Acetic Anhydride → 1-Acetyl-4-phenyl-1,2,4-triazolidine-3,5-dione

Beteiligte Stoffe

Reaktionsschritte

To a suspension of 5.3 g (30 mmol) of 4-phenyl-1,2,4-triazolidine-3,5-dione in 175 ml of chloroform was added dropwise over a 15 minute period 45.9 g (450 mmol) of acetic anhydride with stirring. The reaction mixture was stirred at room temperature for five days. The reaction mixture was filtered to remove a white precipitate which was washed with 30 ml of chloroform to give 3.55 g (54.0 %) of 1-methylcarbonyl-4-phenyl-1,2,4-triazolidine-3,5-dione as white solid, m.p. 215°-218.5° C. The filtrate was washed with three 100 ml portions of water and three 80 ml portions of 10% sodium carbonate. The carbonate washings were acidified with concentrated hydrochloric acid. No precipitate was formed. The chloroform solution was dried (Na2SO4) and evaporated under reduced pressure to give a liquid residue containing acetic anhydride. The filtered solid was recrystallized from 95% ethanol to yield pure 1-methylcarbonyl-4-phenyl-1,2,4-triazolidine-3,5-dione: m.p. 216.5°-218.5° C.; IR Nujol) 1726, 1710, 1688 cm-1 (CO); 1H NMR (60 MHz, CDCl3)δ7.90 (s, 5H) 2.55(s, 3H). Found: C, 54.5; H, 4.2: N, 19.4. C10H9N3O3 requires C, 54.8; H, 4.2; N, 19.4.

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