GB2238789A

GB2238789A - Herbicidal 2-(substituted-benzoyl)-acrylonitrile derivatives

Info

Publication number: GB2238789A
Application number: GB9026597A
Authority: GB
Inventors: Christopher James Foster; Terence Gilkerson; Richard Stocker
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1989-12-07
Filing date: 1990-12-06
Publication date: 1991-06-12
Also published as: GB9026597D0; GB8927666D0

Abstract

Herbicidal compounds of general formula I <IMAGE> in which Q represents as group of general formula -C(O)-C(CN)=CH-NR<1>R<2>, the group Q being located ortho or para to the phenoxy group and R<1> & R<2> each independently represents an alkyl group: Z represents a nitrogen atom or a group CH which is unsubstituted by the substituent X; m is 0 or an integer from 1 to 4; the or each Y independently represents a halogen atom or an alkyl group; n is 0 or an integer from 1 to 5; ad the or each X independently represents a halogen atom, a group selected from alkyl, haloalkyl, cyanoalkyl, alkenyl, alkynyl, alkenyloxy, alkynyloxy, alkoxy, haloalkoxy, haloalkylthio, alkylthio, alkenylthio, alkylnylthio, cyano, nitro, alkylsulphonyl, alkylsulphinyl and sulphonoamino, or a phenyl group (optionally substituted by one or more moieties independently selected from alkyl, haloalkyl and alkoxy groups, and halogen atoms) or two adjacent groups X may together represent an alkylendioxy group.

Description

HERBICIDAL ACRYLONITRILE DERIVATIVES This invention concerns certain herbicidal acrylonitrile derivatives, their preparation, herbicidal compositions containing such derivatives and to a method of combating undesired plant growth using such derivatives and compositions.

The preparation and herbicidal use of certain acrylonitrile derivatives has been described in German Offenlegenschrift 2 330 913. Such acrylonitriles have an i -carbonyl linkage with a substituent selected from phenyl; naphthyl; thienyl; and furyl groups, optionally substituted by halogen, nitro, alkoxy and alkyl groups.

The present invention concerns 2- or 4- aryl- or heteroaryl-oxybenzoyl acrylonitrile compounds.

Accordingly, the present invention provides a compound of the general formula I

in which Q represents a group of general formula -C(O)-C(CN)=CH-NRlR2, the group Q being located ortho 1 and R or para to the oxygen linkage, R and R each independently represents an alkyl group, Z represents a nitrogen atom or a group CH which is unsubstituted or substituted by a substituent X, m is O or an integer from 1 to 4, the or each Y independently represents a halogen atom or an alkyl group, n is O or an integer from 1 to 5, and the or each X independently represents a halogen atom, a group selected from alkyl, haloalkyl, cyanoalkyl, alkenyl, alkynyl, alkoxy, haloalkoxy, haloalkylthio, alkenyloxy, alkynyloxy, alkylthio, alkenylthio, alkynylthio, cyano, nitro, alkylsulphonyl, alkylsulphinyl and sulphonamido, or a phenyl group optionally substituted by one or more moieties independently selected from alkyl, haloalkyl and alkoxy groups and halogen atoms; or two adjacent groups X may together represent an alkylenedioxy group.

As used herein the term alkyl, alkenyl or alkynyl in respect of a radical or moiety refers. to a straight or branched chain radical or moiety.

Suitably an alkyl radical or moiety has from 1 to 12 carbon atoms, preferably from 1 to 6 and especially from 1 to 4 carbon atoms. Alkenyl and alkynyl radicals or moieties suitably have from 2 to 12 carbon atoms, preferably from 2 to 6, especially from 2 to 4, carbon atoms. Preferred halogen atoms are bromine, fluorine and chlorine atoms, especially fluorine and chlorine atoms.

Preferably R1 and R2 each independently represents an alkyl group of from 1 to 4 carbon atoms, and most preferably R1 and R2 are the same and each represents a methyl group.

Z preferably represents an unsubstituted group CH, the compound of general formula I then being a diphenyl ether derivative.

When m is greater than 1, the substituents Y may be the same or different and may suitably be selected from chlorine, bromine and especially fluorine atoms and methyl groups. Preferably m is O or 1.

When n is greater than 1, the substituents X may be the same or different and may suitably be selected from halogen atoms, especially fluorine, chlorine and bromine atoms, C1-6 alkyl groups, C1-6 haloalkyl groups, C1 6 alkoxy groups, and cyano groups; or two adjacent groups X may together represent an alkylenedioxy group. Preferably n is 1 or 2 and the or each substituent X independently represents a fluorine or chlorine atom, a C14 alkyl group, especially methyl, a C14 haloalkyl group, especially trifluoromethyl, a C14 alkoxy group, especially ethoxy, or a cyano group; or two adjacent groups X together represent a methylenedioxy group.

Preferably a phenyl group substituted by Xn is 3-trifluoromethylphenyl.

Preferably the group Q is ortho to the oxygen linkage.

Preferred compounds of general formula I are aryl-/heteroaryl- (preferably aryl-) oxybenzoyl-2acrylonitrile derivatives.

The compounds of general formula I may either be prepared from a corresponding diphenyl ether or pyridyl phenyl ether derivative by reaction in one or more steps to introduce the dialkylaminoacrylonitrile moiety, or be prepared by introducing a suitable phenyl or pyridyl moiety into an appropriate benzoyldialkylamino acrylonitrile derivative.

Therefore, according to a further aspect of the present invention, there is provided a process for the preparation of a compound of general formula I, which comprises reacting a compound of general formula II

wherein X, Y, Z, n and m are as defined above and W represents a halogen atom or a cyanomethyl group, with, in the case where W is halogen, a dialkylaminoacrylonitrile under basic conditions, or, in the case where W is cyanomethyl, either with a dialkylformamide dialkyl acetal or with a trialkylorthoformate followed by reaction with a dialkylamine, or reacting a compound of general formula III

wherein n, X and Z are as hereinbefore defined and L represents a leaving group, with a compound of general formula IV

wherein m, Q and Y are as hereinbefore defined, under basic conditions, and, if desired or required, converting a resulting compound of general formula I into another compound of general formula I.

When W in a compound of general formula II represents a cyanomethyl group, the reaction to form the compound of formula I is suitably carried out using a dialkylformamide dialkyl acetal, preferably dimethyl formamide dimethyl acetal. Suitably the reaction is carried out in the presence of an inert organic solvent, suitable solvents being halogenated hydrocarbons, for example dichloromethane, ethers, such as diethyl ether, or esters, such as ethyl acetate; mixtures of solvents may also be utilised.

Preferably the reaction is carried out at a temperature in the range of from 0 to 50 C, suitably at ambient temperature.

Alternatively, when W in a compound of general formula II represents a cyanomethyl group, the reaction may be carried out in a two-stage procedure by reacting the cyanomethyl carbonyl compound II with a trialkylorthoformate, preferably trimethylorthoformate, followed, optionally after isolation of the alkoxyaroyl acrylonitrile so formed, by reaction with excess dialkylamine, preferably dimethylamine in a suitable solvent. Suitably solvents are, for example, halogenated hydrocarbons, such as dichloromethane, alcohols, such as ethanol, ethers, such as diethyl ether, and esters; mixtures of solvents are also suitable.The reaction may be carried out at a temperature in the range of from -10 to 100"C. Preferably the first stage is carried out at elevated temperature, for example at a temperature in the range of from 60 to 100"C, suitably at approximately 80 C, while the second stage is carried out at a lower temperature, suitably a temperature below 60iC and conveniently ambient temperature. Preferably the reaction is carried out without isolation of the intermediate acrylonitrile.

When W in a compound of general formula II represents a halogen atom, preferably chlorine, the compound of formula II is reacted with a dialkylaminoacrylonitrile, preferably dimethylaminoacrylonitrile, preferably in the presence of a solvent, for example an ether solvent, and in the presence of a base, for example, a tertiary amine. A preferred ether solvent is dioxan and a preferred tertiary amine base is triethylamine.

The reaction is preferably carried out at a temperature in the range of from 50 to 120 e Ct conveniently at the reflux temperature of the solvent employed.

Compounds of the general formula I may also be prepared by reacting a compound of general formula III with a compound of general formula IV.

Preferably the reaction is carried out under basic conditions and in the presence of a suitable solvent.

Suitably the reaction is carried out in the presence of an alkali metal or an alkaline earth metal carbonate, for example potassium carbonate. Suitable solvents are organic solvents that are inert to the reaction media and conveniently may be, for example, dimethyl formamide; again mixtures of solvents may be used. Preferably the reaction is carried out under anhydrous conditions. The reaction may conveniently be effected by a temperature in the range of from oec to the reflux temperature of the reaction mixture, but is preferably carried out at reflux.

A leaving group represented by L may be any group that will, under the reaction conditions, cleave from the reactant III thus promoting reaction at a specified site. The group L in a compound of general formula III is suitably a halogen atom, preferably chlorine or fluorine.

A preferred process for the preparation of a compound of general formula I employs a compound of general formula II wherein W represents a cyanomethyl group. Preferably, the reaction of such a compound of general formula II is with a dialkylformamide dialkyl acetal.

Compounds of general formula I may be converted into other compounds of general formula I using various standard methods. For example, a compound of formula I having certain groups R and R may be converted to another compound of general formula I having at least one different group R or R, by displacement reaction with a secondary amine RRNH, suitably in the presence of an inert solvent, for example ethanol, at an elevated temperature, suitably under reflux.

Following their preparation the resulting compounds of general formula I may be isolated and purified using conventional techniques, for example by solvent extraction, evaporation and recrystallisation or by chromatography on silica.

Compounds of general formula II are believed to be novel intermediates.

Compounds of general formula II in which W represents a cyanomethyl group may be prepared from the alkyl ester of the corresponding diaryl or aryl heteroaryl ether, by reacting a compound of general formula V:

wherein X, Y, Z, n and m are as defined above and R represents an alkyl group, with acetonitrile under basic conditions.

Preferably the basic conditions are provided by an alkali metal amide, such as sodamide or potassium amide, suitably in liquid ammonia, or sodium or potassium hydride in a solvent such as dimethylformamide or diethyl ether. Alternatively the basic conditions may be provided by an alkoxide such as sodium or potassium methoxide with excess acetonitrile as solvent. A suitable temperatures for the reaction is in the range of from -70 to 100 C and is usually determined by the basic conditions used.

Compounds of formula V may be prepared by esterification of the corresponding acid with an alcohol, such as methanol, in the presence of an acidic catalyst, for example concentrated sulphuric acid, dry hydrogen chloride gas or p-toluene sulphonic acid. The reactant acids may suitably be prepared by oxidation of the corresponding diaryl/aryl heteroaryl ether aldehyde using, for example, chromium trioxide in the presence of an acetic acid or, more preferably, sulphuric acid in an inert solvent such as aromatic solvent, e.g. benzene, or a ketone, e.g. acetone, or manganese dioxide in an inert solvent such as a halogenated hydrocarbon, e.g.

dichloromethane, an ester, e.g. ethyl acetate, or a ketone A suitable reaction n tinpratur≈is in the range of from -20 to 50'C, preferably -5 to 20it.

The ether aldehydes may themselves conveniently be prepared by condensation of an optionally substituted phenol or phenolate and an optionally substituted halobenzaldehyde, for example in the presence of an alkali metal alkoxide, such as sodium methoxide, followed by treatment with a copper catalyst, if necessary, such as cuprous chloride in pyridine and an aromatic hydrocarbon, such as xylene, as described in U.K. patent specification No.

2,050,168. The reaction may alternatively be carried out in the presence of an alkali metal carbonate, for example sodium or potassium carbonate, followed by treatment- with cuprous oxide and/or copper powder in dimethylformamide or quinoline. The reaction may suitably be carried out at a temperature in the range of from 20 to 1500C and conveniently the reaction is carried out at the reflux temperature of the reaction mixture. The ether aldehydes may also be prepared by condensation of an optionally substituted hydroxybenzaldehyde and an optionally substituted halobenzene or halopyridine, suitably under the conditions of UK specification No. 2,050,168 described above.

Alternatively, the compounds of general formula V may be prepared by condensation of an optionally substituted phenol or phenolate with an optionally substituted halobenzoic acid ester, or by reacting an optionally substituted hydroxybenzoate with an optionally substituted halobenzene or halopyridine, suitably under conditions of UK specification No. 2,050,168 described above.

The compounds of general formula V may also be derived by reacting together an optionally substituted halobenzonitrile with an optionally substituted phenol or phenolate, and hydrolysing and esterifying under standard conditions to yield the ester group from the nitrile.

Compounds of general formula II in which W represents a halogen atom may be derived from the corresponding ether carboxylic acid, for example by reaction of the acid with thionyl chloride. The acid may be derived as described above from a phenolic compound and a halobenzaldehyde or halobenzoic acid ester.

Compounds of general formula III are known compounds and may be prepared using conventional techniques.

The compounds of general formula IV are believed to be novel and may be prepared by reacting a compound of general formula VI

in which Ym is as defined above and W represents a cyanomethyl group, with a dialkylformamide dialkyl acetal, preferably dimethylformamide dimethylacetal, under the same conditions as described above for the reaction of compounds of general formula II in which W is a cyanomethyl group, with a dialkylformamide dialkyl acetal.

The compounds of the invention have been found to have surprisingly high herbicidal activity with a wide spectrum of activity against grasses and, especially, broadleaved weeds, particularly when applied post-emergence.

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, preferably post-emergence. The dosage of active ingredient used, may, for example, be in the range of from 0.01 to 10 kg/ha, suitably 0.05 to 4 kg/ha. The locus may, for example, be the soil or plants in a crop area, typical crops being cereals such as wheat, barley and rice.

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, 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.

Suitably 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; 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 superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexenone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosene 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, sorbitol, 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 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 0.5-10% 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 0.5-75% 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-Z0% 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.

Aqeuous 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 compositions of the invention may also contain other active ingredients, for example compounds possessing insecticidal or fungicidal properties or other herbicidal compounds.

The following Examples illustrate the invention.

Examples 1 to 20 relate to the preparation of starting materials, Examples 21 to 40 to the preparation of novel intermediates of general formula II and Examples 41 to 60 to the preparation of compounds of general formula I. Structures were confirmed by mass spectroscopy and 300'H nmr.

Example 1 Preparation of methyl-2- (3 '-o',o4 o(, -trifluoromethylphenoxy)benzoate A solution of sodium methoxide (from 2.65g sodium and 45ml methanol) was added to a solution of 3-t -trifluoromethylphenol (17.8g) in xylene (100ml). The resulting solution was evaporated to dryness in vacuo. Fresh xylene (l00ml) was added to the sodium phenolate and the xylene re-evaporated.

Pyridine (50ml) and xylene (loom) were added to the dry sodium phenolate, followed by cuprous chloride (3g). The solution was heated to reflux with stirring and a solution of methyl -2 -bromobenzoate (21.5g) in xylene (25ml) was added dropwise. The resultant mixture was refluxed for 16 hours. After cooling the reaction mixture was poured into water, acidified with dilute hydrochloric acid and the aqueous phase extracted with diethyl ether. After drying over anhydrous magnesium sulphate, the ether was evaporated. The residual oil was purified on a silica-gel column using methylene dichloride as eluant to give the title compound (21g) as an orange oil.

m/e - Found: Theory, 296 : 296.

Analysis: Calculated for C15H11O3F3 : C 60.8 H 3.7% Found : C 60.6 H 3.8% The compounds of general formula V listed in Table 1 below, were prepared by methods similar to that described in Example 1 above (using methyl-4-bromobenzoate in the case of Examples 14, 15, 16 and 17).

Table 1

(General Formula V Z is CH; R is CH3)

Elemental Analysis (%) C H Melting m/e Ester group (Calc. (Calc. Point (Theory Example Xn Ym position Found) Found) ( C) Found) No. (to-o-) 2 - - 2 73.7 5.3 oil 228 74.0 5.4 228 3 3-CF3,4-Cl - 2 54.5 3.0 oil 330 53.9 3.1 330 4 3-Cl - 2 64.1 4.2 oil 262 63.6 4.5 262 5 2,4-Cl2 - 2 56.8 3.4 oil 296 56.2 3.6 296 Table 1 (continued)

Elemental Analysis (%) C H Melting m/e Ester group (Calc. (Calc. Point (Theory Example Xn Ym position Found) Found) ( C) Found) No. (to-o-) 6 4-Cl - 2 64.1 4.2 39-41 262 63.5 4.1 262 7 3-CH3 - 2 74.4 5.8 oil 242 74.9 5.7 242 8 3-CN - 2 71.1 4.3 (N 5.5) 53-54 253 71.6 4.2 (N 5.6) 253 9 3.4-O-CH2-O- - 2 66.2 4.4 oil 272 66.0 4.4 272 10 3-F - 2 68.3 4.5 oil 246 66.3 4.5 246 11 3-OC2H5 - 2 70.6 5.9 oil 272 67.0 5.7 272 Table 1 (continued)

Elemental Analysis (%) C H Melting m/e Ester group (Calc. (Calc. Point (Theory Example Xn Ym position Found) Found) ( C) Found) No. (to -o-) 12 3,5-Cl2 - 2 56.8 3.4 68-71 296 56.9 3.4 296 13 2-Cl - 2 64.1 4.2 oil 262 64.4 4.3 262 14 - - 4 73.7 5.3 58-59 228 73.6 5.5 228 15 3-CF3 - 4 61.9 4.2 oil 310 62.2 4.2 310 16 3-Cl - 4 65.2 4.7 oil 276 65.6 4.8 276 17 3-CF3 3-CH3 4 61.9 4.2 oil 310 61.7 4.1 310 18 3-CF3 3-F 2 57.9 3.2 oil 314 59.2 3.7 314 Example 19 Preparation of ethyl-2-(5'-α, ,-trifluoromethyl- pyridyloxy)benzoate Ethyl-2-hydroxybenzoate (16.6g) in dry dimethylformamide (40ml) was added to a stirred mixture of anhydrous potassium carbonate (13.8g) and 2-chloro-5-(α,α,α-trifluoromethyl)pyridine (16.2g) in dry dimethylformamide (120ml). The mixture was refluxed for 3 hours. After cooling to ambient temperature, the solution was poured into an equal volume of water and the aqueous mixture extracted with diethyl ether.The extracts were dried over anhydrous magnesium sulphate and the ether evaporated. The residual oil was purified on a silica gel column using 10% diethyl ether-petroleum ether (v/v) as eluant to give the title compound (13.lg) as a colourless oil.

m/e - Theory : Found 311:311.

Analysis: Calculated for C15H12O3NF3 : C 57.9 H 3.9 N 4.5% Found : C 59.0 H 4.5 N 4.5% Example 20 Preparation of methyl-2-(3'-α,α,α-trifluoromethyl phenoxy)-4-fluorobenzoate The title compound was prepared in standard manner by hydrolysis of the corresponding nitrile followed by esterification, the nitrile having been prepared from 3-b Dc,&num;-trifluoromethylphenol and cyano-2,4-difluorobenzene which were coupled using the method of Example 19. The title compound was an oil.

m/e - Theory : Found, 314: 314 Calculated for C15H10O3F4 : C 57.3 H 3.2% Found : C 57.7 H 3.2% Example 21 Preparation of 2-(3'-α,α,α-trifluoromethylphenoxy)- benzoylacetonitrile To a suspension of sodamide (prepared from 1.2g sodium metal in 60ml liquid ammonia with O.lg ferric nitrate) was added a solution of dry acetonitrile (2.lg) in dry diethyl ether (5ml) over 5 minutes.

After a further 5 minutes, methyl-2-(3'-D,,- trifluoromethylphenoxy)benzoate, the title compound of Example 1, in diethyl ether (25ml) solution was added as quickly as possible. After stirring for a further 1 hour at below -30 C, the ammonia was removed by warming on a water bath, whilst at the same time diethyl ether was added to maintain the reaction mixture volume of approximately 100ml. The ethereal solution was then cautiously poured onto ice (50g). The aqueous layer was separated, washed with diethyl ether and acidified with 6M hydrochloric acid. The aqueous mixture was extracted with diethyl ether, the extracts dried over anhydrous magnesium sulphate and the ether evaporated to give a red oil.

Purification on a silica gel column using 10% (v/v) diethyl ether-methylene dichloride as eluant gave the title compound (6.2g) as a yellow oil.

m/e - Theory : Found 305: 305.

Analysis: Calculated for C16H10NO2F3 : C 62.9 H 3.3 N 4.6% Found : C 61.8 H 3.7 N 4.6% The compounds of general formula II listed in Table 2 below, were prepared by methods similar to that described in Example 21 above, from the intermediates of Examples 2 to 20.

Table 2

(General Formula V W is cyanomethyl)

Elemental Analysis (%) C H N Melting m/e Ester group (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to-o-) 22 - CH - 2 75.9 4.6 5.9 82-83 237 75.6 4.7 5.4 237 23 3-CF3,4-Cl CH - 2 56.6 2.7 4.1 81-82 339 56.7 2.7 4.1 339 24 3-Cl CH - 2 66.4 3.7 5.2 73-74 271 66.1 3.6 5.3 271 25 2,4-Cl CH - 2 59.0 3.0 4.6 104-105 305 58.6 3.1 4.7 305 Table 2 (continued)

Elemental Analysis (%) C H N Melting m/e Ester group (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to-o-) 26 4-Cl CH - 2 66.4 3.7 5.2 87-88 271 66.0 3.7 5.2 271 27 3-CH3 CH - 2 76.5 5.2 5.6 88-89 251 76.2 5.0 5.6 251 28 3-CN CH - 2 73.3 3.8 10.7 90-91 262 73.3 4.0 10.6 262 29 3.4-O-CH2-O- CH - 2 68.3 3.9 5.0 90-92 281 68.0 4.1 5.6 281 30 3-F CH - 2 70.6 3.9 5.5 59-60 255 70.5 4.0 5.7 255 31 3-OC2H5 CH - 2 72.6 5.3 5.0 70-72 281 69.3 5.2 5.0 281 Table 2 (continued)

Elemental Analysis (%) C H N Melting m/e Ester group (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to-o-) 32 3.5-Cl2 CH - 2 59.0 3.0 4.6 102-104 305 59.0 3.0 3.9 305 33 2-Cl CH - 2 66.4 3.7 5.2 104-105 271 66.1 3.7 5.6 271 34 - CH - 4 75.9 4.6 5.9 95-96 237 75.9 4.6 5.9 237 35 3-CF3 CH - 4 63.0 3.3 4.6 78-80 305 63.0 3.4 4.7 305 36 3-Cl CH - 4 66.4 3.7 5.2 oil 271 64.5 3.7 5.1 271 37 3-CF3 CH 3-CH3 4 - - - - Table 2 (continued)

Elemental Analysis (%) C H N Melting m/e Ester group (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to-o-) 38 3-CF3 CH 3-F 2 59.4 2.8 4.3 oil 323 59.3 3.0 4.2 323 39 4-CF3 N - 2 58.8 2.9 9.2 80-81 306 (to N) 57.7 3.1 9.7 306 40 3-CF3 CH 4-F 2 59.4 2.8 4.3 80-82 323 (to 0) 59.4 2.9 4.5 323 Example 41 Preapration of 2-[2-(3'-α,α,α-trifluoromethyl- phenoxy) benzoyl 1 -3-dimethylaminoacrylonitrile To a solution of 2-(3'-α,α,α;-trifluoromethyl- phenoxy)benzoyl acetonitrile (6g), the title compound of Example 19, in dichloromethane (100ml) was added dimethylformamide dimethylacetal (lOml). After stirring at ambient temperature for 30 minutes, the dichloromethane was removed by evaporation. The residue was purified on a silica gel column using 10% diethyl ether-dichloromethane (v/v) as eluant to give the title compound (6.5g) as a white solid of m.p. 61-63'C.

m/e - Theory : Found, 360 : 360.

Analysis: Calculated for ClgH15N202F3 : C 63.3 H 4.2 N 7.8% Found : C 63.8 H 4.3 N 7.7% The compounds of general formula I listed in Table 3 below were prepared by methods similar to.

that described in Example 41 above, from the intermediates of Examples 22 to 40 above.

Table 3

(General Formual I Q is C(O)C(CN)=CHN(CH3)2)

Elemental Analysis (%) C H N Melting m/e Acryloyl (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to -o-) 42 - CH - 2 74.0 5.5 9.6 81-82 232 74.2 6.0 9.6 292 43 3-CF3,4-Cl CH - 2 57.9 3.6 7.1 38-41 394 57.9 3.7 7.2 394 44 3-Cl CH - 2 66.3 4.6 8.6 73-74 326 66.3 4.6 8.7 326 45 2,4-Cl2 CH - 2 60.0 3.9 7.7 68-70 360 59.9 4.1 7.8 360 Table 3 (continued)

Elemental Analysis (%) C H N Melting m/e Acryloyl (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to -o-) 46 4-Cl CH - 2 66.3 4.6 8.6 148-149 326 65.6 4.7 8.5 326 47 3-CH3 CH - 2 74.5 5.9 9.2 105-106 306 75.2 6.3 9.6 306 48 3-CN CH - 2 71.9 4.7 13.2 124-125 317 71.6 5.0 13.2 317 49 3.4-O-CH2-O- CH - 2 67.9 4.8 8.3 124-125 336 68.6 4.8 8.4 336 50 3-F CH - 2 69.7 4.8 9.0 96-98 310 69.6 5.0 9.0 310 51 3-OC2H5 CH - 2 71.4 6.0 8.3 105-107 336 71.8 6.1 8.5 336 Table 3 (continued)

Elemental Analysis (%) C H N Melting m/e Acryloyl (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to -o-) 52 3,5-Cl2 CH - 2 60.0 3.9 7.8 118-120 360 59.5 3.9 8.1 360 53 2-Cl CH - 2 66.3 4.6 8.6 100-101 326 66.3 4.8 8.7 326 54 - CH - 4 74.0 5.5 9.6 98-99 292 74.1 5.8 9.3 292 55 3-CF3 CH - 4 63.3 4.2 7.8 94-96 360 63.6 4.2 8.0 360 56 3-Cl CH - 4 66.3 4.6 8.6 97-99 326 65.4 4.6 8.2 326 57 3-CF3 CH 3-CH3 4 64.2 4.5 7.5 oil 374 63.6 4.9 7.8 374 58 3-CF3 CH 3-F 2 60.3 3.7 7.4 39-41 378 60.2 4.3 7.0 378 Table 3 (continued)

Elemental Analysis (%) C H N Melting m/e Acryloyl (Calc. (Calc. (Calc. Point (Theory Example Xn Z Ym position Found) Found) Found) ( C) Found) No. (to -o-) 59 5-CF3 N - 2 59.8 3.9 11.6 49-50 361 (to N) 59.4 4.2 11.4 361 60 3-CF3 CH 4-F 2 60.3 3.7 7.4 97-98 378 (to 0) 60.5 3.9 7.7 378 Herbicidal Activity To evaluate their herbicidal activity, compounds of formula I according 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 usitatissimum (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 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 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 Table 4 below. A blank space in Table 4 indicates a rating 0, and the symbol - indicates that no result was obtained.

Table 4

Compound Foliar spray of Soil drench 10 kg/ha Dosage 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 41 6 3 6 4 - 7 6 6 5 5 2 7 5 5 8 7 7 5 7 4 3 8 9 3 1 3 1 7 3 3 8 6 7 4 7 2 1 8 9 2 42 6 4 6 4 2 7 6 4 5 3 7 2 6 7 8 6 6 4 8 4 3 8 8 2 1 1 3 3 5 6 5 4 6 2 4 43 6 7 3 2 6 5 3 5 5 7 3 5 8 8 7 3 4 5 3 1 2 5 2 3 8 7 7 3 2 2 44 7 4 7 5 2 9 6 7 5 5 2 7 3 6 8 8 6 5 4 6 2 1 4 7 3 1 3 1 5 2 5 6 5 5 4 1 4 1 2 4 1 45 4 5 2 3 1 3 6 4 5 2 1 2 2 4 2 4 2 Table 4 (continued)

Compound Foliar spray of Soil drench 10 kg/ha Dosage 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 46 6 4 6 3 3 5 2 5 4 6 2 3 7 6 5 3 6 2 2 7 6 1 2 4 1 2 6 5 3 2 5 4 2 47 5 5 6 2 5 3 3 5 4 4 2 3 5 7 6 5 5 7 1 2 4 5 3 1 2 1 1 2 3 4 3 2 2 4 1 1 1 48 8 7 8 5 6 8 7 5 6 2 7 2 5 7 8 7 7 6 8 4 2 7 9 5 1 3 1 3 1 3 6 5 6 5 3 7 1 1 6 8 2 49 7 5 7 2 1 7 5 4 1 6 1 5 6 7 4 5 2 5 1 3 1 1 2 3 3 6 6 4 2 1 1 50 7 6 8 6 2 6 7 6 5 5 2 7 3 5 9 0 8 7 5 8 5 2 8 9 2 1 4 1 4 2 3 6 7 5 4 1 6 2 1 5 8 Table 4 (continued)

Compound Foliar spray of Soil drench 10 kg/ha Dosage 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 51 7 7 8 4 2 5 5 7 5 6 2 5 3 4 6 6 6 6 5 8 3 2 6 7 4 1 2 2 4 1 4 5 4 5 5 3 8 4 4 52 7 6 7 6 2 6 6 4 5 6 3 7 4 5 7 8 6 5 4 7 5 3 8 9 4 1 3 3 5 2 4 7 6 5 5 2 6 2 1 5 7 53 4 2 1 5 1 2 2 5 4 3 1 1 1 1 1 1 3 2 3 1 54 5 2 2 3 6 4 1 1 55 3 2 2 5 4 1 7 5 7 9 8 3 1 1 5 2 6 8 5 2 Table 4 (continued)

Compound Foliar spray of Soil drench 10 kg/ha Dosage 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 56 5 2 4 2 5 9 8 4 1 1 4 8 5 57 5 6 5 2 6 9 7 4 1 2 3 7 5 2 58 3 3 5 3 3 2 2 8 6 4 1 1 1 1 5 3 3 59 8 6 6 4 7 6 7 5 4 1 4 3 4 6 5 5 7 4 8 4 3 8 8 5 1 2 1 1 3 5 4 5 4 2 5 6 60 4 2 4 2 2 1 5 3 4 2 3 7 6 4 2 2 1 3 2 3 5 3 2 2

Claims

CLAIMS 1. A compound of general formula I

in which Q represents a group of general formula -C(O)-C(CN)=CH-NRR, the group Q being located ortho or para to the oxygen linkage, R and R each independently represents an alkyl group, Z represents a nitrogen atom or a group CH which is unsubstituted or substituted by a substituent X, m is O or an integer from 1 to 4, the or each Y independently represents a halogen atom or an alkyl group, n is O or an integer from 1 to 5, and the or each X independently represents a halogen atom, a group selected from alkyl, haloalkyl, cyanoalkyl, alkenyl, alkynyl, alkenyloxy, alkynyloxy, alkoxy, haloalkoxy, haloalkylthio, alkylthio, alkenylthio, alkynylthio, cyano, nitro, alkylsulphonyl, alkylsulphinyl and sulphonamido, or a phenyl group optionally substituted by one or more moieties independently selected from alkyl, haloalkyl and alkoxy groups and halogen atoms; or two adjacent groups X may together represent an alkylenedioxy group.
2. A compound as claimed in Claim 1, wherein R1 and R2 are the same and each represents a methyl group.
3. A compound as claimed in Claim 1 or 2, wherein Z represents an unsubstituted group CH.
4. A compound as claimed in any one of Claims 1 to 3, wherein m is 0, or m is 1 and Y represents a fluorine atom or a methyl group.
5. A compound as claimed in any one of the preceding claims wherein n is 1 or 2 and the or each group X is independently selected from fluorine or chlorine atoms and methyl, trifluoromethyl, ethoxy, or cyano groups; or two adjacent groups X together represent a methylenedioxy group.
6. A compound as claimed in any preceding claim,.

wherein a substituent X is located meta to the oxygen linkage and is a trifluoromethyl group.
7. A compound as claimed in any preceding claim, wherein the group Q is ortho to the oxygen linkage.
8. A process for the preparation of a compound of general formula I as claimed in any preceding claim, which comprises reacting a compound of general formula II

in which X, Y, n and m are as defined in any preceding claim, and W represents a halogen atom or a cyanomethyl group, with, in the case where W is halogen, a dialkylaminoacrylonitrile under basic conditions, or, in the case where W is cyanomethyl, either with a dialkylformamide dialkyl acetal, or with a trialkylorthoformate followed by reaction with a dialkylamine or reacting a compound of general formula III

wherein n, X and Z are as defined in any preceding claim and L represents a leaving group with a compound of general formula IV

wherein m, Y and Q are as defined in any preceding claim, under basic conditions;; and if desired or required, converting a resulting compound of general formula I into another compound of general formula I.
9. A process as claimed in claim 8, wherein W is cyanomethyl and the compound of general formula II is reacted with a dialkylformamide dialkylacetal in an inert solvent at a temperature in the range 0 to 50C.
10. A herbicidal composition which comprises a compound as claimed in any one of Claims 1 to 7, together with at least one carrier.
11. A composition as claimed in Claim 10, comprising at least two carriers, at least one of which is a surface-active agent.
12. A 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 7, or a composition as claimed in Claim 10 or Claim 11.
13. The use of a compound as claimed in any one of Claims 1 to 7, or a composition as claimed in Claim 10 or Claim 11, as a herbicide.