3-Nitro-1,2,4-triazole

61-82-5

24807-55-4

General procedure for the synthesis of 3-nitro-1,2,4-triazole from 1H-1,2,4-triazol-5-amine: In a fume hood, 3-amino-1,2,4-triazole (26.3 g, 0.297 mol) was added to an aqueous solution of sodium nitrite (100.0 g, 1.45 mol, dissolved in 150 ml of water) fitted with an overhead mechanical stirrer and a 100 ml homogeneous pressure dosing funnel in a 2.0 liter three-necked round-bottomed flask. The suspension was cooled in an ice water bath and the mechanical stirrer was activated. After stirring for 10 minutes, concentrated nitric acid (85 ml) was slowly added dropwise through the dosing funnel for a controlled period of 2.5-3.0 hours (note the foaming phenomenon). After the dropwise addition was completed, the ice water bath was removed and the yellow suspension was continued to be stirred at room temperature for 1 hr until the foaming stopped. The crude product was collected by filtration and the yellow solid cake was dried overnight under vacuum with an oil pump to give 47 g of product. The crude product was dissolved in boiling methanol (300 ml) for 30 min, followed by room vacuum filtration. The filtrate was cooled to room temperature and placed in a refrigerator at -15°C overnight to crystallize 3-nitro-1,2,4-triazole as a light yellow solid. The crystallized product was washed with cold methanol and dried overnight at a pressure of 1.9 mmHg to give 21-23 g (62%-68% yield) of 3-nitro-1,2,4-triazole with a melting point of 208°C-211°C (literature values 208°C-210°C). The product was characterized by 1H NMR (300 MHz, DMSO-d6): δ 8.86 (s, 1H); 13C NMR (75 MHz, DMSO-d6): δ 163.1,146.3; IR (solid): 3162,2861,2776,2730 cm-1. The purity of the product was determined to be 97% by RP-HPLC with retention time tR=2.01 min (detection wavelength 254 nm).