Preparation method of 4-nitroimidazole

[0029] Preparation of imidazolium sulfate:

[0030] Add 25.8mL of 98% concentrated sulfuric acid into a 250mL three-necked flask and ice-bath to 5°C, add 13.6g of imidazole, and stir at 20°C for 20min after the addition is complete to obtain imidazolium disulfate solution.

[0031] Preparation of nitrating agent:

[0032] Add 40ml 10% oleum in a 250mL three-necked flask and ice-bath to 5°C, then slowly add 8.53mL of 86% concentrated nitric acid and 1.85g of dinitrogen pentoxide to the three-necked flask and keep stirring to obtain N 2 o 5 - Mixed acid nitrating agent.

[0033] Preparation of 4-nitroimidazole:

[0034] Heat the imidazolium disulfate solution in a water bath to 50 °C, and slowly add N at this temperature 2 o 5 - Mix the acid nitrating agent and keep stirring. The molar ratio of concentrated nitric acid to imidazole is 0.8:1. After the addition is complete, stir at 50°C for 30 minutes to make the reaction complete. Cool the reaction system to 0°C, add 7mL of i

[0036] Preparation of imidazolium sulfate:

[0037] Add 25.8mL of 98% concentrated sulfuric acid into a 250mL three-necked flask and bathe it in water to 5°C, add 13.6g of imidazole under constant stirring, keep warm at 20°C and stir for 20min after the addition, to obtain imidazolium disulfate solution.

[0038] Preparation of nitrating agent:

[0039] Take 40ml of fuming sulfuric acid in a 250mL three-necked flask and ice-bath to 5°C, slowly add 10.7mL of 86% concentrated nitric acid and 1g of dinitrogen pentoxide under stirring to obtain N 2 o 5 - Mixed acid nitrating agent.

[0040] Preparation of 4-nitroimidazole:

[0041] Heat the water bath of imidazolium sulfate solution to 55 °C, slowly add N at this temperature 2 o 5 - Mix the acid nitrating agent and keep stirring. The molar ratio of concentrated nitric acid to imidazole is not 1:1. After adding, keep stirring for 30 minutes to make the reaction complete. Then cool the reaction solution to 0°C, add 7mL of ice-wat