GB2099810A - Cyclopropanecarboxylate esters and their use as pesticides - Google Patents

Abstract

There are provided cyclopropanecarboxylate esters of formula <IMAGE> wherein X is a fluorine, chlorine or bromine atom, Y is hydrogen, cyano or ethynyl, and Z is a halogen atom, n is 0 to 4 and Q is hydrogen, halogen or phenoxy; methods for their manufacture; pesticidal compositions containing them and their use as pesticides, e.g. insecticides.

Description

SPECIFICATION Cyclopropanecarboxylate ester and their use as pesticides This invention relates to cyclopropanecarboxylate esters, to their preparation and to compositions containing them for use as Pesticides, especially as insecticides.

According to the present invention there are provided cyclopropanecarboxylate esters of formula

wherein X is a fluorine, chlorine or bromine atom, Y is hydrogen, cyano or ethynyl, and Z is a halogen atom, n is O to 4 and Q is hydrogen, halogen or phenoxy.

It should be noted that the compounds of formula I possess two or three centres of asymmetry, depending on the nature of the substituent Y. There is also EIZ geometric isomerism about the vinyl double bond, i.e. E isomers

Z isomers

Accordingly, as will be appreciated by those skilled in the art, the compounds of formula I may exist as individual geometrical and optical isomers, mixtures of isomers and racemates. In general mixtures of cis-isomers are preferred over mixtures of trans-isomers, and mixtures of cis(Z)-isomers are preferred over mixtures of cis(E)-isomers.

Preferred esters of formula I have one or more of the following features:- (i) X is a bromine atom, (oil) Q is a hydrogen and (Z)n represents 2,6-dihalo, (Ill) Q is halogen and n is 4, (IV) Q is phenoxy and n is 0, and (v) a halogen atom represented by Z or Q is a chlorine atom.

The cyclopropanecarboxylate esters may be prepared by methods analogous to those used for known compounds. A convenient process comprises reacting a compound of formula

with a compound of formula

wherein X, Y, Z, n and Q are as defined above, one of P and W represents a halogen atom, preferably a chlorine or bromine atom, and the other represents a hydroxy group. The reaction is preferably carried out in the presence of a suitable base, for example a tertiary amine such as triethylamine or an alkali metal carbonate such as sodium or potassium carbonate.

Compounds of formula Ill are either known compounds or may be prepared from known materials in known manner. (See e.g. UK Patent Specification No. 1,413,491).

Compounds of formula II may conveniently be prepared from the appropriate isomer or isomers of an alkyl caronaldate of formula

wherein R is an alcohol residue e.g. an alkyl group of 1 to 6 carbon atoms, preferably an alkyl group of 1 to 4 carbon atoms such as methyl or tertiary butyl, by reaction with a dihaloacetonitrile of formula CHXX'CN (V) where X is as defined above and X1 is X or a halogen atom of higher atomic number than X, conveniently in the presence of an alkali metal trichloroacetate, e.g. sodium trichloroacetate, and a polar aprotic solvent such as N,N-dimethylformamide.The resulting compound of formula

may be reacted with phosphorous trichloride in a polar aprotic solvent such as N,N-dimethylformamide with application of heat to give a compound of formula

which may be hydrolysed under acid conditions, conveniently using hydrobromic acid and acetic acid, to give a compound of formula II wherein P represents a hydroxy group, which may if desired be converted to a compound of formula II wherein P represents a halogen atom in known manner, e.g. by reaction with thionyl chloride, conveniently in an inert solvent such as benzene, to give the acid chloride of formula 11.

The cyclopropanecarboxylate esters according to the invention are of interest as pesticides, especially as insecticides for domestic and agricultural outlets. The invention therefore also provides a pesticidal composition which comprises an ester of formula I as defined above in association with a inert carrier. The invention therefore also provides a pesticidal composition which comprises an ester of formula I as defined above in association with an inert carrier. The invention further provides a method of combating pests, e.g. insect pests, at a locus which comprises applying to the locus an ester of formula I or a composition in accordance with the invention.

A carrier in a composition of the invention may be a solid or a liquid, including a material which is normally gaseous but which has been compressed to form a liquid, inorganic or organic, and of synthetic or natural origin. The active ingredient is suitably formulated with at least one carrier to facilitate its application to the locus, for example plants, seeds or soil, to be treated, or to facilitate storage, transport or handling.

Preferably a composition of the invention contains at least two carriers, at least one of which is a surface-active agent. The surface-active agent may be an emulsifier, a dispersing agent or a wetting agent. It may be non-ionic or ionic. Pesticidal compositions are generally formulated and transported in a concentrated form which is subsequently diluted by the farmer or other user before application. A surface-active agent facilitates this process of dilution.

Any of the carriers commonly used in the formulation of pesticides may be used in the compositions of the invention, and suitable examples of these are to be found, for example, in British Patent Specification No. 1 232,930.

The composition of the invention may for example be formulated as a wettable powder, microcapsules, a dust, granules, a solution, an emulsifiable concentrate, an emulsion, a suspension concentrate or an aerosol. The composition may have controlled release properties, or may be suitable for use as a bait.

Wettable powders usually contain 25, 50 or 75% of active ingredient and may contain, in addition to inert solid material, 3-1 0%w of a dispersing agent and, where necessary, 0-1 0%w of a stabiliser, a penetrant and/or a sticker. A dust is usually formulated as a dust concentrate having a composition similar to that of a wettable powder but without a dispersant, and is diluted in the field with further solid carrier to give a composition usually containing 21 0%W of active ingredient.

Granules usually have a size in the range of from 10 to 100 BS mesh (1.676-0.1 52 mm) and may be manufactured by agglomeration or impregnation techniques. Generally, granules will contain 21 25% active ingredient and 0-1 0%w of additives, for example a stabiliser, slow release modifier and/or a binding agent.

Emulsifiable concentrates usually contain, in addition to a solvent, and, when necessary, co solvent. 10--50% wA active ingredient, 2-20% w/v emulsifier and 0--20 w/v of other additives, for example a stabiliser, a penetrant and/or a corrosion inhibitor.A suspension concentrate is a stable, nonsedimenting, flowable product and usually contains 1 0-75%w active ingredient, 0.5-1 5%w of dispersng agent, 0.1-1 0%w of suspending agent, for example protective colloid and/or a thixotropic agent, and 0-1 0%w of other additives including, for example, a defoamer, a corrosion inhibitor, a stabiliser, a penetrant and/or a sticker, and as dispersant, water or an organic liquid in which the active ingredient is substantially insoluble; certain organic additives and/or inorganic salts may be dissolved in the dispersant to assist in preventing sedimentation or as anti-freeze for water.

The aqueous dispersions and emulsions formed by diluting a wettable powder or an emulsifiable concentrate of the invention with water, also lie within the scope of the present invention. Such dispersions and emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick "mayonnaise"-like consistency.

A composition of the invention may also contain other ingredients, for example, one or more other compounds possessing pesticidal, herbicidal orfungicidal properties, or attractants, for example pheromones or food ingredients, for use in baits and trap formulations.

The invention will be further understood from the following Examples.

EXAMPLE I Preparation of trans-a-cyano-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2 dimethylcyclopropanecarboxylate (1) Trans-methyl caronaldate (trans-methyl 2,2-dimethyl-3-formylcyclopropaneca rboxylate) (1 2.1 g, 77.5 mM), dibromoacetonitrile (15.5 g, 77.5 mM) and sodium trichloroacetate (1.5 g, 7.8 mM) were stirred together in N,N-dimethylformamide (50 ml) for 42 hours at ambient temperature. Water was added, followed by dilute hydrochloric acid, and the mixture was extracted three times with 50 ml portions of diethyl ether.The combined ether extracts were washed with water and dilute aqueous sodium bicarbonate solution, were dried over magnesium sulphate and evaporated to yield an orange semi-solid residue (25.3 g), which was purified on a silica column using methylene chloride as eluant to give trans-methyl 3-(2,2-dibromo-2-cyano- 1 -hydroxyethyl)-2,2-dimethylcyclopropanecarboxylate (14.4 g, 52%) m.p. 148--500C.

Phosphorous trichloride (4.0 g, 29.0 mM) was added dropwise to a solution of trans-methyl 3 (2,2-dibromo-2-cyano- 1 -hydroxyethyl)-2,2-dimethylcyclopropanecarboxylate (10.3 g, 29.0 mM) in N,N-dimethylformamide at room temperature, the last drops being washed in with N,Ndimethylformamide (10 ml). The reaction mixture was stirred at 70-800C for 121 hours, and was then poured into ice/dilute hydrochloric acid and extracted three times with 50 ml portions of diethyl ether.

The combined ether extracts were washed with water and dilute aqueous sodium bicarbonate solution, were dried over magnesium sulphate and evaporated to give 7.1 g of a crude neutral product which on recrystallisation from cyclohexane gave trans-methyl 3-(2-bromo-2-cya novinyl)-2,2- dimethylcyclopropanecarboxylate (6.9 g, 92%) m.p. 67-11 80C.

Trans-methyl 3-(2-bromo-2-cyanovinyl)-2,2-dimethylcyclopropanecarboxylate (2.0 g, 7.75 mM), glacial acetic acid (12 ml), 48% hydrobromic acid (8 ml) and water (4 ml) were stirred together under reflux for 2 hours. The reaction mixture was then diluted with water and extracted twice with 20 ml portions of diethylether. The ether extracts were washed with water and then extracted twice with 20 ml portions of aqueous sodium bicarbonate solution. The aqueous extracts were washed with diethyl ether and acidified with concentrated hydrochloric acid and were then extracted twice with 20 ml portions of diethyl ether.The ether extracts were dried over magnesium sulphate and evaporated to yield trans-3-(2-bromo-2-cyanovinyl)-2,2-dimethylcyclopropanecarboxylic acid (1.4 g, 74%) in the form of a buff coloured solid, which was used without further purification in the preparation of the title compound.

Trans-3-(2-brono-2-cyanovinyl)-2,2-dimethylcyclopropanecarboxylic acid (1.4 g, 5.7 mM), a- cyano-3-phenoxybenzyl bromide (1.65 g, 5.7 mM) and potassium carbonate (0.8 g) were stirred together in acetone (10 ml) at room temperature for 3 hours. The reaction mixture was then diluted with water and extracted twice with 20 ml portions of diethyl ether. The ether extracts were washed with aqueous sodium bicarbonate solution, dried over magnesium sulphate and evaporated to yield an orange oil (2.4 g) which was purified on a silica column.Elution with 2% acetone/60-80 petroleum ether removed unreacted a-cyano-3-phenoxybenzyl bromide (0.5 g) and elution with toluene gave the desired trans-a-cyano-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2dimethylcyclopropanecarboxylate (1.2 g, 47%) (1) as an orange oil.

Analysis: C23H,9N203Br: C H N Br Calculated 61.2 4.2 6.2 17.7 % Found 62.0 4.4 6.0 17.8 % NMR: 1 .28(3H,d) 1 .35(3H,d) 1.95(1 H,d), 2.33-2.7(1 H,m), 6.4(1 H,d) 6.52-6.68(1 H,d), 6.9-7.6(9H,m).

EXAMPLES 2 AND 3 Preparation of cis(E)- and cis(Z)-a-ethynyl-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2dimethyicyclopropanecarboxylate (2 s 3) C!s-3-(2-bromo-2-cyanovinyl)-2,2-dimethylcyclopropanecarboxylic acid, prepared from cis methyl caronaldate in similar manner to the preparation of the trans-acid in Example 1, (1.22 g, 5 mM) and thionyl chloride (1.79 g, 1 5 mM) in benzene (30 ml) were refluxed for 27 hours. The benzene was then evaporated off and excess thionyl chloride was removed to yield cis-3-(2-bromo-2-cyanovinyl) 2,2-dimethylcyclopropanecarbonyl chloride, which was dissolved in toluene (20 ml) and added to a solution of a-ethynyl-3-phenoxybenzyl alcohol (1.01 g, 4.5 mM) and triethylamine (0.6 g, 6 mM) in toluene (20 ml).The resulting reaction mixture was stirred for 1 6 hours at ambient temperature, and was then poured into water and extracted twice with 20 ml portions of diethyl ether. The ether extracts were washed with saturated aqueous solutions of sodium bicarbonate and sodium chloride, were dried and evaporated to yield a crude product which was chromatographed on a silica column eluting with toluene to give cis(E)-a-ethynyl-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2- dimethylcyclopropanecarboxylate (0.9 g) (2) (f4 1-70) and cis(Z)-a-ethynyl-3-phenoxybenzyl 3-(2 bromo-2-cyanovinyl)-2,2-dimethylcyclopropanecarboxylate (0.9 g) (3) (f73-1 20) (overall yield of E + Z isomers 89%) 2 Analysis:: C24H20NO3 Br: C H N Calculated: 64.0 4.5 3.1 Found: 63.9 4.5 3.1 NMR: a 1.2-1 .3(6H,s,d), 1 .95-2.4(2H,m), 2.6(1 H,d), 6.4(1 H,dd), 6.8-7.5(1 OH,m).

3 Analysis: C24H20NO3Br: C H N Calculated: 64.0 4.5 3.1 Found: 64.3 4.8 3.1 NMR: 1.25-1 .3(6H,d,d), 2.0--2.4(2H.m). 2.65(1 H,d), 6.4(1 H,dd), 6.8-7.6(1 OH,m).

Assignment of E- and Z-configuration was made following the procedure described in Org. Magn.

Reson., 1975, 7, 617-624.

EXAMPLES 4TO 8 By similar methods to those of Example 1 to 3 were prepared the following compounds: 4 cis( E)-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2-dimethylcyclopropa necarboxylate Analysis: C22H20NO3Br: C H N Calculated: 62.0 4.7 3.3 Found: 62.4 5.0 3.3 NMR: b .28(6H,s), 2.O-2.4(2H,m), 5.1 (2H,s), 6.8-7.5(1 0H,m).

5 cis(Z)-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2-dimethylcyciopropanecarboxylate Analysis: C22H20NO3Br: C H N Calculated: 62.0 4.7 3.3 Found: 62.0 5.0 3.2 NMR: 1 .3(6H,s), 2.0-2.4(2H,m), 5.1 (2H,s), 6.8-7.5(1 OH,m).

Overall yield of4 + 5 67% 6 cis(E)-a-cya no-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyí)-2,2-dimethyícycíopropa necarboxylate Analysis: C23N,9N203Br: C H N Calculated: 61.2 4.2 6.2 Found: 60.4 4.3 6.0 NMR: # 1.27-1 .32(6H,d,d), 2.0-2.55(2H,m), 6.35(1 H,d), 6.9-7.6(1 OH,m), S13C 114.6, 3JC-H 12.1 Hz 7 cis(Z)-a-cya no-3-phenoxybenzyl 3-(2-bromo-2-cyanovinyl)-2,2-dimethylcyclopropanecarboxylate Analysis: C23H1gN2O3 Br: C H N Calculated: 61.2 4.2 6.2 Found: 60.8 4.4 6.0 NMR: S 1.3-1 .33(6H,d,s), 2.0-2.5(2H,m), 6.3H(1 H,d), 6.9-7.6(1 OH,m); S13C 115.9, 3JCIH 5.8 Hz.

Overall yield of 6 + 7 79% 8 cis-pe ntachlorobenzyl 3-(2-b:omo-2-cyanovi nyl)-2,2-di methylcyclopropa necarboxylate Analysis: C,6H"NO2BrCls: C H N Calculated: 37.8 2.2 2.8 Found: 38.4 2.2 2.7 mp 138140 C NMR: S 1.32(6H,d), 1.95--2.45(2H.m), 5.5(2H,s), 7.1-7.5(1 H,m) Yield 63% Pesticidal Tests The insecticidal activity of the compounds under consideration was assessed using the following pests.

Spodoptera littoralis (S.I.) Musca domestica (M.d.) Aphis fabae (A.t) (i) Spodoptera littoralis (S.I.) Aqueous test formulations were made up containing 0.2% by weight of the compound to be tested, 0.05% by weight of TRITON X-1 00 (Trade Mark) wetting agent and 10% by weight of acetone.

Varying concentrations were obtained by diluting the formulations. An artificial diet mixture was prepared by dissolving, with heat, 9.6 g agar ("Oxoid No. 1" - Trade mark) in 540 ml water, blending the resulting solution with a mixture of 150 g finely ground French bean seed, 24 g dried brewers yeast, 24 g ascorbic acid, 0.75 g sorbic acid, 1.5 g methyl p-hydroxybenzoate and 2.6 ml of a 10% aqueous solution of formalin, in 340 ml water, and finally mixing in 8 ml linseed oil and 7 ml of a 1% by weight aqueous solution of a mixture of vitamins consisting of by weight 5 parts nicotinic acid, 5 parts calcium pantothenate, 2.5 parts riboflavin, 1.25 parts aneurine hydrochloride, 1.25 parts pyridoxine hydrochloride, 1.25 parts folic acid, 0.1 parts D-biotin and 0.01 parts cyanocobalamine. Whilst still warm the artificial diet mixture was poured into petri dishes to give an even, thin layer just covering the base of the dish, the dishes were left to enable the diet to cool and set, and the surface of the diet was then sprayed with test formulation and allowed to dry. Each dish was then infested with ten Egyptian cotton leafworm larvae (Spodoptera littoralis). After 24 hours and again after 7 days the percentages of dead and moribund larvae were recorded.

(ii) Musca domestica (M.d.) Batches of ten 2 to 3 day old milk-fed adult female houseflies (Musca domestica) anaesthetised using carbon dioxide were placed on petri dishes lined with filter paper. The dishes were sprayed with aqueous test formulations similar to those used in (i) above using a spray machine operating on a logarithmic dilution principle. The flies were subsequently retained in the petri dishes and were fed with a dilute milk solution which was dripped down the side of the petri dish and absorbed onto the filter paper. Mortality was assessed after 24 hours.

(iii) Aphis fabae (A.f.) Tests were carried out on adult black aphids (Aphis fabae). Pairs of broad bean leaves on filter paper in petri dishes were sprayed side by side with uncounted quantities of aphids in small gauzecovered containers. After passing through the spray the aphids were tipped onto the leaves and lids placed on the petri dishes. Mortality was assessed after 24 hours.

The results are shown in Table I in which the test species are identified by the initials noted above and the activity of the compound is expressed in the form of its Toxicity Index (T.l.) which is calculated from the following equation:- LCso of ethyl parathion (standard) Toxicity Index (T.l.) = LCso of test compound TABLE I

Test Compound Toxicity Index S.I. diet 1 day 7 days M.d. A.f.

1 83 96 B 3 2 210 160 1 A 3 530 440 2 A 4 370 370 7 140 5 1200 890 3 200 6 270 410 6 170 7 1300 1300 9 450 8 190 180 1 78 Grades "A" and "B" in Table 1 indicate that 90100% and 3080% kills respectively were obtained of the relevant test species at the initial test concentration of compound.

Claims (9)

1. A cyclopropanecarboxylate ester of formula

wherein X is a fluorine, chlorine or bromine atom, Y is hydrogen, cyano or ethynyl, and Z is a halogen atom, n is O to 4 and Q is hydrogen, halogen or phenoxy.

2. An ester according to Claim 1 wherein X is a bromine atom.

3. An ester according to Claim 1 or 2 wherein 0 is hydrogen, (Z)n represents 2,6-dihalo, when 0 is halogen n is 4 or when 0 is phenoxy n is 0.

4. An ester according to any one of Claims 1 to 3 wherein a halogen atom represented by Z or Q is a chlorine atom.

5. A process for preparing an ester of formula I as defined in any one of Claims 1 to 5, which process comprises reacting a compound of formula

with a compound of formula

wherein X, Y, Z, n and Q are as defined in Claim 1, one of P and W represents a halogen atom and the other represents a hydroxy group.

6. An ester according to Claim 1 substantially as hereinbefore described in any one of Examples 1 to 8.

7. A process according to Claim 5 of preparing an ester according to Claim 6 substantially as hereinbefore described in Example 1 or 2.

8. A pesticidal composition which comprises an ester of formula I as claimed in any one of claims 1 to 4 and 6 in association with an inert carrier.

9. A method of combating pests at a locus which comprises applying to the locus an ester of formula I as claimed in any one of Claims 1 to 4 and 6 or a composition according to Claim 8.