GB2152032A - Urea herbicides - Google Patents

Abstract

Herbicidally active 3,5-dioxacyclohexyl phenyl urea derivatives having the general formula: <IMAGE> wherein R1, R2 and R3 are alkyl; R is optionally halogenated alkyl; Z is haloalkyl and n is 0 or 1, together with a process for preparing such derivatives, herbicidal compositions containing them and their use as herbicides.

Description

SPECIFICATION Urea herbicides This invention relates to certain urea derivatives, the preparation of such compounds, herbicidal compositions containing them, and to their use in combating undesired plant growth.

Certain substituted phenylurea derivatives are known to be active herbicides, for example those described in US Patents 2655444 to 2655447. Our copending European patent application 83200758.7 (K 507 EPC) described 3,5-dioxacyclohexyl phenyl urea herbicides, in which the 4 position bears alkyl substituents. It has now been found that an improved level of herbicidal activity is present in those 3,5-dioxacyclohexyl phenyl ureas which bear a haloalkyl substituent at the 4-position.

Accordingly, the present invention provides 3,5-dioxacyclohexyl phenyl urea derivatives having the general formula:

wherein R1, R2 and R3, which may be the same or different, each independently represents an alkyl group; R represents an optionally halogenated alkyl group; Z represents a haloalkyl group; and n isO or 1.

The alkyl group present in each of the substituents of formula I is suitably one containing up to 6, preferably up to 4, carbon atoms, in particular methyl, ethyl, or butyl. In the case of the haloaklyl group Z, and R when halogen substituted, the halogen substituent is preferably a single fluorine or chlorine atom, the preferred individual groups being fluoro- and chloromethyl, chloroethyl, and chlorobutyl. When n is 1, the substituent is preferably located ortho to the dioxacyclohexyl substituent.

The invention also provides a process for the preparation of dioxacyclohexyl phehyl ureas as defined above, which comprises reacting an aniline of general formula II, our a hydrohalide salt thereof:

with either (a) a carbamoyl halide of formula III: HalCONR2R3, wherein n, R, R1, R2, R3 and Z are as defined above and Hal represents a halogen preferably chlorine, atom or (b) phosgene to form an isocyanate which is then reacted with a secondary amine of formula IV, HNR2R3.

Process (a) may be carried out with or without a solvent. Suitable solvents include hydrocarbons and halogenated hydrocarbons, for example benzene, toluene or carbon tetrachloride. Preferably it is carried out under substantially anhydrous conditions. Since the reaction is a condensation reaction involving the elimination of hydrogen halide it is preferably carried out in the presence of a dehydrohalogenating agent; organic or inorganic bases are suitable; sodium acetate has been found to be especially useful when working without a solvent, and organic bases such as triethylamine or pyridine are suitable when using a solvent. The reaction is preferably carried out at a temperature in the range of from 0 to 80 C, conveniently at room temperature, and the reaction mixture may be worked up by conventional means.

Process (b) is suitably carried out in the presence of a solvent, for example a hydrocarbon, e.g. toluene, at a temperature in the range of from 80 to 12000; conveniently, the reaction may be carried out at the reflux temperature of the solvent used. If desired, the resulting isocyanate of formula Ill may be isolated from the reaction mixture, but preferably it is reacted in situ with the secondary amine. This reaction is suitably carried out at a temperature in the range of from 0 to 30"C, conveniently at room temperature. The desired product may be isolated by any suitable method.

The compounds of general formula I have been found to show interesting activity as herbicides.

Accordingly, the invention further provides a herbicidal composition comprising a compound of formula I as defined above in association with at least one carrier, and a method of making such a composition which comprises bringing a compound of formula I into association with at least one carrier.

The invention also provides the use of such a compound or composition according to the invention as a herbicide. Further, in accordance with the invention there is provided a method of combating undesired plant growth at a locus by treating the locus with a compound or composition according to the invention.

Application to the locus may be pre-emergence or post-emgerence. The dosage of active ingredient used may, for example, be form 0.05 to 4kg/ha. A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to the locus to be treated which may for example be a plant, seed or soil, or to facilitate storage, transport or handling. A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, and any of the carriers normally used in formulating herbicidal compositions may be used.

Preferably compositions according to the invention contain 0.5 to 95% by weight of active ingredient.

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; aluminum silicates, for example kaolinites, montomorillonites and micas; calcium carbonate, calcium sulphate; ammonium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and syntheric resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosine and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloroethane. Mixtures of different liquids are often suitable.

Agricultural compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution. Thus preferably at least one carrier in a composition according to the invention is a surface-active agent. For example the composition may contain at least two carriers, at least one of which is a surface-active agent.

A surface-active agent may be an emulsifying agent, a dispersing agent or a wetting agent; it may be nonionic or ionic. Examples of suitable surface-active agents include the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation 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 alcohol or alkyl phenols, for example p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylen oxide.

The compositions of the invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiabie concentrates, emulsions, suspension concentrates and aerosols. Wettable powders usually contain 25,50 or 75% w of active ingredient and usually contain in addition to solid inert carrier, 3-10% w of a dispersing agent and, where necessary, 0-10% w of stabiliser(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, and are diluted in the field with further solid carrier to give a composition usually containing 1/2-10% w of active ingredient.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 1/2-75% w active ingredient and 0-10% w of additives such as stabilisers, surfactants, slow release modifiers and binding agents. The so-called "dry-flowable powders" consist of relatively small granules having a relatively high concentration of active ingredient. Emulsifiable concentrates usually contain, in addition to a solvent and. when necessary, co-solvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors.Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10% w of other additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation 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 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 composition of the invention may also contain other ingredients, for example other compounds possessing herbicidal, insecticidal orfungicidal properties.

The invention is illustrated in the following Examples.

Example 1 3-/4-/4-mefh yl-4chloromefh yl-3, 5dioxacyclohexyll-3-m eth ylphen yll- I, 1-dimeth yl urea A. 2-(2-methyl-4-nitrophenyl)-propane 1 ,3-diol (5g) and chloroacetone (2.419) were dissolved in benzene (150ml). To this a catalytic amount of p.toluene sulphonic acid (0.59) was added and the reaction mixture heated to reflux overnight. The water was continuously removed by means of a Dean-Stark trap. The reaction mixture was cooled and benzene removed in vacuo, diluted with dichloromethane (some) and washed with saturated sodium bicarbonate and water and then dried over sodium sulphate. The organic solution was filtered and the solvent removed under reduced pressure to leave a crude product. This was flash chromatographed on silica gel with 1:9 ethyl acetate: petroleum spirit (40/60) to yield 3-(2-methyl-4nitrophenyl)-6-methyl-6-chloromethyl-1,3-dioxane as a crystalline solid.

B. The dioxane obtained in A) above was dissolved in ethanol (50ml) and a catalytic amount of 10% platinum on carbon was added to the solution. The reduction was carried out at room temperature in a hydrogenation apparatus under 3 atmospheres pressure of hydrogen. The hydrogen uptake was complete in 2 hours. The catalyst was removed by filtration and the reaction mixture concentrated to give about 4.09 of an oil, which was taken up in toluene (15ml) and added to a stirred saturated solution of phosgene in toluene (50ml) at room temperature. The reaction mixture was then heated slowly to reflux, and phosgene continuously passed through the reaction mixture. After 0.5-1 hr the phosgene was removed and nitrogen passed through the solution to remove the excess phosgene and the hydrogen chloride formed in the reaction.After 0.5 hrs the reaction mixture was cooled to 00, the nitrogen removed, dimethylamine (20ml) added and the reaction mixture left to stir for 0.5 hrs. The reaction mixture was concentrated under reduced pressure to leave a brown oil. This was flash chromatographed on silica gel with 1:1 Ethyl acetate/Petroleum Ether to yield the desired product as a white crystalline solid, m.pt. 138-139.5.

Analysis Calc. for C16H23N203Ci C 58.8 H 7.0 N 8.6% Found C 58.7 H 7.0 N 8.3% Examples 2 and 3 Following a similar procedure to that of Example 1, further compounds were prepared which differed from that of Example 1 in the nature of the 4'-haloalkyl substituent on the dioxacyclohexyl ring (i.e. in the nature of substituent Z).

Ex. Z M.Pt. "C Analysis No.

2 Fluoromethyl 149 Calc. C61.9 H 7.4 N 9.0% Found C 61.8 H 7.5 N 8.5% 3 1-Chloroethyl 134 Calc. C59.9 H 7.3 N 8.2% Found C 59.6 H 7.2 N 8.1% Example 4 3-(4-(4-chloromethyl-4-(4-chlorobutyl)-3,5-dioxacyclohexyl)-3-methylphenyl)- 1, l-dimethylurea A. 2-(2-methyl-4-nitrophenyl)-propane 1,3-diol (0.62g) and p-toluene sulphonic acid (0.1g) were dissolved in benzene. 1,6-dichioro hex-2-one (0.5g) was added and the reaction mixture maintained overnight at reflux with stirring. The water was continuously removed by means of a Dean-Stark trap.The reaction mixture was treated as in Example 1A to yield 3-(2-methyl-4-nitrophenyl)-6-chloromethyl-6-chlorobutyl-1 3-dioxane as a white solid.

Analysis Calc. C 53.0; H 5.8; N 3.9% Found C 53.7; H 5.9; N 3.9% B. Reduction and phosgenation of the dioxane obtained in A) yields the desired product.

Example 5 HerbicidalActivity To evaluate their herbicidal activity, compounds according to the invention were tested using a representative range of plants: maize, Zea mays (Mz); rice, Oryza sativa (R); barnyard grass, Echinochloa crusgalli (BG); oat,Avena sativa (0); linseed, Linum usitatissisum (L); mustard, Sinapsis alba (M); sugar beet, Beta vulgaris (SB) and soya bean, Glycine max (S).

The tests fall into two categories, pre-emergence and post-emergence. The pre-emergence tests involved spraying a liquid formulation of the compound onto the soil in which the seeds of the plant species mentioned above had recently been sown. The post-emergence tests involved two types of test, viz., soil drench and foliar spray tests. In the soil drench tests the soil in which the seedling plants of the above species were growing was drenched with a liquid formulation containing a compound of the invention, and in the foliar spray tests the seedling plants were sprayed with such a formulation.

The soil used in the tests was a prepared horticultural loam.

The formulations used in the tests were prepared from solutions of the test compounds in acetone containing 0.4% by weight of an alkylphenol/ethylene oxide condensate available under the trade mark TRITON X-155. These acetone solutions were diluted with water and the resulting formulations applied at dosage levels corresponding to 5 kg or 1 kg of active material per hectare in a volume equivalent to 600 litres per hectare in the soil spray and foliar spray tests, and at a dosage level equivalent to 10 kilograms of active material per hectare in a volume equivalent to approximately 3,000 litres per hectare in the soil drench tests.

In the pre-emergence tests untreated sown soil and in the post-emergence tests untreated soil bearing seedling plants were used as controls.

The herbicidal effects of the test compounds were assessed visually twelve days after spraying the foliage and the soil, and thirteen days after drenching the soil and were recorded on a 0-9 scale. A rating 0 indicates growth as untreated control, a rating 9 indicates death. An increase of 1 unit on the linear scale approximates to a 10% increase in the level of effect.

The results of the tests are set out in the Table below. For purposes of comparison, results are included also for those analogues wherein Rand Z are both methyl or both ethyl.

TABLE II Compound Soil Drench 10 kg/ha Dosage Foliar Spray of Example kglha Pre-emergence Number Mz R BG O L M SB S Mz R BG O L M SB S Mz R BG O L M SB S 1 8 8 9 9 9 9 9 8 5 9 8 9 9 9 9 9 9 6 7 9 7 8 9 9 7 1 1 5 9 8 8 9 9 9 2 6 9 6 7 9 8 4 2 9 9 9 9 9 9 9 9 5 9 9 9 9 9 9 9 9 5 5 9 7 8 8 9 6 1 6 8 6 7 9 9 9 8 3 4 9 6 7 8 9 5 3 N.T. 5 N.T. N.T 1 5 8 5 6 9 9 9 9 0 2 8 8 9 9 9 4 R=CH3 6 9 9 8 9 9 9 9 5 7 9 9 7 9 9 9 9 5 3 9 7 9 9 9 6 Z-CH3 1 2 7 7 5 9 9 9 9 0 0 7 2 4 9 9 3 R=C2H5 4 6 8 7 8 9 9 8 5 4 4 9 6 8 9 9 8 0 0 0 0 4 7 7 0 Z=C2H5 1 2 2 9 6 8 9 9 8 0 0 0 0 1 6 6 0

Claims (13)

1. 3,5-dioxacyclohexyl phenyl urea derivatives having the general formula:

wherein R1, R2 and R3, which may be the same or different, each independently represents an alkyl group; R represents an optionally halogenated alkyl group; Z represents a haloalkyl group, and n isO or 1.

2. Compounds as claimed in claim 1 wherein the alkyl group present in each of the substituents contains up to 4 carbon atoms.

3. Compounds as claimed in claim 2 wherein R1, R2 and R3 each represents a methyl group; R represents a methyl or chlorobutyl group; and Z represents a fluoro- or chloromethyl or chloroethyl group.

4. Compounds as defined in claim 1 and specifically named in any one of Examples 1 to 4 herein.

5. Process for the preparation of a compound of the general formula I as defined in claim 1, which comprises reacting an aniline of general formula 11, or a hydrohalide salt thereof:

with either (a) a carbamoyl halide of formula III HalCONR2R3 wherein n, R, R1, R2, R3 and Z are as defined in claim 1 and Hal represents a halogen atom, or (b) phosgene to form an isocyanate which is then reacted with a secondary amine of formula IV HNR2R3

6. Process as claimed in claim 5 characterised in that it is carried out in the presence of a dehydrohalogenating agent.

7. Process as claimed in claim 5 or 6 wherein the compound of formula Ill is dimethylcarbamoyl chloride.

8. Process as claimed in claim 5 carried out substantially as hereinbefore described with particular reference to Examples 1-4.

9. A compound as defined in claim 1, whenever prepared by a process as claimed in any one of claims 5-8.

10. Herbicidal composition, which comprises a compound as claimed in any one of claims 1 to 4 and 9, together with a carrier.

11. A composition as claimed in claim 10, which comprises at least two carriers, at least one of which is a surface-active agent.

12. Method of combating undesired plant growth at a locus, which comprises treating the locus with a compound as claimed in any one of claims 1 to 4 and 9, or a composition as claimed in either of claims 10 and 11.

13. The use of a compound as claimed in any one of claims 1 to 4 and 9 as a herbicide.