In a 250 mL round-bottomed flask, 3,5-dibromo-1H-1,2,4-triazole (8.00 g, 35.3 mmol) was dissolved in N,N-dimethylformamide (DMF, 80 mL) and the solution was cooled to 0-5°C (ice bath). Sodium hydride (60% mineral oil dispersion, 1.69 g, 42.3 mmol) was added in batches and the reaction mixture was stirred at 0-5°C for 45 min, followed by 15 min at room temperature. Iodomethane (10.0 g, 4.41 mL, 70.5 mmol) was slowly added dropwise at 0-5°C (ice bath). After completion of the dropwise addition, the reaction mixture was stirred at room temperature for 18 hours. After completion of the reaction, the mixture was concentrated under reduced pressure and the residue was diluted with ethyl acetate (200 mL) and water (200 mL), the aqueous phase was separated and extracted with ethyl acetate (2 x 200 mL). The organic layers were combined, dried over anhydrous sodium sulfate and concentrated under reduced pressure to afford 3,5-dibromo-1-methyl-1,2,4-triazole as a light yellow solid (8.15 g, 96% yield). The product was characterized by 1H NMR (CDCl3, 300 MHz): δ 3.89 (s, 3H). Mass spectrum (ES+) m/z: 240.0, 242.0, 244.0 [M + H, 2 Br isotope].
