Pyridazinone herbicides

Substituted Pyridazinone Herbicides Structural Requirements for Action on Membrane Lipids... 

Sandman, G., P.M. Brantley, and P. Boger. (1980). The inhibitory mode of action of pyridazinone herbicide norflurazon on cell-free carotenogenic enzyme system. Pestic. Biochem.Physiol., 14 185-191. 

Braumann, T., Grimme, L.H. (1981) Determination of hydrophobic parameters for pyridazinone herbicides by liquid-liquid partition and reversed-phase high-performance liquid chromatography. J. Chromatogr. 206(1), 7-15. 

Metflurazon inhibits photosynthesis and prevents the development of chloro-plastids in sensitive plants (Hilton et al., 1969). The authors also report on their investigation of the mode of action of 4 pyridazinone herbicides on barley. Metflurazon and its phenyl- and unsubstituted amino analogues, structurally similar to pyrazon, also inhibited the Hill reaction and photosynthesis, but showed two further biological features they resisted metabolic oxidation and inhibited chloroplast formation. The latter effect is similar to that of amitrol and dichlormate, but 100-1000 times stronger. 

Substituted pyridazinone herbicides directly inhibit photosystem II, chloroplast pigment biosynthesis, and membrane lipid biosynthesis. Depending on the substitution, pyridazinones can specifically inhibit the synthesis of linolenic acid in galacto-lipids and phospholipids preferentially alter the fatty acid composition of monogalactosyl diglycerides compared with digalactosyl diglycerides and cause a build-up of saturated fatty acids in the chloroplast membranes. 

Substituted pyridazinone herbicides may have a multifunctional mode of action. Inhibitory action by the substituted pyridazinones has been demonstrated at three separate sites (1, 3). The first site involves interference with photo-... 

The pyridazinone herbicides, of which norflurazon and pyrazon (chloridazon) are marketed, are applied pre- or early postemergence. The compounds are of modest to intermediate lipophilicity, and consequently they are readily taken up by the roots and translocated to the shoots, though essentially no symplastic transport has been observed. 

The preparation of new fluorine containing pyridazinones, prepared by electrofluorination in various base. HF systems has been patented by Rikagaku Kenkyusho as a route to herbicidal, insecticidal or bactericidal compounds... 

Pyridines and Pyridazinones. Pyridine herbicides arc auxin-type herbicides generally used fur selective control of hroadleaved weeds in cropland, rangelands, and noncroplands. The pyridazinones arc used primarily for ihe... 

Gas chromatography has been applied to the determination of a wide range of organic compounds in trade effluents including the following types of compounds which are reviewed in Table 15.15 aromatic hydrocarbons, carboxylic acids aldehydes, non ionic surfactants (alkyl ethoxylated type) phenols monosaccharides chlorinated aliphatics and haloforms polychlorobiphenyls chlorlignosulphonates aliphatic and aromatic amines benzidine chloroanilines chloronitroanilines nitrocompounds nitrosamines dimethylformamide diethanolamine nitriloacetic acid pyridine pyridazinones substituted pyrrolidones alkyl hydantoins alkyl sulphides dialkyl suphides dithiocaibamate insecticides triazine herbicides and miscellaneous organic compounds. 

Chemical Name 4-chloro-5-(methylamino)-2[3-(trifluoromethyl)phenyl]-3-(2//)-pyridazinone CAS Registry No 27314-13-2 Uses herbicide... 

Herbicides that seem to have a single site of action on the photochemical pathway, which is associated closely with photosystem 11 are the chlorinated pheny 1 ureas, Ws-carbamates such as phenmedipham, chlorinated s-triazines, substituted uracils, pyridazinones, diphenylethers, 1,2,4-triazinones, azido-s-triazines, cyclopropane-carboxamides, p-alkylanilides, p-alkyl-thioanilides, aminotriazinones, and urea-carbamates (2). 

Uses herbicide, sugar beet Trade names Pyramin (Basf) Type pyridazinone... 

Dichloropyridazine was transformed with sodium 2,2,2-trifluoroethoxide into mono- or di-alkoxy derivatives, but with other sodium fluoroalkoxides, polysubstitution occurred (85CJC3037). 4,5-Dichloro-2-methyl-3(2// )-pyridazinone was used to prepare herbicidal py-ridazino-l,2,4-triazines (87MI16). 

This procedure has previously been reported by Lederle chemists O, 4) and was used to prepare our original screening sample. For preparing a series of substituted phenyl analogs, the choice of benzaldehyde fixed the position of the substituent and the choice of an alkyl- or aryl-substituted acrylate fixed the substitution in the 4- and/or 5-position. All intermediates in this sequence were routinely tested in our herbicide screens, but very few of these, including the dihydropyridazinones and the pyridazinones, showed any significant activity. 

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