Synthesis
Step 1: Synthesis of 5-nitro-2-(trifluoromethyl)benzoic acid
1. 2-Methyl-4-nitro-1-(trifluoromethyl)benzene (1 g, 4.87 mmol) was dissolved in acetonitrile (30 ml).
2. To the above solution, periodate (H5IO6, 5.56 g, 24.37 mmol) and chromium trioxide (CrO3, 0.126 ml, 3.40 mmol) were added sequentially.
3. the reaction mixture was stirred at room temperature for 2 hrs.
4. Chromium trioxide (0.0722 ml, 1.950 mmol) was added additionally and stirring was continued at room temperature overnight.
5. After completion of the reaction, isopropanol (150 ml) was added to the mixture, at which point the suspension turned green.
6. The precipitate was collected by filtration and the filtrate was concentrated to dryness under reduced pressure.
7. The solid residue was ground with ethyl acetate (40 ml) and filtered to give 5-nitro-2-(trifluoromethyl)benzoic acid (1.1 g, 4.68 mmol, 96% yield).
References
[1] Patent: US2014/155391, 2014, A1. Location in patent: Paragraph 0666; 0667
[2] Patent: WO2014/72220, 2014, A1. Location in patent: Page/Page column 49; 50
[3] Patent: US2005/59668, 2005, A1. Location in patent: Page/Page column 17
