GB2219582A - Insecticidal 2-cyclyl-3, 3-difluoropropyl ethers - Google Patents

Abstract

Novel compounds of formula (I): <IMAGE> wherein W represents one, two or three substituents selected from halo, alkyl, alkoxy, alkoxyalkyl, haloalkyl and haloalkoxy, or W represents a bidentate group linking adjacent carbon atoms selected from alkylene and alkylenedioxy; Z is hydrogen, chlorine or bromine; X is hydrogen, halo, hydroxy, alkoxy or acyloxy; and Y is an aryl or heteroaryl group with one or more substituents selected from halo, alkyl, aryl, aralkyl, aryloxy and arylamino may be used as the active component of insecticidal compositions and are useful in combating insect pests. Intermediates of formula (III) are also claimed. <IMAGE>

Description

INSECTICIDAL ETHERS This invention relates to novel fluorinated ethers useful as insecticides, to intermediates useful in the preparation thereof, to insecticidal compositions thereof and to methods of combating and controlling insect pests therewith.

In a first aspect the invention provides compounds of formula I:

where W represents one, two or three substituents selected from halo, alkyl, alkoxy, alkoxyalkyl, haloalkyl and haloalkoxy, or W represents a bidentate group linking adjacent carbon atoms selected from alkylene and alkylenedioxy; Z is selected from hydrogen, chlorine and bromine; X is selected from hydrogen, halo, hydroxy, alkoxy and acyloxy; and Y represents a substituted aryl group where each substituent is selected from halo, alkyl, aryl, aralkyl, aryloxy and arylamino.

Preferred compounds are those wherein W represents fluoro, chloro, bromo, alkyl of up to four carbon atoms, alkoxy of up to four carbon atoms, alkoxyalkyl or up to a total of four carbon atoms, fluoroalkyl of up to two carbon atoms, fluoroalkoxy of up to two carbon atoms, alkylene of three or four carbon atoms or alkylenedioxy of up to two carbon atoms, and Y represents an aryl group selected from phenyl, pyridyl and furyl substituted with fluoro, methyl, phenyl, benzyl, phenoxy, chlorophenoxy, fluorophenoxy, bromophenoxy or fluoroanilino.

Particularly preferred compounds are those wherein W represents a substituent in the 4-position selected from chloro, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy and difluoromethoxy, X is selected from hydrogen, fluoro and chloro and Y is selected from R1 to R14, wherein R1 to R14 have the meanings given below: R1 : 3-phenoxyphenyl R2 : 3-(4-chlorophenoxy)phenyl R3 : 4-fluoro-3-phenoxyphenyl R4 : 3-(4-bromophenoxy)phenyl R5 : 4-fluoro-3-(4-bromophenoxy)phenyl R6 : 4-fluoro-3-(4-chlorophenoxy)phenyl R7 : 3-(2,4-difluorophenoxy)phenyl R8 : 3-benzylphenyl R9 : 3-benzyl-4-fluorophenyl R10 : 3-(4-fluorophenylamino)phenyl Rll : 6-phenoxypyrid-2-yl R12 : 2-methyl-3-phenylphenyl R13 : 4-methyl-2,3,5,6-tetrafluorophenyl R14 : 5-benzylfuran-3-yl Particular examples of compounds according to the inventions are set out in Table I below.In Table I, the compounds correspond to formula I, and the values of Y are given as R1 to R14 as described hereinbefore.

TABLE I

COMPOUND W Z X Y NO 1 4-OC2HT H H R1 2 4-OC2H5 H H R3 3 4-OC2H5 H H R9 4 4-OC2H5 H Cl R 5 4-OC2H5 H Cl R R9 6 4-OC2H5 H Cl 7 4-OC2H5 H OH R1 8 4-OC2H5 H OH R3 9 4-OC2H5 H OH R9 10 4-OC2H5 Cl H R1 11 4-OC2H5 Cl H R2 12 4-OC2H5 Cl H R3 13 4-OC2H5 Cl H R9 14 4-OCF3 H H R1 15 4-OCF3 H H R2 16 4-OCF3 H H R3 TABLE I CONTINUED

COMPOUND W Z X Y NO 17 4-OCF3 H H R9 18 4-OCF3 Cl H R 19 4-OCF3 Cl H R2 20 4-OCF3 Cl H R3 21 4-OCF3 Cl H R9 22 4-OC2H5 H H R2 23 4-OC2H5 Br H R1 24 4-OC2H5 Br H R3 The compounds of formula I contain an asymmetrically substituted carbon atom and may consequently exist in alternative stereoisomeric forms (the R-form and the Sform).The invention includes within its scope not only isomeric mixtures, including racemic mixtures, but also any single isomer of an invention compound.

The compounds of formula I wherein X represents OH may be prepared from an acetophenone of formula II by the two-stage procedure described in Scheme I. The first stage of this procedure produces a compound of formula III. It is not necessary to isolate this compound, as the reaction mixture containing the compound of formula III may be used directly in the second stage of the preparation of the required compound of formula I as described in Scheme I.

The intermediates of formula III are believed to be novel. Accordingly, in a further aspect, the invention provides compounds of formula III wherein W has any of the meanings described hereinbefore and Z is selected from hydrogen, chlorine and bromine.

Scheme I

* TMSI = Trimethylsulphoxonium iodide The compounds of formula I wherein X = OH may then be converted into compounds of formula I wherein X = fluorine and X = chlorine by reaction with an appropriate halogenating agent. Examples are summarised in Scheme II.

Scheme II

*DAST = Diethylaminosulphur trifluoride The compounds of formula I wherein X = chlorine may be reduced to produce the compounds of formula I wherein X = hydrogen; a suitable reducing agent is tri-n-butyltin hydride. This reaction is summarised in Scheme IV. In the case of compounds wherein Z also represents chlorine, competing reduction at the -CF2C1 group may give rise to a mixture of compounds requiring separation to produce the desired product.

Scheme IV

(I, x=Cl) (I, X=H) The acetophenones of formula II may be conveniently prepared by the redaction of a Grignard agent, derived from the appropriate bromine substituted compound of formula IV, with a substituted acetic acid of formula CF2Z-C02H or a derivative thereof. Alternatively, the acetophenones of formula II may be prepared by the reaction of a compound of formula IV with a reagent such as n-butyllithium, followed by reaction with an ester of a substituted acetic acid of formula CF2ZC02H. Examples of these processes are summarised in Scheme V.

The compound of formula II wherein Z is hydrogen may also be prepared from the corresponding compound of formula II wherein Z is chlorine by reduction, for example using tri-n-butyltin hydride.

Compounds according to formula I have at least one asymmetric centre, and are normally prepared in the form of mixtures of the stereoisomers concerned. These mixtures may be separated, for example by chromatographic means using a chiral fixed phase, such as the Pirkle type IA column.

Further details of the above-mentioned processes are set out in the Examples hereinafter.

The compounds of formula I may be used to combat and control infestations of insect pests and also other invertebrate pests, for example, acarine pests. The insect and acarine pests which may be combatted and controlled by the use of the invention compounds include those pests associated with agriculture (which term includes the growing of crops for food and fibre products, horticulture and animal husbandry), forestry, the storage of products of vegetable origin, such as fruit, grain and timber, and also those pests associated with the transmission of diseases of man and animals.

.In order to apply the compounds to the locus of the pests they are usually formulated .into compositions which include in addition to the insecticidally active ingredient or ingredients of formula I suitable inert diluent or carrier materials, and/or surface active agents.

The compounds of the invention may be the sole active ingredient of the composition or they may be admixed with one or more additional active ingredients such as insecticides, insecticide synergists, herbicides, fungicides or plant growth regulators where appropriate.

Suitable additional active ingredients for inclusion in admixture with the compounds of the invention may be compounds which will broaden the spectrum of activity of the compounds of the invention or increase their persistence in the location of the pest. They may synergise the activity of the compounds of the invention or complement the activity for example by increasing the speed of effect, improving knockdown or overcoming repellency.

Additionally multi-component mixtures of this type may help to overcome or prevent the development of resistance to individual components.

The particular insecticide, herbicide or fungicide included in the mixture will depend upon its intended utility and the type of complementary action required.

Examples of suitable insecticides include the following (a) Pyrethroids such as permethrin, esfenvalerate, deltamethrin, cyhalothrin, biphenthrin, fenpropathrin, cyfluthrin, tefluthrin, fish safe pyrethroids for example ethofenprox, natural pyrethrin, tetramethrin, sbioallethrin, fenfluthrin, prallethrin and 5-benzyl-3furylmethyl-(E)-(lR,3S)-2,2-dimethyl-3-(2-oxothiolan-3ylidenemethyl)cyclopropane carboxylate; (b) Organophosphates such as profenofos, sulprofos, methyl parathion, azinphos-methyl, demeton-s-methyl, heptenophos, thiometon, fenamiphos, monocrotophos, profenophos, triazophos, methamidophos, dimethoate, phosphamidon, malathion, chlorpyrifos, phosalone, fensulfothion, fonofos, phorate, phoxim, pyrimiphos-methyl, fenitrothion or diazinon;; (c) Carbamates (including aryl carbamates) such as pirimicarb, cloethocarb, carbofuran, ethiofencarb, aldicarb, thiofurox, carbosulfan, bendiocarb, fenobucarb, propoxur or oxamyl; (d) Benzoyl ureas such.as triflumuron, chlorofluazuron; (e) Organic tin compounds such as cyhexatin, fenbutatin oxide, azocyclotin; (f) Macrolides such as avermectins or milbemycins, for example such as abamectin, avermectin, and milbemycin; (g) Hormones such as juvenile hormone, juvabione, or ecdysones.

(h) Pheromones.

(i) Organochlorine compounds such as benzene hexachloride, DDT, chlordane or dieldrin.

In addition to the major chemical classes of insecticide listed above, other insecticides having particular targets may be employed in the mixture if appropriate for the intended utility of the mixture. For instance selective insecticides for particular crops, for example stemborer specific insecticides for use in rice such as cartap or buprofezin, can be employed.

Alternatively insecticides specific for particular insect species/stages for example ovolarvicides such as clofentazine, flubenzimine, hexythiazox and tetradifon, motilicides such as dicofol or propargite, acaricides such as bromopropylate, chlorobenzilate, or insect growth regulators such as hydramethylon, cyromazin, methoprene, chlorofluazuron and diflubenzuron may also be included in the compositions.

Examples of suitable insecticide synergists for use in the compositions include piperonyl butoxide, sesamex, and dodecyl imidazole.

Suitable herbicides, fungicides and plant growth regulators for inclusion in the compositions will depend upon the intended target and the effect required. An example of a rice selective herbicide which can be included is propanil, an example of a plant growth regulator for use in cotton is "Pix, and examples of fungicides for use in rice include blasticides such as blasticidin-S. The choice of other ingredients to be used in mixture with the active ingredient will often be within the normal skill of the formulator, and will be made from known alternatives depending upon the total effect to be achieved.

The ratio of the compound of the invention to any other active ingredient- in the composition will depend upon a number of factors including the type of insect pests to be controlled, and the effects required from the mixture.

However in general, the additional active ingredient of the composition will be applied at about the rate it would usually be employed if used on its own, or at a lower rate if synergism occurs.

The compositions may be in the form of dusting powders wherein the active ingredient is mixed with a solid diluent or carrier, for example kaolin, bentonite, kieselguhr, or talc, or they may be in the form of granules, wherein the active ingredient is absorbed in a porous granular material, for example pumice.

Alternatively the compositions may be in the form of liquid preparations to be used as dips or sprays, which are generally aqueous dispersions or emulsions of the active ingredient in the presence of one or more known wetting agents, dispersing agents or emulsifying agents (surface active agents).

Wetting agents, dispersing agents and emulsifying agents may be of the cationic, anionic or non-ionic type.

Suitable agents of the cationic type include, for example, quaternary ammonium compounds, for example cetyltrimethyl ammonium bromide. Suitable agents of the anionic type include, for example, soaps, salts of aliphatic monoesters or sulphuric acid, for example sodium lauryl sulphate, salts of sulphonated aromatic compounds, for example sodium dodecylbenzenesulphonate, sodium, calcium or ammonium lignosulphonate, or butylnaphthalene sulphonate, and a mixture of the sodium salts of diisopropyl- and triisopropylnaphthalene sulphonates. Suitable agents of the non-ionic type include, for example, the condensation products of ethylene oxide with fatty alcohols such as oleyl alcohol or cetyl alcohol, or with alkyl phenols such as octyl phenol, nonyl phenol and octyl cresol.Other non-ionic agents are the partial esters derived from long chain fatty acids and hexitol anhydrides, the condensation products of the said partial esters with ethylene oxide, and the lecithins.

The compositions may be prepared by dissolving the active ingredient in a suitable solvent, for example, a ketodic solvent such as diacetone alcohol, or an aromatic solvent such as trimethylbenzene and adding the mixture so obtained to water which may contain one or more known wetting, dispersing or emulsifying agents.

Other suitable organic solvents are dimethyl formamide, ethylene dichloride, isopropyl alcohol, propylene glycol and other glycols, diacetone alcohol, toluene, kerosene, white oil, methylnaphthalene, xylenes and trichloroethylene, N-methyl-2-pyrrolidone and tetrahydrofurfuryl alcohol (THFA).

The compositions which are to be used in the form of aqueous dispersions or emulsions are generally supplied in the form of a concentrate containing a high proportion of the active ingredient or ingredients, the said concentrate to be diluted with water before use. These concentrates are often required to withstand storage for prolonged periods and after suih storage, to be capable of dilution with water to form aqueous preparations which remain homogenous for a sufficient time to enable them to be applied by conventional spray equipment. The concentrates may contain 5-95% by weight of the active ingredient or ingredients. When diluted to form aqueous preparations such preparations may contain varying amounts of the active ingredient depending upon the purpose for which they are to be used.For agricultural or horticultural purposes, an aqueous preparation containing between 0.0001% and 0.1% by weight of the active ingredient is particularly useful.

In use the compositions are applied to the pests, to the locus of the pests, to the habitat of the pests, or to growing plants liable to infestation by the pests, by any of the known means of applying pesticidal compositions, for example, by dusting or spraying.

The compositions of formula I and compositions comprising them are very toxic to wide varieties of insect and other invertebrate pests, including, for example, the following: Myzus persicae (aphids) Aphis fabae (aphids) Meaoura viceae (aphids) Aedes aeqypti (mosquitos) Anopheles spp. (mosquitos) Culex spp. (mosquitos) Dysdercus fasciatus (capsids) Musca domestica (houseflies) Pieris brassicae (white butterfly, larvae) Plutella maculipennis (diamond back moth, larvae) Phaedon cochleariae (mustard beetle) Tetranychus cinnabarinus (carmine spider mite) Tetranychus urticae (red spider mites) Aonidiella spp. (scale insects) Trialeuroides spp. (white flies) Blattella cermanica (cockroaches) Periplaneta americana (cockroaches) Blatta orientalis (cockroaches) SpodoDtera littoralis (cotton leaf worm) Heliothis virescens (tobacco budworms) Chortiocetes terminifera (locusts) Diabrotica spp. (rootworms) Aqrotis spp. (cutworms) Chilo partellus (maize stem borers) Nilaparvata luaens (plant hoppers) Nephotettix cincticeps (plant hoppers) The following Examples illustrate various aspects of this invention. In the preparation Examples the products were usually identified and characterised by means of nuclear magnetic reasonance spectroscopy and infra red spectroscopy. In each case where a product is specifically named its spectral characteristics are consistent with the assigned structure.Except where stated otherwise, exemplified compounds having one or more asymmetrically substituted carbon atoms were prepared in racemic form.

In the Examples, Gas Liquid Chromatography (GLC)

retention times were determined on a Hewlett Packard/5890 Gas Chromatograph, using a Chromopak, C.P. Sil 5 C.B.

column of 12.5M length and 0.2 mm internal diameter.

Unless otherwise stated, the injection temperature was 1000C, and a temperature gradient of 150C/minute employed, up to a maximum temperature of 2800C, maintained for 4 minutes. The carrier gas was helium at a column head pressure maintained at 11 psi. Alternative injection and maximum temperatures are indicated in the Examples where appropriate.

1H Nuclear Magnetic Resonance (NMR) spectrometry was performed at a frequency of 270 MHz on a Jeol FX 270 NMR spectrometer, unless otherwise indicated. 90 MHz, 60 MHz and 400 MHz 1H NMR spectrometry were performed using Jeol FX 90Q, Jeol PMX 60SI and Jeol GX400 spectrometers respectively.

19F NMR spectrometry was performed on a Jeol FX90Q spectrometer at a frequency of 84.26 MHz. All NMR shift values are quoted in ppm relative to a standard (TMS or CFC13).

Molecular Ion (M+) peaks were determined on one of three mass spectrometers : Jeol DX303, Kratos MS80 or Hewlett Packard HP 5992.

EXAMPLE 1 This Example illustrates the preparation of 4-ethoxy i, -difluoro-X-chloroacetophenone.

Magnesium turnings (2.64g), diethyl ether (dried over molecular sieves, 50 cm3) and a few crystals of iodine were placed ir. a 3 neck round-bottom flask and were stirred under an atmosphere of nitrogen. About 10% of a solution of 4-bromophenetole (20g) in dry diethyl ether (100 cm3) was added, and the mixture was warmed gently to initiate the Grignard reaction. When the reaction had begun, the rest of the bromophenetole solution was added at a rate sufficient to maintain a gentle reflux. At the end of the addition the solution was stirred for one hour.

Methyl difluorochloroacetate (28.75g) in diethylether (100 cm3) was placed in a flask under nitrogen and cooled to about -70C (internal temperature). The solution of the 4-ethoxyphenyl magnesium bromide was added dropwise with stirring, then the mixture was allowed to warm to the ambient temperature for about half an hour. The mixture was quenched with water and acidified with hydrochloric acid to assist solubilisation of the magnesium salts. The layers were separated and the aqueous phase was extracted twice with diethyl ether. The combined ether layers were washed twice with water, then dried over anhydrous magnesium sulphate before being concentrated by evaporation under reduced pressure to give a golden brown oil (22.7g).

The oil was heated at about 1100C under reduced pressure (ca. 15 mmHg) to remove residual phenetole. The residual oil was then distilled under high vacuum (ca. 0.1 mmHg). A fraction boiling between 600C and 80 C was discarded, and the product was distilled at about 800C, and was shown to be 97% pure by gas liquid chromatography (3.24g).

1H NMR (CDC13) s (ppm) : 1.46 (3H,t); 4.16 (2H,q); ca.

7.0 and 8.1 (each 2H,d) 19F NMR (CDCl3) S (ppm - relative to CFC13): -60.7 (CF2Cl,S) Infra red (liquid film): 1710 CM-1 EXAMPLE 2 This Example illustrates the preparation of 4-ethoxy &alpha;-difluoroacetophenone.

4-Ethoxy- &alpha;&alpha; -difluoro--chloroacetophenone (lg, prepared according to the method of Example 1), tri-n-butyl tin hydride (1.45g), and a catalytic amount of i, -azo- bis-isobutyronitrile were mixed in dry toluene, maintained at OOC under a nitrogen atmosphere. The mixture was allowed to warm to room temperature and was then heated at the reflux temperature for 4 hours. Analysis of a withdrawn portion of the reaction mixture showed some remaining starting ketone, so further tri-n-butyl tin hydride was added and heating continued for a further 30 minutes. The mixture was cooled, poured into water and separated.The aqueous layer was washed twice with ethyl acetate and the combined organic layers were dried over anhydrous magnesium sulphate, and the solvents evaporated under reduced pressure to give a pale yellow oil (2.9g).

The oil was distilled in a Kugelrohr apparatus and the major product-containing fraction was purified by chromatography on a silica gel support, eluting firstly with n-hexane containing 6% by volume ethyl acetate and secondly with ethyl acetate. 4-Ethoxy- X, difluoroacetophenone (0.3g) was obtained as a yellow oil.

1H NMR (CDC13) (ppm) : 1.46 (3H,t); 4.14 (2H,q); 6.25 (lH,t, J=54 Hz); 6.97 and 8.06 (each 2H,d).

Molecular ion : 200 EXAMPLE 3 The Example illustrates the two-stage procedure for the preparation of l,l-difluoro-2-(4-ethoxyphenyl)-3-(3phenoxybenzyloxy)propan-2-ol.

Stage 1: Preparation of l,l-difluoro-2-(4-ethoxyphenyl) pr Dp-2-ene oxide.

Sodium hydride (0.12 g of a 55% dispersion in oil) was added to a stirred solution of trimethylsulphoxonium iodide (0.5 g) in dry dimethylformamide (6 cm3) under an atmosphere of nitrogen at the ambient temperature (ca.

200C). After the effervescence had subsided, a solution of 4-ethoxy-o(, -difluoroacetophenone (0.47 g) in dry dimethylformamide (4 cm3) was added. Gas liquid chromatography of a sample withdrawn after 5 minutes showed no starting material. This mixture was used in stage 2 without further purification or characterisation.

Stage 2: 3-Phenoxybenzyl alcohol (0.45 g) was added to a mixture of sodium hydride (0.12 g of a 55% dispersion in oil) and dry dimethylformamide (10 cm3) and the resultant mixture was stirred for 2.5 hours under an atmosphere of nitrogen. After this time, the mixture obtained in Stage 1 was added and the combined reaction mixture was heated at 700C for 75 minutes. The mixture was cooled, then poured carefully into water and acidified with dilute hydrochloric acid to about pH 3.

The aqueous mixture was extracted twice with diethyl ether. The combined ether extracts were washed with water, dried over anhydrous magnesium sulphate then evaporated under reduced pressure to leave a yellow oil.

Purification by column chromatography on silica gel, eluting with hexane containing 25% by volume ethyl acetate gave l,l-difluoro-2-(4-ethoxyphenyl)-3-(3phenoxybenzyloxy)propan-2-ol (0.447 g) as a colourless oil.

1H NMR (CDC13) I (ppm): 1.41 (3H,t); 3.19 (lH,s,OH); 3.62 (lH,m); 4.0 (lH,m); 4.06 (2H,q); 4.56 (2H,s); 5.85 (lH,t, J=ca 58Hz); 6.8-7.45 (13H,m) EXAMPLE 4 This Example illustrates the preparation of 1,1 difluoro-2-chloro-2- ( 4-ethoxyphenyl ) -3- (3- phenoxybenzyloxy ) propane.

l,1-Difluoro 2-(4-ethoxyphenyl)-3-(3phenoxybenzyloxy)propan-2-ol (0.37 g) was dissolved in dry acetonitrile (25 cm3) containing imidazole (0.334 g); the mixture was cooled in an ice bath and maIntained under an atmosphere of nitrogen. Thionyl chloride (0.58 g) was added and the mixture was stirred for 45 minutes, then poured into water. The aqueous mixture was extracted with diethyl ether and the combined ether extracts were washed with water, dried over anhydrous magnesium sulphate and evaporated under reduced pressure to leave an oil.This oil was combined with the crude product of a trial experiment run using 0.1 g of the alcohol, and the combined product was purified by column chromatography on silica gel, eluting with hexane containing 40% by volume chloroform, to give l,l-difluoro-2chloro-2-(4-ethoxyphenyl)-3-(3-phenoxybenzyloxy)propane (0.414 g) as a colourless gum.

u NMR (CDCl3) (ppm): 1.41 (3H,t); ca 4.0 (2H,q overlapping with 2H,m); 4.58 (2H,s); 6.19 (lH,t,J=ca 58 Hz); 6.8-7.6 (13H,m) EXAMPLE 5 The Examples illustrates the preparation of 1,1 difluoro-2-(4-ethoxyphenyl)-3-(3-phenoxybenzylOxy)propane.

A mixture of l,l-difluoro-2-chloro-2-(4-ethoxyphenyl) 3-(3-phenoxybenzyloxy)propane (0.36 g), dry toluene (5 cm3) and AIBN (,oc'-azo-bis-iso-butyronitrile, a catalytic amount), was cooled in an ice bath and maintained under an atmosphere of nitrogen. Tri-n-butyltin hydride (0.2 cm3) was added in 1 portion. The mixture was allowed to warm to room temperature, and was then heated at the reflux temperature for 2 hours 45 minutes. The cooled mixture was poured into water and the products were extracted into diethyl ether. The combined ether layers were washed with water, dried over anhydrous magnesium sulphate and evaporated under reduced pressure to give an oil.

Purification of this oil by column chromatography on silica gel, eluting with hexane containing 7% by volume ethyl acetate gave l,l-difluoro-2-(4-ethoxyphenyl)-3-(3phenoxybenzyloxy)propane (0.241 g - 99% pure by gas liquid chromatography) as a colourless oil.

6 NMR (CDCl3) (ppm): 1.40 (3H,t); ca 3.20-3.35 (1H, broad m); 3.7-3.9 (lH,m); 4.0 (2H,t); 4.48 (2H,s); 6.06 (lH,dt, J=ca 5Hz and 57Hz); 6.8-7.4 (13H,m) 19F NMR (CDC13) s (ppm relative to CFCl3): CF2H signal as a double triplet, -123.56 and -124.23 J (J=57Hz and ca 14.5Hz) EXAMPLE 6 This Example illustrates the insecticidal properties of the Products of this invention.

The activity of the Product was determined using a variety of insect pests. The Product was used in the form of liquid preparations containing from 100 to =00 parts per million (ppm) by weight of the Product. The preparations were made by dissolving the Product in acetone and diluting the solutions with water containing 0.18 by weight of a wetting agent sold under the trade name "SYNPERONIC" NX until the liquid preparations contained the required concentration of the Product. "SYNPERONIC" is a Registered Trade Mark.

The test procedure adopted with regard to each pest was basically the same and comprised supporting a number of the pests on a medium which was usually a host plant or a foodstuff on which the pests feed, and treating either or both the pests and the medium with the preparations. The mortality of the pests was then assessed at periods usually varying from one to seven days after the treatment.

In the case of the species Musca domestica (housefly), an additional assessment to determine the knockdown effect of the compounds was performed. Details are given in Table II.

The results of the tests are given in Table III for each of the Products, at the rate in parts per million given in the second column, as a grading of mortality designated as A, B or C wherein A indicates 80-100% mortality or knockdown B indicates 50-79% mortality knockdown or knockdown and C indicates less than 50% mortality or knockdown.

In Table III the pest organism used is designated by a letter code and the pests species, the support medium or food, and the type and duration of test is given in Table II.

TABLE II

CODE LETTERS TEST SPECIES SUPPORT TYPE OF DURATION (Table TV) MEDIUM/FOOD TEST (days) TUa Tetranychus urticae French bean Contact 3 (spider mites - adult) leaf TUe Tetranychus urticae French bean Contact 6 (spider mites -ova) leaf MP Myzus persicae Chiese contact 3 (aphids) Cabbage leaf NC Nephotettix cincticeps Rice plant 3 (green leaf hopper nymphs) HV Heliothis virescens Cotton leaf Residual 3 (tobacco budworm - larvae) DB Diabrotica balteata Filter Paper/ Residual 3 (rootworm iarvae) maize seed TABLE II CONTINUED

CODE LETTERS TEST SPECIES SUPPORT TYPE OF DURATION (Table TV) MEDIUM/FOOD TEST (days) BG Blattella germanica Plastic pot Residual 3 (cockroach nymphs) MD Musca domestica Cotton wool/ Contact 1 (houseflies - adults) sugar MD/KD Musca domestica Cotton/wool Knockdown 4 hours (houseflies - adults) sugar Sp Spodoptera exigua Cotton leaf Residual 3 (lesser army worm - larvae) "Contact" test indicates that both pests and medium were treated and "residual" indicates that the medium was treated before infestation with the pests.

TABLE III

COMPOUND RATE TUa TUe MP NC MD/K MD BG HV SP DB NO 1 500 C C A A A A A C A A

Claims (5)

1. What we claim is: 1. A compound of formula:

   wherein W represents one, two or three substitutents selected from halo, alkyl, alkoxy, alkoxyalkyl, haloalkyl and haloalkoxy or W represents a bidentate group linking adjacent carbon atoms selected from alkylene and alkylenedioxy; Z is selected from hydrogen, chlorine and bromine; X is selected from hydrogen, halo, hydroxy, alkoxy and acyloxy and Y represents a substituted aryl group where each substituent is selected from halo, alkyl, aryl, aralkyl, aryloxy and arylamino.
2. 2. 1,1-Difluoro-2-(4-ethoxyphenyl)-3-(3-phenoxy- benzyloxy)propane.
3. 3. An insecticidal composition comprising an insecticidally effective amount of a compound according to claim 1 in association with an insecticidally inert diluent or carrier material.
4. 4. A method of combating insect pests at a locus which comprises applying to the locus an insecticidally effective amount of a composition according to claim 3.
5. 5. A compound of formula:

   wherein W and Z are as defined in claim 1.