JPS6318922B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a herbicide containing a thiocarbamate derivative as an active ingredient. It has been well known that O-aryl N-arylthiocarbamate compounds have antibacterial and nematocidal effects as medicines. Furthermore, it is generally known that carbamates, thiol carbamates and dithiocarbamate compounds have herbicidal activity. Furthermore, JP-A-48-49925 discloses that certain aryl N-aryl carbamate compounds can be used as herbicides. However, it is not known that O-aryl N-arylthiocarbamate compounds can be used as effective herbicides. The present inventors completed the present invention as a result of extensive research in order to develop an O-aryl N-aryl thiocarbamate derivative with sufficient herbicidal effect and a high degree of selectivity. did. That is, the present invention is based on the general formula () (In the formula, R ₁ and R ₂ represent lower alkyl groups,
X and Y each represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a trifluoromethyl group. R ₁ and R ₂ and X and Y are the same or different from each other. ) A herbicide containing a thiocarbamate derivative represented by the following as an active ingredient is provided. The herbicide containing the thiocarbamate derivative of the present invention as an active ingredient exhibits extremely excellent herbicidal activity against many weeds including field weeds, especially in flooded rice fields, and has no adverse effects on transplanted paddy rice. It is harmless and suitable as a herbicide for paddy fields. In addition, field soil treatment shows excellent selective weeding effects between grass and broad-leaved weeds.
It was also recognized that it has applicability as a herbicide for upland fields. The thiocarbamate derivative represented by the general formula () used in the herbicide of the present invention is:
It can be produced according to the reaction formula below. (In the formula, R ₁ and R ₂ represent lower alkyl groups,
X and Y each represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a trifluoromethyl group. R ₁ and R ₂ and X and Y are the same or different from each other. Hal indicates a halogen atom. ) The above reaction is carried out in the presence of a dehydrohalogenating agent,
Further, the reaction usually proceeds in the presence or absence of a reaction solvent at a reaction temperature of 0°C to 150°C, and the reaction time is about several minutes to 48 hours. Examples of dehydrohalogenation agents include alkali hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth hydroxides such as calcium hydroxide, and alkali carbonates such as sodium carbonate, potassium carbonate, sodium hydrogen carbonate, and potassium hydrogen carbonate. , metal hydrides such as sodium hydride, and tertiary amines such as triethylamine, dimethylaniline, and pyridine. In reaction formula (2), the aniline derivative as a raw material can be used as a dehydrohalogenating agent. Reaction solvents include water, alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone and methyl ethyl ketone, aromatic hydrocarbons such as benzene, toluene, and xylene, ethers such as ethyl ether, tetrahydrofuran, and dioxane, and chlorine. Halogenated hydrocarbons such as benzene, chloroform, carbon tetrachloride and dichloroethane, polar solvents such as dimethylformamide and dimethyl sulfoxide, and the like are used. Next, the method for producing the active ingredient compound used in the herbicide of the present invention will be explained by giving specific synthesis examples. [Synthesis Example 1] O-3-isopropylphenyl N-methyl-
Method for producing N-(3-methylphenyl)thiocarbamate (Compound No. 3) 2.00 g of N-methyl-N-(3-methylphenyl)thiocarbamoyl chloride, 1.36 g of 3-isopropylphenol, and 1.38 g of anhydrous potassium carbonate.
g was added to 50 ml of methyl ethyl ketone and heated under reflux for 15 hours. After cooling the reaction mixture to room temperature,
Poured into cold water and extracted the product with benzene. Benzene solution, 10% sodium hydroxide solution, water,
After washing with saturated aqueous sodium chloride solution and drying over anhydrous magnesium sulfate, benzene was distilled off under reduced pressure. The residue was subjected to column chromatography (silica gel, benzene/hexane = 1/1 (V/
V) Development) to obtain O-3-isopropylphenyl N-methyl-N-(3-methylphenyl)
2.32 g of thiocarbamate (yield 78%, oily) was obtained. When this product was left to stand at room temperature, it crystallized and was recrystallized from ethanol to obtain colorless crystals with a melting point of 48-49.5°C. [Synthesis Example 2] O-3-tert-butylphenyl N-methyl-
Method for producing N-phenylthiocarbamate (Compound No. 4) 1.07 g of N-methylaniline and 1.38 g of anhydrous potassium carbonate were added to 20 ml of acetone, and while stirring at room temperature, O-3-tert-butylphenyl chlorthioform was added. 2.29 g of mate was dissolved in 20 ml of acetone and added. After stirring as it was for 30 minutes, the mixture was heated under reflux for 2 hours. After the reaction mixture was cooled to room temperature, it was poured into cold water and the product was extracted with benzene. The benzene solution was washed with dilute hydrochloric acid, water, and a saturated aqueous sodium chloride solution in this order, dried over anhydrous magnesium sulfate, and then benzene was distilled off under reduced pressure. The residue was purified by column chromatography (silica gel, developed with benzene/hexane = 1/1 (V/V)) to obtain 1.77 g of O-3-tert-butylphenyl N-methyl-N-phenylthiocarbamate (yield: 77
%) was obtained. A part of this product was recrystallized from hexane to obtain colorless crystals with a melting point of 78.5-79°C. Next, representative examples of the compounds represented by the general formula () and their physical properties are shown in Table 1 below.

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[Test example 1]

Weeding effect test under flooded conditions Paddy soil was placed in a porcelain pot with a diameter of 9 cm, water was added, and after puddling, weed seeds were sown on the soil surface.
Paddy rice seedlings (variety, Nipponbare) in the leaf stage are planted at a depth of 1 cm.
Two plants were planted. The next day, the pot was flooded with water to a depth of 2 cm, and the prescribed dose of the hydrating powder of each herbicide of the present invention was added to the pot at 10 ml per pot.
It was diluted in 1 ml of water and dropped onto the water surface. after that,
The plants were left in a greenhouse, and three weeks after the chemical solution treatment, the herbicidal effect and the effect on paddy rice were investigated. The evaluation was displayed on a 6-level scale, and the specific details are as follows. The results are shown in Tables 2 and 3. Display Weeding effect on paddy rice chemical damage 5 Death 100% control (residual weed amount 0%) 4 Severe damage 80% control (residual weed amount 20%) 3 Moderate damage 60% control (remaining weed amount 40%) 2 Minor damage 40 % control (residual weed amount 60%) 1 Slight damage 20% control (remaining weed amount 80%) 0 Harmless 0% control (remaining weed amount 100%)

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[Test example 2]

Herbicidal effect test by surface treatment of field soil Field soil was put into a porcelain pot with a diameter of 12 cm, seeds of several types of plants were sown, and the pot was covered with 1 cm of soil. A predetermined amount of the hydrating powder of the herbicide of the present invention was diluted in 10 ml of water per pot, which was sprayed onto the soil surface, and then left to stand in a greenhouse and watered at appropriate times. Three weeks after the chemical solution treatment, the herbicidal effect and the effect on soybeans and cotton were investigated and evaluated according to Test Example 1. The results are shown in Table 4.

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Claims (1)

[Claims] 1 General formula () (In the formula, R ₁ and R ₂ represent lower alkyl groups,
X and Y each represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a trifluoromethyl group. R ₁ and R ₂ and X and Y are the same or different. ) A herbicide characterized by containing a thiocarbamate derivative represented by the following as an active ingredient.