IT8922821A1 - HERBICIDE COMPOSITION AND RELATED PREPARATION PROCEDURE. - Google Patents

Description

"HERBICIDE COMPOSITION AND RELATED PREPARATION PROCEDURE"

SUMMARY

The present invention relates to a herbicidal composition which comprises, as active ingredient, (S) -l'-methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate or (S) -1? -Ethoxycarbonylethyl 2-bromine -5- (2-chloro-4-trifluoromethylphenoxy-benzoate in an amount of 0.01 to 95.0% by weight together with one or more carrier solids and / or liquids, preferably fragments of a material (s) found in nature or synthetic; and / or with an inert solvent (s), preferably xylene (xylenes) and / or cyclohexanone; and optionally with a surfactant agent (s), preferably an anionic and / or nonionic emulsifying or dispersing agent (s).

The present invention also relates to both the above active ingredients as well as a process for their preparation.

The compounds according to the present invention possess a remarkable herbicidal effect (higher than 90%) and advantageous threshold values of selectivity. against cultivated plants.

DESCRIPTION

The present invention relates to (S) -l'-methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxyJbenzoate and (S) -l'-ethoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) herbicidal active benzoates, herbicidal compositions containing these compounds and a process for the preparation of both active compounds (ingredients).

In the description of the German patent (DE-PS) No. 3,029,728, derivatives of substituted diphenyl ethers of general formula (1) are published

In the German Patent Description (DE-PS) No. 3,029,728, a single substance is published, i.e., (RS) -l'-ethoxycarbonylethyl 2-bromo-5- (2-chloro-4? Trifluoromethylphenoxy) benzoate together with the description of its activity? herbicide. Is it indicated that this compound? effective even in a half dose (140 g / ha) compared to the known sec-butyl 5- (2-chloro-4-trifluoromethylphenoxy) -2-nitrobenzoate. However, no teaching (instructions) is given for the threshold value of selectivity? against cultivated plants.

In the description of the aforementioned patent, n? the procedure for the preparation n? the physical and chemical characteristics n? the properties of both compounds according to the present invention thus, these compounds have not been prepared and are therefore new.

It is commonly known that there is a continuous social demand for new compounds capable of inhibiting the development of unwanted vegetation. The main aim of the research consists in the selective inhibition of the development of weeds in the most cases. frequent such as, wheat, corn, rice, soy or cotton; that is, the uncontrolled growth of weeds? accompanied by a significant loss of production for which the profit of the grower (farmer) is decreased and the consumer's expenses become more? high.

In the course of the Applicant's herbological (plant protection) research yes? found that the compounds according to the present invention (compounds No. 1 and No. 2) possess an activity? significantly higher herbicide than that of the antipodes (R) (D and E) or compared to that of (RS) -l? -methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate (compound A) or to that of (RS) -1'-ethoxycarbonylethyl 2-bromine? 5- (2-chlor-o? 4? trifluoromethi1phenoxybenzoate (compound B) described in the description of German patent No. 3,029,728 or to that of-1 '(RS) -l'-ethoxycarbonylethyl 5- (2-chloro-4-trifluoromethylphenoxy) -2-nitrobenzoate (compound C) claimed in published European patent application No. 0.020.052 A1. However, the threshold values of selectivity ? of the compounds according to the present invention (compounds No. 1 and No. 2) are the same as those of compounds A, B or C.

The activity? herbicide over 90% of the No. 1 and No. 2 compounds expressed A, B and C and 4 to 22 times that of the antipodes R (D and E) respectively (Table 1), an unexpected fact for one skilled in the art.

Furthermore, it is concluded from the equality of the threshold values of the selectivity? (see Table 2) that compounds A, B, C, D and E are phytotoxic, that is? they are harmful to plants grown in a dose that eliminates weeds (from 50 to 500 g / ha) since? this dose? substantially more? high of the threshold values of the selectivity? (from 30 to 200 g / ha) of cultivated plants. Contrary to compounds A, B, C, D and E, both compounds according to the present invention can be used to eradicate weeds in cultivated plants, also because? their threshold value of selectivity? (from 50 to 180 g / ha)? lower than the dose (from 10 to 40 g / ha) required to obtain a herbicidal effect greater than 90%.

Knowing the business? herbicide and the threshold value of selectivity? of compounds No. 1 and No. 2 according to the present invention - in particular on the basis of the herbological behavior of compounds A, B, C, D and E - one can? establish that the considerable activity? herbicide and the significant threshold value of selectivity? of compounds No. 1 and No. 2 according to the present invention, in addition to the superior suitability? of those compounds resulting from the interrelation of both of the above-mentioned characteristics, which were unexpected to one skilled in the art, were not recognized when searching for compounds of similar structure.

Both compounds according to the present invention can be prepared using known methods, for example.

(a) by reacting the enantiomer (S) or the racemate of a lactic acid ester of general formula (I),

wherein R denotes a methyl or ethyl group, with at least a quantity? stoichiometric of a 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzene halide, preferably chloride, suitably in the presence of an acid-binding agent; or (b) reacting the 1 <1> enantiomer (S) or the racemate of an alkyl 2-halopropionate of general formula (II)

and solving the product obtained when one of the reactants? a racemic compound.

In the above reactions you can? use any inert solvent. Suitable solvents are, for example: pentane, hexane, heptane, cyclohexane, petroleum ether, gasoline, ligroin, benzene, toluene, xylene, dichloromethane, dichloroethane, chloroform, carbon tetrachloride, chlorobenzene o-dichlorobenzene, diethyl ether, dibutyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dioxane, acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, acetonitrile. propionitrile, dimethylformamide (DMF), N-methylpyrrolidone, dimethyl sulfoxide (DMSO), tetramethylene sulfone, hexamethylphosphoric acid triamide. Useful as acid binding agent are hydroxides, bicarbonates, carbonates and alkoxides of alkali metals as well as aliphatic, aromatic or heterocyclic amines.

According to a preferred embodiment of the process of the present invention, quantity? approximately equimolar of the starting substances are reacted at a temperature between -20 ° C and the boiling point of the reaction mixture. Preferably, a solution of 2-bromine? 5- (2-chloro-4-trifluoromethylphenoxy) benzoic acid or of 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzene chloride is added, in portions, between -20 ? C and 35? C, and after this addition the reaction mixture is stirred under reflux until the desired progress of the reaction (transformation) is achieved. After cooling, the solution is washed with a dilute acid, then with a dilute base and with water and the phases are separated. The product can? be obtained in any known way, for example, by evaporation.

The invention also relates to a herbicidal composition which contains, as active ingredient (S) -l'-methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate or (S) -l'-ethoxycarbonylethyl 2-brorao -5- (2-chloro-4-trifluoromethylphenoxy) benzoate in an amount? 0.01 to 95.0% by weight together with one or more? solid and / or liquid carriers, preferably naturally occurring or synthetic material fragments; and / or with an inert solvent (s), preferably xylene (xylenes) and / or cyclohexanone; and optionally with a surfactant agent (s), preferably an anionic and / or nonionic emulsifying or dispersing agent (s).

According to another aspect of the present invention, it comes

a process for the preparation of (S) -l'-methoxycarbonyl ethyl 2-bromo-5- (2-chioro-4-trifluoromethylphenoxy) benzoate or of (S) -l'-ethoxycarbonyl ethyl 2-bromo-5- (2-chlorine -4-trifluoromethylphenoxy) benzoate, i.e., for the preparation of both compounds according to the invention, which comprises,

reacting the enantiomer (S) of a lactic acid ester of general formula (I), in which R denotes a methyl or ethyl group, with 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoyl halide , preferably chloride, in a solvent, preferably in the presence of an acid-binding agent, then separating 1 '(S) -l'-methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate or 1' (S) -l'-ethoxycarbonyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate thus obtained from the reaction mixture and, if desired, purify them.

The intermediates used in the synthesis of both compounds according to the present invention are known compounds.

The synthesis of 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoic acid and its halide? described in the description of U.S. Patent No. 3,957,852. (RS) -lactic acid and (S) -lactic acid, their methyl and ethyl esters as well as the methyl and ethyl esters of (RS) -2-halopropionates are commercially available.

The preparation of (RS) -l'-ethoxycarbonyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate used as the reference (standard) compound? published in German patent specification No. 3,029,728; 1 * (RS) -l'-methoxycarbonyleth12-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate? been synthesized in a similar way, except yes? methyl (RS) -lactate used instead of ethyl (RS) -lactate.

The compositions according to the present invention are used (applied) in pre-emergence or, more? preferably, in post-emergency. The dose of the active ingredient can? be made to vary from 10 to 100, preferably from 10 to 75 g / ha depending on the quality? oxide, dolomite, hydrated gypsum, tricalcium phosphate, Fuller's earth. Other suitable solid carriers and thinners are ground tobacco leaf stalks, wood flour, etc.

The following materials are suitable liquid thinners and solvents: water; organic solvents; mixtures of organic solvents and those formed with water, for example, methanol, ethanol, n-propanol, isopropanol, diaceton alcohol, benzyl alcohol; esters of said alcohols, for example, methyl cellosolve; ketones, for example, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc. ethyl acetate, ne isobutyl acetate, amyl acetate, isopropyl myristate, dioctyl phthalate, dihexyl phthalate, etc. aromatic, aliphatic and alicyclic hydrocarbons, for example, paraffinic hydrocarbons, cyclohexene, kerosene, gasoline, benzene, toluene, xylene, tetraline, decalin, etc.; mixtures of alkyl benzenes; chlorinated hydrocarbons, for example, trichloroethane, dichloromethane, perchlorethylene, dichloropropane, chlorobenzene, etc. lactones, for example, ^ -butyrolactone, etc.; lactams, for example, N-methylpyrrolidone, N-cyclohexylpyrrolidone; acid amides, for example, dimethylformamide and the like; oils of vegetable or animal origin, for example, sunflower oil, olive oil, soybean oil, castor oil and the like.

Suitable wetting, dispersing, emulsifying, adhesive, anti-clumping, anti-packing and spraying agents may be ionic or non-ionic in character. The ionic surfactants can be, for example, salts of various saturated or unsaturated carboxylic acids; sulfonates of aliphatic, aromatic or arylaliphatic hydrocarbons; sulphates of alkyl, aryl or aralkyl alcohols; sulfonates of alkyl, aryl or aralkyl acids, esters and ethers; sulfonates of condensation products of phenol, cresol and naphthalene; sulphonated vegetable and animal oils, alkyl, aryl and aralkyl phosphate esters; salts of the above compounds formed with alkali or alkaline earth metals or with organic base (for example, various aramines, alkanolamines and the like). As preferred representative of the above surfactants, the following compounds can be mentioned: sodium lauryl sulfate, sodium 2-ethylhexyl sulfate, sodium ethanolamine, diethanolamine, triethanolamine and isopropylamine salt of dodecylbenzenesulfonic acid; sodium mono and diisopropylnaphthalen sulfonate; sodium salt of naphthalenesulfonic acid, sodium diisooctyl sulfosuccinate; sodium xylene sulfonate; sodium or calcium salt of petroleum sulfonic acid; soaps, potassium stearate, sodium, calcium, aluminum, magnesium and the like. The phosphate esters can be, for example, alkyl phenol ethers or phosphated fatty alcohols formed with polyglycols and their forms partially or completely neutralized with the cations or organic bases mentioned above. As further suitable representatives of anionic surfactants, disodium N-octadecylsulfosuccinate, sodium N-oleyl-N-methyltaurride and various lignosulfates can be mentioned.

Suitable nonionic wetting, dispersing and emulsifying agents are ethylene oxide ethers formed with alcohols, for example stearyl polyoxyethylene, oleyl polyoxyethylene and the like; ethers formed with alkylphenols, for example, polyglycol ethers formed with tert-butyl-, octyl noniiphenol, etc.; esters of various acids, for example, polyethylene glycol ester of stearic acid or myristic acid or polyethylene glycol oleate, etc. block polymers of ethylene oxide and propylene oxide; partial esters of fatty acids and oleic acid formed with hexitol anhydrides; sorbitol esters formed with oleic acid or with stearic acid; condensation products of the above compounds formed with ethylene oxide; tertiary glycols, for example, 3,6-dimethyl-4-octine-3,6-diol or 4,7-dimethyl-5-decin-4,7-diol; polyethylene glycol thioethers, for example, dodecyl mercaptan ester formed with polyethylene glycol, etc.

As adhesive agents it is possible to use, for example, soaps of alkaline earth metals, salts of esters of sulfosuccinic acid; water-soluble natural or artificial macromolecules, for example, casein, starch, gum arabic, cellulose ethers, methylcellulose, hydroxycellulose, polyvinylpyrrolidone and polyvinyl alcohol, etc.

Suitable anti-foaming agents are block polymers of polyoxyethylene and low molecular weight polyoxypropylene (where the number of octyl-, nonyl- and phenylpolyoxyethylene / ethylene oxide units is> 5); long chain alcohols, for example, octyl alcohol, special silicone oils, etc.

By using suitable additives, the formulated compositions of the present invention can be made chemically colloidally compatible with various fertilizers.

The selective herbicidal compositions of the present invention may comprise known pesticides and / or nutrient components, if necessary.

Wettable powders (WPs) can be prepared for example by mixing the active ingredient (s), an auxiliary agent (s) and a surfactant (s) with the vehicles, then grinding and finally homogenizing the mixture. The liquid surfactants can be applied, for example, by spraying them on the solid organic or inorganic carrier (s) or on a powder mixture comprising the solid active ingredient. When using a liquid surfactant, the previously ground solid components can be suspended in an organic solvent which includes liquid surfactants. This suspension can? be dried, for example, by spraying. Then, the surfactant is applied to the surface of a mixture of the solid active ingredient and the solid diluent.

Can you? prepare a self-emulsifiable liquid, suitable for the preparation of dispersed aqueous emulsions (the so-called emulsifiable concentrate / EC /) by dissolving the active ingredient, or a mixture thereof, in a solvent immiscible with water. The emulsifiable concentrate cos? obtained, it forms with water, spontaneously or under a slight mechanical effect, an emulsion to be sprayed which remains unchanged and stable even after a long period of storage.

Can you? Prepare a water-soluble (SL) solution concentrate by dissolving the active ingredient and suitable water-soluble auxiliary materials (additives) in water and / or a water-miscible solvent. After dilution with water, you can? obtain a liquid to be sprayed with the desired concentration. The concentrate in aqueous solution of the active ingredient can? be dispersed also in a liquid immiscible with water by choosing (selecting) a suitable emulsifying agent to obtain a so-called "reverse" emulsion. Therefore, by means of an appropriate selection of the solvent and of the surfactants, compositions can be prepared which, due to the effect of mixing with water or with liquids immiscible with water, give rise to homogeneous molecularly dispersed phases which remain unaltered even after a long period (of storage) .

Can you? prepare a suspension concentrate (SC) by dissolving the wetting and dispersing agents in a mixture of water (preferably ion exchanged water) and an anti-foaming component (preferably ethylene glycol or glycerol), if necessary under heating. To the solution cos? obtained, a mixture of the solid active ingredients (powder or crystalline) is added under continuous stirring and, if desired, an anti-packing component is added. The suspension cos? obtained (solid particles - liquid phase) is ground in a wet mill (for example a closed Dyno mill) to the desired particle size, preferably to a maximum particle size of 5 µm. After grinding, an anti-foaming agent and a thickening agent are added under homogenization. Alternatively, the order of succession of the addition of the components can? be varied or other agents (for example, dyes) can be added. In addition to said active ingredients, other active ingredients can also be added. Solid active ingredients with a low melting point can also be introduced in the form of a melt without or with an emulsifier.

ULV compositions can be formulated similarly to EC compositions (or in some cases similar to SC compositions).

Granules suitable for direct use (G) can be prepared by extrusion, lamination, application on a granular carrier (for example, ground limestone) or by absorbing a liquid component in a carrier that has a capacity for processing. absorption.

Applicable granules for spraying purposes (WG) can be prepared from WP and / or SC with the aid of an agglomeration technology, for example, in a dragee container using a binding agent.

Can you? obtaining a spray or a sprinkling powder suitable for use in agriculture from the above compositions by known methods by dilution with water or an inert solid carrier. The active ingredient content of the said ready-to-use compositions? generally below 5% by weight, preferably 0.01-3% by weight.

In the compositions to be used (applied) the quantity? of the active ingredient can? be made to vary between wide limits; its value essentially depends on the desired effect.

The invention is illustrated in detail by the following non-limiting examples.

In the H-NMR and 13C-NMR spectroscopic data given in the examples,? the identification method indicated in the general formula (III)

Although this is different from the indication according to the nomenclature it nevertheless makes it possible to carry out a uniform spectroscopic evaluation.

Example 1

/

they are weighed in a three-necked flask equipped with a stirrer, dropping funnel and reflux condenser. The mixture is cooled to 10 ° C and a solution containing 113.7 g (0.2747 mol) of 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) is added drop by drop, under vigorous stirring. benzoyl chloride in 100 ml of benzene at a speed? such that the temperature of the reaction mixture remains between 10 and 20 ° C under external cooling. After this addition, the suspension is stirred at 20-30 ° C for another 10 hours and is then poured over 300 ml of 3% hydrochloric acid. After separation, the organic phase is washed in succession with 200 ml of a solution of sodium bicarbonate at 3% saturated with sodium chloride and then with 200 ml of a saturated aqueous solution of sodium chloride. After having dried the benzene solution on anhydrous magnesium sulfate, the solvent is evaporated at atmospheric pressure and then under the water jet pump. The title compound is obtained as a pale yellow oily product with a yield of 110.2 g (92.7%).

The characteristic fragments of the mass spectrum of the title product show the characteristic isotope ratio of compounds containing one chlorine atom and one bromine atom.

are weighed in a three-tube bottle equipped with stirrer, dropping funnel and reflux condenser. After cooling the homogeneous solution to 10 ° C, a solution containing 51.8 g (0.1252 moles) of 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoyl chloride in 100 ml of benzene is added, drop by drop, under stirring, and under external cooling to maintain the temperature of the reaction mixture at 10-20 ° C. Then, the suspension is heated to the boiling point and is kept under reflux at the same temperature for 6 hours, under stirring. After cooling, 200 ml of 3% hydrochloric acid are poured into the reaction mixture. After stirring for a short period of time, the organic phase is separated and washed in succession with 150 ml of a 3% sodium bicarbonate solution saturated with sodium chloride, then with 150 ml of a saturated aqueous solution of sodium chloride. After drying the benzene solution on anhydrous magnesium sulphate, the solvent is evaporated first at atmospheric pressure then under pressure of the water jet pump. The title compound is obtained as a pale yellow oily product with a yield of 55.6 g (89.4%).

The characteristic fragments of the mass spectrum of the title compound show the isotope ratio that characterizes compounds that contain a chlorine atom and a bromine atom.

Example 3

Preparation of (R) -1? -Methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate (compound D)

This compound was prepared substantially following the procedure of Example 1 using methyl (R) -lactate instead of methyl (S) -lactate, with a yield of 92.7%.

The characteristic fragments of the mass spectrum of the product of

1 13

title, the data of the H- and C-NMR spectra correspond to those of the enantiomer (S) obtained in Example 1.

Example 4

Preparation of (R)? 1? -Ethoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate (compound E)

This compound was prepared substantially following the procedure given in Example 2 using ethyl (R) -lactate instead of ethyl (S) -lactate, with a yield of 88.7%.

The characteristic fragments of the mass spectrum of the title product, the data of the 1H and 13C-NMR spectra correspond to those of the enantiomer (S) obtained in Example 2.

Example 5

a) Preparation of an emulsifiable concentrate (20 EC)

% by weight

Compound No. 2 20

2-ethoxyethanol 10

Cyclohexanone 35

Emulsogen EL 360 (l) 7

Tensiofix CD 5 (2) 3

Xylene 25

(1): ethoxylated castor oil

(2): Ethoxylated coconut alcohol

L1Emulsogen EL 360 and Tensiofix CD 5 are dissolved in the mixture of 2-ethoxyethanol, cyclohexanone and xylene and finally compound No. 2 is introduced into the system, then the solution is stirred for 2 hours. Compositions containing compound No. 1, compounds A, B, C, D and E.

b) Preparation of an emulsifiable concentrate (35 EC)

% by weight

Compound No. 1 35

Cyclohexanone 10

Tensiofix CD 21 (1) 2

Tensiofix B 7453 (2) 8

Xylene 45

(1): A mixture of ethoxylated fatty alcohol, ethoxylated nonylphenol and their phosphates

(2): A solution of calcium dodecylbenzenesulphonate, nonylphenol ethoxylate and nonylphenol ethoxylated propoxylated in n-butanol. The procedure described under a) is followed.

Compositions containing compound No. 2, compounds A, B, C, D and E.

Example 6

Preparation of microgranules

% by weight

Compound No. 2 0.1

Cyclohexanone 5.0

Bentonite 94.9

A solution containing compound No. 2 in cyclohexanone is sprayed onto previously ground bentonite to a particle size of 50 u and placed in a rotated drum. Stirring is continued for 1 hour while the cyclohexanone is evaporated.

A composition containing compound No. 1, compounds A, B, C, D and E.

Example 7

Preparation of water dispersible granules (WG)

% by weight

Compound No. 1 50

Cab-O-Sil M5 (1) 5

Atlox 4862 (2) 3

Polifon 0 (3) 6

Geropon IN (4) 5

Kaolin 31

(1): Amorphous silicon dioxide

(2): Condensation product of naphthalenesulfonate-formaldehyde (3): Binder material (sodium lignosulfonate)

(4): Isopropyl naphthalenesulfonate

The active ingredient is mixed in a grinding mortar with amorphous silicon dioxide, with the dispersing agent Atlox 4862 and with the wetting agent Geropon IN as well as with kaolin. The mixture is ground until fine particles are obtained (until it is obtained that the portion of the particles with a diameter greater than 44 ^ u becomes less than 0.5%). The powder is mixed in a mixer with the aqueous solution of the binding agent Polifon 0 and the granules with a diameter of 1 mm are then prepared in an extruder. The granules are dried in a stream of air.

In a similar way you can? prepare a composition containing compound No. 2, compounds A, B, C, D and E.

Example 8

Biological (herbological) tests

Did they compare the activity? herbicide and selectivity? of the compounds according to the present invention with the antipode (R) (compound D) correlated from the point of view of the structure and with 1 '(RS) -l'-methoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy ) benzoate (compound A) as well as with the antipode (R) (compound E) and with 1 '(RS) -1? -ethoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate (compound B ) and with 1 '(RS)? 1'? ethoxycarbonylethyl 5- (2-chloro-4-trifluoromethylphenoxy) -2-nitrobenzoate (compound C) commercially available as reference substance (standard).

Depending on the plant species, an equal number (20-50) of grains were sown into each plastic growing bottle at a depth of 6 to 9 cm. of 0.5 cm, then the soil was watered when necessary and the bottles were kept in optimal conditions of temperature and light. After the weeds had reached a real 2-4 leaf phase or the cultivated plants had reached the 3-6 leaf phase, respectively, was it done? spraying with a dose of 5, 15, 45, 135, 405 or 1215 g / ha, respectively, of the active ingredient. The evaluation was carried out on the tenth day after the treatment by measuring the percentage of destruction (L. Banki: Bioassay of Pesticides in th? Laboratory, Akad? Miai Kiado, Budapest, Hungary, 1978) and determining from it the doses required for a higher destruction. 90% using probit analysis (analysis using a statistical unit) (D. J. Finney: Probit Analysis, Cambridge University Press, 2 Ed. 1964). At the same time, the threshold values of selectivity were determined. of the cultivated plants, that is? the doses pi? high tolerated by plants without any harm. The results are summarized in Tables 1 and 2.

The abbreviations used in the Tables are as follows: a) Amarantus retroflexus (hairy amaranth)

b) Solanum nigrum (black solanum)

c) Portulaca oleraceae (oily porcelain)

d) Matricaria odorless (odorless matricaria)

e) Datura stramonium (stramonium)

f) Chenopodium album (white clenopodium)

g) Oryza sativa (rice)

h) Triticum vulgare; winter wheat)

i) Holdeum vulgare (winter barley)

j) Glycine soja [soy)

Example 9

Field experiments

These tests were carried out using compounds No. 1 and No. 2, respectively, according to the invention and the reference compounds A, B, C, D and E, respectively, on winter wheat of the Aurora species on 20 m plots, in four repetitions. The compounds used in these experiments were formulated as described under a) in Example 5. The weeds found in the indicated areas were: Anthemis arvensis, Convolvulus arvensis, Matricaria inodora, Veronica hederifolia and Stellaria media. The spraying was done on March 23, when the Stellaria media reached the beginning of flowering and the other weeds were in the development phase of up to 10 cm. The activity? herbicide of the compositions was evaluated at the end of the third week after spraying (L. Banki:

Bioassay of Pesticides in th? Laboratory, Akad? Miai Kiado, Budapest, Hungary, 1978). Except for Stellaria media, 100% of the weeds were eradicated in all treatments. It was observed? an important difference regarding the activity? herbicide on the Stellaria average between the compounds according to the present invention and reference compounds. The medium Stellaria was advantageously extirpated from the compounds according to the present invention while the reference substances were inactive. The coverage by the average Stellaria of the fields treated with a dose of 50 g / ha of the reference substances reached 50%. There is a considerable difference between the phytotoxicity, towards winter wheat, of the compounds according to the present invention and that of the reference compounds.

The data obtained on winter wheat and average Stellaria are summarized in Table 3.

Claims (7)

CLAIMS 1. (S)? 1-methoxycarbonyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate. 2. (S) -l'-ethoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate. 3. Herbicidal composition, which includes, as active ingredient, (S)? 11-methoxycarbonyl ethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate or (S) -l1-ethoxycarbonylethyl 2-bromo-5- ( 2-chloro-4-trifluoromethylphenoxy) benzoate in a quantity? of 0.01-95.0% by weight together with one or more? solid and / or liquid vehicles, preferably fragments of a naturally occurring or synthetic material (s); and / or with an inert solvent (s), preferably xylene (xylenes) and / or cyclohexanone; and optionally with a surfactant agent (s), preferably an anionic and nonionic emulsifying or dispersing agent (s). 4. Composition as claimed in claim 3, which comprises, as active ingredient, (S) -l'-methoxycarbonyl ethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate. 5. Composition as claimed in claim 3, which comprises, as active ingredient, (S) -l'-ethoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate. 6. Process for the preparation of (S) -l'-methoxycarbonyl ethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate or of (S) -l'-ethoxycarbonylethyl 2-bromo-5- (2- chloro-4-trifluoromethylphenoxy) benzoate, which includes reacting the enantiomer (S) of a lactic acid ester of general formula (I), in which R denotes a methyl or ethyl group, with 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoyl halide , preferably chloride, in a solvent, preferably in the presence of an agent which binds the acids and then separates 1 '(S) -l'-methoxy-carbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy} benzoate or 1 '(S) -1' -ethoxycarbonylethyl 2-bromo-5- (2-chloro-4-trifluoromethylphenoxy) benzoate thus obtained from the reaction mixture, and, if desired, purifying them. 7. Method for controlling unwanted weed growth which includes applying a quantity of weed. herbicidal effective of a compound as claimed in claim 1 or 2 to the plant or soil in pre-emergence or post-emergence in the form of a composition as claimed in claim 3.