GB2076805A - Substituted diphenyl ethers having herbicidal activity - Google Patents

Abstract

Substituted diphenyl ethers represented by the formula:- <IMAGE> wherein: A is oxygen or sulfur; X is hydrogen or halogen; Y is halogen or trifluoromethyl; Z is halogen, nitro, or cyano; R is hydrogen or C1-3 alkyl; R<1> is C1-3 alkylidene or monosubstituted C1-3 alkylidene, wherein the substituent is C1-4 alkyl; and R<2> is hydrogen, C1-10 alkyl, C1-10 alkoxy, C3-8 cycloalkyl, or an agronomically acceptable ionic species, are used to control weeds.

Description

SPECIFICATION Substituted diphenyl ethers having herbicidal activity This invention concerns certain substituted diphenyl ethers having herbicidal activity, and the control of weeds therewith.

This invention concerns substituted diphenyl ethers represented by the formula:

wherein: A is oxygen or sulfur; X is hydrogen or halogen; Y is halogen or trifluoromethyl; Z is halogen, nitro, or cyano; R is hydrogen or alkyl containing 1 to 4 carbon atoms; R' is alkylidene or monosubstituted alkylidene containing 1 to 3 carbon atoms, wherein the substituent is alkyl containing 1 to 4 carbon atoms; and R2 is hydrogen, alkyl containing 1 to 10 carbon atoms, cycloalkyl containing 3 to 8 carbon atoms, or an agronomically acceptable ionic species.

Exemplary of halogens represented by X, Y, and Z in the above formula are, for example, bromine, chlorine, or fluorine, preferably bromine or chlorine. Examples of alkyl groups which are represented by R and R2 are methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, t-butyl, n-amyl, hexyl, heptyl, octyl, isooctyl, nonyl and decyl. Exemplary alkylidene radicals represented by R' are, for example, methylidene, ethylidene, or propylidene. Examples of cycloalkyl groups represented by R2 are cyclopentyl, cyclohexyl and cycloheptyl. As examples of agronomically acceptable ionic species represented by R2, there may be mentioned alkali metals e.g. sodium, potassium, or lithium, alkaline earth metals e.g. barium or calcium, ammonium, alkyiammonium containing from 1 to 4 carbon atoms or alkanol ammonium containing from 1 to 4 carbon carbon atoms.

Compounds of the above general formula have herbicidal activity in accordance with this invention. Some specific examples of compounds within the scope of said formula and preferred in accordance with this invention are ethyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate; isopropyl N-[5-(2',4'-dichlorophenoxy)-2-nitro-benzoyl]glycinate; ethyl N-sec-butyl-N-[5-(2',4'dichlorophenoxy)-2-nitro-benzoyl]glycinate; N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycine; ethyl N-[2',4'-dichlorophenoxy)-2-nitrobenzoyl]alaninate; methyl N-[5-(2',4'-dichlorophenoxy)-2nitrobenzoyl]glycinate; ethyl N-[2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]glycinate; secbutyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate; propyl N-[5-(2',4'dichlorophenoxy)-2- nitrobenzoyl]glycinate; n-amyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]-glycinate; ethyl N-[5 (2',4'-dichlorophenoxy)-2-nitrobenzoylj-3-aminopropionate; isopropyl N-[5-(2',4'-dichlorophenoxy)-2nitrobenzoyl]glycinate; N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]glycine; isopropyl N [5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]glycinate; methyl N-[5-(2'-chloro-4'trifluoromethyl)-2-nitrobenzoyl]glycinate; sec-butyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2nitrobenzoyl]glycinate; ethyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl alaninate; ethyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl-3-aminopropionate. Of these exemplary compounds, those having a trifluoromethyl group in the Y- position of the general formula have been found to be especially efficacious.

It is, of course, to be further understood that the stereo and optical isomers of compounds represented by the above formula are within the scope of this invention.

The compounds of this invention are typically synthesized by, for example, reacting an appropriately substituted benzoyl halide with an at least stoichiometric amount of an appropriately substituted amino ester, using techniques known to the art. The substituted benzoyl halides and substituted amino esters may be obtained from commercial sources or prepared by known techniques.

More particularly, an at least stoichiometric amount of substituted benzoyl halide is added, with stirring, to the substituted amino ester preferably in the presence of an acid acceptor, such as, for example, triethylamine, pyridine, or N,N-dimethylaniline. Since the reaction is exothermic, the substituted benzoyl halide is added incrementally so that the temperature of the reaction mixture does not appreciably exceed about 350C. If desired, either or both the substituted benzoyl halide and the substituted amino ester may be dissolved in an inert solvent, such as, for example, benzene, methylene chloride, chloroform, ethyl acetate or tetrahydrofuran. At the completion of addition of the substituted benzoyl halide, the reaction mixture is heated to reflux and maintained at reflux until the reaction reaches the desired degree of completion.The reaction mixture is then cooled to ambient temperature and washed consecutively with dilute mineral acid, dilute caustic soda and water, and allowed to phase separate.

Substituted diphenyl ether may be recovered from the organic phase by any known technique, such as, for example, evaporation, crystallization or vacuum drying. If desired, the product, substituted diphenyl ether, may be further purified by, for example, recrystallization.

The following Examples I to IX are illustrative of the synthesis of certain specific substituted diphenyl ether compounds of this invention.

EXAMPLE I Ethyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate A 1 00 milliliter flask equipped with an addition funnel, reflux condenser, and magnetic stirring bar was charged with a solution of 1.03 grams (0.01 mole) of glycine ethyl ester and 1.01 grams (0.01 mole) of triethylamine in 25 milliliters of benzene. The solution was stirred at ambient temperature, and a solution of 3.450 grams (0.01 mole) of 5-(2',4'-dichlorophenoxy)-2-nitrobenzyl chloride in 25 milliliters of benzene was added dropwise and exotherm heating was observed. Upon completion of the addition, the mixture was stirred at room temperature for two hours and heated to reflux and maintained for two hours and then cooled to room temperature.The mixture was transferred to a separatory funnel, and washed separately with thirty milliliters each of 1 Normal hydrochloric acid, water, 1 Normal sodium hydroxide, and water, respectively. The organic layer was dried over magnesium sulfate and was concentrated on a rotary evaporator at 55cm. to a rust colored solid containing ethyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate. The solid was recrystallized from a minimum amount of benzene:ligroin (30:70 vol/vol) to yield a tan crystalline solid comprised of ethyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyljglycinate (yield 72%) with a melting point of 1 10--1 120C and a mass spectra showing a molecular weight of 412, with fragments at 412, 310, and 236.

EXAMPLE II Methyl N-[5-(2' ,4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate A 100 milliliter three-necked flask equipped with a reflux condenser, an addition funnel, and a magnetic stir bar was charged with a solution of 0.89 grams (0.01 mole) of glycine methyl ester, and 1.0 grams (0.01 mole) of triethylamine in 30 milliliters of tetrahydrofuran. While the solution was stirred at ambient temperature, a solution of 3.45 grams (0.01 mole) of 5-(2',4'-dichlorophenoxy)-2- nitrobenzoyl chloride in 20 milliliters of tetrahydrofuran was added dropwise, and an exothermal heating was observed. Upon completion of the addition, the mixture was heated to reflux while stirring for 2.5 hours, cooled to room temperature, and then transferred to a separatory funnel.It was then diluted with 50 milliliters of ethyl acetate and washed separately with 30 milliliters of 1 Normal hydrochloric acid, 30 milliliters of 1 Normal sodium hydroxide, and 30 milliliters of water, respectively. The organic layer was drained off, dried over magnesium sulfate, and then concentrated on a rotary evaporator at 550C.

to a yellow syrup which crystallized on standing. The crystallized yellow material was then recrystallized from 3 solution of benzene and ligroin (30:70 vol/voi) to yield a fluffy tan solid comprised of methyl N [5-(2',4'-dichlorophenoxy)-2-nitrobenzoyljglycinate which had a melting point of 1 33-1 350C., with a mass spectra showing a molecular weight of 398. 2.5 grams of material corresponding to a yield of 63 percent was obtained.

EXAMPLE Ill Sec-Butyl N-[5-(2',4'-dichlorophenoxy-2-nitrobenzoyl]glycinate 2.06 grams (0.005 mole) of ethyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate (prepared in Example I) was placed in a 100 milliliter flask equipped with a reflux condenser and magnetic stirring bar, and then 0.4 gram (0.01 mole) of sodium hydroxide in 20 milliliters of water was added. The slurry was stirred and heated to reflux until all of the solid dissolved (about 50 minutes) and then for an additional 10 minutes. The solution was cooled and 20 milliliters of 10 percent hydrochloric acid solution were added. A sticky solid formed. The mass was diluted with 50 milliliters of water and extracted twice with 50 milliliters of ethyl acetate. The extracts were combined, washed with water, and then dried over magnesium sulfate.The solvent was removed by a rotary evaporator at 550C. and a light brown syrup of N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycine, which had a mass spectra showing a molecular weight of 384, with fragments of 384 and 310, was obtained.

A solution of 3.84 grams of N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glYcine (prepared as described above) and 0.35 grams of phenolsulfonic acid in 50 milliliters of sec-butanol were added to a 100 milliliter flask which was attached to a Dean-Stark receiver and equipped with a magnetic stirring bar. The solution was stirred and refluxed while the water was azeotropically removed. After about 26 hours of refluxing the solution was cooled and the sec-butanol was removed by a rotary evaporator at 550C. The residue was dissolved in 50 milliliters of methylene chloride and the solution was washed twice with 30 milliliters of 1 Normal sodium hydroxide and once with 30 milliliters of water. The organic layer was then dried over magnesium sulfate, and concentrated on a rotary evaporator at 550C.A light red oil formed which then crystallized upon standing to form a crude product comprised of sec-butyl N 15-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate. The crude product was recrystallized from a minimum amount of hot solvent mixture of ethyl acetate and ligroin (25:75 vol/vol) to form a white solid comprised of sec-butyl N-[5-(2',4', dichlorophenoxy)-2-nitrobenzoyl]glycinate with a molecular weight of 440 as determined by a mass spectography with fragments at 440, 367, and 310.

EXAMPLE IV Isopropyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate A solution of 3.84 grams of N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycine (prepared as in Example lll and 0.35 grams of phenolsulfonic acid in 50 milliliters of isopropanol were added to a 100 milliliter flask which was equipped with a Dean Stark receiver, reflux condenser and a magnetic stirring bar. The solution was brought to reflux and the water was removed azeotropically. After about 26 hours of refluxing, the solution was cooled and the sec-butanol was removed by a rotary evaporator at 550C.

leaving a sticky solid. The solid was dissolved in 50 milliliters of ethyl acetate and the solution was washed with about 30 milliliters of 1 Normal sodium hydroxide and then with 30 milliliters of water.

The organic layer was then dried over magnesium sulfate, and concentrated on a rotary evaporator at 550C. to an off-white colored solid. The solid was recrystallized from a minimum amount of hot solvent mixture of ethyl acetate and ligroin (25:75 vol/vol) to a white powder (3.1 grams, 73% yield) comprised of isopropyl N-[5-(2',4'-dichlorophenoxy)-2-nitrobenzoyl]glycinate with a molecular weight of 426 as determined by mass spectrography with fragments at 426, 367, and 310, and a melting point of 99-1 000C.

EXAMPLE V Ethyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]glycinate The procedure of Example I was followed except that an equivalent amount of 5-(2'-chloro4'-trifluoromethylphenoxy)-2-nitrobenzoyl chloride was used in place of 5-(2',4'-dichlorophenoxy)-2nitrobenzoyl chloride to yield ethyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]glycinate.

EXAMPLE VI Ethyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]alaninate A 100 milliliter, 3-necked flask, equipped with an addition funnel, a reflux condenser, and a magnetic stirring bar, was charged with 1.4 grams (0.012 mole) of alanine ethyl ester and 1.1 grams (0.01 mole) of triethylamine in 30 milliliters of benzene. To the stirred solution, at ambient temperature (approximately 200 C), was added dropwise 3.79 grams (0.01 mole) of 5-(2'-chloro-4'trifluoromethylphenoxy)-2-nitrobenzoyl chloride in 20 milliliters of benzene. (The reaction mixture showed an exotherm). After the addition was complete, the mixture was refluxed for 6 hours, cooled and then transferred to a separatory funnel.It was then washed, separately with 30 milliliters each of 1 Normal hydrochloric acid, water, 1 Normal sodium hydroxide, and water, respectively. The organic phase was then dried over anhydrous magnesium sulfate and concentrated on a rotary evaporator at 550C. leaving 3.8 grams of a clear yellow oil comprised of ethyl N-[5-(2'-chloro-4' trifluoromethylphenoxy)-2-nitrobenzoylj-alaninate with a NMR (acetone, d6) 7.1-8.3 (multiplet, 7H); 4.55S (quartet, 1 H); 4.158 (quartet, 2H); 1 .258 (multiplet, 6H).

The yellow oil crystallized upon standing, and the crystals had a melting point of 98-1 000C.

EXAMPLE VII Ethyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]-3-aminopropionate A 100 milliliter, 3-necked flask, equipped with an addition funnel, a reflux condenser, and a magnetic stirring bar, was charged with 1.4 grams (0.012 mole) of ss-alanine ethyl ester and 1.1 grams (0.01 mole) of triethylamine in 30 milliliters of benzene. To the stirred solution, at ambient temperature (approximately 200C.), was added dropwise, 3.79 grams (0.01 mole) of 2'-chloro-4'trifluoromethylphenoxy-2-nitrobenzoyi chloride in 20 milliliters of benzene. (The reaction mixture showed an exotherm.) After the addition was complete, the mixture was refluxed for 6 hours, cooled and then transferred to a separatory funnel.It was then washed separately with 30 milliliters each of 1 Normal hydrochloric acid, water, 1 Normal sodium hydroxide, and water respectively. The organic phase was then dried over anhydrous magnesium sulfate and was then concentrated on a rotary evaporator at 550C. leaving 3.7 grams of a clear yellow oil comprised of ethyl N-[5-(2'-chloro-4' trifluoromethylphenoxy)-2-nitrobenzoyl]-3-aminopropionate with a NMR (acetone, d) 7.1-8.28 (multiplet, 7H); 4.0S (quartet, 2H); 4.568 (quartet, 2H); 3.62 (triplet, 2H); 1.286 (triplet, 3H) EXAM P LE Vl l l Sec-butyl N-[5-(2'-ch loro-4'-triflu oromethyl phenoxy)-2-nitrobenzoyl] glycinate The glycinate prepared in Example V was hydrolyzed and esterified following the procedure described in Example Ill to yield a sec-butyl N-[5-(2'-chloro-4'-trifl uoromethylphenoxy)-2- nitrobenzoyl]glycinate.

EXAMPLE IX Isopropyl N-[5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl]glycinate The glycinate prepared in Example V was hydrolyzed and esterified with isopropyl alcohol following the procedure described in Example Ill to yield isopropyl N-[5-(2'-chloro-4'- trifluoromethylphenoxy)-2-nitrobenzoyl]glycinate.

Although the mode of synthesis of the compounds of this invention has been illustrated in some detail by the foregoing Examples I to IX, it is to be understood that any compound contemplated to be within the scope of this invention may be prepared by those skilled in the art simply by varying the choice of starting materials and using the illustrated techniques or any other suitable techniques.

The compounds of this invention have been found effective in regulating the growth of a variety of undesirable plants, i.e. weeds, when applied, in an herbicidally effective amount, to the growth medium prior to emergence of the weeds or to the weeds subsequent to emergence from the growth medium.

The term "herbicidally effective amount" is that amount of compound or mixtured of compounds required to so injure or damage weeds such that the weeds are incapable of recovering following application. The quantity of a particular compound or mixture of compounds applied in order to exhibit a satisfactory herbicidal effect may vary over a wide range and depends on a variety of factors such as, for example, hardiness of a particular weed species, extent of weed infestation, climatic conditions, soil conditions or method of application. Typically, as little as 0.2 or less pound per acre to 10 or more pounds per acre of compound or mixtures of compounds may be required. Of course, the efficacy of a particular compound against a particular weed species may readily be determined by relatively straightforward laboratory or field testing in a manner well known to the art.

The compounds of this invention may be used as such or in formulation with agronomically acceptable adjuvants, inert carriers, other herbicides, or other commonly used agricultural compounds, for example, pesticides, stabilizers, safeners or fertilizers. The compounds of this invention, whether or not in formulation with other agronomically acceptable materials, are typically applied in the form of dusts, granules, wettable powders, solutions, suspensions, aerosols, emulsions, dispersions or the like in a manner well known to the art. When formulated with other typically used agronomically acceptable materials, the amount of compound or compounds of this invention present in the formulation may vary over a wide range, for example, from about 0.05 to about 95 percent by weight on weight of formulation.Typically such formulations will contain from about 5 to about 75 percent by weight of compound or compounds of this invention.

The compounds of this invention have been found effective in controlling a variety of broadleaf and grassy weeds at application rates of two (2) pounds per acre or less pre- or postemergence while not significantly damaging desirable crops such as, for example, corn, wheat, rice, and soybeans.

Exemplary of weeds that may be effectively controlled by the application of compounds of this invention are wild mustard (Brassica saber); yellow foxtail (Setaria glauca); crabgrass (Digitari sanguinalis); coffeeweed (Sesbania spp.); velvet leaf (Abutilon theophrasti); johnsongrass (Sorghum halepense); barnyardgrass (Echinochloa crusgalli); jimsonweed (Datura stramonium); teaweed (Sida spinosa); and tall morning glory (Roth).

Certain of the compounds prepared according to Examples I to IX were tested for herbicidal activity against certain weed species under controlled laboratory conditions of light, temperature, and humidity. Seeds of selected weeds were planted in flats i.e. shallow containers. For pre-emergence tests, the flats were treated with the selected compound immediately after planting. For postemergence tests, the flats were treated with the selected compound after a two-week germination period. The compound was applied to the flats by spraying a solvent solution of the compound at the indicated rate of application, the state of growth of the weeds was observed, and the toxic effect of the compound was evaluated periodically after application. The following shows in tabular form the weed species (identified by common name), the compound applied (identified by reference to the Example in which it was prepared) to the weed species, the rate of application of the compound (in pounds per acre), and whether the application was pre- or postemergent.

Weed Compound I V Vl VI VII VII Johnsongrass X X X X X Jimsonweed X X X X X X Wild mustard X X X X X Bamyardgrass X X X X Coffeeweed X X X X X X Velvetleaf X X X X X X Tall morningglory X X X X X X X Yellow foxtail X X X X Large crabgrass X X X Teaweed X X X X Cockleburr = X Application Rate 10 10 2 2 2 2 -emergence Pre Pre Post Pre Post Pre

In each of the foregoing tests, it was observed that all of the various weeds were either killed or injured beyond recovery within 20 to 24 days after application of the particular compound.

Claims (16)

1. A compound represented by the formula:

wherein: A is oxygen or sulfur; X is hydrogen or halogen; Y is halogen ortrifluoromethyl; Z is halogen, nitro, or cyano; R is hydrogen or alkyl containing up to 3 carbon atoms; R' is alkylidene or monosubstituted alkylidene containing up to 3 carbon atoms, wherein the substituent is alkyl of up to 4 carbon atoms; and R2 is hydrogen, alkyl containing up to 10 carbon atoms, cycloalkyl containing from 3 to 8 carbon atoms, or an agronomically acceptable ionic species.

2. A compound according to claim 1 wherein Z is halogen or cyano.

3. A compound according to claim 2 wherein Z is chlorine or bromine.

4. A compound according to claim 1,2 or 3 wherein R is alkyl containing up to 3 carbon atoms.

5. A compound according to claim 1 , 2, 3 or 4 wherein R' is alkylidene containing 2 or 3 carbon atoms or monosubstituted alkylidene containing up to 3 carbon atoms wherein the substituent is alkyl of up to 4 carbon atoms.

6. A compound according to claim 1, 2, 3, 4 or 5 wherein R2 is hydrogen, alkyl containing from 5 to 10 carbon atoms, cycloalkyl containing from 3 to 8 carbon atoms or an agronomically acceptable ionic species, or an agronomically acceptable ionic species.

7. A compound according to claim 6 wherein R2 is an agronomically acceptable ionic species selected from alkali metals, alkaline earth metals, ammonium, alkylammonium containing up to 4 carbon atoms and alkanolammonium containing up to 4 carbon atoms.

8. A compound according to any of claims 1 to 5 wherein R2 is alkyl containing up to 4 carbon atoms.

9. A compound according to any of claims 1 to 8 wherein Y is trifluoromethyl, chlorine or bromine.

10. A compound according to any of claims 1 or 3 to 9 wherein Z is nitro.

11. A compound according to claim 1 selected from ethyl N- 5-(2',4'-dichlorophenoxy)-2nitrobenzoyl glycinate; ethyl N- 5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl glycinate; N- 5 (2',4'-dichlorophenoxy)-2-nitrobenzoyl glycine; N- 5-(2'-dichloro-4'-trifluoromethylphenoxy)-2- nitrobenzoyl glycine; isopropyl N- 5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl glycinate; methyl N- 5-(2'-chloro-4'-trifluoromethylphenoxy)-2-nitrobenzoyl glycinate; sec-butyl N- 5-(2'-chloro4'-trifluoromethylphenoxy)-2-nitrobenzoyl glycinate; ethyl N- 5-(2'-chloro-4'-trifluoromethylphenoxy)2-nitrobenzoyl alaninate; or ethyl N- 5-(2'-chloro-4'-trifl uoromethylphenoxy)-2-nitrobenzoyl-3aminopropionate.

12. A compound of the general formula given in claim 1 substantially as herein described with reference to and as illustrated in any of Examples 1 to 9.

13. A herbicidal composition containing a herbicidally effective amount of a compound according to any of claims 1 to 12 or of a mixture thereof and an agronomically acceptable material.

14. A method of controlling weed growth wherein a herbicidally effective amount of at least one compound as claimed in any of claims 1 to 12 is either applied to the growth medium prior to emergence of the weeds or applied to the weeds subsequent to emergence from the growth medium.

15. A method as claimed in claim 14 wherein the compound is used in a formulation containing an agronomically acceptable material.

16. A method as claimed in claim 1 5 wherein the formulation contains from about 5 to about 75 percent by weight of the compound.