General Steps:
Example 2: Using 2,3-difluorotoluene as raw material, adopting the same reaction conditions as in Example 1, but replacing 96 mass% sulfuric acid with fuming sulfuric acid with a sulfur trioxide concentration of 10 mass%, the reaction was stirred at 80° C. for 8 hours to obtain 2,5-bis(trifluoromethyl)nitrobenzene in a yield of 68.7%.
Example 4: Using 2,3-difluorotoluene as raw material, the same reaction conditions as in Example 1 were used, but 96 mass% of sulfuric acid was replaced with fuming sulfuric acid having a sulfur trioxide concentration of 10 mass%, and 97 mass% of fuming nitric acid was replaced with 98 mass% of concentrated nitric acid, and the reaction was stirred at 80°C for 10 hours to obtain 2,5-bis(trifluoromethyl)nitrobenzene in a yield of 65.3%.
Example 7 (Comparative Example): Using 2,3-difluorotoluene as raw material and the same reaction conditions as in Example 1, but replacing 96 mass% sulfuric acid with fuming sulfuric acid with a sulfur trioxide concentration of 24 mass%, 2,5-bis(trifluoromethyl)nitrobenzene was obtained in a yield of 32.5%.
