Preparation Example 1: General procedure for the synthesis of 2-bromo-5-methylaniline
1. 4-Bromo-3-nitrotoluene (60.35 g, 279 mmol), 5 wt% platinum-carbon catalyst (1.09 g, 0.28 mmol), and triethylamine (112.93 g, 1116 mmol) were added sequentially to the reaction flask.
2. the reaction mixture was heated to 100 °C and 99% formic acid (42.39 g, 921 mmol) was added slowly and dropwise over a period of 20 minutes.
3. The reaction temperature was maintained with continuous stirring for 12 hours.
4. Upon completion of the reaction, cooled to room temperature, ethyl acetate (100 mL) and water (100 mL) were added to the reaction mixture with thorough stirring.
5. Filter through diatomaceous earth to remove the platinum carbon catalyst.
6. Add ethyl acetate (200 mL) and water (100 mL) to the filtrate and extract.
7. The organic phase was separated and washed with deionized water (300 mL x 3 times).
8. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to afford the target product 2-bromo-5-methylaniline (51.30 g, 276 mmol) in 99% yield.
9. The structure of the product was confirmed by 1H-NMR (270 MHz, CDCl3): δ (ppm) 7.260 (1H, d), 6.583 (1H, ... (data not provided in full)).
