GB2201672A

GB2201672A - Diphenyl ether compounds

Info

Publication number: GB2201672A
Application number: GB08630291A
Authority: GB
Inventors: David Munro; Rino Antonio Bit
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1986-12-18
Filing date: 1986-12-18
Publication date: 1988-09-07
Also published as: GB8630291D0

Abstract

Herbicidal compounds of the general formula I, <IMAGE> in which A<1> represents a hydrogen or halogen atom or an alkyl or haloalkyl group, and each of A<2> and A<3> independently represents a hydrogen or halogen atom or an alkyl, haloalkyl, nitro or cyano group; X represents an oxygen atom, R represents a group of formula COZ where Z represents a hydroxy group or an optionally substituted alkyl, alkoxy, aryl or aryloxy group and Y represents a group of formula CR<1> where R<1> represents an optionally substituted aryl group or a group of formula COZ; or X represents an oxygen atom, R represents a hydrogen or halogen atom and Y represents a group of formula CH; or X represents a sulphur atom, Y represents a group of formula CR<1> and R<1> represents a group of formula COZ and R represents a hydrogen atom or an optionally substituted alkyl or aryl group, or a group of formula COZ; or X represents a sulphur atom, Y represents a nitrogen atom and R represents a group of formula COZ; and salts of such compounds.n

Description

DIPHENYL ETHER COMPOUNDS This invention relates to certain diphenyl ether compounds, the preparation of such compounds, herbicidal compositions containing them, and to their use in combating undesired plant growth.

The invention provides diphenyl ether compounds of the general formula I

in which A represents a hydrogen or halogen atom or an alkyl or haloalkyl group, and each of A and A independently represents a hydrogen or halogen atom or an alkyl, haloalkyl, nitro or cyano group; X represents an oxygen atom, R represents a group of formula COZ where Z represents a hydroxy group or an optionally substituted alkyl, alkoxy, aryl or aryloxy group and Y represents a group of formula CR1 where R1 represents an optionally substituted aryl group or a group of formula COZ; or X represents an oxygen atam, R represents a hydrogen or halogen atom and Y represents a group of formula CH;; or X represents a sulphur atom, Y represents a group of formula CR1 where R1 represents a group of formula COZ and R represents a hydrogen atom or an optionally substituted alkyl or aryl group, or a group of formula COZ; or X represents a sulphur atom, Y represents a nitrogen atom and R represents a group of formula COZ; and salts of such compounds.

Generally, when any of the above mentioned moieties comprises an alkyl group this alkyl group may be linear or branched and may suitably contain 1 to 10, preferably 1 to 6, and most preferably 1 to 4 carbon athens, suitable examples being methyl, ethyl and propyl. An aryl group in the above definitions is preferably phenyl. When any groups are designated as being optionally substituted, the substituent groups which are optionally present may be any of those customarily employed in the development of pesticidal compounds, and/or the modification of such compounds or influence their structure/activity, persistence, penetration or other property.

In relation to noieties defined above as comprising an optionally substituted alkyl group, specific examples of such substituents include halogen, especially fluorine, chlorine or branine atoms, and nitro, cyano, hydroxyl, C1-4 alkoxy, C1-4 haloalkoxy, (C1~4 alkoxy)carbonyl groups, amino and C14 alkylamino groups. It is preferred, however, that such alkyl moieties are unsubstituted. In relation to moieties defined above as comprising an optionally substituted aryl group, optional substituents include halogen, especially fluorine, chlorine and branine atoms, and nitro, cyano, amino, hydroxyl, C1-4 alkyl, C1-4 haloalkyl (especially CF3) and C14 alkoxy groups. 1 to 3 substituents may suitably be employed.

Preferably however, such aryl moieties are unsubstituted.

Preferably A is a haloalkyl, especially trifluoromethyl, group, A is a halogen, especially chlorine, atom or a nitro or cyano group and A3, is a halogen, especially chlorine atom or, more preferably, a hydrogen atom.

Preferably, R or R1 as a group of formula COZ is an alkoxycarbonyl group, especially methoxycarbonyl or ethoxycarbonyl, a carboxy group, an alkali metal salt derivative thereof, for example COONa or COOK, or a phenylcarbonyl group, whilst R as a halogen atom is preferably chlorine.

Preferred azole rings conform to the following definitions: X represents an oxygen atom, R represents an alkoxycarbonyl, especially methoxycarbonyl or ethoxycarbonyl group, or a carboxy or phenylcarbonyl group, or a group of formula COOT, and Y represents a group CR1 where R1 represents a phenyl group or an alkoxycarbonyl, especially methoxycarbonyl or ethoxycarbonyl group, or a carboxy or phenylcarbonyl group, or a group of formula COCM; X represents an oxygen atom, R represents a hydrogen or halogen atom and Y represents a group of formula CH;; X represents a sulphur atom, Y represents a group of formula CR1 where R1 represents an alkoxycarbonyl, especially methoxycarbonyl or ethoxycarbonyl group, or a carboxy group, or a group of formula CORM, and R represents a hydrogen atom, an alkoxycarbonyl group, especially rre thoxycarbonyl or ethoxycarbonyl, a carboxy group or a group of formula COOM; or X represents a sulphur atom, Y represents a nitrogen atom and R represents an alkoxycarbonyl, especially methoxycarbonyl group.

The moiety M as defined in the foregoing passage is an alkali metal atom, preferably a potassium or, especially a sodium atom.

In compounds which are especially preferred because of their particularly high activity X represents oxygen or sulphur, R represents an alkoxycarbonyl, especially methoxycarbonyl or ethoxycarbonyl, group and Y represents a C-alkoxycarbonyl group or, when X is sulphur, represents a nitrogen atam; or X is oxygen, R represents a hydrogen atom and Y represents a group of formula CH.

Preferably, the groups R and R , when both are present, are identical.

The invention also provides a process for the preparation of a compound of formula I. The e process according to the invention comprises reacting a compound of formula II

where Q represents a halogen atom or a nitro group or a group of formula -QS' where M' represents a hydrogen or alkali metal atom or a group of formula

with a compound selected from R@-C#C-R, where R represents a group COZ and R1 represents an optionally substituted aryl group or a group COZ when X represents oxygen; and R represents a hydrogen atom or an optionally substituted alkyl or aryl group, or a group COZ, and R represents a group COZ, when X represents sulphur; (R ) (T)C=C(R) (L) where T and L together form an elimination compound, R represents a hydrogen or halogen atom and R1 represents a hydrogen atom, the moiety X in the compound of formula II representing an oxygen atom; and N3C-R where R represents a group COZ, the Tcoiety X in the compound of formula II representing a sulphur atom; and, when the product is a compound in which Q d does s not represent a group of formula

reacting said compound with a compound of formula IV

in which compound W represents a halogen atom or a nitro group when Q represents a group -QM' and W represents such a group -OM' when Q represents a halogen atom or a nitro group; including optionally converting the product of the preceding step(s) into a further compound of formula I.

The reaction of the compound of formula II preferably takes place in the presence of an inert solvent, especially an organic solvent, such as a hydrocarbon, for example dodecane, benzene, toluene or xylene, or a halogenated hydrocarbon, for example carbon tetrachloride, dichlorsmethane or chioroberizene or, especially, ethers and thioethers, for example tetrahydrofuran, dioxan, sulpholane and diethyl ether.

The reaction may be carried out in a wide range of temperatures, e.g. 0 C to 1500C, especially 0 C to 500C, and preferably ambient temperatute.

The compound of formula II is generated in situ. This may be done in a number of ways. Since the reaction of the compound of formula II may take place at various temperatures the actual temperature used may in practice be determined with reference to desirable conditions for the reaction which generates the compound of formula II. One method, used when X is to be an oxygen atom, generates the compound of formula II by treatment of a compound of formula III

where Hal is a halogen, preferably chlorine atom, with a base, for example triethylamine. This reaction preferably takes place at a temperature in the range 10 to 600C, under an inert atmosphere, for example under nitrogen. Another method, used when X is to be a sulphur atom, generates the compound of formula II by carbon dioxide elimination from a compound of formula IV.

This reaction preferably takes place at a temperature in the range 5O0C to the reflux temperature, under an inert atmosphere, for example nitrogen.

Compounds of formula I may be converted to other compounds of formula I, for example by hydrolysis of compounds having ester groups R and/or R. When such a group R or R in a compound of formula I represents a salt derivative of a carboxylic acid, an acid or ester compound of formula I may be reacted with an appropriate base, suitably in a solvent comprising water and/or an organic solvent, for example dioxan, and preferably at an elevated temperature, for example 30-1500C, conveniently at the reflux aperture.

When the above reactions are effected to make compounds in which Q is other than a group

that is to say, compounds in which one of W and Q represents a halogen, suitably chlorine, atom or nitro group and the other represents a group of formula -OM' where M' represents a hydrogen atom or alkali metal atom, it is preferably the moiety Q which represents the halogen atom or nitro group. The reaction is conveniently carried out by reacting a compound of formula II wherein Q represents a halogen, suitably chlorine, atom or a nitro group with an alkali metal alkoxide compound produced by reacting the product of the above defined reaction in which product W represents hydroxy, with an alkali metal hydroxide.The reaction of the alkoxide with the compound III is preferably carried out in a suitable solvent, for example, dimethyl sulphoxide, sulpholane, dimethyl formamide, or dimethyl acetamide at elevated temperature, conveniently under reflux, and also under an inert atmosphere such as nitrogen.

It is preferred, however, to effect the above reactions with starting materials in which Q represents a group

so that a further step to produce compounds of formula I is not required.

The compounds of general formula I have been found to show interesting activity as herbicides. In particular, they are highly active against broad-leaved plant species, but less active against soya, or narrow-leaved, cereal plant species.

Thus they are particularly useful in cereal, especially wheat, crops and in soya crops. 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-emergence.

The e dosage of active ingredient used may, for example, be from 0.01 to 10 kg/ha, suitably 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 aluinnium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, rrontarori Ilonites 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 synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes; and solid fertilisers, for example sùperphosphates.

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 ironic. 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 asides 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 poctylphenol 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 propylene oxide.

The compositions of the invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiable 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 h-10t 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 d-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. flmilsifiable 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 anti-freeze 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 or fungicidal properties.

The invention is illustrated in the following EXamples. The identity of the compounds of the Examples was confirmed by CHN analysis and appropriate spectral techniques, for example nuclear magnetic resonance, infra red spectroscopy and/or mass spectrometry.

Example 1 Preparation of 2-(3-isoxazolyl-4,5-dimethylcarboxylate)-4-(2' chloro-4'-trifluoromethyl phenoxy nitrobenzene.

(a) Sodium acetate (9.8g) was added to hydroxylamine hydrochloride (8.2g) in water. (2'-Chloro-4'-trifluoro- methylphenoxy)-3-formyl-4-nitrobenzene (5g) was added, and ethanol was added with stirring under nitrogen at the reflux temperature until a clear solution resulted. The reaction mixture was then refluxed with stirring for a further 30 minutes. Dichloromethane/water (50/50 by volume; 800 ml) was added, and the organic layer separated, washed and dried. The solvent was removed by evaporation to give a pale yellow oil (4.2g) which solidified.

Recrystallization gave colourless crystals (mp 1200C) of (2'-chloro-4'-trifluoromethylphenoxy)-3-formyloximino-4 nitrobenzene.

(b) The product of step (a) above (3g thereof) in dimethylformamide (10ml) at ambient temperature to about 1/5th of a l.lg portion of N-chlorosuccinimide. The reaction mixture was heated to 50-600C to initiate the reaction and the temperature was then kept below 500C. The remainder of the N-chlorosuccinimide was added. The solution was poured into ice/water (50ml), extracted twice with diethyl ether, the organic layer washed, and dried.

Removal of solvent by evaporation gave (2'-chloro-4' tri f luorce thylphenoxy) -3- chloroformyloximino-4-nitro- benzene as a colourless oil, in quantitative yield.

(c) The product of step (b) (2g thereof) was mixed with diethyl ether (20ml), triethylamine (1g) and dimethylacetylenedi carboxylate (lug) at ambient temperature. Purification by washing, solvent evaporation, chromatography and recrystallisation gave the title compound as colourless crystals (1.5g), m.p. 1100C.

Analysis: Calc. C 48.0% H 2.4% N 5.6% Found C 48.1% H 2.4% N 5.6% Examples 2-6 The following compounds were prepared in analogous manner to the compound of Example I

Example R1 R MPOC C H N(%) 2 COPh COPh 114-6 Calc. 60.8 2.7 4.7 Found 60.8 2.8 4.9 3 Ph CO2C2H5 130-3 Calc. 56.3 3.0 5.3 Found 56.2 3.1 5.3 4+ H C1 Oil Calc. 45.8 1.7 6.7 Found 46.3 2.1 6.3 5 CO2C2H5 CO2C2H5 77-8 Calc. 50.0 3.0 5.3 Found 50.1 3.2 5.5 6 H H Oil Calc 49.9 2.1 7.3 Found 50.3 2.0 7.4 + In Examples 4 and 6 vinyl precursor compounds, 1,1-dichloroethene and vinyl bromide respectively, were employed. In Example 4 the reaction was effected under nitrogen. In Example 6 the reaction was effected at 50C.

Example 7 Preparation of 2-(3-isothiazolyl-4 ,5-din3thylcar- boxylate)-4-(2'-chloro-4'-trifluoromethylphenoxy)nitrobenzene (a) (2'-Chloro-4'-trifluoromethylphenoxy)-3-carboxy-4 nitrobenzene (50g) was dissolved in benzene (300ml).

Thionyl chloride (18.1g) was added and the reaction mixture refluxed for 1 hour under nitrogen. The reaction mixture was cooled to 0 0C and ammonia was passed through the solution for 15 minutes. Solvent was removed by evaporation and the residue purified by chromatography on silica using ethyl acetate as eluent, giving 35g of (2'-chloro-4'-trifluoromethylphenoxy)-3-carbamoyl-4- nitrobenzene.

(b) Chlorocarbonylsulphenyl chloride (26g) was added to a stirred solution of the product of step (a) above (25g) in toluene (500ml) under nitrogen at 1000C. The reaction mixture was stirred overnight at 1000C. The reaction mixture was cooled and solid material was filtered off.

The e filtrate was evaporated and the residue purified by chromatography to give a yellow oil which solidified. On recrystallization 2- (5-2-oxo-1 ,3 ,4-oxathiazolyl) -4- (2' - chloro-4'-trifluoromethylphenoxy)nitrobenzene formed as colourless crystals (16.1g).

(c) The product of step (b) above was mixed with dimethylacetylenedicarboxylate (1.4g) in chlorobenzene (25ml). The reaction mixture was refluxed overnight with stirring under nitrogen. The reaction mixture was cooled and the solvent evaporated leaving a dark brown oil.

Purification by chromatography yielded a pale yellow oil which solidified. Recrystallization gave the title compound as colourless crystals (1.1g), mp 124-60C.

Analysis Calc C 46.5% H 2.3% N 5.4% Found C 46.7% H 2.6% N 5.6% Examples 8-10 The following compounds were prepared in analogous manner to the compound of Example 7.

Example Y R mp( C) C H N(%) + 8 N CO2C2H5 Oil Calc 45.6 2.3 8.9 Found 45.4 2.4 8.9 9 C-CO2CH3 H Oil Calc 47.1 2.2 6.1 Found 46.3 2.9 6.4 10 C-CO2C2H5 CO2C2H5 123-5 Calc 48.5 2.9 5.1 Found 48.7 3.0 5.5 + Example 8: Starting material was NCCO2C2H5 ; solvent was dodecane.

Example 11 Preparation of 2-(3-isothiazolyl-4 ,5-dicarboxylic acid)-4(2'-chloro-4'-trifluoromethylphenoxy)nitrobenzene The ester compound of Example 10 (2g) was mixed with sodium hydroxide (0.75g), water (50ml) and sufficient dioxan to dissolve the ester. The reaction mixture was refluxed for 1 1/2 hours, allowed to cool, then acidified to a pH of 1 with concentrated hydrochloric acid. A pale yellow oil separated.

The mixture was extracted with 2 50ml portions of chloroform.

The combined extracts were dried and solvent was removed by evaporation leaving a yellow oil which solidified.

Recrystallization gave the title compound as colourless crystals (1.6g), mp 1280C (decomposed) Analysis Calc C 44.2% H 1.6% N 5.7% Found C 44.5% H 2.1% N 5.78 Example 12 Preparation of 2-(3-isoxazolyl-4,5-dicarboxylic acid)-4-(2'-chloro-4'-trifluoromethylphenoxy)nitrobenzene The title compound was prepared from the compound of Example 5 in the manner described in Example 11. Mp 1590C (decomposed).

Analysis Calc C 45.7% H 1.7% N 5.9% Found C 46.1% H 2.1% N 5.4% Example 13 Preparation of 2-(3-isothiazolyl-4,5-dicarboxylic acid, disodium salt)-4-(2'-chloro-4'-trifluoromethylphenoxy)nitrobenzene A mixture of the title carpxlund of Example 7 (2g) and sodium hydroxide (0.15g) in dioxan/water (5Qml, 1/1 by volume) was heated at reflux for 4 hours. After cooling the reaction mixture was washed with diethyl ether (2 x 50ml). The e solvent was removed from the aqueous phase leaving the title ccmpound as a yellow solid (1.2g).

Analysis Calc C 40.6% H 1.1% N 5.2% Found C 40.4% H 1.7% N 4.8% Example 14 Herbicidal Activity To evaluate their herbicidal activity, compounds according to the invention were tested using as 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 volurtrt equivalent to 900 litres per hectare in the soil spray and foliar spray test, and at a dosage of 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 preeemergence 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 is indicated as a blank space in the following Table, and denotes growth as untreated control, whilst a rating 9 indicates death. An increase of 1 unit on the linear scale approximates to a 108 increase in the level of effect.

The symbol '-' indicates that testing was not effected.

The results of the tests are set out in Table I below. TABLE 1 Compound of Soil drench 10/kg/ha Dosage Foliar spray Pre-emergence Ex. No. Mz R BG O L M SB S kg/ha Mz R BG O L M SB S Mz R BG O L M SB S 1 5 2 6 3 6 9 9 5 5 7 3 8 7 9 9 9 5 1 2 4 2 8 9 9 2 1 3 6 4 8 9 9 4 1 2 2 8 9 9 2 2 5 4 2 3 2 3 4 1 2 1 2 3 4 3 5 4 2 5 4 5 4 1 2 1 2 1 3 3 4 3 3 7 6 6 8 7 5 5 6 3 9 9 7 7 3 7 2 7 8 8 1 3 4 2 8 8 5 5 1 4 2 6 7 5 3 2 8 6 5 6 6 5 9 9 9 8 6 2 8 9 9 1 2 5 3 9 9 8 8 2 1 7 9 8 TABLE 1 (continued) Compound of Soil drench 10/kg/ha Dosage Foliar spray Pre-emergence Ex. No.Mz R BG O L M SB S kg/ha Mz R BG O L M SB S Mz R BG O L M SB S 6 4 4 6 6 7 9 8 5 5 6 4 9 7 9 9 9 7 4 5 8 6 7 8 9 4 1 6 3 8 6 9 9 9 7 2 1 6 4 5 5 8 3 7 3 2 8 5 7 8 9 5 5 7 4 8 7 9 9 9 6 2 3 6 5 8 9 9 3 1 5 2 8 7 9 9 9 6 1 5 5 8 9 8 3 8 4 3 7 7 8 8 9 3 5 6 3 8 6 9 9 9 6 3 2 7 4 9 9 9 4 1 5 1 6 6 9 9 9 6 2 4 3 7 8 9 3 9 1 8 4 5 1 5 3 7 6 9 9 9 6 2 7 7 8 1 2 5 4 9 8 8 6 1 6 5 7 10 5 7 6 2 5 5 3 7 7 9 9 9 7 1 1 2 1 7 9 8 1 3 2 5 6 9 9 9 4 1 1 6 8 8 TABLE 1 (continued) Compound of Soil drench 10/kg/ha Dosage Foliar spray Pre-emergence Ex. No.Mz R BG O L M SB S kg/ha Mz R BG O L M SB S Mz R BG O L M SB S 11 7 6 4 4 9 9 6 5 2 4 5 3 5 9 8 6 6 1 8 9 9 5 1 1 2 2 2 4 8 6 4 4 1 4 8 9 12 3 4 4 1 4 9 6 5 3 5 2 6 7 6 5 2 9 8 1 1 5 2 5 7 4 4 1 5 3 13 8 7 6 7 6 9 9 4 5 6 7 8 7 9 9 9 6 5 4 7 2 9 9 9 2 1 4 5 6 6 8 9 9 4 0 2 2 0 8 9 8 1 Example 15 Herbicidal Selectivity in wheat A further series of biological evaluations were carried out to demanstrate the selectivity in wheat of the compounds of the invention, and to compare that selectivity with a representative diphenyl ether specifically described in US Patent 4419122. The compounds tested were those of Examples 1 and 7 hereof, and for comparison the compound designated as number 3 of the said U.S.

Patent; this comparison canpound, the commercial herbicide "oxyfluorfen", being designated hereafter as A.

The tests conducted were spray tests, in which seedling plants of a range of species were sprayed with the test compounds. The test plant species were wheat (WH), speedwell (SW), field pansy (FP) and cleavers (GG). The plants were at the stage of 1-3 true leaves.

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

The compounds were tested as technical materials and formulated in a 1:1 acetone : water mix containing up to 0.2% of the alkylphenol/ethylene oxide wetting agent, Triton X155 (trade mark) and applied as single dose foliar sprays in a total volurre of 600 litres/hectare. Application was at 4 different dosage levels designed to produce a range of responses. At least two replicate pots were used for each treatment. Untreated seedling plants were used as controls.

Phytotoxicity compared with the untreated control was assessed visually approximately 2 weeks after treatment using the standard 0-9 scale, 0 indicating no effect and 9 indicating death.

The results were subjected to a standard probit analysis by computer to calculate the dosage of each compuond in g/ha, required to kill 90% of the weed species and to produce 50% level of effect on the crop species. These dosages are are set out below in Tables 2 and referred to as the GID90 and GID50 dosages respectively.

The e GID50 and GID90 values obtained are set out in Table 2 below.

Table 2 GID values expressed in g/ha Test Compound WH* GG + SW + FP + Example 1 62 643 46 2.5 Example 7 27 144 9 2.5 A 6 91 214 3.5 * GID50 + GID90 These GID values were then used to calculate the selectivity factors in wheat by dividing the GID50 value of the compounds in wheat by their GID90 value in each weed species.

(NB. Numbers greater than 1 indicate selectivity between crop and weed and the larger the number the greater the selectivity).

The results are set out in Table 3 below.

Table 3 Selectivity Factors Test Compound GG SW FP Example 1 0.10 1.35 24.9 Example 7 0.5 7.85 28.8 A 0.06 0.03 1.63 Example 16 Herbicidal Activity and Selectivity in Soya A further series of biological evaluations were carried out to demonstrate the selectivity in soya of Examples 1 and 7 hereof in comparison with the compound 5-[2-chloro-4-(trifluoromethylphenoxy]- 2-nitrobenzoic acid of US Patent 3979437, designated as B below.

The tests and analysis were conducted as described in Example 15. The test plant species were soya (S), mourning glory (MG), fat hen (FA), prickly sida (PS) and black nightshade (NB).

Table 4 shows the GID values for 2 sets of tests and table 5 shows the selectivity factors (GID50 on soya divided by GID90 on weeds).

Table 4 GID values expressed in g/ha Test Compound S* MG+ FA+ PS+ NB+ Example 1 95 35 Example 7 21 20 5 20 13 B 82 269 105 174 86 * GID50 + GID90 Table 5 Selectivity factors Test Compound my FA PS NB Example 1 2.74 Example 7 1.05 4.30 1.08 1.65 B 0.31 0.78 0.47 0.95

Claims

CLAIMS 1. A compound of the general formula I

in which A represents a hydrogen or halogen atom or an alkyl or haloalkyl group, and each of A and A independently represents a hydrogen or halogen atom or an alkyl, haloalkyl, nitro or cyano group; X represents an oxygen atom, R represents a group of formula COZ where Z represents a hydroxy group or an optionally substituted alkyl, alkoxy, aryl or aryloxy group and Y represents a group of formula CR1 where R1 represents an optionally substituted aryl group or a group of formula COZ; or X represents an oxygen atom, R represents a hydrogen or halogen atom and Y represents a group of formula CH; or X represents a sulphur atom, Y represents a group of formula CR1 where R1 represents a group of formula COZ and R represents a hydrogen atom or an optionally substituted alkyl or aryl group, or a group of formula COZ; or X represents a sulphur atom, Y represents a nitrogen atom and R represents a group of formula COZ; and salts of such compounds.
2. A compound according to any of claims 1 or 2 wherein A1 2 represents a haloalkyl group, A represents a halogen atom or a nitro or cyano group and A represents a hydrogen or halogen atom.
3. A compound according to claim 2 wherein A represents trifluoromethyl, A represents chlorine and A represents a hydrogen.
4. A compound according to any preceding claim wherein X represents an oxygen atom, R represents a (C1-4alkoxy) carbonyl, a carboxy or phenylcarbonyl group or a group of formula -COOM, and Y represents a group CR1 where R1 represents a phenyl group or a (C1-4alkoxy)carbonyl or phenylcarbonyl group, or a carboxy group or a group of formula C; X represents an oxygen atom, R represents a hydrogen or halogen atom and Y represents a group of formula CH; X represents a sulphur atom, Y represents a group of formula CR1 where R1 represents a (C1 4alkoxy)carbonyl or carboxy group, or a group of formula COCK, and R represents a hydrogen atom, or a (C1 4alkoxy)carbonyl or carboxy group, or a group of formula COOM ;; or X represents sulphur atom, Y represents a nitrogen atom and R represents a (C1-4alkoxy)carbonyl group ; wherein M in the above definitions represents an alkali metal atom.
5. A compound according to claim 4 wherein X represents oxygen or sulphur, R represents a (C1-4alkoxy)carbonyl group and Y represents a (C1-4alkoxy)carbonyl group or, when X is sulphur, represents a nitrogen atom; or X is oxygen, R represents a hydrogen atom and Y represents a group of formula CH.
6. A compound of formula I, as named herein or substantially as herein described with reference to the Examples.
7. A process for the preparation of a compound of formula I, as clairred in any preceding claim, comprising reacting a compound of formula II

where Q represents a halogen atom or a nitro group or a group of formula -OM' where M' represents a hydrogen or alkali metal atom or a group of formula

with a compound selected from R1-C=C-R, where R represents a group COZ and R1 represents an optionally substituted aryl group or a group COZ when X represents oxygen; and R represents a hydrogen atom or an optionally substituted alkyl or aryl group, or a group COZ, and R1 represents a group COZ, when X represents sulphur; (R1)(T)C=(R) (L) where M and L together form an elimination compound, R represents a hydrogen or halogen atom and R1 represents a hydrogen atom, the moiety X in the compound of formula II representing an oxygen atom; and N=C-R where R represents a group COZ, the moiety X in the compound of formula II representing a sulphur atom; and, when the product is a compound in which Q does not represent a group of formula

reacting said compound with a compound of formula IV

in which compound W represents a halogen atom or a nitro group when Q represents a group -OM' and W represents such a group -OM' when 0 represents a halogen atom or a nitro group including optionally converting the product of the preceding step(s) into a further compound of formula I.
8. A process substantially as hereinbefore described with reference to the Examples.
9. A compound of formula I whenever prepared by the process of claim 7 or 8.
10. A herbicidal composition comprising a compound of formula I as defined in any one of claims 1 to 6, or claim 9, with at least one carrier.
11. The use of a compound according to claim 1 to 6, or claim 9, or of a composition according to claim 10, as a herbicide.
12. A method of combating undesired plant growth at a locus by treating the locus with a confound of formula I as defined in any of claims 1 to 6, or claim 9, or a composition according to claim 10.