NEW MATERIAL:The 6-substituted-phenyl-4-mercapto-4,5-dihydro-3( 2H )pyridazinone compound of formula I [R1 and R3 are H or halogen; R2 is H, alkyl or alkoxy; at least one of R1WR3 is other than H; R4 is alkyl or alkenyl which may have substituent group (OH, alkoxy, carboxy, etc.) or phenyl, aralkyl or pyridyl which may be substituted with alkyl, halogen or nitro].
EXAMPLE: 6-( 3,5-Dichloro-4-methylphenyl )-4-methylthio-4,5-dihydro-3(2H)pyridazinone.
USE: Fungicide for agricultural and horticultural use. It controls sheath blight of rice effectively by scattering to the plant or applying to the water surface.
PROCESS: The compound of formula I can be prepared by reacting the 4-substituted-phenyl-4-oxo-2-butenoic acid of formula II with the thiol of formula R4-SH, and reacting the product with hydrazine.
OTO TAKAO
JIYOUJIMA TERUOMI
