CA1039076A - Herbicidal compounds - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Herbicidal compositions containing as active ingredient a compound selected from the group consisting of 4-[4'-chlorophenoxy]-a-phenoxypropionic acid, 4-[2',4'-dichlorophenoxy]-.alpha.-phenoxypropionic acid, 4-[2',4'-dichlorophenoxy]-.alpha.-phenoxypropionic acid 2-methyl-n-propyl ester, 4-[2',4'-dichlorophenoxy]-.alpha.-phenoxypropionic acid isopropyl ester, 4-[4'-iodophenoxy]-.alpha.-phenoxypropionic acid 4-[4'-bromophenoxy]-.alpha.-phenoxypropionic acid in form of their racemic mixtures in combination with a herbicidally acceptable carrier, and methods for control-ling or eradicating weed grasses in crop plants.

Description

37~j The present application is a divisional of our copending Canadian Pate~t Application Serial No. 171,539, filed May 16~ 1973.
The present inYention relates to herbicidal compositions~
In Ge~man Offenlegungsschrift 1,668,896 (Applicant:
Hoechst AG) Published April 13, 1972 optionally substituted 4-phenoxy-phenoxy-alkane_carboxylic acids and dèriva~ives thereof are disclosed and their action on the lipide and cholesterin metab-olism is described. Compounds of the aforesaid class are also the object of German OffeI~legungsschrift 2,136,828 (Applicant: Hoechst AG) Published February 8, 1973.
It has surprisingl~ been found that several compounds expressly described in the above patents also exhibit an excellent selective herbicidal effect against weed grasses in crop plants.
Thus, the present invention therefore provides herbicidal compositions containing as active ingredient a compound selected from the group consisting of:
1) 4-[4-chlorophenoxy]-a-phenoxypropionic acid,

2) 4-[2t,4t-dichlorophenoxy]~-phenoxypropionic acid,

3) 4-~2~4~-dichlorophenoxy]~-phenoxypropionic acid 2-methyl-n-propyl ester

4) 4-[2',4~-dichlorophenoxy]~-phenoxypropionic acid isopropyl ester~

5) 4-[4'-iodophenoxy]~-phenoxypropionic acid,

6) 4-[4~-bromophenoxy]~-phenoxypropionic acid, in forrn of .. ...
their racemic mixtures~ in combination with a herbicidally acceptable carrier.
The compositions according to the invention are selective in the pre-emergence as well as in the post-emergence process against weed grasses7 even if used in high amounts, while broad 2 - ~;~

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leaved weeds are damaged to a small extent only. This special action on grasses contrasts with the action of chemically related growth-promoting compounds of the phenoxy-alkane-carbox~lic acid series (for example 2,4-dichlorophenoxy-acetic acid (2,4-D) and 2,4-dichlcrophenoxy-propionic acid (2,4-DP), the principal effect of which is the destruction of broad-leaved weeds. Simultaneously the novel compositions do no harm to dicotyledonous (broad-leaved) crop plants.
Surprisingly, the compositions according to the invention do not damage crop grasses such as rice, barley, oat and wheat.
Hence, the novel compositions can be used to combat weed grasses in cereals~ i.eO crop grasses, which has been very difficult so far.
Moreover, weed grasses can be efficiently controlled in dicotyledon-ous crop plants, for example in sugar beet, leguminosae, celery, clover, lucerne, melon, cucumber, and tobacco.
Owing to this special action against weed grasses, above all foxtail grass, bent and the like, the novel compositions are superior to a number of known herbicides such as alachlor, monolin-uron, linuron, pyrazon, phenmedipham, sodium trichloroacetate, and prynachlor, when applied in fields strongly infested with weed grasses. Moreover, the amounts necessary for a complete destruction of the weed grasses are much smaller than with the above known herbicides. The amounts may vary within wide limits, for example, in the range of from 0 1 to 10 kg of active ingredient per hectare~
preferably 0.2 to 5 kg per hectare.
The compounds used according to this invention and the compositions containing them have a low toxicity agains* warm-blooded animals.

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~LV396~76 The compounds contained in the herbicidal compositions of the invention are obtained by known methods as described in the German Offenlegungsschrifts mentioned above.
Hence, they may be conveniently prepared by reaction of the appropriate halogen-substituted phenol with an ~-halogeno-propionic acid or an appropriate ester thereof.
The compositions according to the invention contain the active ingredients generally in an amount of from 2 to 95% by weight. They can be used in the form of wettable powders, emul-sifiable concentra~es, sprayable solutions, dusts, or granules, in admixture with the usual formulation auxiliaries.
Wettable powders are preparations that can be uniformly dispersed in water, and contain, besides the active ingredient, a diluent or an inert substance, a wetting agent, for example, poly-oxethylated alkylphenols, polyoxethylated oleyl_ or stearyl-amines alkyl- or alkylphenyl sulfonates, and dispersing agents, for example the sodium salts of lignin-sulfonic acid, 2,2t-dinaphthyl-methane-6,6~-disulfonic acid, dibutyl-sulfonic acid or oleylmethyl-taurine.
Emulsion concentrates are obtained by dissolving the active ingredient in an organic solvent, for example butanol, cyclohexanone, dimethylformamide, xylene, or aromatic hydro-carbons havingahigher boiling point. To obtain suspensions or emulsions in water having good properties, wetting agents as specified above are also added.
Dusting powders are obtained by grinding the active ingredient with finely divided, solid substances, for example talc, natural clays such as kaolin, bentonite, pyrophillite, or diatomace-ous earths.

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Spraying solutions commercially available as aerosol sprays contain the active ingredient dissolved in an organic solvent~ and in addition thereto a propellantj for example a mixture of fluorochlorohydrocarbons.
Granules can be produced by atomizing the active in-gredient on to an adsorptive, granulated inert material, or by applying concentrates of the active ingredient to the surface of a support, for example, sand, kaolinite or a granulated inert material, with the aid of an adhesive~ for example poly-vinyl alcohol, the sodium salt of polyacrylic acid, or mineral oils. Alternatively, suitable active ingredients may be made into granules, if desired in admixture with fertilizers, in the manner commonly used for the manufacture of granulated fertilizers.
The commercial herbicidal preparations contain varying concentrations of the active ingredients. In wettable powders the concentration of active ingredient varies, for example, from about 10 to 95 %~ the remainder being the above formula-tion additives. Emulsion concentrates contain about 10 to 80 %
of active ingredient, while dusting powders mostly contain 5 to 20 ~ of active ingredient and sprayable solutions about 2 to 20 %. In the case of granules, the content of active ingredient partially depends on whether the active ingredient is liquid or solid and on the type of granulation auxiliary or filler used.
For application the commercial concentrates are option-ally diluted in usual manner, the wettable powder or emulsifiable co~centrate~ for example with water. Dusts and granulated formulations as well as sprayable solutions are not dilu~ed further with an inert substance before their application. The , ,, . . - . . .. ~ , .. . .

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~5 ~mount appl~ed varies with th~ external conditions, such as temp~r2ture, humidity and the like. In general, about 0.015 to 0~25 gra~ and preferably about 0.03 to 0.12 gram of acti~e ingredient per ~quare meter are used.
29 The her~icides according to the present ~n~ention may be com~ined wit~ other herblcides and soil insecticides.
, ~en the acti~e ingredients according to the invention , are mixed with fertili~ers, preparations are obtained which simultaneously ha~e a fertilizing and a herbicidal effect.
' ~ormul2tion examples E x a ~ p ~_~ A -A wettable powder which is readily dispersible in water can be obtained by m~xing . --5 par~s by weight of 4~ chlorophenoxy)-~-phenoxy-. propionic acid as active ingredients 64 parts by weight of kaolin-containing quartz as inert' ~ ' subætance J 10 parts by .Yeight of the potassium salt of li~nin-' sulfonic acid . 25 , 1-par~ ~y weight of sodium oleylmethyl tauride as wetting and dispersing agent, and grindin~ the mixture obtained in a disk attrition mill.
E x a ~ p l e B
; 29 A d?~sting powder having good herbicidal properties can ~ -6-. .. . ~ , .. -. ~ .. . .. . - - ~ . ~

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.' ' ', ' ' , be obtalned by mixing 10 parts by weight of 4-(4~chloroph~noxy)- ~-phenoxy-propionic acid as actiYe ingredient 90 part~ by weight of talcum as inert substance and grinding ~he mixture obtained in a cross-beater mill.
E x a m ~ l e C
An emulsifiable concen~a~ consists of 15 parts by weight of 4-(4~chlorophenoxy)-~ -pheno-~y-propionic acid ~`J 1~75 parts by weight of cyclo~exanone as sol~ent and 10 parts by weight of nonyl (ethoxy)10 phenol as emulsifier.
The following examples illustrate the i~vention.

APplication Examples .
E x a ~ p l e , Seed3 of weeds of di~ferent botanic families were ~own in ' pots and the pots were placed ~n the greenhouse for about 3 weeks for g~rmlnation. They were then sprayed with wettable powder ~or~ulations suspended in water and containing as ac~ive ingr~dient compounds 1 or 2 ! ' in ~arious concentrations- Asi~comparative agents 2,4-D (2,4-dichlorophe~xy-acetic acid) and 2,4-DP (2-(2', 4'-dichloro-phenoxy)-pr~p~onic acid) were used in the same manner.
Other pots in which seeds o~ the same species of weed~ had pre~iously been ~ow~ were sprayed with the same s~y liquors (pre-emergence treatment).
The results ~and also the results of all following tables) ~, 15 were ~aluated according to the following scheme in degree ,i; o~ damage i~ per cent:
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to~ C 9~ ~lO to. l~ -6 75 to~ C ~5 ~15 to.... ~5

7 65 to- ~ ~5 ~25 to.- 35 B 32, 5 ~co C 65 ~ 35 ~co; 67, 5 9 0 -to~ ~ 3~,5 >67,~ to ~ lO0 _~
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In this sche~e number 4 is s~lll cons~dered an acceptable 29 herbicidal e~fect l~ weeds ~nd satisfactory p~eser~ing effect on crop plants (cf. Bolle NachrIchtenbl~tt des Deutschen.
Pflanzenschutzdienstes 16. 1964, pages 92 - 94).
The results of the followlng Table I show that in contrast to the compounds 2,4-D and ~,4-DP, the compounds of the in-~ention did not exhibit or hardly exhibit an action again~t broad-leaf weeds, even if used in high amounts. Their special effect was restricted to specie~ of the family of graminacea, ~hown by the examples of Lolium, Alopecurus and Echinochloa, against which 2,4-D and 2,4-DP were ineffecti~e.
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The compounds as u~ed in Example I were sprayed in pre-emergence as well as in post-emergence appl~ca~on on different broad-leaf crop plants. The results of Table II show that compositions according to the invention, containing a active ingredient compounds 1 and 2, fully spared the in-dicated broad-leaf crops even lf applied in high dosages of 2.5 kilograms per hectare of acti~e ingred~ent, where~s the . same dosage o~ ~nown phenoxy-fatty acid derivatives completely destroyed the crop plants whell applied to the leaves (post-emergence application7 and caused heavy damages in part when applied to the soil (pre-emergence application). Analogous ,.
results were obtained with the aforesaid preparat~ons in other .
crops such as horse bean, kldney bean, ~etch, clover, lucerne, ~unflower, saf~lower, cucumber, pumpkin, flax, tomatoe, sugar melon, water melon, salad~tobacco, celery, and ~arious types of cabbage.
. Crop grasses su-^h.as barley, oat and wheat, were not ~3 d~maged by the compounds o~ the invention when applied in *~e j 20 same manner.
~ ..... E x a m ~ 1 e III -:~ Seeds of some weed grasses and crop plants were sown in pots and after 3 weeks , in the 2- or 3-leaf-stage the plants . .
- were sprayed with suspensions of compounds 1 and 2.
.. 25 The results obtained 4 weeks after the treatment are:.indicated .; in the f ollowing Table III.
:~ The indicated results show that with post-emergence application the compounds of the invention exhibited a good and in part ex-cellent effect in low dosages against certain weed grasses with-out damaging dicotyledonous crop plants, such as pea, sugar beet, .~ sunflower, or soybean.

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1(~3~ 76 E x a m ~ l e IV
About 4 weeks after germination a logarithmlc spray test ~as preformed in a sugar beet f1eld using two compounds of the ln~ention. me results 5 weeks after application ~re indicated in Table IV.
Q 10 The two compounds considerably damaged Alopecurus (foxtail grass) but did no harm to the beet plants. Higher dosages (from 1 to 2 kg/ha) of acti~e ingredient destroyed the ~eed grass. An infe~tation by foxtail grass could thu~ be eliminated after germi~ation of the crop plant.

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E x a m ~ ~ e V l~3~76 Seeds of foxtail grass and sugar beet were sown together in 20 cm deep containers. Part o~ the containers was treated on the same day with v~arying doses of compounds 1 and 5, respectiYely, according to the invention and o~ ~he comp~rat~ve agents pyrazon ~5-amino-4-chloro-~-phenyl-pyridazin-3(2H~-one) and sodium trichloroacetate, while the other part was sprayed three weeks after sowing. In the latter case, besides pyrazon, phenmedipham was used as comparative agent. (3-methoxycarbonyl-C)10 aminophenyl-N-(3~-methylphenyl)-carbamate) Pyrazon is normally used to comb~t dicotyledonous weeds in pre- and post emergence applica~ion.
Phenmedipham is used to combat dicotyledonous weeds in post emergence application.
Sodium trichloroacetate is used to control weed grasses in pre-emergence application.
The results summarized in Table ~ evaluated about 4 weeks a~ter the last treatment show that the compounds of the in I ~ vention were very effective against foxtail grass bot~ in pre-emergence and post-emergence application without damaging the sugar beet plants. The comparative agents pyrazon and phenmedipham were absolutely ineffective against foxtail grass, while sodium TCA exhi~ited an effect-only in a very high dosage (15 kg/ha), but at the same time seriously damaged the sugar beet plants.
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x ~ 3~ ~7~ - ' Maize and soybean ~ere sown in a fleld;strongly infested with weed grasse~. A~ter sowing the field was subdivided into sections each having a size of 20 m2 and the sections were treated with different doses of eompound 5 of the in~ention, As compa~tiye agent alachlor ~2-chloro-2',67-diethyl-~-(methox~
methyl)-ace-tanilide)was used under the same conditions.
6 Wee~s after treatment it could be seen that co~pound 1 had a distinc~ly better effect on the weed grasses than ala-chlor used in the same amounts (cf. Table VI ). The crop plants were'not da~aged, 3L~ YII
Seeds o~ foxtail grass, kidney beans and peas were sown in 20 cm deep c~ntainers and at the day of sowing the surface of the, soil was sprayed with aqueous suspensions containing com-pounds of the invention a~ act~ve ingredient. Monolinuron (N-4-chlorop~enyl-N'-methyl-N'-methoxy urea) and linuron (N-3,4-dichlor~phenyl-N~,-methyl-N'-methoxy urea) were used as com-, parative agents~ ' 4 Weeks after treatment it could be seen that compounds 1 and 2 did no harm to ki~ney beans and peas when applied ~n an amount of ~.62 kg/ha. Mono-linuron frequently used in kidney beans satis~actorily contr~led but did not destroy foxtail grass in a dose of 0.62 kg/ha, The kidney bean~ were seriously damaged at that dosage. Linuron which is often used in peas damaged the foxtail gra~s only slightly e~en when used in twice the amount (1.25 ~g/ha) (cf.
Table YII) . - . . . ' . .

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-Cotton and soybeans were sown in a field strongly in-fested with weed grasses. 4 Weeks after sowing sectio~s o~ 20 - were treate~ with varying dosages of active ingredients of the invention. The results lndicated in TablevlII shows that the weed grasse~ were destroyed almost completely, partially with very low dosages (0.25 kg/na). Even a manifold overdosages did nbt damage the crop plants cotton and soybean.

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Barley, wheat, oat, and rape were so~m in spring side by side in a field infested with grass weeds. After germination of the crop plants section~ of 20 m2 were sprayed with 5 aqueous suspension containing invention com~ounds in different c~ncentrati~ns. The results ind1cated in the following Table IX show that compounds1 and 5 had an excellent e~fect on foxtail grass (Alopecurus) a~d bent (Apera) and that even a manifold o~erdose did no damage.to the crop plants.
E x a m p l e In a further field test maize, sunflower, peas, kidney beans~ rape and carrots were sown and immediately a~ter sowing sections o~ 20 m2 were sprayed with liquors containing compounds of the invention in different concentrations. As comparati~e agent prynachlor (N-butin (1)-yl-(3)-~ -chloroacetanilide) was used. 5 Weeks after treatment it could be seen that compound~
1 and 2 had a good effect against -germinating ~eed grasses, such as Echinochloa and Digitaria, and (~ 20 at the same time did no harm to the crop plantsThe herbicidal ei'fect oi prynachlo- w-s distlnctly inierior.

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4 Weeks ol~ rice seedling~ were planted in pots hav~ng a diameter of ~5 cm into which seeds of Echinochloa crus-galli had previously been sown. One week after planting of the seedlings the pots were filled with water to a height of 1 cm above soil surface. At that time the Echinochloa plants had already ger~inated. . - . - .
Aqueou~ suspensions containing compound 1 as active i~gredient were added to the supernated water and C~10 the mixture ~as cautiously stirred. 4 Weeks after treat~nt the followi~g result ~as observed. tcf. Table XI~
Similar results were obtained with co~pound 5~
The results demonstrate . the~electivity of the claimed compounds in pl~nted rice and their excellent effect on Echinochloa which is difficult to combat.

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The weed grasses Avena fatua and Alopecuru~ myosuroides together with crop plants were sown in pots and after germi-nation were sprayed with different dosages of compounds of the invention. The results indicated in Table XII show that compound 3 had an excellent effect on both Avena and Alo-pecurus, with no or almost no damage to sugar beets and peas.
The compound did only little damage to wheat and barley. The comparative Gompound chlophenpropme~hyl ( B-~4-chlorophenyl3 ~ -chloropropionic acid methyl estêrj, which can be used for combati~ Avena fatua (wild oat) in various crops had an excellent effect on wild oat but was ineffective against Alopecurus ~foxtail grass) . .
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Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A herbicidal composition containing as active ingredient a compound selected from the group consisting of:
4-[4-chlorophenoxy]-.alpha.-phenoxypropionic acid, 4-[2,4-dichlorophenoxy]-.alpha.-phenoxypropionic acid, 4-[2,4-dichlorophenoxy]-.alpha.-phenoxypropionic acid 2-methyl-n-propyl ester, 4-[2,4-dichlorophenoxy]-.alpha.-phenoxypropionic acid isopropyl ester, 4-[4-iodophenoxy]-.alpha.-phenoxypropionic acid, 4-[4-bromophenoxy]-.alpha.-phenoxypropionic acid in the form of their racemic mixtures, in combination with a herbicidally acceptable carrier.

2. A method for controlling or eradicating weed grasses in crop plants which comprises applying to the weeds or the habitat thereof, either before or after emergence of the weeds, of a compound as defined in claim 1 or a composition containing such a compound in an amount sufficient to control or eradicate said weed grasses.

3. A herbicidal composition according to claim 1 in which the active ingredient is racemic 4-[4-chlorophenoxy]-.alpha.-phenoxypropionic acid.

4. A herbicidal composition according to claim 1 in which the active ingredient is racemic 4-[2,4-dichlorophenoxy]-.alpha.-phenoxypropionic acid.

5. A herbicidal composition according to claim 1 in which the active ingredient is racemic 4-[2,4-dichlorophenoxy]-.alpha.-phenoxypropionic acid 2-methyl-n-propyl ester.

6. A herbididal composition according to claim 1 in which the active ingredient is racemic 4-[2,4-dichlorophenoxy]-.alpha.-phenoxy isopropyl ester.

7. A herbicidal composition according to claim 1 in which the active ingredient is racemic 4-[4-iodophenoxy]-.alpha.-phenoxypropionic acid ethyl ester.

8. A herbicidal composition according to claim 1 in which the active ingredient is racemic 4-[4-bromophenoxy]-.alpha.-phenoxypropionic acid methyl ester.