GB2054562A

GB2054562A - Cyclopropanecarboxylic acid esters having insecticidal activity

Info

Publication number: GB2054562A
Application number: GB8019850A
Authority: GB
Original assignee: Sankyo Co Ltd
Current assignee: Sankyo Co Ltd
Priority date: 1979-06-18
Filing date: 1980-06-18
Publication date: 1981-02-18
Also published as: DE3022739A1; FR2459223A1; PH15125A; JPS55167255A; GB2054562B; JPS6052144B2

Abstract

m-(p-Halophenoxy)benzyl 3-[2- (chloro- or bromo-)-1-propenyl]-2,2- dimethyl-1-cyclopropanecarboxylates, in which the benzyl group optionally has a cyano substituent at the alpha -carbon atom, are new compounds having excellent insecticidal activity but much lower toxicity to fish than comparable known compounds, thus rendering them particularly useful in suitable insecticidal preparations for agricultural use, especially application to paddy fields and the like.

Description

SPECIFICATION Cyclopropanecarboxylic acid esters having insecticidal activity The present invention relates to certain new rr > ( halophenoxy)benzyl 3-[2-(chloro- or bromo-)-1 propenylj-2,2-dimethyl-1-cyclopropanecarboxylates, to methods for preparing them and to insecticidal preparations containing them as the active ingredient.

Many esters of cyclopropanecarboxylic acids are known to have insecticidal properties, including both the naturally occurring pyrethrins and their synthetic analogues, the pyrethroids.

For example, our United Kingdom Patent Specification No. 1,552,751discloses the m phenoxybenzyl esters of 3-(2-halo- I -propenyl)-2, 2-dimethyl- 1 -cyclopropanecarboxylic acids, and Japanese Patent Application No. 54-22344, as laid open to public inspection, discloses the im phenoxy-a-cyanobenzyl esters of the same acids. Similar compounds, the n > (substituted phenoxy)-ci-cyanobenzyl esters of 3-(2 , 2-dichlornvinyl)-2, 2-dimethyl- 1 -cyclopropanecarboxylic acid, are disclosed in Japanese Patent Applications No. 54-5947 and 54-5948, as laid open to public inspection.However, these compounds are highly toxic to fish, even the compounds of United Kingdom Patent No. 1,552,751, where the fish toxicity was significantly reduced as compared with the compounds then known. As a result of this high toxicity to fish, there are serious limitations to the practical use of these compounds.

Agricultural chemicals can contaminate environmental water by their direct application to wellwatered land such as paddy fields, by entrainment with rain water of chemicals spread on the ground or floating in the air, by flowing with irrigation water from farms or by discharge from factories. In fact, almost any agricultural chemical applied to land will, itself or its degradation products, ultimately contaminate the environmental water. Accordingly, it is important that any agricultural chemical should have as low a toxicity to fish as possible and this applies especially to insecticides, where it is difficult to achieve good insecticidal activity combined with low fish toxicity.

We have now discovered certain new rr > ( halophenoxy)benzyl 3-(2-halo-1-propenyl)-2,2 dimethyl-1-cyclopropanecarboxylates which successfully achieve a combination of good insecticidal activity with low fish toxicity.

The compounds of the present invention are those compounds of formula (I):

in which: R1 represents a chlorine atom or a bromine atom; R2 represents a hydrogen atom or a cyano group; and R3 represents a halogen atom, preferably a chlorine atom or a bromine atom.

The invention also provides an insecticidal composition comprising, as active ingredient, one or more of the compounds of formula (I) together with an insecticidally acceptable carrier or diluent.

In the compounds of the present invention, where R2 represents a hydrogen atom or a cyano group, it preferably represents a cyano group.

The compounds of formula (I) can exist in the form of various stereo, geometric and positional isomers. Both the individual isomers and mixtures thereof are contemplated by the present invention. Thus, the compounds exhibit stereoisomerism with respect to the substituents on the cyclopropane ring, geometric isomerism with respect to the substituents on the carbon atoms forming the ethylenic double bond and optical isomerism arising from the presence of various asymmetric carbon atoms.

In general, we prefer those isomers which are trans with respect to the cyclopropane ring and, in the following Examples, except where otherwise stated, the compounds produced are specific single isomers with respect to the cyclopropane ring and mixtures of isomers with respect to the ethylenic double bond and asymmetric carbon atoms. However, as the compounds of the invention can be prepared by a variety of stereospecific synthetic routes, the skilled man can readily produce any desired combination of isomers or any desired single isomer.

The trnnscycloprnpane isomers have been found to exhibit particularly potent insecticidal activity, but the other isomers also have good activity as well as low fish toxicity.

The compound of the invention can be prepared by the following methods.

Method A They may be prepared by reacting an alcohol, a halide or a quaternary ammonium salt of formula (ill):

[in which: R2 and R3 are as defined above; and X represents a hydroxy group, a halogen atom or a combination of a trialkylammonium ion and an anion (to form a quaternary ammonium salt)j with a cyclopropanecarboxylic acid of formula (III):

(in which R1 is as defined above) or with a reactive derivative thereof, e.g. an acid halide, an acid anhydride, an alkali metal salt or a salt with a tertiary organic base. The reaction may be carried out in the presence of a reaction promoter, the nature of which may vary depending on the reagents.

The conditions under which the reaction is carried out will vary depending upon the nature of the two reagents. Thus, where the compound of formula (II) is an alcohol (i.e. X represents a hydroxyl group) and the acid of formula (Ill) itself is employed, the reaction is preferably carried out under dehydrating conditions, for example in the presence of a dehydrating agent, such as dicyclohexylcarbodiimide. The reaction is also preferably carried in the presence of an inert solvent, the nature of which is not critical, provided that it has no adverse effect upon the reaction. We prefer a hydrocarbon solvent, such as benzene. The reaction is preferably carried out at a temperature of from 0 to 50"C, more preferably at about room temperature.

Where the compound of formula (III) is an alcohol (X represents a hydroxy group) and the reactive derivative of the carboxylic acid (Ill) is a halide, the reaction is preferably carried out in the presence of an acid binding agent, for example an organic tertiary base, such as pyridine or triethylamine. The reaction is preferably carried out in the presence of an inert solvent, the nature of which is not critical, provided that it has no adverse effect upon the reaction; preferred solvents are hydrocarbons such as benzene or toluene. The reaction temperature is also not critical and, for this reason, we normally prefer to carry out the reaction at about room temperature.

Where the compound of formula (II) is an alcohol (X represents a hydroxy group) and the reactive derivative of the carboxylic acid (III) is an anhydride, the reaction will normallyproceed at room temperature but is promoted by the application of heat. The reaction can be carried out in the presence or absence of a solvent, but the use of a solvent is preferred in order to promote a smooth reaction; preferred solvents are aromatic hydrocarbons, such as benzene, toluene or xylene. However, it should be noted that the use of heat and of a solvent are not essential.

Where the compound of formula (II) is a benzyl halide (X represents a halogen atom) and the reactive derivative of the carboxylic acid (III) is an alkali metal salt or an organic tertiary base salt, the reaction is preferably carried out in the presence of a solvent, such as benzene, toluene or water, and, if necessary, in the presence of a phase-transfer catalyst (such as benzyltriethylammonium bromide). The reaction is preferably carried out at a temperature at or below the boiling point of the solvent employed.

Where the compound of formula (III) is a tertiary ammonium salt (X represents a combination of a trialkylammonium ion and its counter ion) and the reactive derivative of the carboxylic acid (Ill) is an alkali metal salt, the reaction conditions employed are preferably those described above for the case where the compound (II) is a benzyl halide and the reactive derivative of carboxylic acid (III) is an alkali metal or organic base salt.

Method B Compounds of formula (I) in which R2 represents a cyano group may also be prepared by reacting an aldehyde of formula (IV):

(in which R3 is as defined above) with a cyclopropane-carboxylic acid halide of formula (V): Take in block 5

(in which R1 is as defined above and Y represents a halogen atom) and an alkali metal cyanide.

The reaction is preferably effected in the presence of an inert solvent, although the nature of the solvent is not critical, provided that it has no adverse effect upon the reaction; hydrocarbon solvents such as benzene and toluene are preferred. The reaction is also preferably carried out under anhydrous conditions. The presence of a catalyst has been found to be advantageous, a crown ether being particularly effective. If the reaction is carried out in a two-phase system comprising an inert solvent and water, we also prefer to use a phase-transfer catalyst, such as benzyltriethylammonium chloride.

Preparation of the compounds of the invention is illustrated by the following non-limiting Examples.

EXAMPLE 1 m-(p-Chlorophenoxy)benzyl 3-(2-chloro- 1 -propenyl)-2, 2-dimethyl-trans- 1 -cyclopropanecarboxylate A solution of 0.23 g of 3-(2-chloro-1 -propenyl)-2,2-di methyl- trans 1 -cyclopropanecarboxyI chloride in 5 ml of benzene was added dropwise, with ice-cooling, to a solution of 0.26 g of m (pchlorophenoxy)benzyl alcohol and 0.1 5 g of pyridine in 10 ml of benzene. The mixed solutions were left to stand overnight at room temperature. The reaction mixture was then poured into dilute hydrochloric acid and extracted with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium chloride and then dried over anhydrous magnesium sulphate.The solvent was distilled off under reduced pressure and the resulting residue was purified by column chromatography through silica gel eluted with a 4:3 by volume mixture of hexane and benzene, to give 0.3 g of the desired product.

Infrared Absorption Spectrum (liquid film) Vmax cm-': 1730, 1580, 1490, 1255, 1170.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.15 (3H, singlet, CH3); 1.26 (3H, singlet, CH3); 1.53 (1H, doublet, J = 5.5 Hz); 2.12 (3H, singlet, CH3); 2.0-2.5 (1 H, multiplet); 5.10 (2H, singlet);

5.21 (doublet, J = 8.0 Hz) 5.33 (doublet, J = 8.0 Hz) J 7.1-7.6 (8H, multiplet).

Rf value (developer-85: 15 by volume mixture of hexane and ethyl acetate):0.64, 0.67.

The compound produced in this Example was a mixture of two diesteroisomers, thus resulting in two Rf values and two nuclear magnetic resonance values shared between a single proton.

Similarly, the products of Examples 2, 3, 4, 5, 7, 8, 9, 10, 1 2 and 13 are mixtures of two isomers.

The procedures described in Example 1 were repeated with different starting materials to prepare the following compounds of Examples 2-6.

EXAMPLE 2 m-(p-Chlorophenoxy)benzyl 3-(2-chloro- 1 -propenyl)-2, 2-dimethyl-cis- 1 -cyclopropanecarboxylate Infrared Absorption Spectrum (liquid film) ltmax cm-1: 1730, 1580, 1485, 1255, 1140.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.22 (6H, singlet, two CH3 groups); 1.78 (1 H, doublet, J = 8.9 Hz); 2.12 (3H, singlet, CH3); 2.0-2.4 (1 H, multiplet); 5.10 (2H, singlet); 5.36 (1 H, doublet, J = 8.0 Hz); 6.9-7.6 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate):0.63, 0.70.

EXAMPLE 3 m-(p-Chlornphenoxy)benzyl 3-(2-bromo- 1-propenyl)-2,2-dimethyl-trans- 1-1 cyclopropanecarboxylate Infrared Absorption Spectrum (liquid film) may cm-1: 1725, 1610, 1580, 1485, 1255, 1160, 1110.

Nuclear Magnetic Resonance Spectrum (CDCls) S ppm: 1.12-1.38 (6H, multiplet, two CH3 groups); 1.57 (1H, doublet, J = 5.0 Hz); 1.92-2.57 (1H, multiplet); 2.30 (3H, singlet, CH3); 5.1 5 (2H, sinqlet);

5.48 (doublet, J = 8.0 Hz) 1H; 5.65 (doublet, J = 8.0 Hz) 6.85-7.60 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.62, 0.67.

EXAMPLE 4 m-(p-Chlorophenoxy)benzyl 3-(2-bromo- 1 -propenyl)-2, 2-dimethyl-cis- 1 -cyclopropanecarboxylate Infrared Absorption Spectrum (liquid film) Vmax cm-': 1730, 1610, 1580, 1485, 1255, 1180, 1135.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.20 (3H, singlet, CH3); 1.23 (3H, singlet, CH3); 1.74-2.50 (2H, multiplet); 2.28 (3H, broad singlet, CH3); 5.11 (2H, singlet); 5.93-6.37 (1H, multiplet); 6.85-7.55 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.63, 0.70.

EXAMPLE 5 m-(p-Bromophenoxy)benzyl 3-(2-chloro- 1 -propenyl)-2, 2-dimethyl4rans- 1 -cyclopropanecarboxylate Infrared Absorption Spectrum (liquid film) vmax cm~': 1730, 1580, 1260, 1165.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.12-1.36 (6H, multiplet, two CH3 groups); 1.55 (1 H, doublet, J = 5.6 Hz); 2.12 (3H, singlet, CH3); 2.31(1 H, quartet, J = 5.6 and 8.0 Hz); 5.10 (2H, singlet);

5.21 (doublet, J = 8.0 Hz) \ 1H; 5.37 (doublet, J = 8.0 Hz) 6.8-7.6 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.51, 0.54.

EXAMPLE 6 m-(p-Bromophenoxy)benzyl 3-(2-chloro- I -propenyl)-2, 2-dimethyl-cis- 1 -cyclopropanecarboxylate Infrared Absorption Spectrum (liquid film) vmax cm-1: 1730, 1580, 1260, 1222, 1140.

Nuclear Magnetic Resonance Spectrum (CDCI,)G ppm: 1.23 (6H, singlet, two CH3 groups); 1.80 (1H, doublet, J = 8.0 Hz); 2.12 (3H, singlet, CH3); 2.17 (1H, triplet, J = 8.0 Hz); 5.0 (2H, singlet, CH2); 5.76 (1 H, doublet, J = 8.0 Hz); 6.75-7.50 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.57 EXAMPLE 7 m-(p-Chlorophenoxy)-a-cyanobenzyl 3-(2-chloro- 1 -propenyl)-2, 2-dimethyl4rans- 1-cyclopropanecarboxylate A solution of 0.24 g of m(pchlorophenoxy)benzaldehyde and 0.22 g of 3-(2-chloro-1 propenyl)-2,2-dimethyl-trana1-cyclopropanecarboxyl chloride in 5 ml of benzene was added dropwise at room temperature to a suspension of 0.078 g of sodium cyanide and 0.024 g of 15-crown-5 ether in 10 ml of benzene. The mixture was stirred overnight at room temperature and then poured into a saturated aqueous solution of sodium hydrogen carbonate and the mixture was extracted with ethyl acetate. The extract was then treated as described in Example 1 to give 0.3 g of the desired product.

Infrared Absorption Spectrum (liquid film) vmax cm-1: 1740, 1585, 1485, 1245, 1135.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.1-1.4 (6H, multiplet, two CH3 groups); 1.57 (1H, doublet, J=5.1 Hz); 2.13 (3H, singlet, CH3); 1.9-2.15 (1H. multiDlet):

5.31 (doublet, J = l Hz) 5.43 (doublet, J = 8.0 Hz) I 6.50 (1H, singlet); 6.9-7.6 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.48, 0.53.

The compounds of Examples 8-13 were then prepared following the same procedure as described in Example 7.

EXAMPLE 8 m-(p-Chlorophenoxy)-a-cyanobenzyl 3-(2-chloro-1 -propenyl)-2, 2-dimethyl-cis-l -cyclopropanecar- boxylate Infrared Absorption Spectrum (liquid film) #max cm-1: 1740, 1580, 1485, 1245, 1130.

Nuclear Magnetic Resonance Spectrum (CDCI3) S ppm: 1.1-1.4 (6H, multiplet, two CH3 groups); 1.81(1 H, doublet, J = 9.0 Hz); 2.11 (3H, singlet, CH3); 2.0-2.5 (1H, multiplet); 5.73 (1 H, doublet. J = 8.0 Hz):

6.36 ('singlet) I 1H 1H; 6.38 (singlet) 6.8-7.5 (8H, multiplet).

Rf value (developer-85:15 by volume mixture of hexane and ethyl acetate): 0.41, 0.43, 0.50.

EXAMPLE 9 m-(p-Chlorophenoxy)-α-cyanobenzyl 3-(2-bromo- 1 -propenyl)-2, 2-dimethyl4rans- 1 -cyclopropanecarboxylate Infrared Absorption Spectrum (liquid film) #max cm-1: 1740, 1600, 1580, 1485, 1240, 1135, 1110.

Nuclear Magnetic Resonance Spectrum (CDCl3) 8 ppm: 1.13-1.38 (6H, multiplet, two CH3 groups); 1.58 (1 H, doublet, J = 5.0 Hz); 1.90-2.46 (1H, multiplet); 2.29 (3H, broad singlet, CH3);

5.49 (doublet, J = 7.5 Hz) 1H; 5.63 (doublet, J = 7.5 Hz) J 1 H; 6.89-7.63 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.50, 0.55.

EXAMPLE 10 m-(p-Chlorophenoxy)-a:-cyanobenzyl 3-(2-bromo- 1-pro pen yl)-2, 2-dimethyl-cis- 1-cyclopropanecar- boxylate Infrared Absorption Spectrum (liquid film) vmax cm-1: 1740, 1580, 1480, 1245.

Nuclear Magnetic Resonance Spectrum (CDC13) 8 ppm: 1.1-1.4 (6H, multiplet, two CH3 groups); 1.5-2.1 (2H, multiplet); 2.2-2.4 (3H, multiplet);

6.03 (doublet, J = 7.5 Hz) 1H; 6.17 (doublet, J = 7.5 Hz) 6.9-7.8 (8H, multiplet).

Rf value (developer--85:15 by volume mixture of hexane and ethyl acetate): 0.40, 0.43, 0.49.

EXAMPLE Ii m-(p-Bromophenoxy)-a-cyanobenzyl 3-(2-bromo- 1 -propenyl)-2, 2-dimethyl- 1 -cyclopropanecarboxy- late (mixture of cis and trans isomers) Infrared Absorption Spectrum (liquid film) Vmax cm-1: 1745, 1600, 1575, 1480, 1240.

Nuclear Magnetic Resonance Spectrum (CDC13) 8 ppm: 0.97-1.27 (6H, multiplet, two CH3 groups); 1.37-2.33 (2H, multiplet);

2.11 (broad singlet \ 3H 2.18 (broad singlet) 5.39, 5.50 (broad doublet, J = 7.0 Hz) 1 H; 5.87, 6.00 (broad doublet, J = 7.0 Hz) 6.33 (singlet) 6.37 (singlet) 1H 6.71-7.68 (8H, multiplet).

Rf value (developer-85: 15 by volume mixture of hexane and ethyl acetate): 0.39.

EXAMPLE 12 m-(p-Bromophenoxyl)-a:-cyanobenzyl 3-(2-chloro- I -propenyl)-2, 2-dimeth yl4rans- 1 -cyclopropane- carboxylate Infrared Absorption Spectrum (liquid film) vmax cm-1: 1745, 1580, 1480, 1250, 1140.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.0-1.4 (6H, multiplet, two CH3 groups); 1.49 (1 H, doublet, J = 4.5 Hz); 2.05 (3H, singlet, CH3); 1.9-2.5 (1H, multiplet);

5.20 (doublet, J = 6.5 Hz) 1 H 5.32 (doublet, J = 6.5 Hz) 1 H; 6.38 (1H, singlet); 6.7-7.7 (8H, multiplet).

Rf value (developer-85:15 by volume mixture of hexane and ethyl acetate): 0.43, 0.46.

EXAMPLE 13 m-(p-Bromophenoxy)-a-cyanobenzyl 3-(2-chloro- 1-propenyl)-2,2-dimethyl-cis- 1-cyclopropanecar- boxylate Infrared Absorption Spectrum (liquid film) vmax cm-1: 1745, 1580, 1480, 1250, 1130.

Nuclear Magnetic Resonance Spectrum (CDCl3) S ppm: 1.1-1.3 (6H, multiplet, two CH3 groups); 1.73 (1 H, doublet, J = 9.0 Hz); 2.08 (3H, singlet, CH3); 1.9-2.5 (1H, multiplet);

5.71 (broad doublet, J = 8.5 Hz) 1 1H; 5.85 (broad doublet, J = 8.5 Hz) 6.33 (1 H, singlet); 6.8-7.8 (8H, multiplet).

Rf value (developer-85:1 5 by volume mixture of hexane and ethyl acetate): 0.44, 0.49.

EXAMPLE 14 m-(p-Chlorophenoxy)-a-cyanobenzyl 3-(2-chloro- 1 -propenyl)-2, 2-dimethyl-trans- 1 -cyclopropanecarboxylate 104 mg of 3-(2-chloro-1 -propenyl)-2 ,2-dimethyl-transl -cyclopropanecarboxyl chloride and 1 29 mg of m-(chlorophenoxy)-a-cyanobenzyl alcohol in 2 ml of benzene were added dropwise to a solution of 47 mg of pyridine in 3 ml of benzene, with ice-cooling. The mixture was then stirred at room temperature for 5 hours. After completion of the reaction, water was added and the mixture was then acidified with 1 % w/v aqueous hydrochloric acid. The mixture was then extracted with diethyl ether and the extract was washed with water and dried over anhydrous magnesium sulphate.The solvent was removed by evaporation under reduced pressure and the residue was purified by column chromatography through neutral alumina eluted with a 1:1 by volume mixture of hexane and benzene to give 47 mg of the desired compound.

The product of this Example had the same properties as the product of Example 7.

The cyclopropanecarboxylic acid esters of the present invention are potent insecticides, even at low concentrations, and are effective against a wide variety of pests of sanitary importance, including mosquitoes, house flies and cockroaches, as well as plant pests, such as stem borers, leafhoppers, planthoppers, mites and aphids. Moreover, the compounds of the invention have a very low toxicity to mammals and, of particular importance, they also have a low toxicity to fish.

They are also relatively stable to light. As a result, they can be applied to paddy fields and to swamps without giving rise to harmful pollution of the environmental water.

The compounds of the invention may be formulated, as is well-known in the art, with various carriers or diluents and the resulting compositions may be solid or liquid. For example, liquid compositions (such as oils, emulsions, sprays and aerosols) can be formulated by dissolving the ester of formula (I) in an appropriate solvent or diluent and, if required, then adding a surfactant. Solid compositions (such as dusts, granules, wettable powders and fumigants) can be formulated by mixing the ester of formula (I) with a suitable solid carrier or diluent and, if desired, an appropriate adjuvant. The compositions of the invention may also contain synergists, such as piperonyl butoxide or safroxane and, if desired, the compounds of the invention may be blended with other natural or synthetic insecticides or fungicides.

The activity of the compounds of the invention and their low toxicity to fish are illustrated by the following Experiments. In these Experiments, the compounds of the invention are as prepared in the preceding Examples and are identified by the Example number by which they were prepared. In certain of the Experiments, some known compounds were used as controls and these are identified as follows: Control A: rmphenoxybenzyl 3-(2-chloro- 1 -propenyl)-2,2-d imethyl- trans 1 -cyclopropanecarboxylate; Control B: mphenoxybenzyl 3-(2-bromo- 1 -propenyl)-2, 2-dimethyl-trans 1 -cyclopropanecarboxylate; Control C: mphenoxybenzyl 3-(2-bromo- 1 -propenyl)-2,2-di methyl-cis- 1 -cyclopropanecarboxylate; Control D:: mphenoxy-e-cyanobenzyl 3-(2-chloro-1 -propenyl)-2, 2-dimethyl-trans l-cyclopropane- carboxylate; Control E: ,mphenoxy-a-cyanobenzyl 3-(2-bromo- 1 -propenyl)-2, 2-dimethyl-trans 1 -cyclopropanecarboxylate; Control F: m-phenoxy-a-cyanobenzyl 3-(2-bromo- 1 -propenyl)-2,2-dimethyl-cisl -cyclopropanecarboxylate; Control G: m(pchlorophenoxy)-cu-cyanobenzyl 3-(2, 2-dichlorovinyl)-2, 2-dimethyl- 1 -cyclopropanecarboxylate (mixture of cis and trans isomers); Control H: mphenoxybenzyl 3-(2, 2-dichlorovinyl)-2, 2-dimethyl- 1 -cyclopropanecarboxylate (mixture of cis and trans isomers) = Permethrin.

Where wettable powders were used in the Experiments, these were prepared by homogeneously mixing and pulverizing three times in a pulverizer 10 parts by weight of the compound under test, 4 parts by weight of sodium dodecylbenzenesulphonate, 2 parts by weight of polyvinyl alcohol and 84 parts by weight of clay.

EXPERIMENT 1 Toxicity in Fish 10% wettable powders of each test compound, prepared as described above, were dispersed in water to obtain a test solution containing the test compound in the required concentration.

Eight 21 day-old guppies were released to each 300 ml beaker containing 200 ml of the test solution and two beakers were used for each concentration of each compound. The beakers were maintained at 25"C and TLm (median tolerance limit = lethal concentration 50%) values were assessed after exposing the guppies to the test solutions for 48 hours. The results are given in Table 1.

Table 1 Compound TLM of Ex. No. (ppm) 1 > 10 2 > 10 3 > 10 4 > 10 7 > 10 8 L10 9 > 10 10 > 10 Control A 1 -3 B 0.5-1 C 0.1-0.3 D 0.3 E 0.1 F 0.1 G 0.1-0.3 H 0.2 From the results given in Table 1, it can be seen that the TLm values of the compounds of the present invention are all more than 10 ppm, which means that the compounds of the invention are 10-100 times as safe as the control compounds.

EXPERIMENT 2 Effect against larvae of American cockroaches Acetone solutions of each test compound were placed in glass bottles (diameter about 2 cm, height about 5 cm) and the acetone was evaporated off. Ten first instar larvae of American cockroaches were put into each bottle. The bottles were plugged and 24 hours later the dead insects were counted. The results are given in Table 2 according to the following code: 6: 100% mortality at 1 y9; 5: 100% mortality at 10g.

Table 2 Compound of Ex. No. Activity 1 5 2 5 3 5 4 5 7 6 8 6 9 6 10 6 Control G 5 EXPERIMENT 3 Effect aginst houseflies Denken strain houseflies (4 day-old female post emergence imagines), which had been reared for successive generations, were anaesthetized with carbon dioxide. 1 !Ll of an acetone solution containing one of the test compounds shown in Table 3 was applied to an insect on its dorsal thorax using a microsyringe. 1 3 insects were put into each Petri dish and kept at 25"C. The mortalities of the insects after 24 hours were assessed and, from the results, the 50% lethal concentration (LD50,ug/insect) were calculated and the results are given in Table 3.

Table 3 Compound LD50 of Ex. No. (yg/insect) 7 0.068 8 0.176 9 0.117 EXPERIMENT 4 Effect against green rice leafhopper Soil and water were placed into plastics pots of inner diameter about 10 cm and height about 10 cm so that the water stood to a depth of about 2 cm and the test pots thus obtained were in a situation similar to paddy fields. Young rice plants were then planted into each test pot and reared at room temperature to a height of 1 5 cm. At this stage, the rice plants were dusted with one of the test compounds shown in Table 4 to various concentrations and final instar nymphs of a strain of green rice leafhopper resistant to both phosphate and carbamate insecticides were released onto them. Each pot contained 10-15 nymphs. The pots were covered and left to stand at room temperature.After 3 days, nymphal mortalities were assessed and the results are shown in Table 4.

Table 4 Leafhopper Nymphal Mortality (%) Amount (g) of test compound per 10 ares Compound of Ex. No. 1.41 0.75 0.141 0.075 1 78 37 - 3 100 94 - - 4 88 68 - 7 100 100 56 37 9 100 100 58 39 10 100 100 50 36 EXPERIMENT 5 Effect against the green peach aphid A wettable powder prepared as described above was diluted with water to give a concentration of the test compound of either 200 ppm or 100 ppm and then 0.01 % w/v of Gramin (a spreader) was added. Using a sprayer, the dilute solution thus obtained was sprayed onto the leaves of a cabbage bearing green peach aphids (Myzus persicae) in an amount of 10 ml per leaf. The leaves were then placed in petri dishes and left in a room maintained at 25 C. After 24 hours, the percentage mortality of the aphids was assessed.The results are given in Table 5, which also gives the result obtained in a control experiment where the solution applied contained no active compound.

Table 5 Aphid mortality (%) at active Compound compound concentration of of Ex. No. 200ppm 100ppm 1 100 100 2 100 93 3 100 92 4 100 97 5 100 100 6 100 100 7 100 100 8 100 97 9 100 100 10 100 97 11 100 100 12 100 100 13 100 100 Control o EXPERIMENT 6 Effect against the tobacco cutworm A wettable powder prepared as described above was diluted until the concentration of the active compound was 100 ppm or 20 ppm. Cabbage leaves were then dipped for 30 seconds into one of the resulting solutions, after which the leaves were air-dried and each leaf was placed into a plastic icecream cup having a diameter of 8 cm.

Third instar larvae of the tobacco cutworm (Spodoptera lituna) were released into each cup and, beginning on the day after their release, they were fed untreated fresh cabbage leaves.

After 5 days, the percentage mortality of the larvae was assessed. The tests were conducted in duplicate, using 10 larvae in each test. The results are given in Table 6.

Table 6 Larval mortality (%) at active Compound Compound concentration of of Ex. No. 100ppm 20ppm 1 100 80 2 100 100 3 100 80 4 100 80 7 100 70 8 100 100 9 100 70 10 100 95 Control o

Claims

1. Compounds of formula (I):

in which: R' represents a chlorine atom or a bromine atom; R2 represents a hydrogen atom or a cyano group; and R3 represents a halogen atom.

2. Trans isomers of compounds according to Claim 1.

3. Cis and/or trans m-(pchlorophenoxy)benzyl 3-(2-chloro-1-propenyl)-2,2-dimethyl-1 -cyclopropanecarboxylate.

4. Cis and/or trans m4Rchlorophenoxy)benzyl 3-(2-bromo-1 -prnpenyl)-2,2-dimethyl-1 -cyclopropanecarboxylate.

5. Cis and/or trans mip-bromophenoxy)benzyl 3-(2-chloro-1-propenyl)-2,2-dimethyl-1-cyclo- propane-carboxylate.

6. Cis and/or trans m4Rchlorophenoxy)-a-cyanobenzyl 3-(2-chloro- 1 -propenyl)-2, 2-dimethyl- 2-cyclopropanecarboxylate.

7. Cis and/or trans m-(-p-chlorophenoxy)-a-cyanobenzyl 3-(2-bromo-1-propenyl)-2,2-dimethyl- 1 -cyclopropanecarboxylate.

8. Cis and/or trans m4*bromophenoxy)-a-cyanobenzyl 3-(2-bromo-1 -propenyl)-2, 2-dimethyl- 1 -cyclopropanecarboxylate.

9. Cis and/or trans m bromophenoxy-a-cyanobenzyl 3-(2-chloro-1 -propenyl)-2, 2-dimethyl1 -cyclopropanecarboxylate.

10. An insecticidal composition comprising an insecticide in admixture with an insecticidally acceptable carrier or diluent, the insecticide being a compound according to any one of the preceding Claims.