Study On The Nitration Of Several Aromatic And N-heterocyclic Compounds

As an important organic reaction, nitration is of great importance in both theoretical study and industrial production. Particularly, nitration of aromatic and N-heterocyclic compounds plays an even decisive role in the synthesis of the explosives and energetic materials. In this paper, o-nitrotoluene, imidazole and2,6-dimethoxy pyrazine, which are of great research values in the field of explosives and energetic materials, were selected as model substrates to study the nitration reactions.(1) With o-nitrotoluene as substrate, nitration reactions were carried out under different nitration systems and various parameters were investigated including the amount of H2SO4, reaction time, reaction temperature and so on. The optimum process conditions were:in the20%oleum-KNO3system, substrate0.1mol,20%oleum50mL,10℃,2h. Under this condition, a p/o value as high as2.83was obtained.(2) Guanidinium TNI was obtained with imidazole as substrate via5-step reactions including a three-step nitration, rearrangement reaction and salt-forming reaction. Various parameters, such as the composition of the mixed acid, the reaction temperature, the reaction time were investigated. The total yield of Guanidinium TNI reached36.5%under the optimum reaction conditions for every step.(3) The nitration of2,6-dimethoxypyrazine was performed under different nitration systems with various parameters evaluateed such as the composition of the mixed acid, the reaction temperature and the reaction time. The optimum process conditions were:in the20%oleum-KNO3system, substrate0.05mol, KNO3in excess of100%compared with that of substrate, the molar ratio of KNO3to20%oleum2:7,25℃,3h. Under this condition, the yield of67.8%was reached for2,6-dimethoxy-3,5-dinitropyrazine.