TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (disclosed): Preparation of the compound (I) involves reacting pyridazinone compound of formula (II) with a compound of formula R3-LG in the presence of triethylamine to obtain the compound (I).LG=leaving group such as halogen, sulfonate or carboxylate. Full Definitions:    R1=H, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 6-14C cycloalkylcycloalkyl, 4-10C halocycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 3-8C cycloalkenyl, 3-8C halocycloalkenyl, 2-8C alkoxyalkyl, 4-10C cycloalkoxyalkyl, 3-10C alkoxyalkoxyalkyl, 2-8C alkylthioalkyl, 2-8C alkylsulfinylalkyl, 2-8C alkylsulfonylalkyl, tetrahydropyranyl, -C(=W6)R4, -C(=W2)W3R5, -S(=O)2R6, -P(=W4)R7R8 or -C(=W5)NR9R10;    R2=H, halogen, cyano, -C(=O)OH, -C(=O)NH2, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 6-14C cycloalkylcycloalkyl, 4-10C halocycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 3-8C cycloalkenyl, 3-8C halocycloalkenyl, 2-8C alkoxyalkyl, 4-10C cycloalkoxyalkyl, 3-10C alkoxyalkoxyalkyl, 2-8C alkylthioalkyl, 2-8C alkylsulfinylalkyl, 2-8C alkylsulfonylalkyl, 2-8C alkoxycarbonyl, 4-10C cycloalkoxycarbonyl, 5-12C cycloalkylalkoxycarbonyl, 2-8C alkylaminocarbonyl, 3-10C dialkylaminocarbonyl, 4-10C cycloalkylaminocarbonyl, 1-6C alkoxy, 1-6C haloalkoxy, 1-6C alkylthio, 1-6C haloalkylthio, nitro, 3-6C cycloalkoxy or 4-8C cycloalkylalkoxy;    R3=H, -C(=W6)R4, -C(=W2)W3R5, -S(=O)2R6, -P(=W4)R7R8 or -C(=W5)NR9R10;    G1=phenyl ring or 5- or 6-membered heteroaromatic ring (both optionally substituted with Rx1 on nitrogen ring members and optionally substituted with up to 4 substituents selected from Rw1 on carbon ring members);    J1=phenyl ring or 5- or 6-membered heteroaromatic ring (both optionally substituted with up to 5 substituents selected from Ru1);    R4=1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 3-8C cycloalkenyl, 2-8C alkoxyalkyl, 4-10C cycloalkoxyalkyl, 3-10C alkoxyalkoxyalkyl, 2-8C alkylthioalkyl, 2-8C alkylsulfinylalkyl, 2-8C alkylsulfonylalkyl, 2-8C alkylaminoalkyl, 3-10C dialkylaminoalkyl, 2-8C haloalkylaminoalkyl, 4-10C cycloalkylaminoalkyl, naphthalenyl or -(CR11R12)nGa1;    R5=1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 3-10C cycloalkenyl, 2-8C alkoxyalkyl, 4-10C cycloalkoxyalkyl, 3-10C alkoxyalkoxyalkyl, 2-8C alkylthioalkyl, 2-8C alkylsulfinylalkyl, 2-8C alkylsulfonylalkyl, 2-8C alkylaminoalkyl, 3-10C dialkylaminoalkyl, 2-8C haloalkylaminoalkyl, 4-10C cycloalkylaminoalkyl, naphthalenyl or -(CR11R12)nGa1;    R6=1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 4-10C halocycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 3-8C cycloalkenyl, 2-8C alkoxyalkyl, 4-10C cycloalkoxyalkyl, 3-10C alkoxyalkoxyalkyl, 2-8C alkylthioalkyl, 2-8C alkylsulfinylalkyl, 2-8C alkylsulfonylalkyl, 2-8C alkylaminoalkyl, 3-10C dialkylaminoalkyl, 2-8C haloalkylaminoalkyl, 4-10C cycloalkylaminoalkyl, 1-6C alkylamino, 2-8C dialkylamino, 2-6Chaloalkylamino, 2-8C halodialkylamino, 3-8C cycloalkylamino, 2-8C alkylcarbonylamino, 2-8C haloalkylcarbonylamino, 1-6C alkylsulfonylamino, 1-6C haloalkylsulfonylamino, naphthalenyl or -(CR11R12)nGa1;    R7 and R8=1-6C alkyl, 1-6C alkoxy, 1-6C alkylamino, 2-8C dialkylamino, 2-6C haloalkylamino, 2-8C halodialkylamino, 3-8C cycloalkylamino, naphthalenyl or -(CR11R12)nGa1;    R9=H, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 3-8C cycloalkenyl, 2-8C alkoxyalkyl, 4-10C cycloalkoxyalkyl, 3-10C alkoxyalkoxyalkyl, 2-8C alkylthioalkyl, 2-8C alkylsulfinylalkyl, 2-8C alkylsulfonylalkyl, 2-8C alkylaminoalkyl, 4-10C dialkylaminoalkyl, naphthalenyl or -(CR11R12)nGa1;    R10=H, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 2-6C haloalkenyl, 2-6C haloalkynyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl or 4-10C cycloalkylalkyl;or    R9+R10+N=3- to 7-membered heterocyclic ring (selected from carbon and optionally O, S, NR13 or C(=O), and optionally substituted on carbon ring members with up to 4 substituents selected from halogen, -CN, 1-3C alkyl and 1-3C alkoxy);    R11 and R12=H or 1-3C alkyl;    R13=H or 1-3C alkyl;    Ga1=phenyl ring, 5- or 6-membered heteroaromatic ring (both optionally substituted with up to 5 substituents selected from Ru1) or naphthalenyl ring (which is optionally substituted with up to 5 substituents selected from Ru1);    Ru1=halogen, cyano, hydroxy, amino, nitro, -CHO, -C(=O)OH, -C(=O)NH2, -SO2NH2, SF5, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 4-10C halocycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 2-8C alkylcarbonyl, 2-8C haloalkylcarbonyl, 2-8C alkoxycarbonyl, 4-10C cycloalkoxycarbonyl, 5-12C cycloalkylalkoxycarbonyl, 2-8C alkylaminocarbonyl, 3-10C dialkylaminocarbonyl, 1-6C alkoxy, 1-6C haloalkoxy, 2-8C alkylcarbonyloxy, 1-6C alkylthio, 1-6C haloalkylthio, 1-6C alkylsulfinyl, 1-6C haloalkylsulfinyl, 1-6C alkylsulfonyl, 1-6C haloalkylsulfonyl, 1-6C alkylaminosulfonyl, 2-8C dialkylaminosulfonyl, 3-10C trialkylsilyl, 1-6C alkylamino, 2-8C dialkylamino, 2-8C alkylcarbonylamino, 1-6C alkylsulfonylamino, phenyl, pyridinyl or thienyl;    Rw1=halogen, cyano, hydroxy, amino, nitro, -CHO, -C(=O)OH, -C(=O)NH2, -SO2NH2, SF5, 1-6C alkyl, 2-6C alkenyl, 2-6C alkynyl, 1-6C haloalkyl, 3-8C cycloalkyl, 3-8C halocycloalkyl, 4-10C alkylcycloalkyl, 4-10C cycloalkylalkyl, 4-10C halocycloalkylalkyl, 5-12C alkylcycloalkylalkyl, 2-8C alkylcarbonyl, 2-8C haloalkylcarbonyl, 2-8C alkoxycarbonyl, 4-10C cycloalkoxycarbonyl, 5-12C cycloalkylalkoxycarbonyl, 2-8C alkylaminocarbonyl, 3-10C dialkylaminocarbonyl, 1-6C alkoxy, 1-6C haloalkoxy, 2-8C alkylcarbonyloxy, 1-6C alkylthio, 1-6C haloalkylthio, 1-6C alkylsulfinyl, 1-6C haloalkylsulfinyl, 1-6C alkylsulfonyl, 1-6C haloalkylsulfonyl, 1-6C alkylaminosulfonyl, 2-8C dialkylaminosulfonyl, 3-10C trialkylsilyl, 1-6C alkylamino, 2-8C dialkylamino, 2-8C alkylcarbonylamino, 1-6C alkylsulfonylamino, naphthalenyl, -O(CR11R12)nGa1 or -(CR11R12)nGa1;    Rx1=H, 1-3C alkyl or 3-7C cycloalkyl;    W1-W6=O or S;    n=0-3.    ACTIVITY - Herbicide. The efficacy of 5-hydroxy-2-methyl-4-(5-methyl-3-(4-(trifluoromethyl)phenyl)-1H-pyrazol-1-yl)-3(2H)-pyridazinone (Ia) was evaluated for herbicidal activity using standard assay on Echinochloa crus-galli, and plant response rating (i.e. weed control) was measured. (Ia) Showed a 100% of plant response rating (i.e. weed control).    MECHANISM OF ACTION - None given.    ADMINISTRATION - The compound is applied at a rate of 0.0001-20 (preferably 0.001-5, especially 0.004-3) kg/hectare). The compound is applied in the form soluble concentrate, suspension concentrate, capsule suspension, concentrated emulsion, microemulsion, dusts, powders, granules, pellets, pastilles, tablets, seed coatings and spray.    SPECIFIC COMPOUNDS - 6 Compounds are specifically claimed as the compound (I) e.g. 5-hydroxy-2-methyl-4-(5-methyl-3-(4-(trifluoromethyl)phenyl)-1H-pyrazol-1-yl)-3(2H)-pyridazinone (Ia), 4-(3-(4-chlorophenyl)-5-methyl-1H-pyrazol-3-yl)-5-hydroxy-2-methyl-3(2H)-pyridazinone, 5-(3-(4-chlorophenyl)-5-methyl-1H-pyrazol-1-yl)-1,6-dihydro-1-methyl-6-oxo-4-pyridazinyl-1-methylethyl carbonate, 4-(3-(4-bromophenyl)-5-methyl-1H-pyrazol-1-yl)-5-hydroxy-3(2H)-pyridazinone, 4-(5-ethyl-3-(4-(trifluoromethyl)phenyl)-1H-pyrazol-1-yl)-5-hydroxy-2-methyl-3(2H)-pyridazinone.    EXAMPLE - A solution of 3-methyl-5-(4-trifluoromethylphenyl)pyrazole (2 g) and 4,5-dichloro-2-methyl-(2H)-pyridazinone (0.85 g) in N,N-dimethylformamide (15 ml) was treated with potassium carbonate (1.9 g). The reaction mixture was heated at 100 degrees C for 11 hours and then poured onto ice water. After work-up, 2-methyl-4,5-bis(5-methyl-3-(4-(trifluoromethyl)phenyl)-1H-pyrazol-1-yl)-3(2H)-pyridazinone (T1) was obtained. A solution of (T1) (0.74 g) in methanol (20 ml) was treated with sodium methoxide (0.8 ml). The reaction mixture was heated to reflux to dissolve suspended solids and then stirred at 25 degrees C for 6 hours. The resulting mixture was quenched with saturated aqueous ammonium chloride solution (20 ml) and diluted with ethyl acetate (30 ml). After work-up, 5-methoxy-2-methyl-4-(5-methyl-3-(4-(trifluoromethyl)phenyl)-1H-pyrazol-1-yl)-3(2H)-pyridazinone (T2) was obtained. To a solution of (T2) (0.25 g) in dichloromethane (5 ml) was added a solution of boron tribromide (0.82 ml). The reaction mixture was stirred at room temperature for 2 hours and then treated with aqueous sodium hydroxide solution (4 ml). After stirring for 15 minutes, the reaction mixture was adjusted to pH 4 with aqueous hydrochloric acid (4 ml). After work-up, 5-hydroxy-2-methyl-4-(5-methyl-3-(4-(trifluoromethyl)phenyl)-1H-pyrazol-1-yl)-3(2H)-pyridazinone (210 mg) was obtained.