GB1594261A

GB1594261A - Benzyloxime ethers

Info

Publication number: GB1594261A
Application number: GB7012/77A
Authority: GB
Original assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Current assignee: SHELL INT RESEARCH; Shell Internationale Research Maatschappij BV
Priority date: 1977-02-18
Filing date: 1977-02-18
Publication date: 1981-07-30
Also published as: IL54061A; IT7820345A0; TR19839A; IE46335B1; LU79074A1; BR7800948A; FR2381025B1; IL54061A0; AU517746B2; IE780334L; BE863890A; FR2381025A1; CA1166652A; MX5186E; ZA78914B; DK69878A; DE2806664A1; AU3334778A; JPS53103449A; ES467027A1

Abstract

Compounds of the general formula: <IMAGE> in which R<1> is a substituted or unsubstituted aryl or alkyl group, R<2> is a substituted or unsubstituted cycloalkyl group, X is an oxygen atom or a methylene group, Y is a hydrogen or halogen atom or an alkyl or alkoxy group, and n is an integer from 1 to 5 are used for pest control, in particular against insects and ticks.

Description

(54) BENZYLOXIME ETHERS (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ a V., a company organised under the laws of The Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a group of compounds, which may be termed benzyloxime ethers, having interesting pesticidal activity. It also relates to a method of preparing the compounds and to a pesticidal composition comprising one or more of the compounds.

The present invention provides compounds of the following general formula:-

wherein R1 is an optionally-substituted aryl or alkyl group; R2 is an optionally-substituted cycloalkyl group; X is an oxygen atom or a methylene group; Y is a hydrogen or halogen atom, or an alkyl or alkoxy group; and n is an integer of 1 to 5.

When R1 represents an optionally-substituted aryl group in Formula I it is preferably a naphthyl group or an optionally-substituted phenyl group of the following structure:-

wherein Z is a hydrogen or halogen atom, or an alkyl or alkoxy group, and m is an integer of 1 to 5. Generally speaking, better insecticidal activity has been observed when there is a substituent in the 4 position and m is 1 or 2; Z may be e.g. chlorine, bromine, fluorine, methyl, ethyl, tertiarybutyl or methoxy.

When Rl represents an opticnally-substituted alkyl group, it can be a straight or branched-chain alkyl group and may have as substituent or substituents one or more halogen atoms, or alkoxy or aryl groups, e.g. chlorine, bromine, fluorine, methoxy or phenyl. The alkyl group preferably contains up to 10 carbon atoms.

The substituent Y preferably represents a hydrogen atom but can also be an alkyl or alkoxy group of 1 to 4 carbon atoms or a halogen atom, e.g. chlorine, fluorine or bromine atom.

The group R2 preferably represents a substituted or unsubstituted cycloalkyl group of 3 to 6 carbon atoms, e.g. a cyclopropyl or cyclobutyl group, for example a cyclopropyl group having the following formula:-

wherein Ra and Rb both represent hydrogen atoms, alkyl groups having from 1 to 6 carbon atoms, especially methyl, or halogen atoms, especially chlorine or bromine atcms; or Ra and Rb together represent an alkylene group having from 2 to 6, especially 3, carbon atoms; or Ra represents a hydrogen atom and Rb represents an alkenyl group having from 2 to 6 carbon atoms, especially an isobutenyl group, or an haloalkenyl group having from 2 to 6 carbon atoms and from 1 to 3 chlorine or bromine atoms, especially a mono- or dichlorovinyl group; Rd and Rd both represent hydrogen atoms or alkyl groups having 1 to 6 carbon atoms, especially methyl, or Rd is hydrogen and Rd is an alkenyl group having from 2 to 6 carbon atoms, especially an isobutenyl group, or an haloalkenyl group having from 2 to 6 carbon atoms and from 1 to 3 chlorine or bromine atoms, especially a mono-or dichlorovinyl group; or Rd and Rd together represent an alkylene group having from 2 to 6, especially 3 carbon atoms. A better level of pesticidal activity has generally been noted where R2 in the general formula I represents an unsubstituted cyclopropyl group.

Because of their high level of activity against the corn-ear worm (Heliothis zea) the following group of compounds are preferred :

wherein R1 is phenyl, cblorophenyl, dichlorophenyl, bromophenyl, dibromophenyl fluorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, methoxyphenyl, butylphenyl, ethylphenyl or naphthyl; and Y is hydrogen, chlorine, fluorine or bromine.

It will be appreciated that the compounds according to the invention exhibit geometrical isomerism about the oximic double bond and, accordingly, the invention also extends to these individual isomers and to mixtures thereof. It has been found that, in general terms, the isomer in which R2 (the optionally-substituted cycloalkyl group) and the 3-substituted benzyloxy group in the compounds of formula I are in a syn relationship about the double bond is more insecticidally-active than the isomer in which the two groups are in anti relationship; more correctly the nomenclature of these two geometric isomers should be referred to as the E- and Z-isomers, the E isomer being the more active form. Accordingly, the preferred form of the compounds according to the invention is the E-isomer or a mixture of the two isomers in which the E-isomer predominates.

The compounds according to the invention may be prepared by methods known for the preparation of oxime ethers. A ketoxime of formula:-

wherein Rl and R2 have the meanings previously defined, is a preferred starting material. A method for the preparation of compounds of the invention comprises reacting an alkali metal salt of a ketoxime of formula V with a substituted benzyl halide of formula:-

wherein X, Y and n have the meanings previously defined and Q is a halogen, preferably bromine, atom. The reaction is preferably carried out in the presence of a polar aprotic solvent; particularly suitable solvents are anhydrous acetonitrile, dimethylformamide in toluene, or tetrahydrofuran. Reaction temperatures are generally in the range 60-1S00C preferably in the range 1OO-1100C and reaction times of 2 to 10 hours may be used. Altematively the reaction of the alkali metal salt of a ketoxime of formula V with a substituted benzyl halide of formula VI may be carried out in a two-phase organic/inorganic system in the presence of a phase transfer catalyst. The phase transfer catalyst may be any reagent which will accelerate interphase reactions in organic-inorganic two-phase systems. The alkali metal salt of the ketoxime of formula V may be prepared by the reaction of an alkali metal hydride with the ketoxime, for example, sodium hydride, or by reaction of aqueous potassium or sodium hydroxide with the ketoxime. Under normal conditions the alkali metal salt of the ketoxime is prepared in situ.

The benzyl oxime ethers of the invention are of interest as pesticides, in particular as insecticides, tickicides and acaricides for agricultural and domestic outlets.

The invention therefore includes within its scope pesticidal compositions comprising a carrer and/or a surface-active agent together with, as active ingredient, a benzyl oxime ether of formula I. The invention also includes a method of combating insect, tick and/or acarid pests at a locus which comprises applying to the locus a pesticidally effective amount of a benzyl oxime ether of the invention or composition containing such a compound.

The term'carrier'as used herein means a material, which may be inorganic or organic and of synthetic or natural origin, with which the active compound is mixed or formulated to facilitate its application to the plant, seed, soil or other object to be treated, or its storage, transport or handling. The carrier may be a solid or a liquid.

Any of the materials usually applied in formulating pesticides, herbicides, or fungicides may be used as the carrier.

Suitable solid carriers are 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, montmorillinites and micas; calcium carbonates; calcium sulphate; synthetic hydrates silicon oxides and synthetic calcium or aluminium silicates; elements for example, carbon and sulphur; natural and synthetic resins such as, for example, coumarone resins, polyvinyl chloride and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes such as for example, beeswax, paraffin wax, and chlorinated mineral waxes; and solid fertilisers, for example, superphosphates.

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

The surface-active agent may be an emulsifying agent or a dispersing agent or a wetting agent; it may be nonionic or icnic. Any of the surface-active agents usually applied in formulating pesticides, herbicides or fungicides, may be used. Examples of suitable surface-active agents are the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitan, sucrose or pentaery thritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohols or alkyl phenols for example p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, or 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 sodium dodecylbenzene sulphate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders are usually compounded to contain 25, 50 or 75% of toxicant and usually contain, in addition, to solid carrier, 3-10 0/0w 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 3--lo%w of toxicant. Granules are usually prepared to have a size between 10 and 100 Bs mesh (1.670--0.152 mm), and may be manufactured by agglomeration or impregnation techniques. Generally granules will contain --25%w toxicant and 0-10%w of additives such as stabilisers, slow release release modifiers and binding agents. Emulsifiable concentrates usually contain, in addition to the solvent and, when necessary, co-solvent, 10-50%w toxicant, 2--20%w/v emulsifiers and 0-200/0w/v of appropriate additives such as stabilisers, penetrants and corrosion inhibitors. suspension concentrates are compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-750/0w toxicant, 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 appropriate additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and as carrier, water or an organic liquid in which the toxicant is substantially insoluble; certain organic solids or inorganic salts may be dissolved in the carrier to assist in preventing sedimentation or as antifreeze agents 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 present invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick "mayonaise"-like consistency.

Th compositions of the invention may also contain other ingredients, for example, other compounds possessing pesticidal, herbicidal or fungicidal properties.

The invention is further illustrated in the following Examples.

Example 1.

Preparation of cyclopropyl-4-fluorophenyl ketoxime 3-phenylbenzyl ether.

Cyclopropyl-4-fluorophenyl ketoxime (2.4 g) in dry acetonitrile (50 ml) and sodium hydride (0.64 g of 50% dispersion in oil) was stirred at room temperature for 2 hours. 3-Phenoxybenzyl bromide (3.5 g) was added and the mixture refluxed for 3 hours. The reaction mixture was cooled, filtered, evaporated and the residue dissolved in diethyl ether. The ether solution was washed in turn with 7% sulphuric acid solution, 10% sodium bicarbonate and water and dried over sodium sulphate.

The solvent was then removed under reduced pressure and the residue was chromato graphed on silica gel in hexane, using 4:1 toluene:hexane as eluant to give the desired product as a colourless oil.

Analysis Calculated for C2,H20NO2F: C 76.4; H 5.5; N 3.8% Found: : C 76.8; H 5.7; N 3.8% Example 2.

Preparation of cyclopropyl-2,4-xylyl ketoxime 3-phenoxybenzyl ether.

Cyclopropyl 2,4-xylyl ketoxime (1.89 g) in dry acetonitrile (50 ml) and sodium hydride (0.5 g of 50% dispersion in oil) were stirred at room temperature for 1 hour. 3-Phenoxybenzyl bromide (2.88 g) was added and the mixture refluxed for 4 hours, then stirred for a further 48 hours. The reaction product was then filtered, the filtrate evaporated and the residue dissolved in diethyl ether. The residue obtained after washing and removal cf solvent, as'in the above preparation, was chromatographed on silica gel in hexane using toluene as eluant to give the desired product as a colourless oil.

Analysis Calculated for C2H2NO,: C 80.8; H 6.8; N 3.8% Found: : C 80.7; H 6.9; N 3.6% Example 3.

Preparation of cyclopropyl-4-chlorophenyl ketoxime 3-phenylbenzyl ether Cyclopropyl-4-chlorophenyl ketoxime (1.95 g, 0.01 mole) in 20% dimethylformamide/toluene (25 ml) was added dropwise to sodium hydride (1.0 g of a 50% dispersion in oil) in dimethylformamide/toluene (20 ml) at 70--80"C over 30 minutes. 3-Phenoxybenzyl bromide (2.9 g, 0.01 mole) in 20% dimethylformamide/ toluene (25 ml) was then added and the mixture refluxed for 3 hours. After cooling 5 ml of methanol was added and the reaction mixture was poured onto ice/hydrochloric acid and the product then extracted with diethyl ether, washed with 10% sodium carbonate solution (X4) and dried over sodium sulphate. The solvent was removed and the residue chromatographed on silica gel using toluene as eluant. Two fractions were eluted from the column. After removal of solvent the residue from the first fraction, obtained as an oil, was identified as isomer E. R.I. nD22 = 1.6078.

The residue from the second fraction, obtained as an oil, was identified as a 1:1 E:Z isomer mixture, R.I. nD22 = 1.6059. The Z isomer was isolated with an R.I. of nD1' 1.5940.

Analysis Calculated for C23H20NO2Cl: C 73.1; H 5.3; N 3.7% Found: E isomer : C 73.1; H 5.5; N 3.4% 1:1 E:Z isomer mixture : C 72.1; H 5.4; N 3.5% Z isomer : C 73.4; H 5.2; N 3.4% Example 4.

Preparation of cyclobutyl-4-fluorophenyl ketoxime 3-phenoxybenzyl ether.

Cyclobutyl-4-fluorophenyl ketoxime (1.35 g, 0.007 mole) in 20% dimethylformamide/toluene (25 ml) was added dropwise to sodium hydride (0.7 g of 50% disnersion in oil) in dimethylformamide/toluene (20 ml) at 70--80"C over 10 minutes.

3-Phenoxybenzyl bromide (1.85 g, 0.007 mole) in 20% dimethylformamide/toluene (20 ml) was then added and the mixture refluxed for 3 hours at 100-1100 C. The reaction mixture was then cooled to room temperature filtered and the filtrate evaporated and the residue dissolved in diethyl ether. The residue obtained after washings and removal of solvent was chromatographed on silica gel using toluene as eluant to give the desired product as an oil R.I. nD20 1.5858.

Analysis Calculated for C2tH22NO2F : C 76.8; H 5.9; N 3.7% Found: : C 77.2; H 5.9; N 3.7% Examples 5-10.

Further examples of the compounds according to the invention were prepared by the methods disclosed in the preceding examples. The structure and physical data of these compounds are shown in Table I.

TABLE I

Example Compound R.I. or Number R1- m.p. Analysis 5 phenyl oil Calculated for C23H21NO2 C 80.4; H 6.2% Found C 80.1; H 6.2% 6 4-bromophenyl nD17 1.6209 Calculated for C23H20NO2Br C 65.4; H 4.7% Found C 65.7; H 4.9% 7 4-tertiary-butylphenyl nD20 1.5872 Calcualted for C23H29NO2 C 81.2; H 7.3% Found C 81.7; H 7.4% 8 4-methoxyphenyl nD20 1.5934 Calculated for C24H23NO3 C 77.2; H 6.2% Found C 76.9; H 6.4% 9 3,4-dimethylphenyl nD20 1.5953 Calculated for C25H25NO2 C 80.9; H 6.7% Found C 80.5; H 7.0% 10 4-ethylphenyl nD20 1.5939 Calculated for C25H25NO2 C 80.9; H 6.7% Found C 81.1; H 6.7% Examples 11-22.

Twelve further compounds according to the invention wre prepared by the methods disclosed in Examples 1 to 4. The structure and physical data are shown in Table II.

TABLE II

Example R.I. or Number R1 R@ Y m.p. Analysis 11 4-bromo-phenyl H F nD19 1.6090 Calculated for C23H19NO2BrF C 62.7; H 4.3; N 3.2% Found C 62.6; H 4.2; N 3.0% 12 4-chloro-phenyl 2,2,3,3-tetramethyl H nD19 1.5822 Calculated for C27H28NO2Cl C 74.7; H 6.5; N 3.2% Found C 74.6; H 6.8; N 3.9% 13 4-chloro-phenyl 2,2-dimethyl H nD22 1.5920 Calculated for C25H24NO2Cl C 74.0; H 5.9; N 3.4% Found C 73.9; H 5.7; N 3.2% 14 3,4-dichloro-phenyl H H nD16 1.6160 Calculated for C23H19NO2Cl C 67.0; H 4.7; N 3.4% Found C 67.3; H 4.7; N 3.2% 15 3-chloro-phenyl H H nD16 1.6080 Calcualted for C23H20NO2Cl C 73.1; H 5.3; N 3.7% Found C 73.5; H 5.5; N 3.6% 16 4-methyl-phenyl H H nD16 1.600 Calculated for C24H23NO2 C 80.2; H 6.5; N 3.9% Found C 80.3; H 6.3; N 3.5% TABLE II (cont.)

Example R.I. or Number R1 R Y m.p. Analysis 17 4-methoxy-phenyl H F nD16 1.592 Calculated for C24H22NO3FC C73.6; H 5.7; N 3.6% Found C 73.6; H 5.8; N 3.2% 18 4-fluoro-phenyl H F nD18 1.582 Calculated for C23H19NO2F2 C 72.8; H 5.1; N 3.7% Found C 72.7; H 5.0; N 3.2% 19 4-chloro-phenyl H F nD21 1.5970 Calculated for C23H19ClFNO2 @ C 69.8; H 4.8; N 3.5% Found C 69.8; H 5.0; N 3.4% 20 4-chloro-phenyl H H nD21 1.614 Calculated for C23H19BrClNO2 C 60.3; H 4.2; N 3.1% Found C 62.0; H 4.5; N 3.4% 21 4-chloro-phenyl 2-chloro H (insulfficient material available for analysis - but the structure was confirmed by NMR spectroscopy) 22 naphthyl H H nD16 1.639 Calcualted for C27H23NO2 C 82.4; H 5.9; N 3.6% Found C 81.9; H 6.2; N 3.4% Example 23.

The insecticidal and tickicidal activity of the compounds according to the present invention was assessed employing the following pests: Insects:- Musca domestica (M. d.) Spodoptera littoralis (S.1.) Heliothis zea (H.z.) Ticks : Boophilus microplus (B.m.) The test methods employed for each species appear below:- (i) Musca domestica (M.d.) A 0.4% by weight solution in acetone of the compound to be tested was prepared and taken up in a micrometer syringe. Two to three days old adult female houseflies (Musca domestica) were anaesthetized with carbon dioxide, and 1 zzl of the test solution was applied to the central side of the abdomen of each fly, 20 flies being tested. The treated flies were held in glass jars covered with paper tissue held by an elastic band. Cotton-wool pads soaked in dilute sugar solution were placed on top of the tissue as food. After 24 hours the percentage of dead and moribund flies were recorded.

(ii) Spodoptera littoralis (S.1.).

Pairs of leaves were removed from broad beans plants and placed on filter paper inside plastic petri dishes. The leaves were sprayed on the undersurface with a formulation containing 20% by weight of acetone, 0. 05% by weight of acetone, 0. 05% by weight of TRITON X-100 ("TRITON" is a regis tered trade mark) as wetting agent and 0.4% by weight of the compound to be tested. Varying concentrations were obtained by diluting the formula tion. After spraying, the leaves were left for a 91 hour drying period and then each leaf pair was infested with ten larvae of the Egyptian cotton leaf worm (Spodoptera littoralis). After 24 hours the percentage of dead and moribund larvae were recorded.

(iii) Boophilus microplus (B.m.).

The compounds to be tested were formulated as solutions or fine suspen sions in acetone containing 10% by weight of polyethylene glycol having an average molecular weight of 400. The formulations contained 0.1% by weight of the compound to be tested. 1 ml of the above-mentioned solution was applied evenly to a filter paper situated inside a petri dish. After the paper was sufficiently dry it was folded in half and partly crimped along the outer edge to form a packet. About 80-100 larval ticks (Boophilus microplus) were transferred into the packet which was then sealed completely.

The packets were placed inside an incubator, maintained at 27"C and 80% relative humidity, before assessing mortality 24 hours later.

(iv) Heliothis zea (H.z.).

A 0.2% by weight solution of the compound to be tested was prepared by adding 2 ml of a 1% acetone solution to 8 ml of 0. 05% ATLOX 1045A ("ATLOX" is a registered trade mark) solution. The cut broad bean plant was sprayed with 4 ml of test solution using a hand sprayer. Immediately after spraying 5 larvae of the corn earworm (Heliothis zea) were transferred to each plant which was inserted into water through the centre hole of a test board and covered with a wire screen. 44-46 hours after spraying the percentage of dead and moribund larvae were recorded.

The results are shown in Table III in which the test species are identified by the initials noted above and the activity of each compound is expressed in the form of their Toxicity Index (T.I.) which is calculated from the following equation:- LC,0 of ethyl parathion Toxicity Index (T.I.) = LC50 of test compound wherein LC50 is the lethal concentration required to kill 50% of the test species.

TABLE III INSECTICIDAL AND TICKICIDAL ACTIVITY

Compound Toxicity Index of Example M.d. S.l. B.m. H.z.

5 7 78 40 19 1 17 380 39 56 8 7 37 4 2 108 40 6 3 94 17 284 6 77 210 200 10 31 54 72 11 59 23 175 14 20 55 15 13 20 16 47 43 76 17 35 16 18 22 35 19 48 68

Claims

WHAT WE CLAIM IS:1. Compounds of the following general formula:-

wherein R1 is an optionally-substituted aryl or alkyl group; R2 is an optionally-substituted cycloalkyl group; X is an oxygen atom or a methylene group; Y is a hydrogen or halogen atom, or an alkyl or alkoxy group; and n is an integer of 1 to 5.
2. Compounds according to claim 1 wherein R1 represents a naphthyl group or an optionally-substituted aryl group of the following structure:

wherein Z is a hydrogen or halogen atom, or an alkyl or alkoxy group, and m is an integer of 1 to 5.
3. Compounds according to claim 1 wherein Rl represents an optionally-substituted alkyl group of up to 10 carbon atoms, the substituents being one or more halogen atoms, or alkoxy or aryl groups.
4. Compounds according to any one of the preceding claims wherein Y represents a hydrogen atom or an alkyl or alkoxy group of 1 to 4 carbon atoms or a halogen atom.
5. Compounds according to any one of the preceding claims wherein R2 represents a cyclopropyl group having the following formula:-

wherein R, and Rb both represent hydrogen atoms, alkyl groups having from 1 to 6 carbon atoms, or halogen atoms; or Ra and Rb together represent an alkylene group having from 2 to 6 carbon atoms; or Rd represents a hydrogen atom and Rb represents an alkenyl group having from 2 to 6 carbon atoms, or an haloalkenyl group having from 2 to 6 carbon atoms, and from 1 to 3 chlorine or bromine atoms; Rd and Rd both represent hydrogen atoms, alkyl groups having from 1 to 6 carbon atoms, or Rd is hydrogen and Rd is an alkenyl group having from 2 to 6 carbon atoms, or an haloalkenyl group having from 2 to 6 carbon atoms and from 1 to 3 chlorine or bromine atoms; or Rd and Rd together represent an alkylene group having from 2 to 6 carbon atoms.
6. Compounds according to claim 1 having the following general formula:-

wherein R1 is phenyl, chlorophenyl, dichlorophenyl, bromophenyl, dibromophenyl fluorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, methoxyphenyl, butylphenyl, ethylphenyl or naphthyl; and Y is hydrogen, chlorine, fluorine or bromine.
7. A compound according to claim 1 specifically described herein in any one of Examples 1 to 10.
8. A compound according to claim 1 specifically described herein in any one of Examples 11 to 22.
9. Compounds according to any one of the preceding claims which are in the form of their E-isomer or a mixture of the E- and Z-isomers in which the E-isomer predominates.
10. A process for the preparation of the compounds claimed in any one of the preceding claims wherein the alkali metal salt of a ketoxime of formula:-

wherein R' and R2 have the meanings previously defined is reacted with a substituted benzyl halide of formula:-

wherein X, Y and n have the meanings previously defined and Q is a halogen atom.
11. A process according to claim 10 wherein the alkali metal salt of the ketoxime is prepared by the reaction of an alkali metal hydride with the ketoxime or by the reaction of aqueous potassium or sodium hydroxide with the ketoxime.
12. A process according to claim 10 or 11 wherein the alkali metal salt of the ketoxime is prepared in situ.
13. A process according to claim 10 substantially as hereinbefore described and with reference to any one of Examples 1 to 22.
14. A compound prepared by a process according to any one of claims 10 to 13.
15. A pesticidal composition comprising a carrier and/or a surface-active agent together with, as active ingredient a benzyl oxime ether according to any one of claims 1 to 9 or 14.
16. A pesticidal composition according to claim 15 substantially as hereinbefore described and with reference to the Examples.
17. A method of combating insect, tick and/or acarid pests at a locus which comprises applying to the locus a pesticidally-effective amount of a benzyl oxime ether according to any one of claims 1 to 9 or 14 or of a composition according to claim 15 or 16.