| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new compound having an excellent weeding activity to weeds such as Panicum crus-galli and useful as a herbicide, comprising a specific pyridazinone derivative. SOLUTION: This compound is expressed by formula I [R1 is a 1-6C alkyl; R2 is H or a 1-3C alkyl; R3 is a 1-3C haloalkyl; Q is (substituted) phenyl], e.g. 2-(4-chlorophenyl)-6-ethoxycarbonyl-5-trifluoromethylpyridazin-3-one. The compound of formula I is obtained by reacting a compound of formula II (Q1 is a group such as formula III or the like; X is H or a halogen; Y is a halogen, nitro or the like; B1 is H, a halogen or the like) with a compound of the formula: (C6H5)3P=C(R2)COOR33 (C33 is a 1-6C alkyl) [e.g. (carbethoxymethylene) triphenylphospholane] usually in a solvent such as toluene preferably at 20-130 deg.C usually for instant to 72 hrs.
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