288-88-0

75-03-6

16778-70-4

Scheme 3. Synthesis of 1-ethyl-1H-1,2,4-triazole (26a). Scheme 6. Preparation of intermediate 26a. Step 1. Synthesis of 1-ethyl-1H-1,2,4-triazole (26a): ethyl iodide (7 mL, 86.9 mmol) was added to an anhydrous THF (50 mL) solution of 1,2,4-triazole (5 g, 72.4 mmol) under ice bath conditions. Subsequently, DBU (10.8 mL, 72.4 mmol) was added slowly and dropwise over 10-20 min to the cloudy reaction system. The reaction mixture was gradually warmed to room temperature and stirred overnight. After completion of the reaction, the mixture was filtered through a diatomaceous earth pad and the filtrate was concentrated under reduced pressure to give 10 g of crude product as a yellow liquid. The crude product was purified by Kugelrohr distillation (~300 mTorr, 35-40 °C) to give 4.9 g (70% yield) of the target product 26a as a clear liquid.