JPS605587B2 - Pyrazole derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel pyrazole derivatives useful as herbicides.

JP-A No. 50-126 and JP-A No. 51-106738 describe that 4-penzoyl-5-hydroxypyrazole derivatives, salts thereof, or organic acid esters thereof are useful as herbicides.

The present inventors have discovered that a novel pyrazole derivative having the following general formula (1) has significant herbicidal activity.

In the formula, R represents a lower alkyl group.

R2 represents a hydrogen atom or a phenyl group. X represents a halogen atom. n indicates 2. Z represents a lower alkyl group. In the general formula (1), R is preferably methyl,
ethynole, n-propyl, isopropyl, n-butyl,
isobutyl, sec-butyl, rt-butyl, n-pentyl, isobentyl, SeC-amyl, 2-methylbutyl, te-amyl, n-hexyl, 2-hexyl,
2-Methylbentyl, 3-methylbentyl, 4-methylbentyl, 3-hexyl-2-ethylbutyl "linear or branched having 1 to 6 carbon atoms, especially 1 to 3 carbon atoms, such as 2-methyl-2-bentyl or 212-dimethylbutyl" Indicates a chain lower alkyl group.

X preferably represents a halogen atom such as chlorine, bromine, fluorine or iodine.

When Z is an alkyl group, it is, for example, methyl,
It can be a straight-chain or branched alkyl radical having from i to 4 carbon atoms, such as ethyl, propyl, n-butyl or 2**-butyl, preferably methyl.

The compound of general formula (1) is easily produced by (substituted) alkylating the compound of formula (0) with a (substituted) alkylating agent corresponding to the group Z, as shown in the following reaction formula. be able to.

(In the above-mentioned formula, R,, R2-X "Z and n are the same as described above.

) As the (substituted) alkylating agent corresponding to the group Z, various types known as alkylating agents can be used, for example halides such as chlorides, bromides or iodides, or epoxides or multi-bond compounds. , halides are particularly preferably used.

The reaction expressed by the above formula is preferably carried out in the presence of a solvent, and such a solvent is not particularly limited as long as it does not participate in this reaction, such as diethyl ether, tetrahydrofuran, dioxane, etc. ethers, aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, and trichloroethane, and acetone.
Examples include ketones such as inbutyl methyl ketone, esters such as ethyl acetate and amyl acetate, acetonitrile, and mixed solvents thereof, but aromatic hydrocarbons and ethers are preferably used.

When using halides as (substituted) alkylating agents, it is preferred to use deoxidizing agents, such as inorganic bases such as sodium carbonate, potassium carbonate, sodium bicarbonate, triethylamine, etc. ,
Examples include organic bases such as pyridine and N●N-jethylaniline. The reaction temperature is not particularly limited, and the reaction is carried out at room temperature to the reflux temperature of the solvent.

The reaction time varies depending on the reactant and reaction temperature. Usually 3
The time range is from 0 minutes to 24 hours. After completion of the reaction, the target product is isolated according to a conventional method and, if necessary, purified by methods such as column chromatography and recrystallization.

The compound of general formula (1) is used as a herbicide and has the characteristic of causing weeds to turn white and die.

In paddy fields, by treating the soil before or after the germination of weeds, it is possible to prevent the effects of weeds on transplanted rice and direct-seeded rice, and to prevent fireflies, which are difficult to control with ordinary herbicides, weeds of the Cyperaceae family, such as Cyperaceae, It can particularly effectively exterminate perennial weeds such as Omodacaceae weeds such as Prunus japonicus, and monocotyledonous weeds such as Poaceae weeds such as Prunus nigra and Prunus spp.
Effectively exterminates broad-leaved weeds such as weeds of the family Lythraceae such as azalea, purple moss, and Japanese aphrodisiacs; cruciferous weeds such as nightweed, waterweed, and Japanese burdock; weeds of the family Lythraceae such as Lythrum, and Asteraceae; be able to.

In addition, in upland areas, by treating the soil before or after the germination of weeds, it is particularly effective against strong weeds in upland areas such as chickweed, flea weeds, staghorn weeds, cloverweeds, etc., as well as weeds of the Portulaceae family such as Portulacae. Weeds of the family Chenopodiaceae, such as pigweed, silverwort, and silverwort; weeds of the family Chenopodiaceae, such as pigweed, white sardine, and koakaza; weeds of the Asiatica family, such as dayflower; It is possible to effectively exterminate broad-leaved weeds such as leguminous weeds such as peas and Japanese field peas, and weeds of the family Weedaceae such as hackberry and chinensis.

Furthermore, among narrow-leaved weeds, it is particularly effective against Cyperaceae such as Cyperus japonica and Cyperus japonica;
It is also possible to effectively exterminate weeds of the family Poaceae, such as grasshopper, rice grasshopper, dogweed, hackberry, goldenrod, and sparrowweed.

On the other hand, at practical dosages, crops such as rice, corn, beets, soybeans, cotton, radish, tomatoes, carrots, Chinese cabbage, and lettuce do not suffer from chemical damage. It can also be used effectively as a herbicide in non-agricultural lands, mountains, forests, etc.

The compound of the present invention can be mixed with a carrier and, if necessary, other adjuvants to form a formulation commonly used as a herbicide, such as a powder, a coarse powder, a fine granule, a granule, a wettable powder, an emulsion, etc.
It is prepared and used as an aqueous solution, aqueous solution, oil suspension, etc.

The carrier here refers to a synthetic or natural carrier that is mixed into the herbicide to help the active ingredient reach the area to be treated. Refers to inorganic or organic substances.The herbicides prepared in various dosage forms in this way are used as ``For example, when treating the soil before or after the germination of weeds in paddy fields or fields, the active ingredient is added per melon. Weeds can be effectively exterminated by applying 10 to 2,000 yen, preferably loo to 500 yen.

In addition, non-agricultural land such as roads, grounds, house sites,
When attempting to non-selectively exterminate weeds on railroad tracks, etc., use 200% or 4000% of the active ingredient per melon.
Weeds can be effectively exterminated by casting in the evening. Production example 1 4-(2,4-dichlorobenzoyl)-3-methyl-5
-Hydroxypyrazole 1.43 hours, benzene 15 minutes
, a mixture of 0.650 μl of triethylamine and 0.601 μl of methylfuromide was added, and the mixture was heated under reflux for 1 hour.

After wrapping, water is added to separate the salt, washed with a 5% aqueous sodium bicarbonate solution and then with water, dried over anhydrous sodium sulfate, and the solvent is removed to give a 1.75% oil. This was separated by column chromatography (eluted with silica gel: benzene: ethyl acetate = 6:1) for 1.34 days (
Yield: 89%) of 4-(2,4-dichlorobenzoyl)
-3-methyl-5-methoxypyrazole is obtained. m
p179-183 o (recondensed from n-hexane). Production example 24-(204-dichlorobenzoyl)-3-methyl-1-phenyl-5-hydroxypyrazole 12.1
Outside "acetonitrile 70", potassium carbonate (anhydrous)
Add 4.85 liters of water and let it stand at room temperature for 2 hours, then add a solution of 3.96 ml of L methyl bromide dissolved in 10 parts of acetonitrile, and reflux for 1 hour under a hood.

Claims (1)

[Claims] 1 Formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 represents a lower alkyl group. R_2 represents a hydrogen atom or a phenyl group. X represents a halogen atom. n represents 2. Z represents a lower alkyl group).