CS208667B2 - Herbicide means and method of making the active substances - Google Patents

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

BACKGROUND OF THE INVENTION The present invention relates to herbicidal compositions for the selective control of weeds in useful plants containing a novel substituted urea as an active ingredient and to a process for the preparation of the active ingredient.

The invention also provides 3-trifluoromethyl-4-ethylaniline, a process for its preparation and its use as an intermediate for the preparation of chemical compounds.

It is well known that certain trisubstituted phenylureas are valuable selective herbicides. In particular, Belgian Patent No. 594,227 discloses herbicidal compositions comprising as active ingredient N- (3-trifluoromethylphenyl) -N ', Ν'-dimethyl urea, which compositions can be used for total or selective weed control in maize when administered post-emergence in a dose 2.5 kg / ha. However, the aforementioned compound has hitherto been commercially used only in cotton, since its selectivity to other useful plants has been considered very narrow.

Furthermore, 4-alkylphenyl-N ', Ν'-dimethylureas are known which exhibit good properties as selective herbicides in useful plants, especially cereals. However, the selectivity of these substances for cotton has never been utilized since the results of experiments conducted in the wild did not confirm the results found in the greenhouse experiments.

Surprisingly, it has now been found that N- (3-trifluoromethyl-4-ethylphenyl) -N *, N * -dimethylurea instead of showing lower selectivity in cereals, maize and cotton as expected due to the simultaneous presence of the trifluoromethyl substituent at the 3-position and a lower alkyl substituent at the 4-position of the phenyl core, it exhibits a higher selectivity, its selectivity being even better than that of the aforementioned ureas.

208667. 2

French Patent No. 2,001,791 describes a group of substituted ureas wherein the substituents include those present in the compound of the invention, but this group comprises a large number of possible compounds (more than 100,000), a single subgroup thereof. , which is in fact exemplified by physicochemical characteristics, does not apply to products containing a trifluoromethyl group on the phenyl core. With respect to biological activity, it should be noted that, although cereal selectivity of certain compounds, including chlorotoluron in particular, has been demonstrated, the behavior of the compounds in the Bavarian is not experimentally documented, even in the descriptive section.

Due to the above, the invention discloses a new chemical compound of formula ^C 2 ^H 5 \ ° / NHCON ~ \ ^{CH3) CH3}

CF ₃ as well as herbicidal compositions containing the compound as an active ingredient, and a method for selectively controlling weeds in a wide variety of crop plants using such compositions.

The compound of the invention may be prepared by methods known per se.

Firstly, 3-trifluoromethyl-4-ethylphenylisocyanate can be condensed in dimethylamine according to the following reaction scheme:

/ L / C ^H3

- (O> ~ nhcon

W ^x cH ³

CF, CE / ^CH 3 N = C — O + ΗΝζ --- ► C ₂ H ₅

CH ₃

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

The isocyanate used can be prepared in a manner known per se by reacting phosgene with β 3-trifluoromethyl-4-ethylaniline. The reactants are reacted in solution in an organic solvent, for example an aromatic solvent which is inert under the reaction conditions, such as toluene or chlorobenzene, at a temperature between 0 ° C and the boiling point of the solvent used. . The relatively high temperature aids in the development of the hydrogen chloride produced by the following reaction:

nh ₂ + COCl ₂

Another method for preparing a compound of the invention is to react hexametapol (hexamethylphosphoric triamide) and gaseous carbon dioxide with 3-trifluoromethyl-4-ethylaniline according to the following reaction scheme:

Г (СНз) ₂ П] ₂ РОН

The reaction is carried out in the presence of pyridine at a temperature between 15 and 100 ° C

Finally, the compound of the invention can be prepared by reacting dimethylcarbamoyl chloride with 3-trifluoromethyl-4-etilenin in a mixture of the following reaction scheme:

/ ^ch 3

NH 2 i-CICON 4

CH3

CH ₃

+ '+ HCl CH ₃

This reaction is carried out in the presence of the acyl acceptor as. trierylmin.

· 3- Tifluormetyll4-enyl (Milin _i which represents a liquid product distilling at a pressure of 2133 Pa at a temperature of 96-97 ° C is a novel intermediate which can be prepared by catalytic hydrogenation of the nitro derivative in the present odpooldnícího example palladium on UHI and methanol , in accordance with the following reaction scheme:

The necessary oitroderilate can be prepared by nitnc! o- (trilormormll) elybbenze by a mixture of sulfuric Easter eggs and kiaelin nitric acid, in accordance with the following lubrication scheme:

H2SQ4;

The starting o- (trifluoromethyl) elylbenzene can be obtained by catalytic hydrogenation of o-trifluoroomeeyl-2 *, 2 *, 2 * -tichichloroethylbenzene in the presence of palladium on active union in an alkali methanolic medium, in accordance with the following lubrication scheme:

+ KOH + 3 H ₂

CH3-CH

^CF 3

-F 3 KCI

The tertiary derivative can be obtained by reaction of linide dichloride with a halide, in particular a dilonium chlooid derived from 2- (1-O) -tyl amine, in acetone in the presence of copper (I) chloride, in accordance with the following scheme:

+ HCl + NaNO ₂ --- ►

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The preparation and herbicidal properties of (3-trifluoromethyl-4-ethylphenyl) dimethyl urea are illustrated by the following non-limiting examples.

He did

Preparation of (3-Trifluoro-ethyl-4-ethyl-phenyl) -dimethyl-urea according to the first procedure e

A solution of 35 g (0.162 mol) of 3-trifluoromethyl-4-ethylphenylisocyanate in 100 ml of toluene is added dropwise to a solution of 8.1 g (0.18 mol) of dimethylamine in 50 ml of toluene. ° C, then the solvent is evaporated and the precipitate formed is recrystallized from a mixture of methanol and water (30:70). The product resulting in 63% yield melts at 105-106 ° C.

NMR analysis (60 MHz, hexadeuterodimethylsulfoxide, tetramethylsilane as internal standard) is (3-trifluoromethyl-4-ethylphenyl) dimethylurea.

The 3-trifluoromethyl-4-ethylphenylisocyanate used as starting material is prepared as follows:

A solution of 39.7 g (0.21 mol) of 3-trifluoromethyl-4-ethylaniline in 400 ml of toluene is added dropwise to a solution of 83.2 g (0.84 mol) of phosgene in 600 ml of toluene.

The reaction is carried out with stirring at a temperature of about 0 ° C. After the addition of the aniline solution is complete, the reaction mixture is allowed to warm to room temperature and is then slowly heated to reflux. After the evolution of hydrogen chloride gas has evolved and the excess phosgene has evaporated, the reaction mixture is refluxed for 1 hour. yield 95% yielding a liquid product boiling at 50 mbar at 50-51 ° C.

The above structure of the product is unequivocally confirmed by NMR spectroscopy analysis

Preparation of a compound of the invention by a second process

In a three-necked round-bottomed flask equipped with a condenser, carbon dioxide gas extending almost to the bottom of the vessel and an agitator, 8.1 g (0.0427 mol) of 3-trifluoromethyl-4-ethylaniline, 7.0 g (0, Hexamethylphosphoric triamide and 22 ml of pyridine, which has been dried beforehand. The temperature is adjusted to 60 ° C and carbon dioxide gas is introduced into the reaction mixture for 6 hours. The resulting mixture was evaporated to dryness and the residue was taken up in 20% ethanol to precipitate urea. Recrystallization from a mixture of equal parts of methanol and water gave 7.7 g (69%) of N- (3-trifluoromethyl-4-ethylphenyl) -N < + >, N ' -dimethylurea, the structure of which was confirmed by NMR spectroscopy.

Example 3

Preparation of 3-trifluoromethyl-4-ethylaniline

To a mixture of 43.8 g (0.2 mol) of (2-trifluoromethyl-4-nitro) ethylbenzene, 2.5 g of 5% palladium on carbon, moistened with 1 ml of water, and 350 ml of methanol are heated to 48-50 ° with heating. C at 10 bar indicates hydrogen.

The reaction is carried out with stirring for 30 minutes, the reaction mixture is cooled and filtered. Evaporation of the methanol yielded a liquid product distilling at 96-97 degrees Celsius in a total yield of 85%.

T-Trifluoromethyl-4-nitro-4-ylbenzene was prepared as follows:

To 80 g (0.46 mol) of (2-trifluoromethyl) ethylbenzene was added dropwise a mixture of 70.7 g of 92% sulfuric acid and 47.5 g of 100% nitric acid while maintaining the temperature at 38-40 ° C. After completion of the dropwise addition of sulfuric acid and nitric acid, the reaction mixture was stirred for 1 hour, then poured into 2 liters of crushed ice and extracted with an organic solvent such as methylene chloride. Meeylene chloride extracts were washed and dried over anhydrous sodium sulfate. Evaporation of the solvent yielded a colored liquid product (87.6% yield) which crystallized at 5 ° C.

(Z-TrifluoromethylDiethylenenene is prepared as follows;

In a 1000 ml autoclave, 70 g (0.25 mol) of 2-trifluoromethyl-2 ', 2', 2'-trichloroethylbenzene, 4 g of 5% palladium on carbon moistened with 5 ml of water and 300 ml of methiol are added. a solution of 44 g (0.785 mol) of potassium hydroxide in a mixture of 350 m of methanol and 35 ml of water was introduced into the autoclave under a pressure of 0.4 MPa. The temperature of the reaction mixture is maintained at 28-30 ° C during hydrogen uptake. The resulting methyl solution is filtered, the filtrate is diluted with 6 liters of water, the organic phase is decanted and the aqueous phase is extracted with methylene chloride. The organic phase is combined with methylene chloride extracts, washed with water and dried over anhydrous sodium sulfate, and the methylene chloride is drained off. A total product of 91% yielded a liquid product de-distilling at 2000 Pa at 40-41 ° C.

2-Chloro-methyl-2 ', 2', 2'-richloromethylbenzene was prepared as follows:

First, a diazotizing salt of 2-trifluoromethylanilide is prepared. To this, a solution of 197.5 g (1 mol) of 2-trifluoromethylaniline hydride in 500 ml of water and simultaneously a solution of 69 g (1 mol) of a sodium dream in 150 ml of water are simultaneously introduced into ~ 130 ml of 10 N hydrochloric acid. . Upon completion of the reaction at 0-5 ° C, a light yellow solution of 2-trifluoromethylbenzenediazine chloride is obtained.

This solution, still cooled to 0-5 ° C, is added to a mixture of 116.4 g (1.2 mol) of vinylidene dichloride, 1 liter of acetone and 10 g of cuprous chloride dihydrate dissolved in 50 ml of water while maintaining the reaction temperature. at 27 to 28 ° C. The nitrogen discharged vapor-disulfide was condensed in a circulating-brine-cooled condenser to -10 ° C. After the addition of the palladium salt solution is complete, the reaction mixture is heated to 30 ° C with stirring until the evolution of nitrogen ceases. The reaction mixture is then diluted with 5 liters of water, the organic phase is separated, washed with water and dried over anhydrous sodium sulfate. After filtration, a slightly colored liquid product is obtained in a yield of 78%, boiling at 2000 Pa at 108-110 ° C.

Example 4

The herbicidal efficacy in the conversion and post-emergence treatment of useful and undesirable plants

A number of seeds are sewn into 9 x 9-x 9 cm dishes filled with light agricultural land, which are governed by the plant type and seed size. The seeds are then covered with a 3 - mm thick layer of soil.

After moistening the soil, the trays are sprayed with the active ingredient containing the active ingredient at the appropriate dose, the spray rate being equal to 500 liters per hectare.

The spray formulation is obtained by diluting the emulsifiable concentrate of the following composition (w / w%) test active ingredient 20% emulsifier (ethoxylated nonylphenol containing 17 ethylene oxide units) 10% solvent (xylene) 70% diluted with water to apply the active ingredient formulation in the desired concentration. The active substances are used in the tests at concentrations of 0.25 kg / ha to 8 kg / ha.

The treated trays were placed in troughs to allow the trays to be irrigated with openings on their days and maintained at room temperature and 70% relative humidity for 35 days.

After 35 days, the degree of damage was evaluated relative to the condition of control plants treated under the same conditions with the active substance-free spray.

The post-emergence test is carried out as above, with the treatment of small plants in the second right leaf stage for grassy plants, and in the case of dicotyledonous plants in the stage of two developed cotyledons with an open apex bud.

The following plant species are used as test plants, i.e. crop plants and undesirable plants:

Corn plants (Zea mays) Evil wheat (Triticum vulgare) TV cotton (Gossypium barbadense) GB soya (Glycine max) GM

Undesirable Plants ove8 Deaf (Avena fatua) AF Bloodthroat (Digitaria sanguinalis) DS Hedgehog Corn Echinochloa crus-galli album) CH Black Eggplant (Solanum nigrum) SN White Mustard (Sinapis alba) SA Chickweed (Stellaria média)

The following active substances are used in the tests: (3-trifluoromethyl-4-ethylphenyl) dimethylurea (compound of the invention - Example 1), (3-trifluoromethyl-4-butylphenyl) dimethylurea (compound (3-trifluoromethyl-4-butylphenyl) monomethylurea ( compound B), (3-trifluoromethylphenyl) dimethyl urea (a compound known by the generic name fluometuron).

These compounds were prepared as described in Example 1.

The results below are expressed in kg / ha and mean:

(a) in the case of crops, the selectivity threshold, which represents the maximum dose tolerated by the crops without damage. Accordingly, a compound with a selectivity threshold of 4 kg / ha has twice the selectivity of a compound with a selectivity threshold of 2 kg / ha;

(b) in the case of undesirable plants, the efficacy threshold, ie the minimum dose required for complete destruction (> 90%) of the relevant plant species. Accordingly, compound 8 is an activity threshold of 1 kg / ha twice as potent as a compound with an activity threshold of 2 kg / ha. Thus, the compound used for selective weed control will be better the higher its selectivity threshold (for example at least 4 kg / ha) and its lower efficiency threshold (for example not more than 1 kg / ha), i.e., at the same time. the greater the difference between efficiency and selectivity. Compliance with these requirements allows the use of a weed control agent and the greatest possible safety for the crop.

The results obtained in the tests described above are summarized in the following tables.

Table I

Selectivity threshold for crops in kg / ha

active substance experimental plants and method of treatment preemergent postemergent wheat maize cotton soya wheat maize cotton a compound of the invention 4 > 8 > 8 2 4 4 4 AND > 8 > 8 > 8 > 8 > 8 > 8 > 8 В > 8 > 8 > 8 > 8 > 8 > 8 > 8 fluometuron 0.5 0.5 4 0.5 1 2 8

It is clear from this table that the compound of the invention exhibits a significantly higher selectivity than fluometuron. On the other hand, the compound of the invention has inferior selectivity than compounds A and B, but the selectivity of these compounds corresponds to their general ineffectiveness, including ineffectiveness to undesirable plants, as shown in the following table.

Table Ila

Efficiency threshold in kg / ha against undesirable plants in pre-emergence treatment of the undesired plant active ingredient

AF DS EG LM SF AM CH SN SA

invention AND В 1 <0.25 0.5 1 0,5 ineffective v ineffective v 1 dose 8 <0.25 kg / ha kg / ha <0.25 4 <0.25 dose 8 fluometuron 0.50 0.50 0.50 1 0.50 1 <0.25 0.50 0.50 <0.25

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Table lib

Threshold of efficacy in kg / ha against undesirable plants during post-emergence treatment

active substance AF OS ЕС unwanted plants Ui SF AJ CH SN SA SM a compound of the invention 4 2 1 0.50 2 4 0.50 1 2 1 AND 8 except mustard ineffective in dose 8 kg / ha В ineffective at a rate of 8 kg / ha fluometuron 1 > 8 2 2 4 4 0.50 8 1 4

It is clear from the above two tables that the compound of the invention exhibits herbicidal activity which is substantially equivalent to that of fluometuron in pre-emergence treatment, and is incomparably higher in post-emergence treatment.

Of course, the herbicidal activity of a compound of the invention is considerably higher than that of compounds A and V, both in pre-emergence and post-emergence treatments, since these compounds are ineffective at 8 kg / ha, and with the exception of Compound B, which 8 kg / ha kills mustard.

The above tests clearly demonstrate the surprising herbicidal activity of the compound of the invention compared to both homologous 4-alkyl-3-trifluoromethylphenyl derivatives and fluometuron.

N- (3-Trifluoromethyl-4-ethylphenyl) -N ', N'-dimethylurea can therefore be used as an active ingredient in compositions for the selective control of weeds in useful plants, in particular cereals (wheat and barley), maize, cotton and soybean.

For herbicidal treatment, the active compound according to the invention can be used at a rate of from 0.25 to 8 kg / ha, depending on the crop plant and the soil type. The aforementioned dose is preferably from 0.5 to 5 kg / ha.

In practice, the compound of the present invention is rarely used alone, but most often forms part of compositions which generally contain 0.5 to 95% by weight of the active ingredient of the invention, carrier and / or surfactant (generally in an amount of 0 to 10%, preferably in an amount of 0.1 to 10% by weight).

For the purposes of the present invention, the term carrier refers to an organic or inorganic, natural or eynthetic material with which the active ingredient is combined to facilitate its application to plants, their seeds or soil or soil, or to facilitate transport or handling. The carrier may be solid (clays, natural or synthetic silicates, resins, waxes, solid fertilizers, etc.) or liquid (water, alcohols, ketones, petroleum fractions, chlorinated hydrocarbons and liquefied gases).

The surfactant may be an emulsifier, dispersant, or wetting agent, and the materials may be ionic or non-ionic. Examples of such agents include polyacrylic acid salts, phenolsulfonic or naphthalenesulfonic acid salts, and polycondensation products of ethylene oxide with fatty alcohols, fatty acids, or fatty amines.

The compositions of the invention may be prepared in the form of wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension suspensions and aerosols.

Wettable powders are generally formulated to contain from 20 to 95% by weight of the active ingredient and, in addition to the solid carrier, usually contain 0 to 5% by weight of the wetting agent and 3 to 10% by weight of one or more stabilizers and / or other additives. as panatizing agents, adhesives, anti-caking agents, dyes, etc. By way of example, the following powder compositions are exemplified.

Active ingredient (compound of Example 1) - 50% Calcium HgOsulphate (deflecting agent) 5% sodium propylpropylphthalosulfate (anitic surfactants) 1% non-caking silicon dioxide 5% kaolin (ploidy) 39%

Typically, granulates intended for application to the soil are produced in such a way that their particle size is between 0.1 and 2 mm. and can be prepared by agglomeration or digestion. The granules generally contain from 0.5 to 25% of active ingredient and from 0 to 10% of other ingredients such as stabilizers, opioids, which are slowly slow. release of the active ingredient, binders and solvents.

The sprayable compositions generally contain, in addition to the solvent and optionally co-solvent, 10 to 50% (w / v) of the active ingredient and 2 to 20% (w / v) of suitable additives, such as stabilizers, penetration agents. , corrosion inhibitors, dyes and adhesives.

By way of example, the following is the composition of the extractable concentrate, where the individual weights are expressed in grams per liter:

active substance (compound of Example 1) alkali metal diethylbenzene hydrochloride - ethoxylated otert-phenol containing the molecule ethylene oxide cyclohexanone aromatic, solvent - add to

400 g g

G

200 g liter

Suspension concentrates, which can also be applied by spraying, are prepared so as to obtain a stable liquid product from which the individual components are deposited. These suspension concentrates generally contain from 10 to 75% by weight of active ingredient, from 0.5 to 15% by weight of surfactants, from 0.1 to 10% by weight of triaxing agents, from 0 to 10% by weight of suitable additives such as antifoams, corrosion inhibitors, stabilizers , penetrating agents and adhesives, and as a water-borne or organic liquid in which the active substance is practically insoluble. Certain organic solids or inorganic salts may be dissolved in the said carrier, which additives are intended to help prevent sedimentation or act as antifreeze agents.

The invention also extends to dispersions or emulsions, for example compositions obtained by diluting the compatible powders or emulsifiable concentrates of the invention with water. These emulsions may be of the water-in-body type or oil-in-oil type, and may also have a thick consistency, such as mayonnaise conozsteoci.

The compositions according to the invention may also contain additives, for example, protective colloids, adhesives or thickeners, thixstric agents, stabilizers or comolexing agents, as well as other known active substances exhibiting pesticidal properties, in particular insecticide. or a fuejicido property.

Claims (2)

SUBJECT OF THE INVENTION A herbicidal composition for the selective control of weeds in useful plants, in particular cereals, maize, cotton and soya, characterized in that it contains from 0.5 to 95% of N- (3-trifluoromethyl-4-ethylphenyl) -N *, N * -dimethylurea, in combination with conventional carriers and / or surfactants. 2. A process according to claim 1, wherein the 3-trifluoromethyl-4-ethylphenylisocyanate is reacted with dimethylamine in an inert organic solvent at a temperature between 0 [deg.] C. and the boiling point of the solvent. Sevarog raffia. n. plant 7,