DE2133866A1 - 1-methyl-1-methoxy-3-phenylureas - with herbicidal activity - Google Patents

Abstract

Cpds. of formula (I):- (where X1 and X2 are CF3O, Cl or H, one being CF3O) are herbicides, and may be prepd. by (a) reacting 3-X2-4-X1-phenyl isocyanate (II) with Me-NH-OMe in a solvent; or (b) reacting (II) with NH2OH, followed by methylation.

Description

N-aryl ureas, process for their preparation and their use as herbicides The present invention relates to new N-arylureas which are herbicidal Have properties, as well as processes for their manufacture.

It is already known that N-aryl-N'-alkylureas as Herbicides can be used. It is also known that N- (3-trifluoromethyl-4-chlorophenyl) -N'-methyl-N'-O-methylurea can be used as a herbicide (cf.

Belgian patent 612 773).

It has been found that the new N-arylureas of the general formula in which X1 and X2 are trifluoromethoxy, chlorine and hydrogen, where X1 or X2 is tri = fluoromethoxy, have good herbicidal properties.

It has also been found that the ureas of the formula (I) are obtained if (a) isocyanates of the formula in which -X1 and X2 have the meaning given above, with O, NI> imethylhydroxylamine of the formula Reacts in the presence of a solvent or (b) isocyanates of the formula (II) with hydroxylamine to give the N'-hydroxyureas of the formula in which X1 and X2 have the meaning given above, are reacted in the presence of a solvent, and then the compound of the formula (IV) is reacted with a methylating agent to give the ureas of the formula (I) according to the invention.

It is extremely surprising that the active ingredients according to the invention have a higher herbicidal activity than the chemically closest known ones Active ingredients with the same type of action.

The course of the reaction according to process variant (a) can be reproduced by the following equation when using 4-? Rifluoromethoxyphenyl isocyanate and O, N-dimethylhydroxyamine as starting materials: The course of the reaction according to the process variant (br can be reproduced by the following formula scheme when using 3-trifluoromethoxy-4-chlorophenyl isocyanate, hydroxylamine and methyl bromide as starting materials: The starting materials according to formulas (II) and (III) are already known.

Examples of isocyanates which can be used according to the invention are: 3-chloro-4-trifluoromethoxyphenyl isocyanate, 3-trifluoromethoxyphenyl isocyanate and 3-trifluoromethoxy-4-chlorophenyl isocyanate.

As a methylating agent, for. B. methyl chloride, methyl bromide and dimethyl sulfate can be used.

Water, methanol and inert organic solvents are used as diluents Solvent in Prague. These include in particular ethers, such as dioxane and diethyl ether, Hydrocarbons such as benzene and chlorinated hydrocarbons such as chlorobenzene.

The reaction temperatures can be varied within a relatively wide range be in. In general, the range is 0-5000, preferably OK-2500.

Approximately equimolar amounts of isocyanate are used in the process and hydroxylamine or 0, N-dimethylhydroxylamine, but an excess of hydroxylamine is harmful: not. Working up is carried out in the customary manner.

The active compounds according to the invention have strong herbicidal properties on. They can therefore be used to destroy weeds.

As weeds in the broadest sense are plants that are in cultures or grow up in other places where they are undesirable. Whether the invention Active ingredients act as fotal or selective substances, depends essentially on the applied amount.

The substances according to the invention can, for. m. in the following plants are used: dicots, such as mustard (Sinapis), cress (Lepidium), burdock herb (Galium), chickweed (Stellaria), chamomile (Matricaria), French herb (Galinsoga), Goosefoot (Chenopodium), nettle (Urtica), ragwort (Senecio), cotton (Gossypium), Beets (Beta), carrots (Daucus), beans (Phaseolus), potatoes (Solanum), coffee (Coffea); Monocots, such as timothy grass (phleum), bluegrass (poa), Fescue (Festuca), Eleusine (Eleusine), Fennich (Setåria), Raygrass (Lolium), Trespe (Bromus), chicken millet (Echinochloa), maize (Zea), rice (Oryza), oats (Avena), barley (Hordeum), wheat (Triticum), millet (Panicum), sugar cane (Saccharum).

The active ingredients according to the invention are particularly suitable for selective use Weed control in cotton, grain, corn, rice and carrots.

The active compounds according to the invention can be used in the customary formulations such as solutions, emulsions, suspensions, powders, pastes and granulates. These are made in a known manner, e.g. B. by mixing the active ingredients with extenders, i.e. liquid solvents and / or solid carriers, optionally with the use of surface-active agents, that is to say emulsifiers and / or dispersants. In the case of using water as an extender, you can z. B. organic solvents can also be used as auxiliary solvents. as Liquid solvents are essentially suitable: aromatics, such as xylene and Benzene, chlorinated aromatics such as chlorobenzenes, paraffins such as petroleum fractions, alcohols, such as methanol and butanol, strongly polar solvents such as dimethylformamide and dimethyl = sulfoxide, as well as water; as solid carrier materials: natural rock flour, such as kaolins, Alumina, talc and chalk, and synthetic rock powder, such as finely divided silica and silicates; as emulsifiers: non-ionic and anionic emulsifiers, such as Polyoxyethylene fatty acid ester, Polyoxyäthy = len fatty alcohol ether, z. B. alkylaryl polyglycol ethers, Alkyl = sulfonates and arylsulfonates; as a dispersant: e.g. B.

Lignin, sulphite waste liquors and methyl celulose.

The active compounds according to the invention can be mixed in the formulations with other known active ingredients.

The formulations generally contain between 0.1 and 95 percent by weight Active ingredient, preferably between 0.5 and 90 percent by weight.

The active ingredients can be used as such, in the form of their formulations or the application forms prepared therefrom, such as ready-to-use solutions, emulsions, Suspensions, powders, pastes and granulates. The application happens in the usual way by spraying, misting, pouring, dusting or scattering.

The active ingredients can be applied according to the pre-emergence method with particularly good success, but according to the post-emergence procedure.

In particular, the amount of active ingredient per unit area depends on the intended use and type of application different. In general, between 0.1 and 10 kg of active ingredient applied per ha, preferably between 0.2 and 6 kg / ha.

Example A Pre-emergence test Solvent: 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether Active ingredient preparation is mixed 1 part by weight of active ingredient with the specified Amount of solvent, add the specified amount of emulsifier and dilute the concentrate with water to the desired concentration.

Seeds of the test plants are sown in normal soil and, after 24 hours, watered with the preparation of the active compound. The amount of water per unit area is expediently kept constant. The concentration of the active substance in the preparation does not matter; The only decisive factor is the application rate of the active ingredient per unit area. After three weeks, the degree of damage to the test plants is determined - and denoted by the code numbers O-5, which have the following meaning: -O no effect 1 slight damage or growth retardation 2 significant damage or growth inhibition 3 severe damage and only poor development or only 50% emerged 4 plants partially destroyed after germination or only 25% emerged 5 plants completely dead or not emerged Active ingredients, application rates and results are shown in the table below, table pre-emergence test Active ingredient Active ingredient- Echino- Cheno- Sina- Galin- Stella- Loli- Matri- Tree- Wei- Maize effort chloa podium pis soga ria um caria wool zen kg / ha CF3 O CH3 # # # Cl - # - NH-CN 2.5 3 5 4-5 4-5 5 3 4 0 1 1 # OCH3 1.25 2 3 4 4 3 2 3 0 0 1 (known) Cl O CH3 # # # CF3O - # - NH-CN 2.5 4-5 5 5 5 5 5 5 1 0 1 # OCH3 1.25 3 4-5 5 5 5 4 4-5 0 0 0 Example B Post-emergence test Solvent: 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce an appropriate preparation of active ingredient - 1 part by weight of active ingredient is mixed with the specified amount of solvent, the specified amount of emulsifier is added and the concentrate is then diluted with water desired concentration.

Test plantsZ which one are sprayed with the active compound preparation Height of 5-15 cm have such that the amounts of active ingredient given in the table per Area unit are applied.

The amount of water used depends on the concentration of the spray liquid between 1000 and 2000 l / ha. After three weeks the degree of damage to the plants will be and marked with the code numbers 0-5, which have the following meaning: Noticeable effect 1 single light burn marks 2 significant leaf damage: 3 individual leaves and stem parts partly

dead 4 plant partially destroyed 5 plant totally dead Active ingredients "Application rates and results" are shown in the following table: Table post-emergence test Active ingredient Active ingredient- Echino- Cheno- Sina- Galin- Stella- Loli- Matri- Tree- Wei- Maize effort chloa podium pis soga ria um caria wool zen kg / ha CF3 O CH3 1 4 4-5 5 2 2 5 0 3 1 1 # # # Cl - # - NH-CN 0.5 3 2 4-5 1 1 2 0 2 1 1 # OCH3 0.25 1 2 4 1 0 1 0 1 0 0 (known) Cl O CH3 1 4-5 5 5 5 5 5 1 4-5 5 1 # # # CF3O - # - NH-CN 0.5 3 5 5 5 5 5 0 4 2 1 # OCH3 0.25 2 5 5 5 5 5 0 3 0 0 Example 1a 47.5 g of 3-chloro-4-trifluoromethoxyphenyl isocyanate are added dropwise to a solution of 10 g of hydroxylamine in 200 ml of water at 5-100 ° C. with stirring, the N- (3-chloro-4-trifluoromethoxyphenyl) - N'-hydroxyurea crystallizes out immediately. The product is filtered off with suction and dissolved in 300 ml of methanol. 50 ml of 10 normal sodium hydroxide solution and 63 g of dimethyl sulfate are simultaneously added dropwise to this solution from two dropping funnels while stirring, so that the cooled reaction solution does not exceed 20.degree. After the reaction, it is poured into ice water.

A slowly crystallizing oil separates out.

Recrystallization from white spirit gives 18 g of N- (3-chloro-4-trifluoromethoxyphenyl) -N'-methyl-N'-methoxyurea from melting point 70 - 720C.

Example 1b In the implementation of 3-chloro-4-trifluoromethoxyphenylisocya = nat with O, N-dimethylhydroxylamine in dioxane, the same N- (3-chloro-4-trifluoromethoxyphenyl) -N'-methylZ is obtained methoxyurea of pp. 70-72 ° C.

The following ureas can be prepared analogously to the procedure according to example la or ib: Table Example connection melting point No. £ oj . . . . 2 P3 5 lECONxoeH 59-61 OCP, 3 / CK OcH3

Claims (6)

Claims t N-aryl ureas of the formula in which X1 and X2 are trifluoromethoxy, chlorine and hydrogen, where X1 or X2 is trifluoromethoxy. 2) procedure. for the production of N-arylureas, thereby. characterized in that (a) isocyanates of the formula in which X1 and X2 have the meaning given above, with O, N-dimethylhydroxylamine of the formula Reacts in the presence of a solvent or (b) isocyanates of the formula (II) with hydroxylamine to give hydroxy = ureas of the formula in which X1 and X2 have the meaning given above, reacted and then methylated to ureas of the formula (I). 3) Herbicidal agent, characterized by a content of N-arylureas according to claim 1. 4 Weed control methods, characterized by that one N-arylureas according to claim 1 on the weed or its habitat can act. 5) Use of N-arylureas according to claim 1 for combating of weeds. 6) Process for the preparation of herbicidal agents, characterized in that that N-aryl ureas according to claim 1 with extenders and / or surface-active Means mixed up.