JPS625906B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to novel pyrazole derivatives.

JP-A-50-126830 and JP-A No. 51-106738 describe that 4-benzoyl-5-hydroxypyrazole derivatives, salts thereof, or organic acid esters thereof are useful as herbicides.

The present inventors have discovered a novel pyrazole derivative having herbicidal activity and having the following general formula ().

formula In the formula, R ₁ and R ₂ represent a methyl group. X represents a chloro atom, a nitro group or a methyl group. n is 2
or an integer of 3, and X may be the same or different from each other.

Z represents a lower alkyl group, a phenacyl group or a benzyl group which may be substituted with one methyl. However, the case where X is a chlorine atom or a nitro group and n is 2 is excluded.

When Z is a lower alkyl group, it can be a straight-chain or branched alkyl group having 1 to 3 carbon atoms, such as methyl, ethyl, propyl, preferably methyl.

When Z is a phenacyl group optionally substituted with methyl on the phenyl ring, it is, for example, a phenacyl group or a 4-methylphenacyl group.

The compound of the general formula () of the present invention can be easily produced by (substituted) alkylating the compound of the formula () with a (substituted) alkylating agent corresponding to the group Z, as shown in the following reaction formula. can do.

(In the above formula, R ₁ , R ₂ , X, Z and n are the same as those described above.) Examples of the (substituted) alkylating agent corresponding to the group Z include chloride, bromide or iodide. The halides are particularly preferably used.

The reaction represented 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.
For example, ethers such as diethyl ether, tetrahydrofuran, and dioxane, aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, and trichloroethane, acetone, isobutyl methyl ketone, etc. Examples include ketones, esters such as ethyl acetate and amyl acetate, acetonitrile, and mixed solvents thereof, but aromatic hydrocarbons and ethers are preferably used. When using a halide as an alkylating agent, it is preferable to use a deoxidizing agent;
Such deoxidizers include, for example, inorganic bases such as sodium carbonate, potassium carbonate, sodium bicarbonate, triethylamine, pyridine, N.N.
-Organic bases such as diethylaniline.

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, and is usually 30 minutes to 24 hours.

After the reaction is completed, the target product is isolated according to a conventional method,
If necessary, it is purified by methods such as column chromatography and recrystallization.

Examples of compounds of formula () of the present invention are shown.

Example 4-(2,4,5-trichlorobenzoyl)-
1,3-dimethyl-5-hydroxypyrazole
To 427 mg, add 5 ml of acetonitrile and 185 mg of potassium carbonate (anhydrous), stir at room temperature for 1.5 hours, add a solution of 319 mg of phenacyl bromide in 2 ml of acetonitrile, and reflux for 1 hour while stirring. The salts are removed, the liquid is evaporated and the residue is dissolved in ethyl acetate and washed with water. Dry over anhydrous sodium sulfate and remove the solvent to obtain a residue (250 mg).
I got it. This was subjected to silica gel column chromatography (n-hexane:ethyl acetate = 2:1), and 4-(2.4.5-trichlorobenzoyl)-
200 mg of 1,3-dimethyl-5-phenacyloxypyrazole (beakish-like; oily substance) is obtained. n ²⁸ _D 1.6058 The following compound is produced according to the method of the above example.

4-(2,4-dimethylbenzoyl)1,3-
Dimethyl-5-ethoxypyrazole n ¹⁶ _D 1.5530 4-(2-nitro-5-methylbenzoyl)-
1,3-dimethyl-5-benzyloxypyrazole mp 110-111℃ 4-(2-nitro-5-methylbenzoyl)-
1,3-dimethyl-5-phenacyloxypyrazole mp ~134℃ (Reference) 4-(2,4-dichlorobenzoyl)-1,3-
Dimethyl-5-(4-methylphenacyloxy)
Pyrazole n ³⁰ _D 1.5945 The compound of the general formula () 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, weeds such as Cyperaceae and Cyperaceae, which are difficult to control with ordinary herbicides, can be removed without causing any harm to moved or directly sown rice. It can particularly powerfully exterminate perennial weeds such as Omodacaceae weeds such as Prunus japonicus, and monocotyledonous weeds such as Poaceae weeds such as Japanese grasshopper, Japanese grasshopper, and Poaceae weeds.
It is also possible to effectively exterminate broad-leaved weeds such as weeds of the family Asteraceae, such as azalea, moss moss, and staghorn moss, weeds of the family Brassicaceae, such as weeds of the family Asteraceae, such as weeds, weeds, and weeds of the family Asteraceae, such as weeds of the family Asteraceae, such as argentina and staghorn moss.

In addition, in fields, by treating the soil before or after the germination of weeds, it is particularly effective against weeds of the Caryophyllaceae family, such as chickweed, flea weed, Japanese clover, and clover, as well as weeds of the Caryophyllaceae family, such as Purslane. , weeds of the Amaranthaceae family, such as dogweed and silverweed, weeds of the Chenopodiaceae family, such as pigweed, whitewort, and koakaza, weeds of the family Araceae, such as dayflower, weeds of the Lamiaceae family, such as oxalis and Oxalis oxalis, weeds of the family Lamiaceae such as oxalis,
It is possible to effectively exterminate broad-leaved weeds such as leguminous weeds such as catfish, sycamore, and crow pea, and weeds of the euphorbiaceae family such as hackberry and cornucopia.

Further, among narrow-leaved weeds, it is particularly effective against weeds of the Cyperaceae family such as Cyperus japonica and Cyperus japonica, and can also effectively exterminate weeds of the Poaceae family such as Cyperaceae, Cyperus spp. On the other hand, in practical doses, rice, corn, beets, soybeans, cotton, radish, tomatoes,
Crops such as carrots, Chinese cabbage, and lettuce do not suffer from chemical damage.

Furthermore, the compound having the general formula () is
It can also be effectively used as a herbicide in orchards, non-agricultural lands, 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 powder, coarse powder, fine granules, etc.
It is prepared and used as granules, wettable powders, emulsions, aqueous solutions, aqueous solutions, oil suspensions, etc. The carrier here refers to a synthetic or natural carrier that is mixed into the herbicide to aid in the reach of the active ingredient to the area to be treated, and to facilitate the storage, transportation, or handling of the active ingredient. means an inorganic or organic substance.

Powders, for example, usually contain 1 to 10% of the active ingredient compound.
It contains 25 parts by weight, and the remainder is solid carrier.

Wettable powders usually contain, for example, 25 to 90 parts by weight of the active ingredient compound, with the remainder being a solid carrier and a dispersing wetting agent, with protective colloid agents, thixotropic agents, antifoaming agents, etc. being added as necessary.

Granules, for example, usually contain 1 to 1 active ingredient compound.
It contains 35 parts by weight, and the remainder is mostly solid carrier. The active ingredient compound is uniformly mixed with the solid carrier, or is uniformly fixed or adsorbed on the surface of the solid carrier, and the particle size is approximately 0.2 to
It is about 1.5mm.

Emulsions, for example, usually contain 5 to 5 active ingredients.
This includes approximately 5 to 20 parts by weight of an emulsifier, and the remainder is a liquid carrier, with a rust preventive added as needed.

When the herbicide of the present invention, which has been prepared in various formulations in this way, is used to treat soil before or after the germination of weeds in paddy fields or upland fields, the amount of the active ingredient is preferably 10 to 2000 g per 10 acres, preferably 100 to 2000 g. Weeds can be effectively exterminated by throwing 500g. In addition, when attempting to non-selectively exterminate weeds in non-agricultural lands, such as roads, grounds, house grounds, railroad tracks, etc.,
Weeds can be effectively exterminated by applying 200 to 4000g of the active ingredient per 10g.

Claims (1)

[Claims] 1 Formula () (In the formula, R ₁ and R ₂ represent a methyl group. X represents a chloro atom, a nitro group, or a methyl group. n represents an integer of 2 or 3; Indicates a lower alkyl group, a phenacyl group or a benzyl group which may have one methyl substituted on the phenyl ring.However, except when X is a chloro atom or a nitro group and n is 2.) Compound.