Synthesis
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%.
References
[1] Patent: EP1468983, 2004, A1. Location in patent: Page 6
[2] Patent: EP1468983, 2004, A1. Location in patent: Page 5; 6
[3] Journal of the American Chemical Society, 1953, vol. 75, p. 4967
[4] Journal of Organic Chemistry, 1995, vol. 60, # 22, p. 7348 - 7350
[5] Patent: WO2011/150156, 2011, A2. Location in patent: Page/Page column 132
