CN106699649A - 2-(hexahydric aryloxy phenoxy)alkanoic acid derivative and application thereof - Google Patents

Abstract

The invention discloses 2-(six-membered aryloxyphenoxy)alkanoic acid derivatives and their application as herbicides, the chemical structural formula of which is shown in Formula I: In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ are any one of hydrogen or C ₁ ~C ₃ alkyl or C ₁ ~C ₃ haloalkyl; X is nitrogen or carbon; Y is nitrogen or oxygen; X ¹ and X ² are any one of hydrogen, fluorine, chlorine, bromine, iodine, trifluoromethyl, cyano or nitro. The present invention also relates to the application of compositions containing the above-mentioned compounds and 2-(six-membered aryloxyphenoxy) alkanoic acid derivatives in agricultural herbicides. Some compounds have very high herbicidal activity. A good control effect can be obtained under the dosage.

Description

2-(Six-membered aryloxyphenoxy)alkanoic acid derivatives and their applications

technical field

The invention relates to a compound, in particular to a 2-(six-membered aryloxyphenoxy)alkanoic acid derivative and application thereof.

Background technique

Aryloxyphenoxypropionic acid (APP) derivatives, as grass weed herbicides, have attracted much attention since their listing due to their high efficiency, low toxicity, high selectivity and environmental friendliness. This kind of herbicide inhibits the acetyl coenzyme A carboxylase (ACCase) in grass weeds and blocks the synthesis of fatty acids in plants, so as to effectively and selectively control grass weeds, so that it has no effect on broad-leaved crops .

Usually, the R configuration of such compounds is the active ingredient of herbicides. In 1991, Novartis developed the first APP herbicide for wheat fields—clodinafop-propargyl. Since then, Dow Chemical and Korea Chemical Technology Research Institute have successively developed two APP herbicides for rice fields. Agents - cyhalofop-methyl (P1) and fenpyramid (P2). The study found that when phenoxy was replaced by pyridyloxy, the selectivity and activity would be greatly improved. Among such APP herbicides, haloxyfop (P3) is a representative herbicide.

In order to obtain compounds with higher activity, the inventors designed and synthesized a series of 2-(hexaaryloxyphenoxy)alkanoic acid derivatives which have not been reported in the literature, and found that they have significant herbicidal activity.

Contents of the invention

The invention provides a 2-(six-membered aryloxyphenoxy)alkanoic acid derivative and its isomers, characterized in that its chemical structural formula is as shown in formula I:

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ are any one of hydrogen or C ₁ ~C ₃ alkyl or C ₁ ~C ₃ haloalkyl; X is nitrogen or carbon; Y is nitrogen or oxygen; X ¹ and X ² are any one of hydrogen or fluorine or chlorine or bromine or iodine or trifluoromethyl or cyano or nitro;

In the definition of compound (I) given above, the terms used no matter used alone or in compound words represent the following substituents:

Alkyl: refers to straight chain or branched chain alkyl;

Haloalkyl: Refers to straight chain or branched chain alkyl, the hydrogen atoms on these alkyl groups are partially or completely replaced by halogen atoms;

The compounds of the present invention may exist in one or more isomeric forms. Isomers include enantiomers, diastereomers, geometric isomers. The compound shown in the formula (I) of the present invention forms stereoisomers (representing different configurations with R and S respectively) due to four different substituents connected to one carbon atom, and the present invention includes R-form isomers and S-isomers and their mixtures in any proportion.

In a preferred scheme, the specific structural formula of the 2-(six-membered aryloxyphenoxy)alkanoic acid derivative is:

The present invention also relates to the herbicidal activity of the 2-(six-membered aryloxyphenoxy)alkanoic acid derivative, which has significant herbicidal biological activity at a dosage of 5 g/mu.

The compound of formula (I) provided by the present invention has good weed control effect, and good effect can be obtained at very low dosage.

The compound of formula (I) provided by the present invention has biological activity and some compounds have very good biological activity, especially in the control of agriculture, gardening, flowers and hygienic weeds. Weeds described here include, but are not limited to:

Grass weeds: crabgrass, barnyardgrass, foxtail, hard grass, oystergrass, brome, arpeggios, barley, soda, star grass, wild oats, ryegrass;

Broad-leaved weeds: velvet hemp, chickweed, nightshade, quinoa, amaranth, amaranth, etc.

The compounds of formula (I) of the present invention are effective in controlling weeds when used alone, but they can also be used in combination with other biochemical substances, including other herbicides.

The present invention also relates to the application of the 2-(six-membered aryloxyphenoxy)alkanoic acid derivatives in agricultural herbicides.

The synthetic raw materials of the 2-(six-membered aryloxyphenoxy)alkanoic acid derivative involved in the present invention are easy to obtain, the preparation method is simple, and the industrial production is easy.

detailed description

Below in conjunction with specific implementation, further illustrate the present invention. These examples should be understood as only for illustrating the present invention but not for limiting the protection scope of the present invention. After reading the contents of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Embodiment 1: the preparation of (R)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl)phenoxy]propionate phenylethyl ester (1)

N,N-Dimethylformamide (40mL), (R)-(+)-2-(4-hydroxyphenoxy)propionic acid (0.02mol, 3.64g), potassium carbonate (0.02mol, 2.76g), After stirring at 75°C for 0.5h, an equal amount of potassium carbonate was added, and the stirring was continued for 0.5h. 2,3-difluoro-5-chloropyridine (0.02 mol, 3.00 g) was slowly added dropwise. After the dropwise addition, the reaction temperature was maintained at 75° C. overnight. Stop heating, cool to room temperature, pour the reaction solution into 200mL ice water, adjust the pH to 4-5 with dilute hydrochloric acid, filter, wash with a small amount of ice water three times, and dry in vacuum to obtain (R)-2-[4-(3-fluoro -5-Chloropyridine-2-oxyl)phenoxy]propionic acid 3.86g white solid, yield 62.0%.

Toluene 40mL, (R)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl)phenoxy]propionic acid (3.3mmol, 1.04g), was added to a 100mL single-necked flask, stirred After dissolving, add thionyl chloride (20mmol, 2.24g), reflux for 4h, and distill under reduced pressure to obtain (R)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl)phenoxy Base] propionyl chloride yellow oily liquid, without separation and purification, directly used in the next reaction.

To (R)-(+)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl)phenoxy]propionyl chloride reaction flask, first add dichloromethane (40mL), then add benzene Ethanol (0.40g, 3.3mmol), 4-dimethylaminopyridine (DMAP, 0.02g), and stirred under ice bath for 15 minutes. Triethylamine (1.37mL, 10mmol) was added dropwise. After the dropwise addition, stirring was continued for 10 minutes, then the ice bath was removed, and allowed to return to room temperature naturally, and stirred for 4 hours, during which the reaction was monitored by TLC. Stop the reaction, pour the reaction solution into a separatory funnel, and then pour 150 mL of ice water into it, extract three times with dichloromethane, 40 mL each time, and combine the dichloromethane extracts from the lower layer. The organic phase was first washed twice with 50 mL of saturated sodium bicarbonate solution, and finally washed three times with 100 mL of water. The organic phase after washing with water was poured into a Erlenmeyer flask, and an appropriate amount of anhydrous sodium sulfate was added for overnight. Filtration, dichloromethane was evaporated under reduced pressure, and the product was separated and purified by silica gel column chromatography, eluent (V _{petroleum ether} : V _{ethyl acetate} = 4:1), to obtain (R)-2-[4-(3-fluoro -5-Chloropyridine-2-oxy)phenoxy]propionic acid phenylethyl ester 0.35g, colorless oily liquid, yield 25.5%; ¹ H NMR (CDCl ₃ , 400MHz) δ: 1.56(d, J= 6.8Hz, 3H, CHC H ₃ ), 2.95(t, J=6.8Hz, 2H, OCH ₂ CH ₂ ), 4.40(t, J=6.8Hz, 2H, OCH ₂ CH ₂ ), 4.68(q, J＝6.8Hz, 1H, CH CH ₃ ), 6.84(d, J＝9.2Hz, 2H, PhH), 7.03(d, J＝9.2Hz, 2H, PhH), 7.17～7.31(m, 5H, PhH ), 7.49 (dd, J＝9.2Hz, 2.4Hz, 1H, Py-H), 7.85 (d, J＝2.4Hz, 1H, Py-H); ¹³ C NMR (CDCl ₃ , 100MHz) δ: 18.58, 34.94, 65.56, 73.06, 116.01, 122.25, 124.82, 125.00, 126.65, 128.52, 128.87, 137.30, 140.09, 145.64, 146.95, 148.28, 154.91, 172.02.

Embodiment 2: the preparation of N-phenethyl-(R)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl group) phenoxy group] propionamide (2)

(R)-(+)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl)phenoxy]propionyl chloride The preparation method is as in Example 1, to which dichloromethane (40mL) is added , 2-phenylethylamine (0.33g, 2.7mmol), 4-dimethylaminopyridine (DMAP, 0.02g), stirred under ice bath for 15 minutes. Triethylamine (1.1 mL, 8.2 mmol) was added dropwise. After the dropwise addition, stirring was continued for 10 minutes, then the ice bath was removed, and allowed to return to room temperature naturally, and stirred for 4 hours, during which the reaction was monitored by TLC. Stop the reaction, pour the reaction solution into a separatory funnel, and then pour 150 mL of ice water into it, extract three times with dichloromethane, 40 mL each time, and combine the dichloromethane extracts from the lower layer. The organic phase was first washed twice with 50mL saturated sodium bicarbonate solution, and finally washed three times with 100mL water, dried over anhydrous sodium sulfate, filtered, dichloromethane was evaporated under reduced pressure, the product was separated and purified by silica gel column chromatography, and the eluent (V _{petroleum Ether} : V _{ethyl acetate} = 3:1), N-phenethyl-(R)-2-[4-(3-fluoro-5-chloropyridine-2-oxyl)phenoxy]propionamide white Solid 0.25g, yield 22.3%, melting point 108.0℃～109.1℃; ¹ H NMR (CDCl ₃ , 400MHz) δ: 1.54(d, J=6.8Hz, 3H, CHCH H ₃ ), 2.71～2.85(m, 2H ,NHCH ₂ CH ₂ ),3.47～3.66(m,2H,NHC H ₂ CH ₂ ),4.61(q,J＝6.8Hz,1H, CH CH ₃ ),6.45(br,s,1H,NH) ,6.86(d,J＝8.8Hz,2H,PhH),7.08～7.10(m,4H,PhH),7.18～7.29(m,3H,PhH),7.51(dd,J＝8.8Hz,2.4Hz,1H , Py-H), 7.85 (d, J=2.4Hz, 1H, Py-H); ¹³ C NMR (CDCl ₃ , 100MHz) δ: 18.93, 35.67, 40.06, 75.57, 116.24, 122.55, 124.90, 125.09, 126.53 ,128.64,128.76,138.46,140.09,140.15,147.23,150.14,154.26,171.92.

Embodiment 3: Preparation of (R)-2-[4-(3-chloro-5-trifluoromethylpyridine-2-oxyl)phenoxy]propionate phenylethyl ester (3)

(R)-2-(4-Hydroxyphenoxy)propionic acid (3g), DMF (35ml), slowly added K ₂ CO ₃ (4.55g), raised the temperature to 70-80°C, stirred for 1h, and added 2 , 3-dichloro-5-trifluoromethylpyridine (3.56g), kept stirring at 70-80°C for 8h, stopped the reaction, cooled to room temperature naturally, poured the mixture into ice water (200mL), adjusted the pH with dilute hydrochloric acid 4-5, extracted with ethyl acetate, washed the organic phase with water, dried, and precipitated to obtain (R)-2-[4-(5-trifluoromethyl-3-chloropyridine-2-oxyl)phenoxy] Propionic acid brown liquid 5.03g, yield 84.4%.

(R)-2-[4-(5-trifluoromethyl-3-chloropyridine-2-oxyl)phenoxy]propanoic acid (3.3mmol, 1.08g), dissolved in toluene (35mL), dropwise Add SOCl ₂ (20mmol, 2.24g), heat to reflux, react for 4h, and remove the solvent to obtain (R)-2-[4-(5-trifluoromethyl-3-chloropyridine-2-oxyl)phenoxy] Propionyl chloride was used directly in the next step.

The obtained acid chloride was dissolved in dichloromethane (35 mL), the intermediate 2-phenylethanol (0.34 g) and a catalytic amount of DMAP were added, and triethylamine (0.85 g) was slowly added dropwise under stirring, and the reaction was stirred for 5 h. After the reaction was complete, the mixture was poured into ice water (100 mL), extracted with dichloromethane (80 mL*2), the organic phase was washed with water, dried, and solvent removed. Purified by column chromatography to obtain (R)-2-[4-(3-chloro-5-trifluoromethylpyridin-2-oxyl)phenoxy]propionic acid phenylethyl ester (3) transparent viscous Liquid 0.27g, yield 21.27%. ¹ H NMR: δ1.57(d, J=6.8Hz, 3H, CHC H ₃ ), 2.95(t, J=6.8Hz, 2H, CH ₂ CH ₂ ), 4.41(t, J=6.8Hz, 2H , CH ₂ CH ₂ O), 4.698 (q, J=6.8Hz, 1H, CH CH ₃ ), 6.87 (d, J=9.2Hz, 2H, Ph-H), 7.03 (d, J=9.2Hz ¹³ C NMR: δ18.57, 34.93, 65.58, 73.03, 116.00, 119.13, 121.48, 122.07, 122.58, 126.65, 128.52, 128.86, 136.22, 137.28, 142.56, 146.70, 155.22, 171.395,

Example 4: Preparation of N-phenethyl-(R)-2-[4-(3-chloro-5-trifluoromethylpyridine-2-oxyl)phenoxy]propanamide (4)

(R)-(+)-2-[4-(3-Chloro-5-trifluoromethylpyridine-2-oxyl)phenoxy]propionyl chloride is prepared as in Example 3, and the resulting acid chloride is dissolved in dichloro In methane (35 mL), 2-phenylethylamine (0.33 g) and a catalytic amount of DMAP were added, and triethylamine (0.85 g) was slowly added dropwise under stirring, and the reaction was stirred for 5 h. After the reaction was complete, the mixture was poured into ice water (100 mL), extracted with dichloromethane (80 mL*2), the organic phase was washed with water, dried, filtered with suction, and solvent removed. Purified by column chromatography to obtain N-phenethyl-(R)-2-[4-(3-chloro-5-trifluoromethylpyridin-2-oxyl)phenoxy]propionamide (4) as a white solid 0.65g, mp146～148°C, yield 50.79%. ¹ H NMR: δ1.59 (d, J=6.8Hz, 3H, CHC H ₃ ), 2.74-2.91 (m, 2H, CH ₂ CH ₂ ), 3.48-3.57 (m, 1H, CH ₂ CH ₂ N),3.64-3.73(m,1H,CH ₂ CH ₂ N),4.66(q,J＝6.8Hz,1H, CH CH ₃ ),6.50(br,1H,NH),6.93(d,J =9.2Hz, 2H, Ph-H), 7.12-7.15(m, 3H, Ph-H), 7.24-7.33(m, 4H, Ph-H), 8.02(s, 1H, Py-H), 8.29( s,1H,Py-H); ¹³ C NMR: δ18.93,35.68,40.06,75.59,116.25,119.12,122.87,126.53,128.64,128.75,136.28,138.40,142.51,146.96,154.59,171,85

Embodiment 5: the preparation of (R)-2-[4-(4-cyano-2-fluorophenoxy) phenoxy] propionate phenylethyl ester (5)

In N,N-dimethylformamide (DMF, 40mL), add (R)-2-(4-hydroxyphenoxy)propionic acid (3.03g, 0.02mol), and add potassium carbonate (5.52g, 0.04mol), the temperature was raised to 70°C~80°C, and the stirring was continued for 1h, and 3,4-difluorobenzonitrile (2.38g, 0.02mol) was added gradually, and the stirring reaction was continued for 6~7h. Cool to room temperature, pour into ice water (250mL), slowly add dilute hydrochloric acid, adjust to pH 4~5, filter with suction, wash with water, and dry in a vacuum oven to obtain (R)-2-[4-(4-cyano -2-fluorophenoxy)phenoxy]propionic acid The title compound was 3.26 g of gray solid, yield 65.7%.

(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid (1g, 3.3mmol) was dissolved in toluene (40ml), and SOCl ₂ (1.18g, 10mmol), reflux reaction for 5h, after removing the solvent with a rotary evaporator, (R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propionyl chloride was obtained, and the next step was directly carried out reaction.

Dissolve the obtained acid chloride in dichloromethane (40ml), add phenethyl alcohol (0.40g, 3.3mmol) and a catalytic amount of 4-dimethylaminopyridine (DMAP), stir for 10min under ice bath, and add triethylamine dropwise Amine (1 g, 10 mmol). Stirring was continued for 3h to 10h. After the reaction is completed, pour into 100ml~200ml of ice water, extract with dichloromethane, collect the organic phase, and wash with water (100ml×2), the obtained crude product is dried with anhydrous sodium sulfate, and purified by silica gel chromatography column after desolvation to obtain a transparent Oily liquid (R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propanoic acid phenylethyl ester (5) 0.71 g, yield 52.8%. ¹ H NMR: δ1.57(d, J=6.8Hz, 3H, CHC H ₃ ), 2.95(t, J=6.8Hz, 2H, CH ₂ ), 4.41(t, J=6.8Hz, 2H, C H ₂ ), 4.67(q, J=6.8Hz, 1H, CH CH ₃ ), 6.81-6.87(m, 3H, Ph-H), 6.94(d, J=9.2Hz, 2H, Ph-H), 7.17-7.34 (m, 6H, Ph-H), 7.44 (dd, J = 10.0Hz, 2.0Hz, 1H, Ph-H); ¹³ C NMR: δ18.52, 34.93, 65.56, 72.98, 105.93, 116.52, 118.47, 120.41, 120.62, 121.00, 126.67, 128.50, 128.82, 129.31, 137.24, 148.44, 151.08, 153.58, 154.95, 171.81.

Embodiment 6: Preparation of N-phenethyl-(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy)propanamide (6)

(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy]propionyl chloride is prepared as in Example 5, the resulting acid chloride is dissolved in methylene chloride (40ml), and benzene is added Ethylamine (0.40g, 3.3mmol) and a catalytic amount of 4-dimethylaminopyridine (DMAP) were stirred in an ice bath for 10min, and triethylamine (1g, 10mmol) was added dropwise. Stirring was continued for 3h to 10h. After the reaction was completed, pour into 100ml of ice water, extract with dichloromethane, collect the organic phase, and wash with water (100ml×2), the obtained crude product was dried with anhydrous sodium sulfate, purified by silica gel chromatography column after precipitation to obtain white solid N-phenethyl-(R)-2-[4-(4-cyano-2-fluorophenoxy)phenoxy)propionamide (6) 0.90g, yield 67.4%, melting point 104℃～105 ℃. ¹ H NMR: δ1.54 (d, J=6.8Hz, 3H, CHCH ₃ ), 2.71～2.84 (m, 2H, Ph- CH ₂ ), 3.46～3.54 (m, 1H, NH- CH ₂ ),3.58～3.67(m,1H,NH- CH ₂ ),4.59(q,J＝6.8Hz,1H, CH CH ₃ ),6.43(br s,1H,NH),6.84～6.90(m, 3H, PhH), 6.99(d, J=8.8Hz, 2H, PhH), 7.09(d, J=6.4Hz, 2H, PhH), 7.19～7.28(m, 3H, PhH), 7.34(dt, J= 8.4Hz, 1.6Hz, 1H, PhH), 7.46 (dd, J = 10.0Hz, 2.0Hz, 1H, PhH); ¹³ C NMR: δ18.88, 35.64, 40.04, 75.73, 116.86, 117.57, 118.73, 120.55, 120.77, 121.06, 126.57, 128.62, 128.71, 129.32, 129.36, 138.44, 148.99, 153.72, 154.26, 171.73.

Embodiment 7: Herbicidal activity evaluation

The method is as follows: (1) Quantitatively pack soil into a plastic pot with a cross ^- sectional area of 64 cm to flatten it, place it in a stainless steel pot, select seeds with plump grains and the same size, and divide them into monocotyledonous weeds (Digitaria sanguinalis, barnyardgrass) Echinochloa crus-galli, Setaria viridis) and dicotyledonous weeds (Abutilontheophrasti (or Stelleria media or Solanum nigrum), Chenopodium album, Amaranthus ascedense or Amaranthus retroflexus) in separate pots , each accounting for 1/3 of the pot area, covered with 1cm thick fine soil, adding water from the bottom of the plastic pot to the upper soil infiltration, placing it in the greenhouse for cultivation, and performing the test treatment when the test material grows to the required leaf age; (2) Weigh An appropriate amount of 2-(hexaaryloxyphenoxy)alkanoic acid derivative provided by the present invention is dissolved in N,N-dimethylformamide, then a small amount of Tween 80 emulsifier is added, stirred evenly, and quantitative clear water is added, Prepare the required concentration, and set the corresponding solvent and clear water as the control; (3) Treatment method: the pre-emergence soil treatment is carried out the next day after the test material is sown. Post-emergence stem and leaf treatment at the true leaf stage; (4) Quantitatively pipette the medicinal liquid according to the set dose for stem and leaf spray and soil spray treatment, respectively using spray solvent and clear water as controls; (5) Treat the test materials in the greenhouse for cultivation (6) after 15-25 days, the growth situation of the upper part of the ground was visually observed, and according to the findings, the following formula was used to calculate the control effect of each compound on weeds: control effect (%)=100*(contrast plant height-handling plant height)/ Control plant height; (7) Grading the herbicidal activity according to the control effect: A-level control effect > 90%, B-level control effect 75-90%, C-level control effect 50-75%, D-level control effect 25-50%, Class E control effect <25%. The results show that the compound of the present invention has selective herbicidal activity to monocotyledonous weeds under the dose of 5g/mu, and wherein compounds 1, 3, and 4 have A-level herbicidal activity to monocotyledonous weed stem and leaf treatment and soil treatment , Compound 2 mostly has A-level herbicidal activity against monocotyledonous weed stem and leaf treatments, and compounds 5 and 6 have C-level herbicidal activity against monocotyledonous weed stem and leaf treatments. Some results are as follows.

Claims (6)

1. a kind of 2- (hexa-atomic aryloxyphenoxy) acid derivative, it is characterised in that its chemical structural formula is shown in formula I：

In formula, R¹、R²、R³、R⁴、R⁵、R⁶It is hydrogen or C₁~C₃Alkyl or C₁~C₃Any one in haloalkyl；X is nitrogen or carbon； Y is nitrogen or oxygen；X¹、X²It is any one in hydrogen or fluorine or chlorine or bromine or iodine or trifluoromethyl or cyano group or nitro；It is given above Compound I definition in, no matter term used is used alone also being used in compound word, represent following substitution base：Alkyl：Refer to Straight or branched alkyl；

Haloalkyl：Refer to straight or branched alkyl, hydrogen moiety on these alkyl or all replaced by halogen atom.

2. 2- (hexa-atomic aryloxyphenoxy) acid derivative according to claim 1, it is characterised in that：Described 2- The concrete structure formula of (hexa-atomic aryloxyphenoxy) acid derivative is：

3. 2- (hexa-atomic aryloxyphenoxy) acid derivative described in claim 1 or 2 also includes that R types isomers and S types are different The mixture of structure body and their any ratios.

4. 2- (hexa-atomic aryloxyphenoxy) application of acid derivative on herbicide is prepared described in claim 1 or 2.

5. the application described in claim 4, it is characterised in that the weeds of described herbicide action include grassy weed, tool Body includes lady's-grass, barnyard grass, green bristlegrass, hard grass , Wang grass, bromegrass, amur foxtail, Triticum tauschii, alkali thatch, stinkgrass flower, wild oat, rye Grass.

6. the application described in claim 4, it is characterised in that the consumption of described herbicide is 5 grams/acre.