CS204021B2 - Herbicide and process for preparing effective compound - Google Patents

Description

The invention relates to herbicidal compositions which contain as active ingredient novel derivatives of substituted 3-phenoxy- and phenoxyalkanecarboxylic acid having a substituent in the α-phenoxy group in the para position to the 3-phenoxy group. The invention further relates to a process for the production of these novel herbicidally active compounds, as well as to the use of these active compounds or of compositions containing them for the selective control of weeds in crops.

The new active substances correspond to the general formula I

in which

B is —OR2 or —SR3, Hal is halogen, n is an integer of 0 or 1

R1 is hydrogen or (C1-C2) -alkyl,

R 2 is hydrogen or an alkali or alkaline earth metal cation, a copper cation, or a C 1 -C 4 alkylammonium group.

R 2 and R 3 are C 1 -C 8 -alkyl which is unsubstituted or optionally substituted by halogen, cyano, C 1 -C 4 -alkoxy, C 3 -C 8 -alkenyl or C 3 -C 8 -alkynyl, furthermore are C 3 -C 12 cycloalkyl, phenyl or benzyl which is unsubstituted or substituted by halogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, nitro, cyano or trifluoromethyl.

In this formula, alkyl groups are both branched and unbranched and contain the indicated number of carbon atoms.

From DOS Nos. 2 136 828, 2 223 894, 2 433 067 and 2 531 643 similar phenoxyphenoxyalkanecarboxylic acid derivatives are known which, however, contain an alkanecarboxylic acid residue in the para-position.

These known compounds have a special activity against grasses and are suitable for the selective control of grass weeds in monocotyledonous and dicotyledonous crop plants. However, these compounds are not effective at all or only in very high application rates against dicotyledonous weeds.

Surprisingly, it has now been found that the novel phenoxy-.alpha.-alkanecarboxylic acid derivatives of formula I having an alkanecarboxylic acid residue in the meta-position are surprisingly suitable for controlling dicotyledonous weeds in predominantly monocotyledonous crops such as cereals (wheat, barley, sorghum), maize, as well as rosehip (Sagittaria) and lupine (Cyperus) species in rice, as well as selective weed control in dicotyledonous crops such as sugar beet, soybean, cotton.

It has been found to be particularly well tolerated against rice, both rice grown under dry conditions and under irrigation conditions.

The compounds of formula I have proved to be most effective against the following dicotyledonous weeds:

rosehip (Sagittaria pygmeaj, white mustard (Sinapis alba),

Sida spinosa,

Sesbania exaltata, Ipomoea purpurea, Galium aparina, Chrysantbemum leucum, Abutilon, Solar niggers,

Ammania indica,

Rotola indica, Cyperus diíforrais,

Elatine triandra,

Lindemia proeumbens etc.

Although the novel compounds are also effective in pre-emergence administration, post-emergence administration has proven to be particularly effective and useful.

Some of the new active ingredients are also suitable for desiteal and defoliation of cotton or potatoes shortly before harvesting.

The amount of herbicide used according to the invention per hectare depends on the effectiveness of the active ingredient used, the soil properties, the climatic and weather conditions, the method of application and the time of application and the type of crop and weeds to be varied between 0.1 and 10.0. kg and preferably is 0.5 to 4 kilograms.

Compounds of formula Ia have proven to be particularly well suited according to the invention

in which

B and Hal are as defined in Formula I.

The novel compounds of formula (I) are prepared by methods known per se for such syntheses.

The last step of the synthesis always consists of the following step and represents the process according to the invention:

whereas

Hal, n, R 1 and B have the meanings given above.

Thus, in the process of the invention, the 3-hydroxy diphenyl ether of formula II is used as the starting material, which is reacted with an α-haloalkane acid derivative of formula III in the presence of a base.

When carboxylic acids (COOH) are used as starting materials of formula III in this process, this group can additionally be converted to another of the groups defined in formula I, either directly or via the corresponding acid chloride.

Using an ester of formula III, the compound can be saponified to the free carboxylic acid, its salt, and then the amide.

In formulas II and III, n and B and Z have the meanings given in formula I and Hal is a halogen atom such as chlorine, bromine, etc.

Said reaction may be carried out in the presence or absence of inert solvents or diluents which are inert to the reactants. Suitable solvents are polar organic solvents such as methyl ethyl ketone, dimethylformamide, dimethylsulfoxide, and the like.

Reaction temperatures are between 0 and

200 [deg.] C., preferably between 20 and 100 [deg.] C., and the reaction time depends on the starting material used, the reaction temperature and the solvent chosen, and is between 1 hour and several days. The process is generally carried out at atmospheric pressure. Suitable bases (condensing agents) for the reaction are customary bases, such as potassium hydroxide, sodium methoxide, sodium bicarbonate, potassium carbonate, potassium tert-butoxide, etc., but also organic bases such as triethylamine, etc.

The starting materials of the formula III are known or can be easily prepared by conventional methods. The starting phenols of the formula II are also known.

The hitherto not described phenoxyphenols of formula II can readily be prepared according to conventional methods and conventional techniques, as described, for example, in DOS 2,433,066 and DOS 2,433,067.

The following examples illustrate the preparation of several phenoxyphenoxyalkoxycarboxylic acid derivatives of the formula I. Further corresponding active ingredients produced are shown in the following table. Temperatures are given in degrees Celsius.

Example

3- (2‘-Cyano-4‘-chlorophenoxy) -α- (6-chlorophenoxy) propionic acid methyl ester

(a) 66 g of resorcinol are introduced into 220 ml of dimethylsulphoxide and 37.4 g of potassium hydroxide (powder) are added with stirring, the temperature rising to 55 ° C. The mixture was maintained at 60 ° C for 30 minutes and then 51.6 g 2,5-dichlorobenzonitrile was added portionwise.

The reaction mixture was then stirred at 90 ° C for 7 hours and poured into ice / water after cooling. Upon adjustment to pH 6 with concentrated hydrochloric acid, a brown oil precipitated first and soon solidified into a crystalline product. This product crystallizes from a mixture of toluene and water to give 49.6 g of 3- (2‘-cyano-4‘-chlorophenoxy) -phenol, m.p. 118-120 ° C.

b) 40 g of 3- (2 ^{<cyano-4'-chlorophenoxy)} phenol and 24.8 ml triethylamiinu are placed in 200 ml of tetrahydrofuran, and with stirring was added dropwise 12.2 ml of acetyl chloride (ice bath cooling). Then the reaction mixture was further stirred for 8 hours at room temperature. After filtration, the filtrate was evaporated in vacuo to give 45 g of 3-acetoxy-2'-cyam-4'-chlorodiphenyl ether. Melting point 64.5 ° C.

(c) 10 g of this 3-acetoxy-2 &apos; -cyano-4 &apos; -chilordiphenyl ether are introduced in 100 ml of acetic acid. Chlorine is introduced at 20 ° C until the presence of the starting material in the gas chromatogram can no longer be detected. After evaporation, the product was distilled under high vacuum to give 7 g of 3-acetoxy-2'-cyano-4,4'-dichlorodiphenyl ether. Boiling point 174 ° C / 6.7 Pa.

d) Saponification of this acetate with sodium hydroxide in a mixture of water and ethanol at reflux afforded 3-hydroxy-2 &apos; -cyain-4,4 &apos; -dichlorophenyletheir, which precipitated upon cooling. Melting point 132 ° C.

(e) 60 g of 3-hydroxy-2'-cyano-4,4'-dichlorodiphenylether and 24 ml of 2-bromopropionic acid methyl ester are stirred together with 29.6 g of potassium carbonate at 100 ° C (bath temperature) in 600 ml of ethyl methyl ketoma. night. After inorganic salts are filtered off, the filtrate is evaporated to dryness. The crystalline mass is recrystallized from methanol. 81.7 g of 3- (2‘-cyano-4‘-chlorophenoxy) - N - (6-chlorophthioxy) propionic acid methyl ester of melting point 105 ° C are obtained.

In an analogous manner to that described in the above example, the following were also produced:

3- (2'-chloro-4'-cyanophenoxy) -a- (6-chlorophenoxy) propionic acid methyl ester, boiling point 200 ° C / 1 Ja, 3- (2'-chloro-4'-cyanophenoxy) thiobenzyl ester - α- (6-chlorophenoxy) propionic acid, boiling point 183-192 ° C / 5 Pa, as well as 1 compounds listed in the following table:

compound C. Ri R physical constants 1 CH3 OCH3 mp 104-105 ° C / 1.3 Pa 2 C2H5 OC2H5 oil 3 GHj OCiH9sek. oil 4 CH3 OC1H9ÍS0 oil 5 CH3 OCdhm oil 6 CH3 OC3H7n oil 7 CH3 OC3H7ÍSO oil 8 OH OCH2COOCH3 mp 105-108 ° C 9 CH3 OCH2COOC2H5 mp 65-67 ° C 10 CH3 OCH 2 CH (CH 3) C 2 H 5 oil 11 CI-I3 mp 121-122 ° C 12 CH3 OH mp 135-136 ° C 13 CH3 OCH 2 —C = CH oil 14 CH3 OCH _{2 -} CH = CH 2 oil 15 Dec CH3 SCH3 mp 79-80 ° C 16 CH3 SC2H5 mp 68-69 ° C 17 CH3 n _D ²³ 1.6110 18 CH3 SCH 2 = CH = CH 2 oil New active ingredients of the formula And they are permanent Liquid processing: compounds, which are soluble in the usual organic solvents such as solutions. alcohols, ethers, ketones, dimethylformamide, dimethylsulfoxide etc. Concentration of the active ingredient in the compositions Resources according to the invention are being prepared according to the invention is 1 to 80% by weight in a well-known manner, and these concentrations may optionally be at by grinding and grinding the active substances in general application of low concentrations to move formula I p suitable carriers about 0.05 to 1%. bo / a thinners, optionally after addition of pro- The compositions according to the invention described

anti-foaming agents, wetting agents, dispersing agents and / or solvents inert to the active ingredients. The active substances can be present in the following processing forms and can be applied in the same forms.

solid forms of processing:

dust, grit, granulate, coated granulate, Impregnated granulate and homogeneous granulate;

other biooid active substances or compositions can be admixed. Thus, in addition to the compounds of the formula I, the novel compositions can contain, for example, insecticides, fungicides, bactericides, fungistatics, baiktertostatics, inematocides or other herbicides for the purpose of broadening the spectrum of action. Granulate:

The following ingredients are used to prepare the 5% granulate:

water-dispersible concentrates of the active substance:

wettable powder, pastes, emulsions, emulsion concentrates;

parts of the active ingredient of the formula I, 0.25 parts of epichlorohydrin,

0.25 parts of cetyl polyglycol ether, 3.50 parts of polyethylene glycol, parts of kaolin (particle size 0.3-0.8 mm).

The active ingredient is mixed with epichlorohydrin and the mixture is dissolved in 6 parts of acetone, after which polyethylene glycol and cetyl polyglycol ether are added. The solution thus obtained is sprayed onto kaolin and then the solvent is evaporated off under vacuum.

Wettable powder:

To prepare a) 70% and b) 10% wettable

a) parts of 3- (4'-cyano-2'-chlorophenoxy) -α- (6-chlorophenoxy) propionic acid methyl ester, parts of sodium dibutylnaphthylsulfonate, parts of the condensation product of naphthalene-sulfonic acids, phenolsulfonic acids and f-ormaldehyde (3: 2) 1), parts of kaolin,

- parts of chalk (prov. Champagne);

(b) parts of 3- (2‘-chloro-4‘-cyanophenoxy) -α- (6-chlorophenoxy) propionic acid methyl ester,

parts of a mixture of salt salts of saturated sulfated fatty alcohols, parts of the condensation product of naphthalenesulfonic acids and formaldehyde, parts of kaolin.

The active ingredient is applied to the appropriate carriers (kaolin and chalk) and then the other ingredients are admixed and the mixture is ground. A wettable powder of excellent compatibility and suspensibility is obtained. Suspensions containing from 0.1% to 80% of the active compound which are suitable for controlling weeds in crop plants can be obtained from such powders.

Paste

The following substances are used to prepare 45% paste:

parts of 3- (4'-chloro-2'-cyanophenoxy) -α- (6-chlorophenoxy) propionic acid methyl ester or another of the said active compounds of the formula I, parts of sodium silicate, parts of cetyl glycol ether with 8 moles of ethylene oxide, part oleyl polyglycol ether with 5 molar-1-ethylene oxide, parts of spindle oil, parts of polyethylene glycol, parts of water.

The active ingredient is intimately mixed with the ingredients in devices suitable for this purpose and the mixture is ground. A paste is obtained from which suspensions of any desired concentration can be prepared by dilution with water.

Emulsion concentrate:

To prepare 25% of the emulsion concentrate, the following are mixed together:

parts of 3- (2'-cyano-4'-chlorophenoxy) -α- (6-chlorophenoxy) propionic acid methyl ester or other active ingredient of the formula I, parts of nonylpheno-1-polyoxy-e-thylene and calcium dodecylbenzenesulfuric acid, parts of cyclo -hexanone, parts of xylene.

This concentrate may be diluted with water to emulsions of suitable concentrations, for example from 0.1 d-0-10%. Such emulsions are suitable for controlling weeds in crop plants.

The 3-phenoxy-.alpha.-phenoxyalkanecarboxylic acid N-derivatives as well as the compositions containing them have an excellent selective herbicidal activity against weeds in various crop plants, and have a growth regulating effect. plant.

A particularly preferred field of application is the selective control of, in particular, dicotyledonous weeds in cereal crops and, moreover, of the species Sagittarius and Cyperus in rice. The dihalogenophenoxyalkanecarboxylic acid derivatives, in particular the dihalogeno-phenoxypropioic acid derivatives of the formula I, have proved to be the most effective.

Although the novel active compounds of the formula I are effective in pre-emergence and post-emergence application, p-o-emergence application as contact herbicides seems to be advantageous, although pre-emergence use is also important.

Advantageously, the new active ingredients are formulated, for example, as 25% wettable powders or as 20% emulsifiable concentrates, which are diluted in water and then applied post-emergence to the plant stands.

Herbicidal effect of application of active substances after emergence of r-ills (postemergence)

Various s-e crops and weeds are grown from s-em-en in pots in a greenhouse until they reach a 4-6 leaf stage. Then, the plants are sprayed with aqueous emulsions of the active compound (which were obtained from 20% emulsifiable concentrate) in various doses. The treated plants are then maintained under optimal conditions of light, irrigation, heat (22-25 ° C) and air humidity (5-0-70% relative air humidity). 15 days p-o treatment s-e performs the evaluation of the experiment.

The condition of the plants shall be assessed and expressed on the following scale:

= normal state

1 = - dead plants up to 2 = intermediate

The herbicidal action of a number of active substances according to the invention was compared with the known active substances described in British Patent Specification No. 1,423,006. The application rate of active substance was 4 kg per 1 ha. The active compounds according to the invention are indicated by numbers which correspond to the numbering in the tables.

The following active compounds from the Patent Specification No. 1,423,006 (6 active compounds) served as comparative compounds:

A) Cj

Br compound

C.

• tomatoes

Siinapis Stellaria bab • alba media

AND

(B)

C

D

E

F

9

17

7 5

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2

8 9 4 5

6

4 4 8 8

4

Selective herbicidal effect on rice in post-emergence application

The 25-day-old rice plants are planted in large rectangular bowls of eternit in a greenhouse. Between the rows of rice plants we then sow the seeds of the weeds found in the rice, namely hedgehogs (Echinochloa crus galii), rose hips (Sagittaria pygm.j), broadleaf (Cyperus difformis), Ammania indica, Rotala indica, Elantine triandra and Lindernia The dishes are well watered and kept in a greenhouse at a temperature of about 25 ° C and at a high relative humidity.After 12 days, when the weeds have emerged and reach the 2-3 leaf stage, the soil is covered with a 2.5 cm high layer in the bowl. The active ingredient is then applied in the form of an emulsion concentrate by pipette or in the form of a granulate between rows of plants, the emulsion concentrate being diluted and applied so that the application rate in the field corresponds to 4, 2, 1 and 0.5 kg of active substance per 1 The experiment is evaluated 4 weeks after treatment.

In this test, Compound (1) noticeably damages the weeds: Ammania indica, Rotala indica, Lindernia, Elatine, Cyperus, and Sagittaria. Echinoehloa crus galii has only minor damage to the hedgehog. The rice remains undamaged.

Claims (5)

SUBJECT A herbicidal composition comprising as active ingredient at least one phenoxy-α-femoxyalkanecarboxylic acid derivative of the general formula I in which: B is —OR2 or SR3, Hal is a halogen atom, n is an integer of 0 or 1, R 1 is hydrogen or C 1 -C 2 alkyl, VYNALEZU R2 is hydrogen of an alkali metal or alkaline earth metal cation or copper cation, an alkyl ammonium group having 1 to 4 carbon atoms in the alkyls, R2 and R3 are C1 -C8 alkyl which is unsubstituted or optionally substituted by halogen, cyano, C1 -C4 alkoxy, C3 -C8 alkenyl or alkynyl, C3 -C3 cycloalkyl radicals; a phenyl or benzyl radical which is unsubstituted or substituted by halogen, a C1-C4 alkyl group, a C1-C4 alkoxy group, a nitro group, a cyano group or a trifluoromethyl group. 2. A composition according to claim 1 comprising at least one phenoxy-.alpha.-phenoxypropionic acid derivative of the formula Ia as active ingredient. It is believed that the 3-hydroxy diphenyl ether of formula (II) in which: B and Hal are as defined in formula I in point 1. 3. A composition according to claim 1, wherein the active ingredient is methyl 3- (2 &apos; -cyano-4 &apos; -chlorophenoxy) - [alpha] - (8-chlorophenoxy) propionic acid. 4. A composition according to claim 1, wherein the active ingredient is 3- (2 &apos; -chloro-4 &apos; -cyanophenoxy) - [alpha] - (6-chlorophenoxy) propionic acid methyl ester. 5. A process for the preparation of an active ingredient according to claim 1, wherein: Hal is a halogen atom, n is as defined above, acts with an α-haloalkanecarboxylic acid derivative of the general formula III CH3 Hal — CH — COB (III) wherein B and Hal have the meanings given in formula I in point 1, in the presence of a base.