CA1178600A - Herbicidal coumaran ureas - Google Patents

Abstract

Abstract of the Disclosure Coumaran ureas of the formula:

Description

- 1 - K-3307 (US) ~RL:mp HERBICIDAL COUMAR~N UREAS

Description of the Invention It has been found that coumaran ureas of the formula t --`1' R
wherein R is methyl or cyclopropyl, are useful as herbicides.
The individual species of formula I wherein R is methyl (hereinafter referred to as Compound 1) was prepared as follows:
A solution of 71.9 g of acetyl chloride in 75 ml of aceto-nitrile was added drop-by-drop over a period of 90 minutes to a cooled (5-10C) and stirred mix~ure of 99.5 g of coumaran and 155.8 g of silver nitrate in 416 ml of acetonitrile. The resulting mixture was stirred overnight at room temperature, cooled to 5C and diluted with 1250 ml of water. After two hours, the mixture was filtered, the soLid was extracted with ether, and the ether was evaporated from the extract. The residue (a syrup) was chromatographed over silica gel, using an 80:16:4 (v:v:v) mixture of hexane, ethyl acetate and tetra-hydrofuran as eluent. Two fractions were obtained. The second fraction, having the lower ~ value, on work-up gave 2,3-dihydro-7-nitrobenzofuran (lA), as a yellow crystalline solid, mp: 95-97C.
A solu~ion of 39.4 g of lA in 200 ml of tetrahydrofuran, containing 2 g of Raney nickel catalyst, was hydrogenated in a Parr shaker at 50 p.s.i.g. hydrogen pressure for 3 hours. The resulting mixture was filtered and the solvent was evaporated. The residue was recrystallized from ether to give 7-amino-2,3-dihydrobenzofuran (lB~, as a solid, mp: 70~7ZC.
A solution of 6.7 g of lB and 3.7 ml of methyl isocyanate in 50 ml of ether, containing 10 drops of triethylamine as catalyst, was held at room temperature for 24 hours. The resulting mixture was filtered, the solid was washed with ether, and dried to give 1 (i.e., N-(2,3-dihydrobenzofuran-7-yl)-N'-methylurea) as colorless needles, mp: 173-175C.
The individual species of formula I wherein R is cyclopropyl (hereinaf~er, Compound 2) was prepared as follows:

2 --A solution of 4.9 g of lB in 50 ml of ethyl acetate was added to a mixture of 50 g of phosgene and 200 ml of ethyl acetate. The resulting mixture was refluxed for one hour, then the salvent was evaporated. The residue was taken up in tetrahydrofuran, 2.3 g of cyclopropylamine was added, and the mixture was held at room temperature over a weekend. The solvent was evaporated and the residue was chromatographed over silica gel, using a 4:30:66 (v:v:v) mixture of tetrahydrofuran, ethyl acetate and hexane as eluent, to give 2 (i.e., ~-(2,3-dihydrobenzofuran-7-yl)-N'~cyclopropylurea), as a solid, mp: 150-152C.
The identities of the two products were confirmed by appropriate chemical and spectral analyses.
The compounds of Formula I have been found to be useful in inhibiting the growth of unwanted plants. The compounds are active with respect to both broadleaved plants and grasses, being more effective with respect to grasses when applied preemergence (applied to the soil before the seeds have sprouted) than when applied postemergence (applied to the foliage of growing plants). The compounds are particularly effective when applied preemergence, giving excellent control of broad-leaved weeds and good control of grasses.
Accordingly, the invention includes a method of killing weedswhich comprises applying to the locus an effective amount of a compound of Formula I. Likewise, the invention also includes herbicidal compositions comprising a carrier or a sur~ace-active agent, or both a carrier and a surface-active agent, and as active ingredient, a compound of Formula I.
The term "carrier" as used herein means a solid or fluid material, which may be inorganic or organic and of synthetic or natural origin, with which the active compound is mixed or formulated to facilitate its application to the plant, seed, soil or other object to be treated, or its storage, transport or handling.
Suitable solid carriers are natural and synthetic clays and silicates, for example, natural silicas such as diatomaceous earths;
magnesium silicates, for eæample, talcs, magnesium aluminum silicates, for example, attapulgites and vermiculites; aluminum silicates, for example, kaolinites, montmorillonites and micas; calcium carbonates;
calcium sulfate; synthetic hydrated silicon oxides and synthetic calcium or aluminum silicates; elements such as, for example, carbon and sulfur;

natural and synthetic resins such as~ for example, coumarone resins, polyvinyl chloride and styrene polymers and copolymers; solid poly-chlorophenols; bitumen3 waxes such as, for example, beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilizers, for example, superphosphates.
Examples of suitable fluid carriers are water, alcohols, such as for example, isopropanol9 glycols; ketones such as for example, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone;
ethers; aromatic hydrocarbons such as for example, benæene, toluene and xylene; petroleum fractions such as for example, kerosene, light mineral oils; chlorinated hydrocarbons, such as for example, carbon tetra-chloride, perchloroethylene, trichloroethane, including liquefied normally vaporous gaseous compounds. ~ixtures of different liquids are often suitable. The surface-active agent may be an emulsifying agent or a dispersing agent or a wetting agent; it may be nonionic or ionic. Any o~ the surface-active agents usually applied in formulating herbicides or insecticides may be used. Examples of suitable surface-active agents are the sodium or calcium salts of polyacrylic acids and lignin sulfonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohols or alkyl phenols, for example, p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulfates or sulfonates of these condensation products, alkali or alXaline earth metal salts, preferably sodium salts, or sulfuric or sulfonic acid esters containing at least 10 carbon atoms in the molecule, for example, sodium lauryl sulfate, sodium secondary al~yl sulfates, sodium salts of sulfonated castor oil, and sodium alkyl-aryl sulfonates such as sodium dodecylbenzene sulfonate; and polymers of e~hylene oxide and copolymers of ethylene oxide and propylene oxides.
The compositions of the invention may be formulated as wettable powders~ dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders are usually compounded to contain 25, 50 or 75% by weight of toxicant and usually contain in addition to solid carrier, 3 10% by weight of a dispersing agent, 15% of a surface-active agent and where necessary, 0-10% by weight of stabiliæer(sJ and/or other addi~ives such as penetrants .

or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a disper-sant or surface-active agent, and are diluted in the field with further solid carrier to give a composition usually containing 1/2-10% by weight of toxicant. Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676-0.152 mm) 9 and may be manufactured by agglomera-tion or impregnation techniques. Generally, granules will contain 1/2-25% by weight toxicant and 0-1% by weight of additives such as stabi-lizers, slow release modifiers and binding agents. Emulsifiable con-centrates usually contain, in addition to the solvent and, when necessary,cosolvent, 10-50% weight per volume toxicant, 2-20% weight per volume emulsifiers and 0-20% weight per volume of appropriate additives such as stabilizers, penetrants and corrosion inhibitors. Suspension concentrates are compounded so as to obtain a stable, non-sedimenting, flowable product and usually contain 10-75% weight toxicant, 0.5-5%
weight of dispersing agents, 1-5% of surface-active agent, 0.1-10%
weight of suspending agents, such as defoamers, corrosion inhibitors, stabilizers, penetrants and stickers, and as carrier, water or an organic liquid in which the toxicant is substantially insoluble;
certain organic solids or inorganic salts may be dissolved in the carrier to assist in preventing sedimentation or as antifreeze agents for water.
Aqueous dispersions and emulsions, for example, compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the present invention.
The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick mayonnaise-like consistency.
The compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, especially insecticidal, acaricidal, herbicidal or fungicidal properties.
Protection of a locus or area from undesirable plant~ is effected by applying a compound of Formula I, ordinarily in a composition of one of the aforementioned types, to the foliage of the plants or plant growth medium, e.g., soil in which the plant is growing OL' in which the seeds are present. The active compound, of coursey is applied in an amount sufficient to exert the desired action.

The amount of the compound of Formula I to be used in controlling undesirable vegetation will naturally depend on the condition of the vegetation, the degree of activity desired, the formulation used9 the mode of application, the climate, the season of the year, and other variables. Reco~mendations as to precise amounts are, therefore, not possible. In general, however, application to the locus to be protected of from 0.1 to 10.0 kilograms per hectare of the compound of Formula I will be satisfactory.
Examples of Herbicidal Activity In the following examples, the species of plants that were tested were:
Barnyard grass (watergrass) - Echino&hloa crus-~
Large crabgrass - Digitaria sanguinalis Downy brome - Bromus tectorum Giant foxtail - Setaria faberi Wild oats - Avena fatua Yellow foxtail - Setaria lutescens Hemp sesbania (coffeeweed) - Sesbania exaltata ~imsonweed - Datura stramonium Ivyleaf morningglory - Ipomoea hederacea Wild mustard - ~rassica kaber Redroot pigweed - Amaranthus retroflexus Prickly sida - Sida spinosa Sicklepod - Cassia obtusifolia Velvetleaf - Abutilon theophrasti Garden cress - Lepidium sativum Corn - Zea maize (deKalb X363) Cotton - Gossypium hirsutum (Acala SJ-2) ~ice - ~ sativa (Calrose) Soybean - Glycine max (A~soy 71) Wheat - Triticum aestivum (Cajeme 71) Sugar beet - Beta vulgaris Cocklebur - Xanthium pensylvanicum Johnsongrass - Sorghum halepense Grain Sorghum - Sorghum vulgare (Pioneer 265) The preemergence herbicidal activity of Compounds 1 and 2 was evaluated by planting seeds of barnyardgrass, garden cress, downy brome, velvetleaf, yellow foxtail, and sicklepod in test tubes, . :

nominally maasuring 25 x 200 millimeters, filled about three-q-uarters full of untreated soil, in each case covered on top with about 2.5 cubic centimeters of soil treated with the test compound at the rates of 0.1 and 1 milligram respectively, Table I at Rates I and II, respectively.
The dosages of te~t compound were approximately two and twenty pounds of test compound per acre, respectively. The seeds were plantedon the treated soil and covered with about 1.5 cubic centimeters of untreated soil. The planted soil was held under controlled conditions of temperature, moisture, and light for g to 10 days. The amounts of germination and growth in each tube were evaluated on a 0 to 9 scale, the numeric ratings having the following meanings:
Rating _ Meaning 9 No living tissue 8 Living tissue, but plant expected to die 7 Plant badly damaged, but expected to live 6 Plant badly damaged, but expected to recover completely Unacceptable damagP for crop plants, insufficient damage to weeds

3-4 Definite damage 1-2 Plant slightly affected, possibly by the chemical, possibly due to biological variability 0 No visible effect The postemergence activity of Compounds 1 and 2 was evaluated by spraying 10-day old large crabgrass plants, 13-day old redroot pig-weed plants, 6-day old downy brome plants, 9-day old velvetleaf plants, 9-day old yellow foxtail plants and 9-day old sicklepod plants to runoff with a liquid formulation of the test compound at the rates of 2.4 milliliters of a 0.025% solution (about one pound of the test compound per acre), designated Rate I in Table I, and 2.4 milliliters of a 0.25%
solution (about ten pounds of the test compound per acre), ~esignated Rate II in Table I. The sprayed plants were held under controlled conditions of temperature, moisture and light for 7 to 8 days and the effect of the test compound was then evaluated visually, the results being rated on the 0 to 9 scale described above.
The results of the tests are summarized in Table I.

Table I

. _ _ _ Preemergence (Soil) Postemergence (Foliar) _ __ _ _ ___ ,~

u~ ~ ~ ~d t~l u~ a) 4 tU . 4 b~ S~ O ~' O ~ tO O 0 O a s~l aJ ~ o ~n !-1 o 1~ O
. ~ ~ ~ ~ ~ ~ ~1 ~ ~ ~ æ ,, ~ ~ a4~ '''I
t3 ~ O al aJ ~r~ ~ .~_~ O ~ ~ ., ~1 ~ ~ ~ ~ U~ C.) ~1 ~ ~ ~ U~
_ _ _ _ _.
C ~ e III III II III III III III III III III III III
_ _ _ _ _ .
l 3 9 8 9 4 8 9 9 5 7 8 9 3 6 8 9 6 9 9 9 3 8 6 9 _ _.
2 7 9 9 8 9 9 7 8 9 3 7 3 9 _ 9 3 9 3 8 The preemergence herbicidal activity of Compounds 1 and 2 was further determined with respect to several common species of weeds, by spraying a formulation of the compound on the soil in which seeds of the weeds had been sown. In each series of tests, the plants were grown in narrow trays and sprayed with the test compound. The solution of the test compound was sprayed over the tray, from one end to the other, the concentration of the test compound in ~he formulation varying log-arithmically fro~ a higher value (5 pounds of the test compound per acre) at one end of the band to a lswer value (0.55 pound of the test compound per acre) at the other end of the band. The effect of the test compound was evaluated visually and reported as the nominal rate of application, in pounds of the test compound per acre of soil band, at which 90% inhibition of the growth of the weeds occurred, this being referred to as the 90% growth inhibition, or GIDgo~ dosage. Results of theltest, as well as the weed species involved, are set out in Table I-r~
Table II
GIDgo Barnyard Downy Yellow Crab- Velvet- Pig-Compound Grass Brome Foxtail ~ leaf Mustard weed Sicklepod 1 2.1 2.8 0.9 0.66 -0.55a) 0.66 -0.55 1.1 2 1.9 2.1 1.0 2.1 -0.55 -0.55 2.1 ].. 6 a~ The symbol "-" means "less than".

- ; ' ' : ' ' ` .

.~

_~ -- 8 The postemergence herbicidal activity of Compounds 1 and 2 was further determined with respec~ to several common species of weeds, by spraying a formulation of the compound on the foliage of young growing weeds. In each series of tests, the plants were grown in narrow trays and sprayed with the formulation. The formulation of the test compound was sprayed over the tray, from one end to the other, to run-off, the concentration of the test compound in the formulation varying log-arithmically from a higher value (5 pounds per acre) at one end of the series to a lower value (0.55 pound per acre) at the other end of the series. The effect of the test compound was evaluated visually and reported as the nominal rate of application, in pounds of the test compound per acre, at which 90% inhibition of the growth of the weeds occurred, this being referred to as the 90% growth inhibition or GIDgo dosage. Results of the test, as well as the weed species involved, are set out in Table III.
Table III
GIDgo Barnyard- Downy Yellow Crab- Velvet- Pig-Compound grass Brome Foxtail grass leaf Mustard weed Sickle~od 1 +5.0a) ~5.0 +5.0 5.0 1.02.1 1.9 +5.0 2 +5.0 +5.0 +5.0 5.0 2.5 3.4 1.0 5.0 a) The symbol "+" means "more than".
The pre- and postemergence activity of Compound 1 was further determined with respect to a number of crop plants and common species of weeds, using the above procedures except that the test compound 25 was applied preemergence at four different fixed dosages of 0.25, 0.5, 1.0 and 2.0 pounds of Compound 1 per acre and postemergence at three different fixed dosages of 0.5, 1.0 and 2.0 pounds of Compound 1 per acre, and the results were evaluated with reference to the 0-9 scale described in Example l. The results of the tests are reported in Table IV.

~'7~

Table IV
Phytotoxicity ~ating at Indicated Dosage Preemergence Postemergence Plant Species 0.25 0.5 1.0 2.0 0.5 1.0 2.0 Corn 0 2 5 6 0 0 0 Cotton 0 2 5 8 2 2 4 Rice 5 7 7 7 0 0 0 Grain Sorghum O 0 2 6 0 2 2 Soybean 4 7 9 9 1 1 2 Sugar beet 9 9 9 9 3 5 8 l~heat 4 5 6 9 0 0 0 Barnyardgrass 4 5 9 9 Crabgrass 3 9 5 9 0 0 0 Downy Brome 4 4 9 9 0 O O
Giant Foxtail 4 6 8 9 0 0 2 Johnsongrass 3 4 5 9 2 3 2 Wild Oats 9 9 9 9 0 0 2 Yellow Foxtail 0 6 9 9 0 0 0 Cocklebur 9 9 9 9 4 5 8 Coffeeweed 9 9 9 9 2 3 5 Jimsonweed 9 9 9 9 6 9 9 Morningglory 9 9 9 9 5 6 9 Mustard 3 9 9 9 0 2 3 Pigweed O O 0 9 5 9 9 Prickly sida 5 7 9 9 9 9 9 Sicklepod 3 9 9 9 2 4 5 Velvetleaf 9 9 9 9 2 ~ 9 Compound 2 was tested for its preemergence activity in the same manner~ using dosages of 0.5, 1.0 and 2.0 pounds per acre, the results being reported in Table V.

Table V
Phytotoxicity Rating at Indicated Dosa&_ Preemergence Plant Species 0.5 1.0 2.0 Corn 4 7 Cotton 5 9 9 Rice 5 7 7 Grain Sorghum 0 2 4 Soybean 7 8 9 Sugar beet 9 9 9 ~heat 3 4 8 Barnyardgrass 6 9 9 Crabgrass 3 8 9 Downy Brome 4 9 9 Giant Foxtail 6 8 9 Johnsongrass 3 5 9 Wild Oats 9 9 9 Yellow Foxtail 6 8 8 Cocklebur 9 9 9 Coffeeweed 9 9 9 Jimsonweed 9 9 9 Morningglory 9 9 7 Wild Mustard 9 9 g Pigweed 9 9 g Prickly sida 9 9 9 Sicklepod 0 3 9 Velvetleaf 9 9 9

Claims (2)

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

1. A compound of the formula (I) wherein R is methyl or cyclopropyl.

2. A method for killing unwanted plant growth at a locus, which comprises applying to the locus a herbicidal amount of a compound of claim 1 or a composition containing it.