GB2068955A

GB2068955A - Herbicidally active phenyl urea derivatives

Info

Publication number: GB2068955A
Application number: GB8103897A
Authority: GB
Original assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Current assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Priority date: 1980-02-11
Filing date: 1981-02-09
Publication date: 1981-08-19
Also published as: BR8100768A; AR225490A1; KE3403A; GB2068955B

Abstract

N-cyclopropyl-N'-fluorophenyl ureas of the formula:- <IMAGE> wherein R represents a hydrogen or fluorine atom, and their use, suitably as herbicidal compositions incorporating a carrier and/or surface- active agent, in controlling undesired plant growth, especially in grain sorghum plantations.

Description

SPECIFICATION N-cyclopropyl-N'-fluorophenyl ureas and their use as herbicides This invention relates to certain novel N-cyclopropyl-N'-fluorophenyl ureas which have been found to have useful selective herbicidal activity in grain sorghum crops.

Accordingly, the invention comprises N-cyclopropyl-N'-fluorophenyl ureas of the formula:-

wherein R represents a hydrogen or fluorine atom.

These compounds exhibit useful herbicidal activity, being active with respect to both broad-leaved plants and grasses, and being effective when applied either pre-emergence (applied to the soil before the seeds have sprouted) or post-emergence (applied to the foliage of the growing plants). They are somewhat more effective with respect to broad-leaved species of plants than with respect to grassy plants, and their activity is combined with a low activity against sorghum, which thus makes them of value in the selective control of weeds in grain sorghum plantings. Hence, a further aspect of the invention provides a method for the protection of a locus from undesired plant growth, and in particular a locus supporting or which subsequently supports a sorghum crop, which comprises applying to the locus a herbicidally effective amount of a compound as defined above.The compound may be applied to the foliage of the plants or to the medium (normally the soil) in which the plants are growing or in which the seeds are present. The amount of the compound to be used in controlling undesirable vegetation will naturally depend on the condition of the vegetation, the degree of activity desired, the formulation used, the mode of application, the climate, the season of the year, and other variables.

Recommendations as to precise amounts are, therefore, not possible. In general, however, applications to the locus to be protected of from 0.1 to 10.0 kilograms per hectare of the compound(s) will be satisfactory.

Further, it has been found that application of these compounds to grain sorghum plants prior to treatment of a grain sorghum planting with a triazine herbicide, such as atrazine or cyanazine, significantly reduces the toxicity of the triazine herbicide to the grain sorghum plants.

For application to the locus to be treated, the active compound of the above formula is preferably formulated with a carrier, or a surface-active material, or both.

By "carrier" is meant a solid or a fluid material, which may be inorganic 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 example, talcs, magnesium aluminum silicates, for example, attapulgites and vermiculites; aiuminum silicates, for example, kaolinite; montmorillonites and micas; calcium carbonates; calcium sulfate; synthetic hydrated silicon oxides and synthetic calcium or aluminium 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 polychlorophenols; bitumen, 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, isopropanol, glycols; ketones such as for example, acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic hydrocarbons such as for example, benzene, toluene and xylene; petroleum fractions such as for example, kerosene, light mineral oils; chlorinated hydrocarbons, such as for example, carbon tetrachloride, perchloroethylene, trichloroethane, including liquified normally vaporous gaseous compounds. Mixtures 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 of 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 1 2 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 alkaline 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 alkyl sulfates, sodium salts of sulfonated castor oil, and soldium alkylaryl sulfonates such as sodium dodecylbenzene sulfonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxides.

The compositions 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, 310% by weight of a dispersing agent, 1 5% of a surface-active agent and where necessary, 0-10% by weight of stabilizer(s) and/or other additives 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 dispersant or surface-active agent, and are diluted in the field with further solid carrier to give a composition usually containing 0.510% OO/o by weight of toxicant.Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676-0.152 mm), and may be manufactured by agglomeration or impregnation techniques. Generally, granules will contain 0.525% by weight toxicant and 0--1% by weight of additives such as stabilizers, slow release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to the solvent and, when necessary, cosolvent, 1 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 1075% weight toxicant 0.5-5% weight of dispersing agents, 1-5% weight 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 with water, also are suitable. 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 may also contain other ingredients, for example, other compounds possessing pesticidal, especially insecticidal, acaricidal, herbicidal or fungicidal properties.

The invention is illustrated in the following Examples.

EXAMPLE I Preparation of N-cyclopropyl-N'-(2-fluorophenyl)urea.

26.5 g (0.38 mole) of cyclopropylamine was added drop-by-drop over a 30-minute period to a solution of 50 g (0.365 mole) of o-fluorophenyl isocyanate in one litre of toluene. Reaction was immediate and exothermic, the temperature of the mixture rising from 250C to 500C during the addition. The resulting slurry was stirred for two hours at room temperature and filtered. The filter cake was washed with 1 50 ml of hexane and air dried to give 70 g of the desired product. (93.5% yield, based on the isocyanate), mp: 118-1200C. The identity of the compound was confirmed by appropriate analyses.

EXAMPLE II Preparation of N-cyclopropyl-N'-(2,5-difluorophenyl)urea.

A solution of 3.95 g (0.025 mole) of 2,5-difluoronitrobenzene in 75 ml of tetrahydrofuran containing about 2 g of Raney-nickel catalyst was hydrogenated in a Parr shaker for two hours, 3,5 kg/cm2g hydrogen pressure, room temperature. The resulting mixture was suction-filtered, washed with tetrahydrofuran, and the filtrate was concentrated to a volume of 50 ml. Then 4.15 g (0.05 mole) of cyclopropyl isocyanate was added, followed by three drops of triethylamine, as catalyst. The mixture was stirred for 4 hours at room temperature, the solvent was evaporated under reduced pressure and the residue was recrystallized from ether to give 4.0 g (75% yield) of the desired product, as a white crystalline solid, mp: 106-1 080C. The identity of the product was confirmed by appropriate chemical and spectral analyses.

For the sake of convenience, the products of the above Examples I and il are designated as Compound I and Compound II respectively in the following Examples of herbicidal evaluation.

In these Examples, the species of plants that were tested were: Barnyard grass (watergrass) -Echinochloa crus-galli Crabgrass -- Digitaria sanguinalis Downy bromeBromus tectorum Giant foxtail -- Setaria faberii Wild oats -Avena fatua Yellow foxtail -- Setaria lutescens Hemp sesbania (coffeweed) - Sesbania exaltata Jimsonweed -- Datura stramonium Ivyleaf morningglory . lpomoea hederacea Mustard -- Brassica kaber Redroot pigweed -- Amaranthus retroflexus Prickly sida - Sida spinosa Sicklepod -- Cassia obtusifolia Ve Ivetleaf - Abutilon theophrasti Garden cress-Lepidium sativum Grain sorghum -- Sorghum vulgare (Pioneer 265) Corn -Zea maize (deKalb X363) Cotton -- Gossypium hirsutum (Acala SJ-2) Rice - Oryza sativa (Calrose) Soybean -- Glycine max (Amsoy 71) Wheat -- Triticum aestivum (Cajeme 71) Sugar beet - Beta vulgaris Cocklebur - Xanthum pennsylvanicum La mbsq uarte rs - Chenopodium album Johnsongrass -- Sorghum halopense EXAMPLE Ill The pre-emergence herbicidal activity of Compounds I and II were evaluated by planting seeds of barnyard grass, garden cress, downy brome, velvetleaf, yellow foxtail, and sicklepod in test tubes, nominally measuring 25 x 200 millimetres, filled about three-quarters full of untreated soil, in each case covered on top with about 2.5 cubic centimetres of soil treated with the test compound at the rates of 0.1 and 1 milligram (Table I, Rates I and II, respectively). The dosages of test compound were approximately two and twenty kilograms of test compound per hectare, respectively. The seeds were planted in the treated soil and covered with about 1.5 cubic centimetres of untreated soil. The planted soil was held under controlled conditions of temperature, moisture, and light for 9 to 10 days.The amounts of germination and growth in each tube were evaluated on a O 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 5 Unacceptable damage for crop plants, insufficient damage to weeds 3-4 Definite damage Rating Meaning 1-2 Plant slightly affected, possibly by the chemical, possibly due to biological variability O No visible effect The post-emergence activity of Compounds I and II were evaluated by spraying 10-day old large crabgrass plants, 13-day old red root pigweed 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 millilitres of a 0.025% solution (about one kilogram of active compound, per hectare), designated Rate I in Table I, and 2.4 millilitres of a 0.25% solution (about ten kilograms of active compound, per acre), designated 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 compounds 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.

Preemergence (Soil) j Postemergence (Foliar) (d a, m E ILO m Co ('I IL 9 t ,O n jo m m m p p m r j 8 r r \ lll lll lll lll lll lll l ll l ll lll lll lll lll E g > > 8 I i i . 8 11 9 8 7 88 LS 9 78 9 99 9 9 9 9

EXAMPLE IV The pre-emergence herbicidal activity of Compound I 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 trays were placed on a band and the solution of the test compound was sprayed over each tray, from one end to the other, the concentration of the test compound in the formulation varying logarithmically from a high value (5.6 kg per hectare) at one end of the band to a lower value (0.6 kg per hectare) 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 kilograms of Compound I per hectare of soil band, at which 90% inhibition of the growth of the weeds occurred, this being referred to as the 90% growth inhibition, or GIDs0, dosage. Results of the test, as well as the weed species involved, are set out in Table II.

TABLE II.

Barnyard Downy Yellow Crab- Velvet- Pig Grass Brome Foxtail grass leaf Mustard weed Sicklepod GIT,, Dgo0.6a) -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 (a) The symbol "-" means "less than".

EXAMPLE V The post-emergence herbicidal activity of Compound I was further determined with respect 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 Compound I was sprayed over the tray, from one end to the other, to run-off, the concentration of Compound I in the formulation varying logarithmically from a higher value (5.6 kg per hectare) at one end of the series to a lower value (0.6 kg per hectare) at the other end of the series.The effect of Compound I was evaluated visually and reported as the nominal rate of application, in kilograms Compound I per hectare, at which 90% inhibition of the growth of the weeds occurred, this being referred to as the 90% growth inhibition or GIRD,, dosage. Results of the test, as well as the weed species involved, are set out in Table lil.

TABLE III.

Barnyard Downy Yellow Crab- Velvet- Pig Grass Brome Foxtail grass leaf Mustard weed Sicklepod 'GID,, 4.6 +5.6a) 5.0 -0.68' -0.6 -0.6 -0.6 -0.6 a) The symbol "+" means "more than", the symbol "-" means "less than".

EXAMPLE VI The pre- and post-emergence activity of Compound I was further determined with respect to a number of crop plants and common species of weeds, using the procedure described in Examples IV and V, except that the test compound was applied at three different fixed dosages of Compound I per hectare, and the results were evaluated with reference to the 0--9 scale described in Example Ill. The results of the tests are reported in Table IV.

TABLE IV.

Rating of Effect at Indicated Dosage (kg/hectare) Pre-emergence Post-emergence Plant Species 0.28 0.56 1.1 0.56 1.1 2.24 Corn 2 5 7 0 0 0 Cotton 4 8 9 4 5 6 Rice 5 6 7 0 2 2 Grain Sorghum 2 2 5 2 2 2 Soybean 9 9 9 5 5 8 Sugar Beet 9 9 9 5 9 9 Wheat 7 8 8 .0 0 2 Barnyard Grass 9 9 9 2 0 2 Crabgrass 9 9 9 5 7 7 DownyBrome 9 9 9 0 2 2 Giant Foxtail 5 9 9 - - - Johnsongrass 3 7 9 0 2 2 Wild Oats 9 9 9 0 2 2 TABLE IV. (cont.) Rating of Effekt at Indicated Dosage (kg/hectare) Pre-emergence Post-emergence Plant Species 0.28 0.56 1.1 0.56 1.1 2.24 Yellow Foxtail 9 9 9 Cocklebur 9 9 9 4 5 6 Hemp sesbania 9 9 9 4 6 6 (Coffeeweed) Jimsonweed 9 9 8 5 9 9 Lambsquarters 9 9 9 7 9 9 Morningglory 6 9 9 4 6 9 Mustard 9 9 9 7 7 9 Pigweed 9 9 9 9 9 9 Prickly sida 9 9 9 0 0 9 Sicklepod 9 9 9 4 9 9 Velvetleaf 9 9 9 9 9 9 It will be noted that from these tests, Compound I selectively controls the weed species in plantings of grain sorghum.

EXAMPLE VII The tests described in Example IV were repeated to compare the activity of each of the Compounds I and II with respect to grain sorghum and certain weed species. The procedure was as described in Example IV, except that for Compound I, the lower dosage used was 0.067 kilogram per hectare. The dosages of the Compounds, kilograms per hectare, required to inhibit growth by 10% (Gl1O) and 90% (G150) were determined. The results are reported in Table V.

TABLE V

Co E - Co 1 s e,ip 8 Glgg Glg0 IO'so Glgg GI!90. GI GI!90. Glg0 9 0 1.7 23 i .'O67' 0.15- O:lss 0;6 0:6 Ila) 2.13 i 4;06 I 4;6 L 4;6 L 4;6 L L 4;6 a) The symbol "-"' tneans dess than':' EXAMPLE VIII The tests described in Example V were repeated to compare the activity of Compounds I and II with respect to grain sorghum and certain weed species. The procedure was as described in Example V except that for Compound I the lower dosage used was 0.067 kg per hectare.The dosages of the compounds, kilogram per hectare, required to inhibit growth by 10% (Gl1O) and 90% (Gl90) were determined. The results are reported in Table VI.

TABLE VI

Co E Co = = x E Co X \; \S, X IL Co Ir Co S S 0 0 Co Co Co 0 = 0 ol > | > | o (n Glg0 I G q Dosage G1io. Gl9O. Glso GI90. G190 \ Go90 GI90. G190.

Compound x1 l l I0:67a) +s;6a) 1.0 0:6a) 0:6 1.9 2.13 3.14' C-- 2;13 1 3.14.

11 |i5,6a) 46:6 4;6a); A.6 l 4;6 2,8 +5.6 1 5.0 a) The symbol ";" means "more than"';' the symbol "2' means "less than";'

Claims

1. N-cyclopropyl-N'-fluorophenyl ureas of the formula:-

wherein R represents a hydrogen or fluorine atom.

2. A method for the protection of a locus from undesired plant growth, which comprises applying to the locus a herbicidally effective amount of a compound as claimed in claim 1.

3. Method as claimed in claim 2 wherein the locus supports or subsequently supports a sorghum crop.

4. Herbicidal composition comprising a compound as claimed in claim 1 together with a carrier, or a surface-active agent, or both a carrier and a surface-active agent.