JPH0517910B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a 5-ethyl-1,2,4-oxadiazole derivative and a herbicide containing the compound as an active ingredient. [Prior art] Conventionally, 5-ethyl-1,2, which has herbicidal activity
As a 4-oxadiazole derivative, 5-{1-
[4-(2-chloro-4-trifluoromethylphenoxy)phenoxy]ethyl}-1,2,4-oxadiazole (Japanese Unexamined Patent Publication No. 56-57774), 5-
{1-[4-(5-trifluoro-methyl-2-pyridyloxy)phenoxy]ethyl}-1,2,
4-Oxadiazole (JP-A-183688, 58-
210080, 59-98083), 5-{1-[4-(2,
4-dichlorophenoxy)phenoxy]ethyl}
-1,2,4-oxadiazole (JP-A-1983-
210073) etc. are known. [Problems to be solved by the invention] In rice cultivation, it exhibits a strong herbicidal effect against the harmful weed, Noviea, especially when applied to the surface of the water. The market demand for a herbicide with high intergeneric selectivity that does not have any adverse effects on herbicides remains strong even now, even though a large number of herbicides have already been developed and are on the market. An object of the present invention is to provide a herbicide that meets the demands of the market. [Means for Solving the Problems] The present invention provides 5-{1-[4-(4-cyanophenoxy)phenoxy]ethyl}-1,2,4-oxadiazole (hereinafter referred to as the compound of the present invention) and the present invention. The present invention provides a herbicide characterized by containing a compound as an active ingredient, and the herbicide containing the compound of the present invention as an active ingredient does not cause any phytotoxicity on transplanted paddy rice as well as flooded and directly sown paddy rice, and has a strong effect on paddy fields. It has the characteristic of exhibiting an excellent herbicidal effect against the noxious weed, Noviae. The compound of the present invention is a new compound that has not been described in any literature. [Function] The compound of the present invention can be produced by various methods, and a typical production method is shown by the reaction formula below. (In the formula, X represents a halogen atom.) The condensation reaction (A) in reaction formula () is carried out in the presence of a dehydrohalogenating agent, preferably in the presence of a reaction solvent, at a reaction temperature of usually 0 to 50°C. The reaction time is 1 to 24 hours. Examples of the dehydrohalogenating agent include tertiary amines such as triethylamine, pyridine and dimethylaniline, and inorganic bases such as potassium carbonate and sodium carbonate. Reaction solvents include hydrocarbons such as hexane, benzene, and toluene, ethers such as diethyl ether, tetrahydrofuran, and dioxane, ketones such as acetone and methyl ethyl ketone, and carbon halides such as carbon tetrachloride, chloroform, methylene chloride, and dichloroethane. Hydrogen can be given. The ring-closing reaction (B) in reaction formula () is carried out in an appropriate solvent such as benzene, toluene, xylene, etc. at a reaction temperature of 70 to 130°C and a reaction time of 30 minutes to 10 minutes.
It can be carried out by heating for a period of time. On the other hand, the reaction shown in reaction formula () can be carried out using a suitable solvent such as hydrocarbons such as hexane, benzene, toluene, and xylene, ketones such as acetone and methyl ethyl ketone, ethyl acetate, acetonitrile, dimethylformamide, dimethyl sulfoxide, etc. in the presence of a suitable dehydrohalogenating agent, such as a tertiary amine such as triethylamine, pyridine, or dimethylaniline, or an inorganic base such as potassium carbonate or sodium carbonate, at a reaction temperature of 40 to 120°C.
The reaction can proceed by heating for a reaction time of 1 to 10 hours. Conventionally, weeding of Noviae, which is an important weed in rice fields, takes advantage of the difference in drug resistance due to the difference in the growing period of Noviae and paddy rice, and only controls the Noviae at the time of germination without harming the paddy rice that has advanced in growth. Alternatively, it is a physical option that utilizes the adsorption of treatment chemicals to the soil topsoil to inhibit the germination of wild grass seeds located within the chemical adsorption layer, while leaving the paddy rice root groups distributed outside the chemical adsorption layer unharmed. Weeding has been carried out according to the law. Therefore, it has been extremely difficult to apply these herbicides to seedlings directly sown in water or to young seedlings immediately after transplanting. In order to provide a herbicide that is safe for weak rice such as direct-seeded rice, the present inventors conducted a search for a compound that has a physiological selective activity specific to the drug between paddy rice and wild grass, and as a result, the compound of the present invention was found to be remarkable. It has excellent intergeneric selectivity, has almost no effect on paddy rice, has a strong herbicidal effect on wild grass, has extremely long-lasting effects, and has little change in effectiveness depending on soil type. We discovered that it can be applied to a wide range of fields, from direct sowing to transplanted rice. The amount of the compound of the present invention to be applied varies depending on the application situation, application time, and application method, but generally the amount of active ingredient is 0.01 g to 100 g/a, preferably 0.1 g to 50 g/a.
A range of g/a is suitable. In order to use the compound of the present invention as a herbicide, it is mixed with various adjuvants, such as diluents, solvents, surfactants, etc., and formulated into the form of emulsion, wettable powder, powder, granule, etc., and used. The herbicide of the present invention can be applied in combination with other agricultural chemicals used in the same field, such as insecticides, fungicides, herbicides, plant growth regulators or fertilizers. In particular, it may be appropriate to add and mix the following herbicides for the purpose of reducing spraying labor or expanding the range of grass species that can be effectively controlled. 2,4-dichlorophenoxyacetic acid, its salts, esters and alkylamine salts 2-methyl-4-chlorophenoxyacetic acid, its salts and esters 2-methyl-4-chlorophenoxyacetic acid, its salts and esters d, l-2-(4-chloro-O-tolyloxy)
Propionic acid, its salts and esters 4-cyano-2,6-diiodophenyl octanoate 2,4-dichlorophenyl-4'-nitrophenyl ether 2,4,6-trichlorophenyl-4'-nitrophenyl Ether 2,4-dichlorophenyl-3'-methoxy-
4'-Nitrophenyl ether Methyl 3,4-dichlorocarbanilide Isopropyl 3-chlorocarbanilate S-4-chlorobenzyl diethylthiocarbamate 4-Nitrophenyl-3',5'-xylyl ether hexahydro -1H-azepine-1-carbothioate-S-ethyl 3,4-dichloropropionanilide 2-chloro-2',6'-diethyl-N-(butoxymethyl)acetanidide 2-chloro-2',6'-diethyl -N-(m-propoxyethyl)acetanilide 1-(α,α-dimethylbenzyl)-3-p-tolylurea 2,4-bis(ethylamino)-6-methylthio-1,3,5-triazine 2- ethylamino-4-isopropylamino-
6-Methylthio-1,3,5-triazine 2,4-bis(isopropylamino)-6-methylthio-1,3,5-triazine 5-tert-butyl-3-(2,4-dichloro-
5-isopropoxyphenyl)-1,3,4-oxadiazolin-2-one 2,6-dichlorobenzonitrile 2,6-dichlorothiobenzamide 2-amino-3-chloro-1,4-naphthoquinone 2, 4-dichlorophenyl-3'-carbomethoxy-4'-nitrophenyl ether N-p-chlorobenzyloxyphenyl-3,
4,5,6-tetrahydrophthalimide 2,4-dichlorophenyl-3'-ethoxyethoxy-4'-nitrophenyl ether N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine 4 -(2,4dichlorobenzoyl)-1,3-dimethyl-pyrazol-5-yl-p-toluenesulfonate 4-(2,4dichlorobenzoyl)-1,3-dimethyl-5-(benzoylmethoxy)-pyrazole 4 -(2,4dichloro-3-methylbenzoyl)
-1,3-dimethyl-5-(benzoylmethoxy)
-Pyrazole 0,0-diisopropyl-2-(benzenesulfonamide)-ethylene dithiophosphate 3,3'-dimethyl-4-methoxybenzophenone α-(2-naphthoxy)-propionanilide 0
-Ethyl-0-(3-methyl-6-nitrophenyl)-N- _see -butylphosphorothioamidate 3-isopropyl-2,1,3-benzothiadiazinone (4)-2,2-dioxide and its Salt S-(2-methyl-1-piperidyl-carbonylmethyl)-0,0-di-n-propyl diophosphate S-benzyl-N,N-dimethylthiocarbamate [Example] The manufacturing method will be specifically explained with reference to examples, but the method for manufacturing the compounds of the present invention is not limited to these examples. Example 1 2.13 g of 2-[4-(4-cyanophenoxy)phenoxy]propionyl chloride was dissolved in 50 ml of dichloromethane and 0.45 g of formamide oxime was added at once under stirring at below 10°C. Next, 0.72 g of triethylamine was added dropwise to this mixture over a period of 5 minutes at a temperature of 0 to 5°C. After the addition, the reaction mixture was stirred at room temperature for 6 hours and washed with water. The dichloromethane layer dried over anhydrous magnesium sulfate was concentrated under reduced pressure to obtain a light brown oily residue, which was dissolved in 100 ml of toluene and stirred and refluxed for 3 hours. After the reaction was cooled to room temperature, it was washed with water. The toluene layer dried over anhydrous magnesium sulfate was concentrated under reduced pressure, and the resulting oily residue was purified by silica gel chromatography.
0.65 g of 5-{2-[4-(4-cyanophenoxy)phenoxy]ethyl}-1,2,4-oxadiazole was obtained at 56.5-58°C. Yield 30%nmr.
(CDCI ₃ ) 1.73ppm (3H, d), 5.52ppm (1H, q) 7.13ppm (8H, m), 83ppm (1H, s) Next, examples of specific formulations using the compounds of the present invention state. Example 2 Emulsion 20 parts of the compound of the present invention, (parts mean parts by weight,
(The same applies hereinafter) 73 parts of xylene, 25 parts of polyoxyethylene alkyl ether, 1.5 parts of polyoxyethylene alkyl allyl ether, and 3 parts of calcium alkylbenzenesulfonate are uniformly dissolved to prepare an emulsion. Example 3 Granules 5 parts of the compound of the present invention and 2 parts of white carbon were mixed and pulverized, and 22 parts of benite and talc were added to the mixture.
42.5 parts of clay, 26 parts of sodium lignin sulfonate, 2 parts of sodium lignin sulfonate, and 0.5 part of sodium dodecylbenzenesulfonate are uniformly mixed, water is added, the mixture is made into granules using an extrusion granulator, and the mixture is dried and separated to form granules. Next, the herbicidal effects of the compounds of the present invention will be explained using Examples. Example 4 Effect test on Japanese wildflowers A 1/5000 Ahl Wagner pot was filled with paddy soil, and after plowing, 50 Japanese wildflower seeds were sown. The water was kept at a depth of 3 cm, and when the wildflower seeds germinated and reached the 1.5 leaf stage, the compound of the present invention was made into an emulsion according to Example 2, diluted with water in a predetermined amount, and applied uniformly to the water surface. . On the 15th day after the chemical treatment, the herbicidal effect and chemical damage were investigated, and the results shown in Tables 1 and 2 were obtained. The herbicidal effects shown in Table 1 were judged according to the following criteria. Evaluation index Weed killing effect 5 Complete death 4 80-99% suppression 3 60-79〃 2 40-59% suppression 1 20-39〃 0 No suppression The values in Table 2 indicate the ratio of live weight to the untreated plot. .

【table】

〔Effect of the invention〕

As is clear from Tables 1 and 2, the compound of the present invention also has a 40%
It shows no phytotoxicity at all even in g/a treatment. In addition, it can effectively control wild flies at the germination stage and the 1.5-leaf stage. In this way, the compound of the present invention can be used in flooded direct-seeded rice cultivation,
Alternatively, it can be used as a highly selective herbicide without phytotoxicity in flooded direct transplanted rice cultivation.
It has extremely high utility value. As described above, the compound of the present invention has many excellent characteristics as a herbicide and is highly practical.

Claims (1)

[Claims] 1 5-{1-[4-(4-cyanophenoxy)phenoxy]-ethyl}-1,2,4-oxadiazole. 2. A selective herbicide characterized by containing 5-{1-[4-(4-cyanophenoxy)phenoxy]-ethyl}-1,2,4-oxadiazole as an active ingredient.