especially the new technology routes after 2000.The advantages and disadvantages of the reported methods for the synthesis of DMF were analyzed and contrasted.Through this paper,it provided a theoretical basis for the further research of the DMF synthesis and its catalyst selection.We also describe the development and application of ionic liquid and N-Heterocyclic carbenes,particulary N-Heterocyclic carbenes as an organic catalyst for organic synthesis.As more and more N-Heterocyclic carbenes have been synthesized and applied in organic reactions,their unique catalytic properties will receive more attention thereafter.Based on the work of previous studies,[Bmim]Cl,[Bmim]OH,[Emim]Br,[Emim]OH,[NBuPy]Cl,[NBuPy]OH,IPr,IMes etc was synthesized.This chapter focuses on the synthesis methods of ionic liquids and and N-heterocyclic carbenes,and discusses the major factors in the preparation processes.Then the direct carbonylation reaction of dialkyl amines and CO using the ionic liquids or N-heterocyclic carbenes as the catalysts was investigated.The best yield can up to 93.36%and we also found that the carbene catalysts can be recyclable.The effects of reaction tempreture,pressure and other reaction conditons on this direct carbonylation reaction were examined and finally the optimal conditions were obtained.For example,the yield of DMF can reach 47.64%(based on dimethylamine)in the condition of 130?,200 ml of methanol as the solvent,3 MPa of CO,1 mol of dimethylamine,36 h and 2 mmol of IPr as a catalyst;the 93.36%yield of DMF was got when the IPr catalyst amount was increased to 5 mmol.In conclusion,an efficient N-Heterocyclic carbenes catalyzed the carbonylation of dimethylamine with carbon monoxide was successfully estabilished notably with metal-free catalyst,which provided a new method for the synthesis of DMF.This method solves the problem of crystallization,congestion,and environmental pollution which use sodium methoxide as a catalyst and provide new ways for further research of synthesizes DMF.