GB2219290A - Insecticidal fluoroalkyl-benzene and -pyridine derivatives - Google Patents

Abstract

The invention provides insecticidally active novel compounds of formula (1): <IMAGE> wherein R<1> and R<2> are independently selected from methyl, halo and C1-3 fluoroalkyl; R<3> represents C1-3 fluoroalkyl; W represents O, CH2 or NH; X represents N or CH; and Y and Z are independently selected from hydrogen and halogen. The invention also provides insecticidal compositions comprising the compounds of formula (1) and methods of their use in combating insect pests. <IMAGE>

Description

INSECTICIDAL COMPOUNDS This invention relates to novel fluorinated compounds, useful as insecticides, 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):

wherein R1 and R2 are each independently selected from methyl, halo and fluoroalkyl of 1, 2 or 3 carbon atoms, R3 represents fluoroalkyl of 1, 2 or 3 carbon atoms, W represents oxygen, methylene or NH, X represents a nitrogen atom or a carbon atom bearing a hydrogen atom, and Y and Z are each independently selected from hydrogen and halogen.

Preferred compounds are those wherein R1 and R2 are both methyl, R3 represents difluoromethyl or trifluoromethyl, W is oxygen, X is a carbon atom bearing a hydrogen atom, Y is a fluorine atom in the 4-position relative to the fluorinated alkyl chain and Z is hydrogen.

Particular compounds according to the invention include those set forth in Table I. In Table I, the compounds correspond to formula (I), with given values of R1, R2, R3, W, X, Y and Z.

TABLE I

COMPOUND NO. R R R W X Y Z 1 CH3 CH3 CHF2 O CH H H 2 CH3 CH3 CHF2 O CH 4-F H 3 CH3 CH3 CF3 0 CH 4-F H 4 CH3 CH3 CF3 O CH H H 5 CH3 Cl CF3 O CH 4-F H 6 CH3 F CF3 O CH 4-F H 7 CH3 Cl CF3 O CH H H 8 CH3 F CF3 O CH H H 9 CH3 CH3 CHF2 CH2 CH 4-F H 10 CH3 CH3 CHF2 O N H H Differing values of R1, R2 and R3 may lead to asymmetric substitution at the carbon atom to which these groups are attached. In such a case, the compounds of formula (I) may exist in alternative stereoisomeric forms (the R-form and the S-form). The invention includes within its scope not only mixtures of such isomers, including racemic mixtures, but also any single isomer of an invention compound.

The compounds of formula (I) may be prepared by the following sequence of reactions. An aldehyde of formula (11):

wherein R1 and R2 have any of the meanings given hereinbefore, is first converted to a protected form, for example the 1,3-dioxolane by reaction with ethylene glycol. The protected aldehyde is then reacted with a compound of formula (III):

wherein W, X, Y and Z have any of the meanings described hereinabove, in the presence of tri-o-tolylphosphine and palladium II acetate, to give a compound of formula (IV):

Catalytic hydrogenation of the compound of formula (IV) followed by deprotection of the aldehyde then gives an aldehdye of formula (V):

The aldehyde of formula (V) may then be further converted to compounds of formula (I) by fluorination reactions.

The processes described above are illustrated, by way of example only, for the preparation of compound 1 of Table I in Scheme I.

Scheme I

Key to Scheme I : TOTP = Tri-O-tolylphosphine DAST = Diethylaminosulphur trifluoride.

Further details of the processes for preparing the compounds of the invention may be ascertained from the specific Examples given herinafter.

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-3 furylmethyl-(E)-(lR, 3S)-2,2-dimethyl-3-(2-oxothiolan-3- ylidenemethyl)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, pyrimiphosmethyl, 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 ketonic 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 such 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) Meqoura 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 qermanica (cockroaches) Periplaneta americana (cockroaches) Blatta orientalis (cockroaches) Spodoptera littoralis (cotton leaf worm) Heliothis virescens (tobacco budworms) Chortiocetes terminifera (locusts) Diabrotica spp. (rootworms) Aqrotis spp. (cutworms) Chilo partellus (maize stem borers) Nilaparvata luqens (plant hoppers) Nephotettix cincticeps (plant hoppers) The compounds according to formula (I) and compositions comprising them have shown themselves to be particularly useful in controlling pests of rice such as Nilaparvata spp.This activity is combined with a low level of hazard to aquatic organisms, e.g. fish, which renders the compounds particularly suitable for use in aquatic environments, such as those accountered in the control of insect pests of paddy rice or in the control of insect vectors of disease (e.g. mosquitos).

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 specificall named its spectral characteristics are consistent with they 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 (GL retention times were determined on a Hewlett Packar

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 2-(1,1 dimethylbut-3-en-1-yl ) -1, 3-dixolane.

A mixture of 2,2-dimethyl-4-pentenal (4.4g, commercially available from the Aldrich Chemical Company Ltd., Gillingham, Dorset, England), ethylene glycol (2.48g), para-toluene sulphonic acid (catalytic quantity) and dry toluene was heated at the reflux temperature for a total of 12 hours under a Dean and Stark trap. After this time, 0.2 cm3 of water had been collected in the trap and analysis of the mixture by gas liquid chromatography showed approximately 67% conversion to a reaction product.

The mixture was cooled, washed with water, then brine solution and dried over anhydrous magnesium sulphate.

Evaporation of the solvent under reduced pressure gave an oil (3.83g) which was used without further purification.

1H nmr (CDC13) 8 (ppm) : 0.9 (6H, s); 2.15 (2H, d); 3.9 (4H, s); 4.6 (1H, s); 4.9-5.2 (2H, m); 5.9 (1H, m).

Infra red (liquid film) : 2980, 2880, 1110 cm (major peaks only).

GLC Retention Time (500C-2800C run) : 2.23 minutes.

EXAMPLE 2 This Example illustrates the preparation of 2-[1,1- dimethyl-4-(3-phenoxyphenyl)but-3-en-1-yl]-1,3-dioXolane.

A mixture of 2-(l,l-dimethylbut-3-en-l-yl)-1,3-dioxo- lane (3.lg), 3-phenoxybromobenzene (4.7g), palladium (II) acetate (0.5g), tri-0-tolylphosphine (lg) and N,N,N',N'tetramethylenediamine (2.3g) was heated at the reflux temperature, under an atmosphere of nitrogen for a total of seven days. During this period, analysis by gas liquid chromatography had indicated some starting material remaining, and so a further quantity of palladium (II) acetate had been added.

When analysis by gas liquid chromatography showed an absence of starting materials, the reaction mixture was cooled and poured into dilute hydrochloric acid. The products were extracted into ethyl acetate and the organic layer dried over anhydrous magnesium sulphate. Filtration followed by evaporation of the solvent under reduced pressure gave a dark oil, which was passed through a silica gel column, eluting with petroleum ether (boiling range 40-60"C) containing 5% by volume ethyl acetate, to give an oil containing approximately 48%, by gas liquid chromatographic analysis, of a major product.

The reaction was repeated, but on the second occasion, all starting materials were shown to be consumed after 25 hours at the reflux temperature. The reaction mixture was worked up by quenching in dilute hydrochloric acid and extraction into ethyl acetate. The organic layer was dried over magnesium sulphate filtered and after evaporation of the solvent under reduced pressure, the residual oil was distilled in a Kugel-rohr apparatus (150 C/0.lmmEg), and the residue combined with the product of the first reaction run.Repeated purification by column chromatography on silica gel, eluting firstly with dichloromethane, followed by petroleum ether (boiling range 40-600C) containing 5% by volume ethyl acetate gave a mixture containing 65% of the title compound (Product A) and 25% of an isomeric compound, identified as 2-[1,1- dimethyl-3-(3-phenoxyphenyl)but-3-en-1-yl]-1,3-dioXolane (Product B), and other minor impurities.

Product A - title compound, identified as: 1H nmr (CDC13) S (ppm) : 0.94 (6H, s); 2.2 (2H, d); 3.8 3.95 (4H, m); 4.58 (1H, s); 6.2 6.4 (2H, m); 6.8-7.4 (9H, m).

GLC Retention Time : 10.03 minutes.

Product B 1H nmr (CDCl3) S (ppm) : 0.78 (6H, s); 2.54 (2H, s); 3.8 3.95 (4H, m); 4.48 (1H, s); 5.0 5.3 (2H, 2s); 6.8-7.4 (9H, m).

GLC Retention Time : 9.18 minutes.

EXAMPLE 3 This Example illustrates the preparation of 2-[1,1- dimethyl-4-(3-phenoxyphenyl)butyl]-1,3-dioxolane.

The mixture of products from Example 2 (3.2g) was dissolved in ethyl acetate (30 cm3) and 10% palladium on charcoal (0.2g) was added. The mixture was hydrogenated at 3.3 atmospheres for 1 hour. The mixture was passed through a silica gel plug, the filtrate dried over anhydrous magnesium sulphate, and the solvent evaporated under reduced pressure to give a mixture identified as 2 1,l-dimethyl-4-(3-phenoxyphenyl)butyl-l,3-dioxo1ane (72% -Product A) and 2-[l,1-dimethyl-3-(3-phenoxyphenyl)butyl]- 1,3-dioxolane (26% - Product B).

R nmr (CDC13) & (ppm) : Peaks for Product A.

0.88 (6H, s); 1.2 (2H, m); 1.6 (2H, m); 2.55 (2H, t); 3.8-3.9 (4H, m); 4.52 (7H, s); 6.7-7.4 (9H, m).

GLC Retention Time : Product A 9.55 minutes Product B 8.93 minutes.

EXAMPLE 4 This Example illustrates the preparation of 2,2dimethyl-5-(3-phenoxyphenyl)pentanal.

The mixture of products from Example 3 (3.2g) was dissolved in dichloromethane (60 cm3) and added to a cautiously prepared mixture of concentrated sulphuric acid (2 cm3), water (2 cm3) and silica gel (12g). The mixture was stirred at the ambient temperature (200C) for 40 hours, when analysis by gas liquid chromatography showed only 12% of the starting materials remaining. Sodium hydrogen carbonate (5g) was added gradually to the stirred mixture over 2 hours, and the mixture was then filtered.

The residual silica gel was washed with dichloromethane and the washings added to the filtrate which was separated. The organic phase was washed with water and brine, dried over anhydrous magnesium sulphate and concentrated by evaporation under reduced pressure. The residual oil was purified by column chromatography on silica gel, eluting with petroleum ether (boiling range 40"C-600C) containing 40% by volume dichloromethane, to give pure 2,2-dimethyl-5-(3-phenoxyphenyl)pentanal (1.5g) as a colourless oil.

60 MHz 1H nmr (CDC13) C (ppm) : 1.0 (6H, s); 1.4 (4H, m); 2.7 (2H, m); 6.8-7.4 (9H, m); 9.4 (1H, s).

Infra red (liquid film) : 2700, 1735 cm 1 (major peaks only).

GLC Retention Time : 8.05 minutes.

EXAMPLE 5 This Example illustrates the preparation of 1,1 difluoro-2,2-dimethyl-5-(3-phenoxyphenyl)pentane.

A solution of 2,2-dimethyl-5-(3-phenoxyphenyl)pentanal (0.5g) in fluorotrichloromethane (10 cm3) was cooled to -780C under an atmosphere of nitrogen. 2 Molar equivalents of diethylaminosulphur trifluoride (0.61g) was added slowly with stirring, giving rise to an exotherm.

The solution was allowed to warm to the ambient temperature over 2 hours, when analysis by gas liquid chromatography showed incomplete reaction. The mixture was again cooled to -780C under an atmosphere of nitrogen and further diethylaminosulphur trifluoride (0.25g) was added with stirring. The mixture was again allowed to warm to the ambient temperature, and analysis by gas liquid chromatography showed no remaining starting aldehyde. A mixture of diethyl ether and water was slowly added to the reaction mixture, whereupon effervescence was noticed. Further diethyl ether was added and the mixture separated. The organic phase was washed with water and brine and dried over anhydrous magnesium sulphate.The solvent was evaporated under reduced pressure and the residual orange oil purified by column chromatography on silica gel, eluting with petroleum ether (boiling range 400C-600C) to give l,1-difluoro-2,2-dimethyl-5-(3- phenoxyphenyl)pentane (0.164g) as a colourless oil.

1H nmr (CDC13) 8(ppm) : 0.94 (6H, s); 1.3 (2H, m); 1.6 (2H, m); 2.58 (2H, t); 5.4 (1H, t); 6.8-7.4 (9H, m).

19F nmr (CDC13) (ppm relative to CFC13):- 128.8 (d).

Infra red (liquid film) : 3050 cm-l.

GLC Retention Time : 7.31 minutes.

EXAMPLE 6 This Example illustrates the insecticidal properties of the products of the 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 500 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 0.1% by weight of a wetting agent sold under the trade name "SYNPERONIC" NX until the liquid preparations contained the required concentration of the Product.

"SYNPEROhIC" 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 IV) 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 Chinese Contact 3 (aphids) Cabbage leaf NL Nilaparvata luqens Rice plant Contact 3 (brown plant hopper nymphs) HV Heliothis virescens Cotton leaf Residual 3 (tobacco budworm - larvae) DB Diabrotica balteata Filter paper/ Residual 3 (rootworm larvae) maize seed BG Blattella qermanica Plastic pot Residual 3 (cockroach nymphs) MD Musca domestica Cotton wool/ Contact 1 (houseflies - adults) sugar MD/K Musca domestica Cotton/wool Knockdown 4 hours (houseflies - adults) sugar SP Spodoptera exiqua 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 NO. RATE TUa Tue MP NL MD/K MD BG HV SP DB 1 500 C C A A A C C C A A

Claims (4)

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

   wherein R1 and R2 are each independently selected from methyl, halo and fluoroalkyl of 1, 2 or 3 carbon atoms, R3 represents fluoroalkyl of 1, 2 or 3 carbon atoms, W represents oxygen, methylene or NH, X represents a nitrogen atom or a carbon atom bearing a hydrogen atom and Y and Z are each independently selected from hydrogen and halogen.
2. 2. 1,l-Difluoro-2,2-dimethyl-5-(3-phenoxyphenyl)- pentane.
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 treating the locus with the composition of claim 4.