ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis and herbicidal activity of certain 1-phenyl-6-pyridazone derivatives

P. Rapoš, J. Synak, and P. Winternitz

Forschungsinstitut für agrochemische Technologie, Bratislava

Abstract: From a new herbicide, 1-phenyl-4-amino-5-chloro-6-pyridazone, for sugar beet, 14 derivs. were prepd. In these the original structure of 1-phenyl-6-pyridazone was retained and the type and position of the substituents on the heterocyclic ring in relation to the selective herbicidal activity against sugar beet was studied. Substituted 1-phenyl-6-pyridazines (all known) (substituents and m.p. given) prepd. were: 4,5-Cl₂, 162-3°; 3-OH, 253.5-55°; 3-OH-4-Cl, 250-2°; 3-OH-5-Cl, 199-201°; 3-Cl, 117-18°; 3,4-Cl₂, 138-40°; 3-Cl-4-NH₂, 234-6°; 4-NH₂-5-Cl, 204-6°; 4-Cl-5-NH₂, 142-3.5°; 4-NHMe-5-Cl, 213°; 4-OMe-5-Cl, 160-1°. The unknown compds. were 1-phenyl-4-bromo-5-chloro-6-pyridazone, m. 156° (prepd. from α-chloro-β-bromo-β-formylacrylic acid and PhNH-NH₂); 1-phenyl-3-hydroxy-4,5-dichloro-6-pyridazone, m. 226.5-7.5° (prepd. from phenylhydrazine and dichloromaleic acid); 1-phenyl-4-hydroxy-5-chloro-6-pyridazone, m. 266-70° (prepd. from 1-phenyl-4,5-dichloro-6-pyridazone, KOH, and anhyd. MeOH); and 1-phenyl-4-mercapto-5-chloro-6-pyridazone, m. 178-9° (decomp.) (prepd. from 1-phenyl-4,5-dichloro-6-pyridazone and EtOH soln. of KSH). The degree of phytotoxic properties are affected by the presence of the Cl atom in the 5 position and the amino group in the 4 position.

Full paper in Portable Document Format: 195a403.pdf (in Slovak)

Chemical Papers 19 (5) 403–412 (1965)