Thirty new 2‐substituted‐4‐amino‐5‐alkyl or aryl‐2,4‐dihydro‐1,2,4‐triazol‐3‐ones and ten 2‐substituted‐5‐alkyl or aryl‐4‐(5‐nitro‐2‐furfurylidene)amino‐2,4‐dihydro‐1,2,4‐triazol‐3‐ones were synthesized and characterised by their sharp melting points, elemental analysis, ir and 1H nmr spectra. These new derivatives of 5‐nitro‐2‐furaldehyde were screened for their antibacterial activities. Most of the compounds showed good activity against one test organism, Staphylococcus aureus. For a few compounds, C.M.I. ranged from 4 to 8 μg/ml (higher results than nitrofurantoin).

Aus den Iminoether‐hydrochloriden (I) und Hydrazin‐carbonsäureester (II) erhält man über (III) mit Hydrazin‐hydrat die 4‐Amino‐l ,2,4‐triazol‐3‐one (IV).