反应详情

151 g of 1-phenyl semicarbazide, 135.3 g (2.5 mols) of 85% formic acid (technical) and 25 g (0.25 mol) of concentrated sulfuric acid were stirred for six hours at 95° to 100° C. The viscous mass obtained was diluted with 400 ml of water and cooled. The precipitate consisting of 1-phenyl-1,2,4-triazolone-3 was filtered off and washed neutral with water. Drying at 100° C. and 200 mbar gave 145.5 g=90.3% of the theory, of 1-phenyl-1,2,4-triazolone-3 having a melting point of 285° to 286° C. ##STR2##

1. customThe viscous mass obtained
2. temperaturecooled
3. filtrationwas filtered off
4. washwashed neutral with water
5. customDrying at 100° C.
6. custom200 mbar gave 145.5 g=90.3% of the theory