PHENYLUREA HERBICIDES

Abstract: A compounds of the Formula I wherein R¹ and R² each independently is a hydrogen atom, cyclopropyl, or alkyl or alkoxy containing 1 to 5 carbon atoms; R³ is hydrogen or alkyl or alkoxy containing 1 to 3 carbon atoms; X is 0 or S; Y is hydrogen, alkyl containing 1 to 4 carbon atoms, fluorine, chlorine or bromine; Z is hydrogen or fluorine; and n is 1 or 2, are useful as herbicides.

Description: The present invention relates to novel oximinoalkyl phenylureas, their preparation, their use as herbicides and to herbicidal compositions containing these ureas. It is known from U.S. Patent Nos. 3,778,473 and 3,914,300 that certain phenylurea oximes have fungicidal, herbicidal or plant growth regulator activity. However, it is desirable to have herbicides with a higher level of activity and a better spectrum of activity, particularly against troublesome broadleaf weed species including pigweed, velvetleaf, prickly sida, cotchweed bedstraw and spudwell. The present invention provides novel phenylurea oximes that are more efficient herbicides in activity and week sprectrum while showing greater selectivity to braodleaf crops such as cotton, soybeans and the like, particularly in pre-emergence application. The present invention is directed to novel compounds of the Formula I wherein R¹ and R² each independently is a hydrogen atom, cyclopropyl, or alkyl or alkoxy containing 1 to 5 carbon atoms; R³ is hydrogen or alkyl or alkoxy containing 1 to 3 carbon atoms; X is O or S; Y is hydrogen, alkyl containing 1 to 4 carbon atoms, fluorine, chlorine or bromine; Z is hydrogen or fluorine; and n is 1 or 2. The compounds are useful as herbicides. The oxime substituent group of the compounds of the invention gives rise to geometric isomerism by virtue of the presence of an asymmetrically substituted double bond. These isomers are usually described as follows: The Formula I includes all the possible configurations as well as individual configurations or mixtures. The present invention includes all the herbicidally active forms resulting from synthesis, and of deliberately created mixtures of such forms. Illustrative and representative species of the present invention include: and the corresponding compounds where X is S. In one preferred form of the invention, X is O. Compounds are also preferred where R¹ is methyl or methoxy and R² is methyl. Also preffered are compounds where Y is hydrogen or bromine and Z is hydrogen. In a further preferred form of the invention, R³ is methyl. Preferably, n is 2. The compounds of Formula I of the invention may be prepared from known starting materials, for example, by treating a phenylurea aldoxime or phenylurea ketoxime of Formula II , in which X, R¹ and R² and R³ have the above meanings, and which are known from U.S. Patent No. 3,914,300, with dihydropyran or dihydrofuran at ambient temperatures of about 20°C in the prsence of acid and, preferably, an inert solvent, such as tetrahydrofuran, diethyl ether and the like. Alternatively, the compounds of Formula I, including those wherein Y and Z are other than hydrogen, may also be prepared by nitration of the appropriate Y- and Z-substituted benzaldehyde, e.g. with KNO₃ and H₂SO₄, followed by addition of acidic methanol to form an acetal and reduction of the nitro group to an amino group with hydrogen in the presence of a catalyst e.g. Raney nickel. The resulting amine is treated successively with (a) CXCl₂ (eg COCl₂) in acetic acid, (b) an appropriate ammonia derivative, e.g., N-methoxy-N-methyl ammonium chloride in tetrahydrofuran and (c) hydroxylamine to give the corresponding Y- and Z-substituted phenylurea oxime. Treatment of this urea with 2,3-dihydrofuran or 3,4-dihydro-2H-pyran at ambient temperatures of about 20°C in the presence of acid, and optionally an inert solvent, such as tetrahydrofuran and the like gives the desired compound of Formula I. Therefore according to a further aspect of the present invention, we provide a process for th e preparation of a compound of Formula I as defined above which comprises reacting a compound of Formula III , where R¹, R², R³, X, Y and Z are as defined above, with dihydropyran or dihydrofuran. The products may be recovered by conventional techniques such as precipitation, crystallization, filtration, solvent extraction, chromatography and the like. For application, a compound of Formula I ordinarily is applied most effectively by formulating it with a suitable inert carrier or surface-active agent, or both. The invention, therefore, also includes compositions suitable for combatting unwanted plants, such compositions comprising an inert carrier or surface-active agent, or both, and as active ingredient at least one compound of Formula I. The term "carrier" as used herein means an inert solid or liquid 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 and/or handling. Any of the materials customarily employed in formulating pesticides, herbicides, or fungicides --i.e., horticulturally acceptable carriers -- are suitable. Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements such as, for example, carbon and sulphur; natural and synthetic resins such as, for example, coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; bitumen; waxes such as, for example, beeswax, paraffin wax, and chlorinated mineral waxes; solid fertilizers, for example, superphosphates; and ground, naturally-occurring, fibrous materials, such as ground corncobs. Example of suitable liquid carriers are water, alcohols such as isopropyl alcohol and glycols; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers such as cellosolves; aromatic hydrocarbons such as benzene, toluene and xylene; petroleum fractions such as kerosene and light mineral oils; chlorinated hydrocarbons such as carbon tetrachloride, perchloroethylene and trichloromethane. Also suitable are liquefied, normally vaporous and 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 and 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 alkaline earth metal salts, preferably sodium salts, of 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 sodium alkylaryl sulfonates such as sodium dodecylbenzene sulfonate, and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxides. The compositions of the invention may be prepared as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders are usually compounded to contain 25 to 75% by weight of active compound and usually contain, in addition to the solid carrier, 3-10% by weight of a dispersing agent, 2-15% 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 0.5-10% by weight of the active compound. 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 0.5-25% by weight of the active compound, 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, 10-50% weight per volume of the active compound, 2-20% weight per volume emulsifiers and 0-20% weight per volume of appropriate additives such as stabilizers, pentrants and corrosion inhibitors. Suspension concentrates are compounded so as to obtain a stable, non-sedimenting, flowable product and usually contain 10-75% weight of the active compound, 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 active compound 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. Of particular interest in current practice are water-dispersible granular formulations. There are in the form of dry, hard granules that are essentially dust-free, and are resistant to attrition on handling, thus minimizing the formation of dust. On contact with water, the granules readily disintegrate to form stable suspensions of the particles of active material. Such formulations contain 90% or (up to 95%) more by weight of finely divided active material, 3-7% by weight of a blend of surfactants, which act as wetting, dispersing, suspending and binding agents, and may contain up to 3% by weight of a finely divided carrier, which acts as a resuspending agent. 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 thick, mayonnaise-like consistency. It is evident from the foregoing that this invention contemplates compositions containing as little as about 0.5% by weight to as much as about 95% by weight of a compound of Formula I as the active ingredient. The compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, especially insecticidal, acaricidal, herbicidal or fungicidal properties, as are appropriate to the intended purpose. Protection of a locus or area from undesirable plants is effected by applying a compound of Formula I, ordinarily in a composition of one of the aforementioned types, to soil in which the seeds of the unwanted plants are present, or to the foliage of the unwanted plants, particularly broadleaf weeds. In some cases, the compounds of Formula I are selective to broadleaf crops, e.g. cotton, soybean and the like. The active compound, of course, is applied in an amount sufficient to exert the desired action. The amount of the compound of the invention to be us ed in combatting undesired plants will naturally depend on the condition of the plants, 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, howevr, application to the locus to be protected of from 0.1 to 10.0 kg per hectare of the compound of Formula I will be satisfactory. Examples The present invention is illustrated by the following examples, which should not be regarded as limiting the invention in any way. The products, including intermediates, were identified by elemental, infrared and nuclear magnetic resonance (NMR) spectral analyses as necessary. Example 1 : Compound of Formula Ia To a slurry of 6.0 g of the corresponding ketoxime urea (disclosed in U.S. Patent No. 3,914,300) in 30 ml of tetrahydrofuran was added 9.1 g of dihydropyran, and five drops of concentrated hydrochloric acid. The resulting solution was allowed to stir at room temperature for seventy-two hours. The reaction mixture was diluted with ether, and the solid was collected by suction-filtration and dried under vacuum to give 6.9 g of white solid, m.p.: 146-148°C. Example 2 : Compound of Formula Ib The above compound was prepared as an amber oil by a process similar to Example 1 above, by treating the corresponding ketoxime urea disclosed in U.S. Patent No. 3,914,300 with dihydropyran in tetrahydrofuran containing a catalytic amount of concentrated hydrochloric acid. Example 3 : Compound of Formula Ic To a solution of 2.0 g of the corresponding ketoxime urea (disclosed in U.S. Patent No. 3,914,300) in 25 ml of tetrahydrofuran was added 2.2 g of dihydrofuran and five drops of concentrated hydrochloric acid. The solution was allowed to stir at room temperature for seventy-two hours. The reaction mixture was diluted with 100 ml of ether and washed with 10% aqueous sodium hydroxide (3 x 100 ml). The organic phase was washed with brine, dried over anhydrous magnesium sulfate, suction-filtered, concentrated and adsorbed on silica gel. Purification by chromatography with the solvent mixture (by volume):hexane (80), ethyl acetate (16), tetrahydrofuran (4), gave 1.2 g of the desired product as a light yellow syrup. Example 4 : Compound of Formula Id (a) 2-Bromo-5-nitrobenzaldehyde Potassium nitrate, 54.4 g, was added portionwise to a stirred and chilled (0-5°C) solution containing 99.9 g of 2-bromo-benzaldehyde in 500 ml of concentrated sulfuric acid. After 0.5 hour, the mixture was poured over ice-water, and the product was filtered, washed with water and recrystallized from ether-hexane to give 95.6 g of the desired benzaldehyde, m.p.: 99-100°C. (b) 2-Bromo-5-nitrobenzaldehyde dimethyl acetal A solution containing 94.1 g of the benzaldehyde prepared in (a) above and 1.0 g of hydrogen chloride in 1000 ml of methanol was allowed to stand at ambient temperature for one week. An off-white solid that had formed was removed by filtration. The filtrate was concentrated to a volume of 75 ml and, after cooling, a solid was filtered. The combined solids amounted to 92.2 g, m.p.: 68-71°C. (c) 2-Bromo-5-aminobenzaldehyde dimethyl acetal A mixture containing 92.2 g of the acetal prepared in (b) above and 2.5 g of Raney nickel in 1000 ml of methanol was heated to reflux while 60 ml of 85% hydrazine hydrate was added dropwise over a period of 8 hours. The reaction mixture was filtered and the filtrate was concentrated to a volume of 200 ml, mixed with ether, washed well with water, dried, and concentrated to give 72.6 g of the desired compound as an amber oil. GLC indicated a purity of 90% (d) N′-(4-Bromo-3-((hydroxyimino)methyl)phenyl)-N-methoxy-N-methyl urea A solution containing 12.3 g of 2-bromo-5-aminobenzaldehyde dimethyl acetal prepared in (c) above and 45 g of phosgene in 300 ml of ethyl acetate was refluxed for 4 hours and concentrated under reduced pressure. A solution of the residual oil in 25 ml of tetrahydrofuran was added with stirring to a chilled (5-10°C) solution containing 7.5 g of O,N-dimethylhydroxylamine hydrochloride and 4.5 g of sodium carbonate in 50 ml of water. After one hour, the reaction mixture was acidified with 30 ml of concentrated hydrochloric acid and filtered. Recrystallization of the filter cake from methanol gave 11.2 g of white solid; m.p.: 222-225°C. A slurry of 5.74 g of that compound in 100 ml of methanol was successively treated with a solution of sodium acetate (2 g) in 25 ml of water and hydroxylamine hydrochloride (1.5 g) in 20 ml of water. After one hour, the stirred reaction mixture was poured into 250 ml of water and filtered. The filter cake contained two major compounds (by thin layer chromatography) which were separated by silica chromatography. The compound that emerged from the column was recrystallized from ether-hexane to give 2.3 g of the intermediate urea 4(d), m.p.: 150-152°C. (e) Compound of Formula Id A solution of 0.35 g of the aldoxime urea prepared in (d) above in 50 ml of dihydropyran containing 5 drops of concentrated hydrochloric acid was heated on a steam bath for one hour. the cooled reaction mixture was diluted with ether, and washed with 10% aqueous sodium hydroxide (3 x 100 ml). The organic phase was dried (MgSO₄), concentrated, and purified by flash chromatography with methylene chloride as eluent. Yield, 0.1 g of the desired product of Formula Id as a yellow syrup. Example 5 : Compound of Formula Ie A solution of 0.35 g of the aldoxime urea of Example 4(d) above in 50 ml of dihydrofuran containing 5 drops of concentrated hydrochloric acid was heated to reflux for one hour. The cooled reaction mixture was diluted with 100 ml of ether and washed with 10% aqueous sodium hydroxide (3 x 100 ml). The organic phase was then washed with brine, dried over anhydrous magnesium sulfate, filtered, concentrated under reduced pressure, and purfied by flash column chromatography with silica gel for support and the following solvent mixture (by volume) as eluent:hexane (66), ethyl acetate (30) tetrahydrofuran (4), to give 0.3 g of the desired product as a light yellow syrup, which crystallized on standing; m.p.: 95-98°C. Examples 6-21 Following procedures similar to those described in Examples 1-5 above, the following additional representative species are prepared as set forth in Table 1 below. Example 20 : Activity with Respect to Plants In the following tests, the species of plants that were tested were: Test Procedures The preemergence (soil) herbicidal activity of compounds of Formula I was evaluated by planting seeds of downy brome, johnsongrass, yellow foxtail, barnyardgrass, yellow millet, blackgrass, hemp sesbania, velvetleaf, morningglory, prickly sida, sicklepod and garden cress in test tubes, nominally measuring 25 x 200 millimeters, filled about three-quarters full of untreated soil, in each case covered on top with about 2.5 cubic centimeters of soil treated with 0.1 milligram of the test compound, to give a dosage of 2.24 kg of test compound per hectare (2.0 pounds per acre). The seeds were planted on top of the treated soil and covered with about 1.5 cubic centimeters of untreated soil. The planted soil was held under a controlled regimen of temperature, moisture, and light. At 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: The postemergence (foliar) herbicidal activity of compounds of Formula I was evaluted by spraying 9-day-old large crabgrass plants, 9-day-old pigweed plants, 6-day-old johnsongrass plants, 9-day-old velvetleaf palnts, 8-day-old yellow foxtail plants, 9-day-old sicklepod plants, 5-day-old morningglory plants, 5-day-old barnyardgrass plants, 6-day-old yellow millet plants, 9-day-old nightshade plants, 9-day-old prickly sida plants and 7-day-old field bindweed plants to runoff with 2.4 milliliters of a liquid formulation containing 0.5 milligram of the test compound (1.12 kg of the compound per hectare, one pound of the test compound per acre). The sprayed plants were held under a controlled regimen of temperature, moisture and light for 7 to 8 days, when the effect of the test compound was evaluated visually, the results being rated on the 0 to 9 scale described above. Results of the preemergence and postemergence herbicidal activity tests are set forth in Tables I and II.

Claims: 1. A compound of the Formula I wherein R¹ and R² each independently is a hydrogen atom, cyclopropyl, or alkyl or alkoxy containing 1 to 5 carbon atoms; R³ is hydrogen or alkyl or alkoxy containing 1 to 3 carbon atoms; X is 0 or S; Y is hydrogen, alkyl containing 1 to 4 carbon atoms, fluorine, chlorine or bromine; Z is hydrogen or fluorine; and n is 1 or 2. 2. A compound according to claim 1 wherein X is 0. 3. A compound according to claim 1 or 2 wherein R¹ is methyl or methoxy and R² is methyl. 4. A compound according to claim 1, 2 or 3 wherein Y is hydrogen or bromine and Z is hydrogen. 5. A compound according to any one of claims 1 to 4 wherein R³ is methyl. 6. A compound according to anyone of claims 1 to 5 wherein n is 2. 7. A process for the preparation of a compound of Formula I as defined in claim 1 which comprises reacting a compound of Formula III , where R¹, R², R³, X, Y and Z are as defined in claim 1, with dihydropyran or dihydrofuran. 8. A process according to claim 7 wherein the reaction is carried out at ambient temperature in an inert solvent in the presence of acid. 9. A compound of Formula I when obtained by the process of claim 7 or 8. 10. A herbicidal composition which comprises a herbicidally effective amount of a compound according to any one of claims 1 to 6 or 9 and at least one surface-active agent and/or carrier. 11. A method for combatting unwanted plant growth at a locus comprises applying to the locus a herbicidally effective amount of a compound according to anyone of claims 1 to 6 or 9 or a composition according to claim 10. 12. A method according to claim 11 wherein the combatting of unwanted plant growth is selective control of weeds in cotton.

Inventors: BOZARTH, GENE ALLEN, PILGRAM, KURT HANS GERHARD
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1987
Main classification: C07D307
IPC codes: C07D309, A01N47, C07D307, C07D319, C07D317