WO1980000344A1

WO1980000344A1 - New substituted phenylurea herbicide

Info

Publication number: WO1980000344A1
Application number: PCT/FR1979/000068
Authority: WO
Inventors: G Borrod; P Andre; S Trinh
Original assignee: Rhone Poulenc Agrochimie; G Borrod; P Andre; S Trinh
Priority date: 1978-07-25
Filing date: 1979-07-24
Publication date: 1980-03-06
Also published as: MA18537A1; ZA793754B; GR69974B; IL57758A0; DD145053A5; ES482473A0; GB2027699A; FR2435464A1; PT69964A; EP0016132A1; ES8202790A1; AU4913279A; CS208667B2; OA06494A; DK122780A; PL217326A1; JPS55500454A

Abstract

New herbicide N-trifluoromethyl-3 ethyl-4 phenyl N' N' dimethylurea is appropriate for use as active herbicide material. It is appropriate for selective weed-killing of crops (cereals, corn, cotton, soya bean).

Description

The present invention relates to a new substituted phenylurea, to its preparation, to the herbicidal compositions containing it and to a process for selective weeding of certain crops using these compositions. A subject of the invention is also trifluoromethyl-3-ethyl-4-aniline, its preparation and its use as an intermediate for the manufacture of chemical compounds. It is well known that certain tri-substituted phenylureas have interesting selective herbicide properties. In particular, Belgian patent 594.227 describes herbicidal agents containing, as active material, N-tri-fluoromethyl-3 phenyl N'N-dimethylurea usable as total or selective weedkiller after 2.5 kg / ha of corn. Since then, this compound has been used commercially only on cotton, the margin of selectivity for other crops being considered too narrow.

Furthermore, 4-alkylphenyl N'N'-dimethy.lureas are known, having good selective herbicide properties on crops, especially on cereals. However, their selectivity on cotton has never been used, the results of outdoor experiments have not confirmed those of greenhouse tests.

The Applicant has discovered with surprise that N-trifluoromethyl-3-ethyl-4-phenyl N'N 'dimethylurea, instead of accumulating the reduced selectivities on cereals, corn and cotton that could be expected from the simultaneous presence of the trifluoromethyl subtuants in position 3 and lower alkyl in position 4 on the phenyl nucleus, presents a cumulative desmeileufes selectivities, these being further improved compared to the aforementioned ureas.

Certainly, French patent 2,001,791 describes a family of substituted phenylureas whose substituents cover those of the compounds according to the invention, but this family includes a considerable number of possible compounds (more than 100,000) and the only subfamily actually illustrated by physico-chemical characteristics does not apply to products comprising a trifluoromethyl group on the phenyl ring. On the biological level, if the selectivity of certain compounds, including in particular chltoluron, is illustrated on cereals, their behavior on cotton is not the subject of any test result or even mentioned in the description of the patent cited.

The present invention therefore relates to a new chemical compound of formula:

as well as the herbicidal compositions containing it and a process for selective weeding of an increased number of crops using these compositions.

The compounds according to the invention can be prepared according to methods known per se. First of all, the trifluoromethyl-4-ethyl-phenyl isocyanate can be condensed on the dimethylamine according to the scheme:

This reaction is carried out in an organic solvent medium inert under the conditions of the reaction, for example an aromatic solvent such as toluene or chlorobenzene, at room temperature, preferably with stirring.

The isocyanate used can be obtained in a manner known per se by reacting ^'phosgene on trifluo rométhyl 3-ethyl-aniline 4, the reagents being added as a solution in an inert organic solvent, for exeple an inert aromatic solvent , under the reaction conditions such as toluene or chlorobenzene, at a temperature between 0 ° (: and the boiling point of the solva A relatively high temperature promotes the release of hydrochloric acid from the reaction:

Another mode of preparation consists in reacting hexametapil and carbon dioxide on 3-trifluoromethyl-4-ethyl aniline according to the scheme:

in the presence of pyridine at a temperature between 15 ° C and 100 ° C.

Finally, the compound according to the invention can be prepared by the action of dimethylcarbamyl chloride on trifluoromethy-3 ethyl-4 aniline according to the scheme:

in the presence of an acid acceptor such as triethylamine. Trifluoromethy1-3 ethyl-4 aniline, a liquid product which distills at 96-97 ° C under 16 mm Hg, is a new synthesis intermediate which can be prepared by catalytic hydrogenation dμ. corresponding nitrous derivative in the presence, for example, of palladium on activated carbon, in methanolic medium according to the scheme:

The nitro derivative can be prepared by nitration using a sulfonitric mixture of orthotrifluoromethyl ethylbenzene according to the scheme:

CHi-

The orthotirifluoromethy1 ethylbenzene can be obtained by catalytic hydrogenation, in the presence of palladium on activated carbon, in an alkaline methanolic medium, of 1 'orthotrifluoromethy1 trichloro-2' 2 '2' ethylbenzene according to the scheme:

+ 3KC1

The trichloride derivative can be obtained by reaction, in acetone, in the presence of cupric chloride of dichloro vinylidene on a halide, in particular the diazonium chloride of the trifluoromethy 1-2 aniline according to the

The following examples illustrate the preparation and the herbicidal properties of N- (trifluoromethy1-3-4-ethyl-phenyl) -N'N '-dirtethylethylurea.

EXAMPLE 1 Preparation of N-fcrifluoromethyl-4-ethyl-phenyl) -N'N * -dimethylurea according to the first procedure A solution of 35 g (0.162 mol) of trifluoromethyl-4-ethylphenyl isocyanate is poured in dropwise dissolved in 100 ml of toluene on a solution of 8.1 g (0.18 mole) of dimethylamine in 50 ml of toluene. The reaction is carried out with stirring and at a temperature in the region of 15 ° C for 4 hours. By evaporation of the solvent, a precipitate is obtained which is recrystallized from a methanol / water mixture 30/70. The product obtained (with a yield of 63%) melts at 105-106 ° C. Analysis in nuclear magnetic resonance using a spectrometer at 60 MHz in hexadeuterous dimethyl sulfoxide with tettramethyl silane as internal reference, shows that it is trifluoromethyl-3-ethyl-4-phenyl dimethylurea .

The trifluoromethy-3-ethyl 4-phenyl isocyanate used above was prepared as follows:

A solution of 39.7 g (0.21 mol) of trifluoromethyl-3 ethyl-4 aniline dissolved in 400 ml of toluene is poured in dropwise with a solution of 83.2 g (0.84 mol) of phosgene dissolved in 600 ml of toluene.

The reaction is carried out with stirring and at a temperature in the region of 0 ° C. After the end of the flow of the aniline solution, the medium is allowed to return to room temperature, then slowly heated until boiling. After the gas evolution of the hydrochloric acid formed and the excess of phosgene has ended, the reflux is maintained for another 1 hour. The toluene is then evaporated and a liquid, with a boiling point of 50-51 ° C under 1 mm of mercury, is obtained with a yield of 95%.

NMR analysis of the compound clearly confirms the structure sought.

Example 2: Preparation of the compound according to the invention, according to the second process. In a three-necked flask provided with a condenser and a carbon dioxide inlet tube plunging near the bottom of the flask and with stirring, 8.1 g (0.0427 mol) of trifluoromethyl 1-3 ethyl are introduced. 4 aniline, 7.0 g (0.0427 mole) of hexametapil and 22 ml of previously dried pyridine. The temperature is adjusted to 60 ° C. and the carbon dioxide stream is passed through for 6 hours. After dry evaporation and taken up in 20% ethanol, the urea precipitates. By recrystallization from a methanol / water mixture 50-50, there is obtained, with a yield of 69%, 7.7 g of N-trifluoromethy-3 ethyl-4 phenyl N'N 'dimethylurea with melting point 105 ° C, structure is confirmed by NMR analysis. Example 3: Preparation of trifluoromethyl-3-ethyl-4-aniline.

Hydrogen is introduced under a pressure of 10 bars into a mixture heated to 48-50 ° C,

43.8 g (0.2 mole) of trifluoromethyl 1-2 nitro-4 ethylbenzene, 2.5 g of 5% palladium on charcoal, previously wetted with 1 ml of water and 350 ml of methanol.

The reaction is carried out with stirring for 30 minutes. Then, it is cooled and filtered. After evaporation of the methanol, a li- product is obtained. quide, which distills at 96-97 ° C under 16 mm of mercury, with an overall yield of 85%. '

Trifluoromethyl-2 nitro-4 ethylbenzene is obtained according to the following process:

Poured, drop by drop, - the mixture of 70.7 g of 92% sulfuric acid and 47.5 g of 100% nitric acid on 80 g (0.46 mole) of 2-trifluoromethylethylbenzene. The reaction temperature is maintained at 38-40 ° C. After pouring the sulfuric mixture, the mixture is stirred for one hour. The mixture is then poured into two liters of crushed ice. Extraction is carried out with an organic solvent such as methylene chloride. The chloromethylenic extracts are washed and then dried over anhydrous sodium sulfate. After evaporation of the solvent, a colored liquid is obtained which crystallizes at 5 ° C, the overall yield being 87.6%. Trifluoromethyl 1-2 ethylbenzene is prepared as follows: The following are introduced into a 1000 ml autoclave

70 g (0.25 mole) trifluoromethy1-2 (trichloro-2'2'2 ' ethyl) benzene, 4 g of 5% palladium on charcoal, previously wetted with 5 ml of water, and 300 ml of methanol. A solution of 44 g (0.785 mole) of potassium hydroxide is then added to a mixture of 350 ml of methanol and 35 ml of water. Hydrogen is introduced under a pressure of 4 bars, the temperature of the medium being maintained at 28-30 ° C. for the entire duration of absorption of the hydrogen. The methanolic solution is then filtered, then diluted in 6 liters of water. The organic phase is decanted and the aqueous phase treated with methylene chloride. The organic phase and the chloromethylenic extracts are combined, washed with water and dried over anhydrous sodium sulfate. After evaporation of the methylene chloride, a liquid product is obtained, which distills at 40-41 ° C under 15 mm of mercury, the overall yield being 91%.

Trifluoromethyl-2 (trichloro-2'2'2 ethyl-) benzene is obtained as follows: the diazonium salt is first prepared by diazotization of trifluoromethyl 1-2 aniline. A solution of 69 g (l mole) of sodium nitrite in 150 ml of water is poured simultaneously onto 130 ml of 10 N hydrochloric acid, as well as the solution into 500 ml of 1-97 water, 5 g (1 mole) trifluoromethyl 1-2 aniline hydrochloride. After reaction at a temperature of between 0 and 5 ° C., a clear light yellow solution of trifluoromethyl 1-2 benzene diazonium chloride is obtained.

This solution, still kept at 0-50 ° C, is poured onto a mixture of 116.4 g (1.2 mole) of dichlorovinylidene, one liter of acetone and 10 g of copper chloride dihydrate dissolved in 50 ml of water. The reaction is maintained at a temperature of 27-28 ° C. The dichloro-vinylidene entrained by the evolution of nitrogen is condensed in the cooler cooled to -10 ° C by a circulation of brine. After pouring in the diazonium salt solution, stirring is continued and heating at 30 ° C. until the end of the evolution of nitrogen. The reaction mixture is then diluted in 5 liters of water. We decant the organic phase, wash with water and dry over anhydrous sodium sulfate. After filtration, a slightly colored liquid is obtained with a yield of 78%, distilling at 108-110 ° C under 15 mm of mercury. Example 4: Pre-emergent and post-emergent herbicidal activity of crops and weeds.

In 9 x 9 x 9 cm pots filled with light agricultural soil, a number of seeds is sown according to the plant species and the size of the seed.

We then cover them. seeds of a layer of earth about 3 mm thick.

After moistening the soil, the pots are treated by spraying a quantity of porridge per pot corresponding to a volume of 500 l / ha and containing the active material at the dose considered.

The slurry is prepared by diluting with water an emulsifiable concentrate having the following composition by weight: active material to be tested 20% emulsifying agent: nonylphenol oxyethylenated with 17 ethylene oxide 10% solvent (xylene) 70% at the desired dilution, containing the active ingredient at the dose considered. The tests were carried out for doses of active material ranging from 0.25 kg / ha to 8 kg / ha. The treated pots are then placed in tubs intended to receive the irrigation water, under subirrigation, and kept for 35 days at room temperature under 70% relative humidity.

After 35 days, the destruction rate is compared to a control treated under the same conditions with a spray dispersion not containing the active ingredient. For post-emergence tests, we proceed as above, except that the treatment is carried out killed on seedlings at the 2nd leaf developing stage for grasses and 2 cotyledonary leaves developed with exploded terminal bud for dicotyledons.

The plant species, both crops and weeds tested, were as follows: Crops:

Corn ÇZea mays) MA

Wheat (Tri ^' ticum vulgare) BL

Cotton (Gossypium barbadense) CO

Soy (Glycine max) ^_ SO

Weeds

Wild oats (Avena fatua) FA Digitaria (Digitaria sanguinalis) DI Panisse (Echinochloa crus-galli) PA Ryegrass (Lolium multiflorum) RA Foxtail (Setaria faberii) SE

Vulpin (Alopecurus myosuroïdes) VU

Çhënopode (Chenopodium album) CH

Nightshade (Solanum nigrum) MR

Mustard (Sinapis alba) MO

Stellar (Stellaria media) ST

The compounds tested as active material are:

- 3-trifluoromethyl-4-ethylphenyl dimethylurea (compound according to the invention - Example 1)

- 3-trifluoromethyl-4-butylphenyl dimethylurea (compound A)

- 3-trifluoromethyl-4-butylphenyl mono-ethylurea (compound B)

- trifluoromethyl-3 phenyl dimethylurea (known compound. fluomëturon)

The compounds having been prepared according to the procedure of Example 1.

The results below are expressed in kg / ha and denote: a - in the case of crops, the selectivity threshold, which represents the maximum tolerated dose without damage by culture. According to this evaluation, a compound having a selectivity threshold of 4 kg / ha has a selectivity twice that of a compound whose threshold is 2. kg / ha. b - in the case of weeds, the activity threshold, ie the minimum dose necessary for complete destruction (> 90%) of the species in question. According to this evaluation, a compound with an activity threshold of 1 kg / ha is twice as active as that with an activity threshold of 2 kg / ha. A selective weedkiller will therefore be all the better as. both its selectivity threshold will be higher (for example at least equal to 4 kg / ha) and its activity threshold will be lower (for example at most equal to 1 kg / ha), that is to say that the margin between activity and selectivity will be greater, the weedkiller being usable with all the more security for the crop considered.

The results are recorded in the following tables:

Table 1: Selectivity threshold in kg / ha on crops

This table clearly shows that the compound 1 according to the invention has a much higher selectivity than that of fluometuron. It is, on the other hand, lower than compounds A and B, but the selectivity of these compounds corresponds to general inactivity, including on weeds as will be seen in the following table: Table XIa: Activity threshold in kg.ha Pre-emergent weeds

Table TIB: Activity threshold in kg / ha on post-emergent weeds

From these two tables, it appears significantly that the compound 1 has a herbicidal activity substantially equivalent to that of fluometuron preemergence and incomparably higher postemergence. In addition, the herbicidal activity of this same compound 1 is obviously much higher than that of compounds A and B both pre- and post-emergence, the latter being inactive at 8 kg / ha except compound B which destroys mustard 8kg / ha postemergence. These examples illustrate the surprising herbicidal behavior of the compound according to the invention both vis-à-vis its 4-alkyl trifluoromethyl-3-phenyl dimethylurea counterparts as well as fluometuron.

N-trifluoromethy-3 ethyl-4 phenyl N'N'-dimethylurea can therefore be used as active material in the compositions for the selective weeding of crops and in particular of cereals (wheat, barley), corn, cotton and soybeans.

For the herbicide treatments carried out using the compound according to the invention, the dose of active material to be used can vary from 0.25 to 8 kg / ha, in particular according to the type of crop and the nature of the soil. Preferably, this dose is comprised between 0.5 and 5 kg / ha. For its use in practice, the compound according to the invention is rarely used alone. Most often, it is part of formulations which generally comprise from 0.5 to 95% by weight of the active material according to the invention, a support and / or surfactant (generally from 0 to 10 % by weight, preferably 0.1 to 10%).

The term "support" within the meaning of the present description designates a material, organic or mineral, natural or synthetic, with which the active material is associated to facilitate its application on the plant, on the seeds or on the soil, or its transport or his ma- nipulation. The support can be solid (clay, natural or synthetic silicates, resins, waxes, solid fertilizers) or fluid (water, alcohols, ketones, petroleum factions, chlorinated hydrocarbons, liquefied gases). The surfactant can be an emulsifying, dispersing or wetting agent, each of which may be ionic or nonionic. Mention may be made, for example, of salts of polyacrylic acids, salts of phenolsulfonic acids or sulphonated naphthalene acids, polycondensates of ethylene oxide on fatty alcohols.

The compositions according to the invention can be prepared in the form of wettable powders, dusting powders, granules, solutions, emulsifiable concentrates, emulsions, suspended concentrates and aerosols.

Wettable powders are usually prepared so that they contain from 20 to 95% by weight of active ingredient and they usually contain, in addition to a solid support, from 0 to 5% by weight of wetting agent, from 3 to 10% by weight of one or more stabilizers and / or other additives, such as penetration agents, adhesives or anti-caking agents, glues, etc. As an example, here is the composition of a powder wettable. - active ingredient (compound N ° l) 50%

- calcium lignosulfate (deflocculant) 5%

- sodium isopropylnaphthalene sulfonate (anionic wetting agent) 1% - anti-clumping silica 5%

- kaolin (filler) 39% The granules intended to be placed on the ground are usually prepared so that they have dimensions between 0.1 and 2 mm and they can be manufactured by agglomeration or impregnation. In general, the granules contain from 0.5 to 25% of material active and from 0 to 10% by weight of additives such as stabilizers, slow release modifiers, binders and solvents.

The emulsifiable concentrates applicable in spraying usually contain, in addition to the solvent, and, when necessary, a co-solvent, from 10 to 50% by weight / volume of active material, from 2 to 20% by weight / volume of suitable additives, such as stabilizers, penetrating agents, corrosion inhibitors, and dyes and adhesives.

As an example, here is the composition of an emulsifiable concentrate, the quantities being expressed in g / liter:

- active ingredient (compound No. 1) 400 g - alkali dodecylbenzene sulfonate 20 g

- oxyethylenated nonylphenol with 10 molecules of ethylene oxide 10 g

- cyclohexanone 200 g

- aromatic solvent q.s.p. 1 liter Concentrates in suspension, also applicable as a spray, are prepared in such a way as to obtain a stable fluid product which does not deposit and they usually contain from 10 to 75% by weight of active material, from 0.5 to 15 % by weight of surfactants, from 0.1 to 10% by weight of thixotropic agents, from 0 to 10% by weight of suitable additives, such as defoamers, corrosion inhibitors, stabilizers, penetrating agents and adhesives, and as a carrier, water or an organic liquid in which the active ingredient is substantially insoluble: certain organic solids or mineral salts can be dissolved in the carrier to prevent sedimentation or as antifreeze for water.

Aqueous dispersions and emulsions, for example, compositions obtained by diluting with of water, a wettable powder or an emulsifiable concentrate according to the invention are included in the general scope of the present invention. The emulsions can be of the water-in-oil type or of the oil-in-water type and they can have a thick consistency like that of a "mayonnaise".

The compositions according to the invention may contain other ingredients, for example, protective colloids, adhesives or thickeners, thixotropic agents, stabilizers or sequestrants as well as other known active materials with pesticidal properties, in particular insecticides or fungicides .

Claims

^• RESELL IC AT IONS

1 - As a new industrial product l N-trifluoromethy1-3 ethyl-4 phenyl N'N '-dimethylurea.

2 - Process for the preparation of the compound according to claim 1, characterized in that the reaction of the trifluoromethy1-3 ethyl-4 phenylisocyanate with dimethylamine is carried out, according to the following scheme:

• ^* * - ^* ' ^• - Proc se on ven ication, character ized in that .the reaction is carried out in inert organic solva medium at a temperature between 0 ° C and the boiling point of the solvent.

4 - Process for the preparation of the compound according to claim 1, characterized in that the reaction of the trifluoromethy1-3 ethyl-4 aniline on the xametapil is carried out, according to the following scheme:

in the presence of pyridine at a temperature between 15 and 100 ° C.

5 -—- Process for preparing the compound according to claim 1, characterized in that one carries out the reaction of 3-trifluoromethyl-4-ethyl aniline on dimethyl carbamyl chloride, according to the scheme

6 - Herbicidal composition for weed- selective cultivation of crops, in particular cereals, corn, cotton and soybeans, characterized in that it contains 0.5 to 95% of the compound according to claim 1, as active material, in combination with the carriers and / or usual surfactants.

7 - Process for selective weeding of cereals, corn, cotton, and soybeans, characterized in that a composition according to claim 6 is used, pre- or postemergence.