Pyridazines with Hetero-Atom Substituents in Position 3 and 5, Part VII. Halogenation of 2-Aryl-5-hydroxy-pyridazin-3(2H)-ones in Position 4

Article abstract of DOI:10.1007/BF00810866

The reaction of 2-aryl-5-hydroxy-3(2H)-pyridazinones (1a,b) with bromine yields the 4-bromo derivatives 2a,b and with sulfuryl chloride the chloro compounds 3a,b are obtained.However, with an excess of chlorine or sulfuryl chloride the 4,4-dichloro-pyrida