DE3029728C2 - Substituted diphenyl ethers and herbicidal compositions containing them - Google Patents

Description

A is halogen or cyan,

X is hydrogen or halogen,

Y is hydrogen, halogen, cyano, trifluoromethyl or alkyl with 1 to 4 carbon atoms,

Z is oxygen or sulfur,

R is an alkylene or monosubstituted alkylene radical with 1 to 3 carbon atoms, where the substituent Is alkyl, oxoalkyl or hydroxyalkyl of 1 to 4 carbon atoms, and

R ¹ is hydrogen or alkyl with 1 to 10 carbon atoms, cycloalkyl with 3 to 8 carbon atoms, an ionic group, phenyl or mono-, di- or trisubstituted phenyl, where the substituents are halogen, alkyl or alkoxy with 1 to 10 carbon atoms, cyano, Are nitro or trifluoromethyl.

2. Herbicidal composition, characterized in that it contains a herbicidally effective amount of a A compound or a mixture of compounds according to claim 1 and an agriculturally acceptable one Contains additive.

The invention relates to new substituted diphenyl ethers and herbicidal compositions containing these substituted diphenyl ethers.
The invention relates to substituted diphenyl ethers of the general formula

C-O-R-C-Z-R

where the general symbols in this formula have the following meanings:

A is halogen or cyan,
X is hydrogen or halogen,

Y is hydrogen, halogen, cyano, trilluomethyl or alkyl with 1 to 4 carbon atoms,
Z is oxygen or sulfur,
R is an alkylene or monosubstituted alkylene radical having 1 to 3 carbon atoms, the substituent being alkyl, oxoalkyl or hydroxyalkyl having 1 to 4 carbon atoms, and

R ¹ is hydrogen or alkyl with 1 to 10 carbon atoms, cycloalkyl with 3 to 8 carbon atoms, an ionic group, phenyl or mono-, di- or trisubstituted phenyl, where the substituents are halogen,

Are alkyl or alkoxy of 1 to 10 carbon atoms, cyano, nitro or trifluoromethyl.
These substituted diphenyl ethers are obtained by

a) a correspondingly substituted benzoyihalide, in particular benzoyl chloride, is reacted with a correspondingly _ω- substituted alcohol or a correspondingly substituted alpha-hydroxycarboxylic acid ester

or

b) an appropriately substituted benzoic acid with an appropriately substituted alpha-halocarboxylic acid ester implements.

From the formula of the substituted diphenyl ethers, the person skilled in the art can readily recognize which substituents are the benzoyl halides or benzoic acid, the left part of the formula with the diphenyl radicals contribute, and what substituents the alcohols. alpha-hydroxycarboxylic acid ester or alpha-halocarboxylic acid ester, which form the right part of the formula must have, in order to obtain the desired substituted Diphenyl ethers to come.

Examples of halogens which come in the general formula of the substituted diphenyl ether into consideration are bromine, chlorine, iodine or fluorine, with bromine and (hlor are preferred. Some examples fin alkyl and cycloalkyl for R ¹ in this formula are methyl, ethyl , Isobutyl, η-butyl, t-butyl, n-amyl, heptyl, octyl, iso-octyl, nonyl, decyl, cyclopropyl, cyclopentyl, cyclohexyl and cyclooctyl. Examples of suitable alkyl groups are methylene, ethylene and propylene. The ionic groups should preferably agriculturally acceptable and alkali ions such as N, potassium or lithium, alkali metal ions such as barium or calcium, ammonium ions or alkylammonium or alkynolammonium ions with 1 to 4 carbon atoms are mentioned as examples.

Preferred compounds in the invention are those in which Z is oxygen, R ^{1 is} alkyl of up to 4 carbon atoms, X is hydrogen and Y is halogen.

The compounds according to the invention are distinguished by a herbicidal activity. Some specific examples of preferred compounds are: l '- (ethoxycarbonyl) ithyl-S- (2-chloro-4-tri (chloromethylphenoxy> 2-bromobenzoate, 1' - {ethoxycarbonyl) ethyI-5- {2-chloro-4- trifluonethylphenoxy> -2-cyanobenzoate and l '- (EthoxycarbonyI) ethyl 5- (2-chloro-6-bromo-4-trifluoromethylphenoxy) -2-cyano benzoate.

Of course, the substituted diphenyl ethers according to the formula given above also include the stereo and optical isomers which can be considered.

To prepare the substituted diphenyl ethers, appropriately substituted benzoyl halides can be reacted with an alcohol or an appropriately substituted alpha-hydroxycarboxylic acid ester or an appropriately substituted benzoic acid with an appropriately substituted alpha-halocarboxylic acid ester according to processes known in principle. The substituted benzoyl halides or benzoic acids and the substituted alpha-hydroxy or alpha-halogenated carboxylic acid esters are commercially available or can be prepared by known procedures. It is advantageous to add at least a stoichiometric amount of a substituted benzoyl halide to the substituted alpha-hydroxycarboxylic acid ester with stirring. This reaction is preferably carried out in the presence of an acid acceptor of an organic amine, e.g. B. triethylamine, pyridine or Ν, Ν-dimethylaniline. Since the reaction proceeds with evolution of heat, it is advantageous to add the substituted benzoyl halide in proportions such that the reaction mixture does not substantially exceed a temperature of about ⁰ C 3S. If the substituted diphenyl ethers are prepared by reacting rather substituted benzoic acid with an alpha-halocarboxylic acid ester, the ester is preferably in the presence of an azo compound, such as. B.!, S-Diazobicyclo-iSAOO-undec-S-en (DBU). In each embodiment of the synthesis can be carried out in the presence of an inert solvent, such as. B. in the presence of inert organic solvents such as benzene, methylene chloride, chloroform, ethyl acetate or tetrahydrofuran. When the addition of the substituted benzoyl halide to the alpha-hydroxycarboxylic acid ester is complete (or when the addition of the alpha-halocarboxylic acid ester to the substituted benzoic acid is complete), the reaction mixture is refluxed and kept boiling until the desired degree of conversion is achieved. The reaction mixture is then cooled to ambient temperature and is usually washed sequentially with dilute acid, dilute base and water, allowing phases to separate. The substituted diphenyl ether is isolated from the organic phase by known procedures, such as. B. by evaporation, crystallization or drying in vacuo. If desired, the substituted diphenyl ether can be further purified, e.g. B. by recrystallization.

The invention is explained in more detail in the following example.

example r- (ethoxycarbonyl) ethyl 5- (2-chloro-4-trifluoromethylphenoxy) -2-bromobenzoate

A 100 ml three-necked flask equipped with an addition funnel, reflux condenser, and magnetic stir bar was charged with 1.18 g (0.01 mol) of ethyl lactate and 0.79 g (0.01 mol) of pyridine in 50 ml of methylene chloride. Were added at room temperature (about 2O ⁰ C) added dropwise with stirring 2.07 g (0.005 mole) of 5- (2-chloro-4-trifluoromethylphenoxy) -2-bromobenzoyl chloride in 10 ml of methylene chloride to this solution. An exothermic reaction was observed. After the addition was complete, the reaction mixture was heated to the boil with reflux cooling and kept at the boil for 66 hours. The reaction mixture was then cooled, transferred to a separatory funnel, and washed successively with 30 ml portions of 1N hydrochloric acid, water, 7% aqueous ammonium hydroxide, and water. The washed organic phase was dried over magnesium sulfate and concentrated on a rotary evaporator at 55 ° C. 2.2 g of a viscous yellow syrupy liquid were obtained which was identified as l '- (ethoxycarbonyl) ethyl 5- (2-chloro-4-trifluoromethylphenoxy) -2-bromobenzoate. The data for the nuclear magnetic resonance were as follows:

NMR (acetone D ₆ ) 7.0-8.0 <J (multiples, 6 H);

5.25 δ (Quartet, 1H);

4.18 δ (Doublet, 3H);

1.68 (5 (doublet, 3H);

1.18 (5 (triplet, 6H).

The substituted diphenyl ether of the invention are effective agents for regulating the growth of a number of unwanted plants, especially weeds, if ü-active herbicide in Men) in the growth medium before the weeds germinate or the weeds after they germinate.

f? be practiced. The term "herbicidally effective amount" denotes that amount of a compound or

a mixture of compounds which is necessary to damage the weeds in such a way that they after the Using the above remedy cannot recover. The amount of a specific compound or a specific mixture of different compounds that is required to produce a satisfactory one Producing herbicidal effects can vary widely and depends on a large number of factors from, such as B. Persistence of the particular weed species, degree of infestation by the weeds, climatic conditions, Soil conditions and method of application of the herbicide. Usually 0.22 to 11 kg of the herbicidal compound or the mixture of herbicidal compounds are required per hectare. In individual cases Depending on the effectiveness of the particular compound, the effective amount can be determined as well determine in a known manner.

The compounds according to the invention can be used as such or in formulations with agriculturally acceptable Additives are used. Examples of such additives are inert carriers, other herbicides or compounds commonly used in agriculture such as pesticides, stabilizers and fertilizers. Typically, the compounds are used as such or in formulations in dust form or in the form of granules, wettable powders, solutions, suspensions, aerosols, emulsions and dispersions applied. When the compounds according to the invention with other agriculturally permissible additives are formulated, the proportion of the compounds or mixtures of the compounds according to the invention in such formulations vary within a wide range, e.g. B. between 0.05 to 95 wt .-% of the Formulation, with 5 to 75% by weight being preferred.

The compounds of the invention have been found to control the growth of a variety of broadleaf or grassy weeds at a dosage of 2.2 kg per hectare or less both before also proven after the weeds have germinated, whereby agriculturally desirable plants such as maize, Wheat, rice and soybeans are not harmed. Examples of weeds whose growth is caused by the Compounds that can be controlled according to the invention are: Brassica kaber, Setana glauca, Digitaria sanguinalis, Sesbania spp., Abutilon theophrasti, Sorghum halepense, Echinochloa crusgalli, Datura stramonium, Sida spinosa and Ipomea prupurea (Roth).

The compound, which was prepared according to the example, was opposed to its herbicidal activity certain weed species under controlled laboratory conditions of light, temperature and humidity checked. Selected seeds of such weeds were planted in shallow trays. For the exam before After germination, the flat dishes were treated with the compound immediately after planting. For the exam after germination, the flat dishes were treated with the compound 2 weeks after the germination period. The compound was sprayed onto the flat shells as a solution in the specified concentration. It the state of the growth of the weeds was observed and the toxic effect of the compound was assessed in Intervals after their application.

The following weeds were treated before germination at a dosage of 2.2 kg per hectare:
35

Datura stramonium
Brassica kaber
Setaria glauca and
Digitaria sanguinalis.

All tests showed that within 21 to 22 days of application the weed either destroyed or so badly damaged that it could no longer recover.

In a further series of tests, the following weed species were found with the compound after germination of the example:

Datura stramonium
Brassica kaber
Setaria glauca and
Sesbania spp.
50

It was observed that in each of these tests the weeds were removed within 21 to 22 days of the Use of the herbicide was either destroyed or damaged so badly that it did not recover. In addition, it was found that if the substituent "A" is halogen and especially bromine, as in the example, slightly better herbicidal effectiveness when applied after germination than when applied before germination is present when the dosage is below about 5.5 kg per hectare, e.g. B. at 2.2 kg per hectare or lower.

Comparative experiment

There were a diphenyl ether according to the invention and a known structurally similar diphenyl ether in their herbicidal effectiveness compared.

These are the following compounds r- (thoxycarbonyl) ethyl 5- (2-chloro-4-tritluoromethylphenoxy) -2-bromobenzoate the formula

COOCH (CHj) COOC ₂ H ₅

-Br

(Invention)

and sec-butyl 5- (2-chloro-4-trifluoromethylphenoxy) -2-nitrobenzoate of the formula io

COOCH (CH ₃ ) C ₂ Hs

NO,

(Comparison substance)

These compounds have been tested on a variety of weed species after germination. The well-known Compound was used at a dosage of 0.28 kg / ha and the compound according to the invention at half Dosage, d. H. applied at 0.14 kg / ha. The herbicidal effectiveness was according to the known compound Judged 22 days after application and in the case of the compound according to the invention after 19 days Use. For the evaluation of the herbicidal effectiveness, a scale was used in which O was not effective tenacity and 10 highest effectiveness (all weeds killed). The results are compiled in the table below.

Weed species invention comparative ³ O

substance

Sida spinosa 7 4 Datura stramonium 8 9 _3S Brassica kaber 8 7 Sesbania spp. 8 7 Abutilon theophrasti 10 10

ipomoea purpurea 8 6

As can be seen from this comparison, the compound according to the invention is so superior to the known compound that it shows the same effectiveness even at half the dosage and with some types of weeds even a higher one.

Claims (1)

Patent claims: 1. Substituted diphenyl ethers according to the general formula O O Il Il XC-O-R-C-Z-R ¹ in which the general symbols have the following meanings: