CA1159080A - Insecticidal cyclopropane carboxylic acid derivatives - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Esters of formula I wherein R1 and R2 represent halogen radicals or lower alkyl groups; R3 and R4 represent halogen radicals;
and R5 represents a hydrogen atom or the cyano radical, useful as insecticides.

Description

rrhi~ inven~ion relates to novel esters ? to processes fvr preparing them, to compositions comprising them, and to me~hods o combating insect pests using them.
Accordlngly the presen~ invention provides esters of formulas-CH.Co.oCH(R5) R~R2C=CH.CE~
C(CH3)2 oCH=CR3R4 (I) wherein Rl and R~ represen~ halogen radicals or lower alkyl groups; R3 and R4 represent halogen radicals; and R5 represents a hydrogen atom or the cyano radical.
~y the term "halogen" as used herein is meant fluorine~ ;~
lo chlorine or brcmine; and ~y the term lower alkyl group is meant arl alk~l group containing up to four carbon atoms.
~n a preferred ~orm the invention provides compounds where~n Rl and R~ ars both methyl groups~ or both chlorine radical~ or ~oth bromine radicals. An especially preferred group o compounds within th~ invention are those wherein Rl, R2, R3 and R4 are all chlorine radicaI~.
It will be readily appreciated that the compounds of th~ in~entlon as set out hereinabove are described without referenc~ tQ their stereochemical nature. Thus the above formula does not diferentiate be~ween the cis and trans

- 2 -' .' ' .', .-:

geometrical isomers which are possibly due to the substit-ution pattern around the cyclopropane ring, nor does it differentiate between the various stereoisomeric forms which may be present, and the present invention includes within lts scope all such geometric and optical stereoisomers.
Thus the term "compound" as used herein in relation to esters of the invention refers both to an individual isomer ln isolatlon, and to mixtures of isomers thereof e.g.
racemic mixture3, diastereoisomeric mixtures.
The following compounds are typical example~ o:E compounds according to ~he invention.

3(2,2-dichlorovinyloxy)ben2yl (~) cis~trans-chrysanthemate therelnafter referred to as Compound 1).

3(2,2-dichlorovinyloxy)benzyl (+~ cis/trana-2(2,2-dichloro-vinyl)3,3-dimethylcyclopropane carboxylate (hereinafter refe~red to as Compound 2).

3(2v2-dlchlorovinyloxy)benzyl (+) cis-2(2,2-dichlorovinyl)-3,3-dLmethylcyclopropane carboxylate (hereinafter referred to as Compound 3).

3(2,2-dichlorovinyloxy)benzyl (~) trans-2(2,~-dichlorovinyl)-3,3--dimethylcyclopropane carboxylate (hereinafter referred to a~ Compound 4). ' , . . .

o ~+) -cyano-3(2,Z-dichlorovinyloxy)benzyl (~
2(2,2-dichlorovinyl)3,3-dimethylcyclopropane carboxylate (herelnafter re~erred to as Compound 5).

~ cyano-3(2,2 dichlorovinyloxy)benzyl ( ) cis-2(2,2-dlchlorvvinyl)3,3-dlmethylcyclopropane carboxylate.

(~o~cyano-3(2,2dichlorovlnyloxy)benzyl (+) cis-2(2,2-dichlorovlnyl)3,3-d~methylcyclopropane caxboxylate.

3(2,~-dichlorovinyloxy)benæyl (~) cis/trans-2(2,2-dibromo-vinyl)3,3-d1methylcyclopropane carboxylate.

3~ dib~omovinyloxy)ben2yl t+) ~ -chrysanthemate.

3(2,2-dibromovinylo~y)benæyl (+) cis/trans-2(2,2-dichloro-vinyi)3,3-dimethylcyclopropane carboxylate.

~ ~cyano-3(2,2-dichlorovinyloxy)benzyl (~) cis!trans-chrysan~hemate.
;
lS (~ ~ yano 3(Z,2-dichlorovinyloxy)benzyl (+) cis/trans-~2,2-dibromovinyl)3,3-dimethylcyclopropane carboxylate.

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~he invention compounds may be prepared by ~everal different processes. Thus a compound of formula:-CH . CO . OH
R R C=CH . CH ~ ¦
( C~3 ) ;2 , (II) optionally ln the f?orm of a metal salt thereof, may be reacted with a c~mpound of formula:-XC~I~R5) ~
` 3 4 (ITI) wherein X i5 a halogen atom, preferably a chlorine or bromine atom, and Rl, R2, R3, R4 and R5 have any of the meanings given hereinabove. Alternatively a compound of f?ormula :--,: ' CH.CO~Y
RlR2C=CH.CH / ¦
C(CE13)~
~, ~ - 5 -.,. . . . ~. , , ~ : :' - . I
;
' , may be reacted wlth a compoulld of formula:-, ~
'. , .

' HOCH(R5~ ~
~<

. .

tV) erein ~ is a halogen atom, preferably a chlorine atom, and 1, ~2, R3, R4 a~d R5 have any of the meanings glven herein-before~
: 5 In another process ~he invention esters may be obtained by the;proc~s of transesteri~ication wherein the mixture of ~ a ~lmple e~ter (e.g. a lower alkyl ester such as the methyl ., i , `: or ethyl ester) of the acid of .formula II and the alcohol of formula V is h~ated in a solvent or diluent, preferably in the p~esence of a base ~e.g. a lower alkoxide such as sodium me~hoxlde or e~hoxide).
These~processes may in some cases be carried o~t by hea~ing the reactants together in the absence of a diluent and~or a base, but preferably a solvent or diluent and a base is pre~ent~ Suitable solvents include, for example, non-hydroxylic materials such as allphatic ketones (e.g.
acetone), dimethylformamide, dimethylsulphoxide, sulpholane, acetonitrlle an~ tetrahydrofuran. Of these an aliphatic - - ~ , . . . ~ .

~LlS~BO

ketone such a~, for example acetone is particularly preferred.
Hydroxylated solvent~, for example, methanol and ethanol, may be used in certain clrcumstances when the presence of the hyd~oxyl group does not interfere with the progress of the reaction. Suitable bases include sodium hydride (although not when a hydroxylated solvent or diluent is used), alkall metal carbonates, such as potassium carbonate and alkali metal hydroxides such as potassium hydroxideu The ~emperature at which the reactlon may be carried out will depend upon the choice of reactants, ~olvent or diluent and base. When acetone and potassium carbonate are used the reaction generally takes place at the ambient temperature. Hiyher temperatures, up to 100C, may be employed when other bases are employed. A typical process consists of dissolving or suspending the reactants in a solvent in the presence o a base. After allowing a period of time for the reaction to occur' the product may be isolated by the removal of any insoluble portion by filtxa~ion and evaporation of the filtrate. The product may be purified by distillation under reduced pressure, or by a suitable chromatographic technique.
When it is desired to produce a single geometrically isomeric form o an invention ester this may be achieved either by using a pure cis or trans acid or acid derivative of ~ormula II or III above, or by us~ng a ~ rans mixture thereof and ~eparating the required isomer from the mixture of esters ' ' ~ '' ', . ' " ' ''" "' '"' ' ' ". . .
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produced by for example a chromatographic technique.
The compounds of formula III and formula V which are used in the above processes for the prsparation of the invention es~ers are themselves novel compounds, and may be prepared by the following processes.
Thu~ a compound o formula III whe:rein R5 is hydrogen :~ may be prepared from a compound of the formula:-:~ .
C~3 ~
o-CH(OH)CR3R4Z

(VI) by su~ecting them to chemical or electrochemical reductive dehydrohalogenatlon to give a compound of formula:-C~3 ~

o-CH-CR3R4 (VII) and thereafter halogenating the methyl group of compound VII
to produce the requlred compound of formula III~ Z in ~ormul.a VI i~ a halogen radical, and is preferably the ~ame halogen radical aB that repre~ented by R3 and R4.

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Compounds of formula VI may be prepared by a method ; analogous to ~hat of vcn Hesse and Moll, J. Prakt. Chemie, 1974, 3 (2), 304 in which anhydrous chloral or bromal is reacted with m-cresol in the presence of an acyl halide.
The electrochemicaL reduction procedure may be carried out ln organic solvents, for example lower alcohols, such as methanol or ethanol, cyclic ethers such as dioxa~ or tetra-hydrofuran, aliphatic ketones such as acetone or cyclohexanone, or mlxtu.res of these ~olvents with water or water containing O strong mineral acids such as sulphuric, hydrochloric or phosphoric acids.
The reduction ls believed to occur principally at the cathode with a high hydrogen overvoltage, for example a m~rcury, lead amalgam or lead cathode. The reaction can be : 15 conveniently carried out ln a cell fitted with a ceramic or glass fritted diaphragm, a ~tirrer, a working electrode and a reference electrode. ~he process may be adapted for continuous production of the required product by use of a ~olvent system with which the product of the reaction may be 7.0 extracted, for example methylene chloride.
The metallic reductive dehydrohalogenation may be carried out with a 3uitable reducing medium such as zlnc dust and acetic acld.
Halogenation of the compound~ of formula VII may conv~n:Lently be carried out with the aid of a source of _ g _ ., -. :. :, - .

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po~itive hal~gen, for example an N-haloimide such as N-bromosuccinimide, or N-chlorosuccinimide. The compounds of formula V wherein R5 is hydrogen may conveniently be prepared ~rom the corresponding compounds of formula III by, for example, treating them with an alkali metal hydroxde, or alternatively converting them to the corxesponding tosylate t~-toluenesulphonate) and subjecting the tosylate to hydrolysis.
Compound3 of formula III wherein R5 is hydrogen may be converted to khe corresponding compounds wherein R5 is a cyano raalcal by ~he proce s of treating a compound of formula III whexein R5 18 hydrogen with a source of cyanide ion, e.g. an alkali ~etal cyanide such as sodium cyanide, and thereafter subjecting the compound of formula:-NC . CH

o-cH=~R3R4 (VIII) thus produced to further halogenation. The reaction with cyanide may conveniently be perfoxmed in a polar aprotic ~olvent such as dimethylformamide~ at an elevated temperature i.n the range 50 to 100C. The halogenation step may conveniently b~ parEor~ed in the manner outlined above for the preparation . -of compound of formula III whersin R5 is hydrogen. The compouRds of ormula V wherein R5 is cyano may be obtained from the compounds of formula III where R5 is cyano by analogous processes to those set out above for the corres-ponding compounds where R5 is hydrogen.
A preferred method for the preparation of compounds of formula V where R5 is cyano is however based on a different appxoach in which a comp~und of formula VII i5 selectively oxidised to a cvmpound of formula:-'~

OHC ~

O-CH=CR R

; (IX) and this compound is then onverted to its cyanohydrin by reaction with hydrogen cyanide, or, preferably, vLa the bisulphite compound, with cyanide ion ~e.g. sodium cyanide).
An alternative process for preparing compound IX involves the oxidation of compound V where R5 is hydrogen with aluminium isopropoxide and acetone under the conditions of the Oppenauer reaction.
In another aspect therefore the invention provides compounds o formula III~ V, VII, VIII and IX, all use~ul as intermediates ln the preparation of the invention esters of -; , : .
:

formula I~ and processes for the preparation of the said compound~ oE formula III, V, VII, VIII and IX.
A~ sta*ed above th~ invention esters of formula I are useful as lnsecticides, and are most conveniently used as such when formulated into compositions~ In another aspect therefore the lnvention provi~es lnsecticidal compositions which compxlse as an active ingredient an invention ester of ormula I in assoclation with agriculturally and horticult urally acceptable diluPnt or carrier materials.
lV In a pxeferment of thi~ aspect of the invention the.
actlve ingredient is selected from amongst the ~pe~ifically named e~ters of the invention set out hereinabove.
The compositions are for use in ~griculture or hortl-culture but the type of composition used in any in~tance w~ depend upon the particular purpose for which it is to be used.
The compoiitions may he in the form of granules or powd~rs comprising the active ingredient and a solid diluent or carrIer~ The compo6itions may also be in the ~orm of liquid preparations to be used as dips or sprays which are yenerally aqueous dlspersion~ or emulsions.
The composltions ~o be used as sprays may also be in the form of aero~ols wherein the formulation is held in a container under pressure in the presence of a propellant ~S such as fluorotrichlorometh~ne or dichloxodifluorom~thane.

For agricultural or horticultural purposes, an aqueous preparation containing between 0.0001~ and 1.0% by weight of ~he active ingredient or ingredients may be used.
The composi.tions of the present invention may, if S desired, al~o comprise in addition to a compound of the present invention, at lea~t one other biologically active ingredient, for example, an insecticide or a fungicide.
They may also comprise a ~ynergist of the type u~eful in synergi~ing the activity of pyrethroids type insecticides~
In u~e, the inventlon compounds or compositions may be used to combat insect~ in a variety of ways. Thus the in~ects themselves r or the locus of the insects or the habltat of the lnsects is treated with a compound or a compo61tion according to the invention.
The lnventlon also provides a method of treating plants to render them less susceptible to damage by insects, which compr!ises treating the plants, or the seeds, corms, bulbs, tubers, rhl20mes or other propagative parts of the plants, or th~ medium in which the plants are growing with a compound or composition according to the lnvention.
Thus the compounds of the invention are toxic towards a wide variety of insect and other invertebrate pests, including for example the following~-.

0 ~ ~

Tetran~chus _larius Blatella ~ermanica ~his fabae Musca domestica e~oura viceae Pieris brassicae APdes ~X~ Plutella maculipennis S The inven~lon is illustrated by ~he following Ex.amples.

E ~PLE 1 Thls Ex~mple illustrates the preparation of Compound no. 1.
A mixture of dl-chrysanthemic acid (50:50t cis:trans;
lo~ g) ~ 3(2~2-dichlorovinyloxy)benzyl bromide (2.0 g), anhydrou~ pota~sium carbonate ~1.0 g) and acetone (25 ml) wa~ ~tirred at the ambient temperature (ca. 18-22C) for 1~
hours. The ln801tlble portion was removed by filtration and the g11trate evaporated under reduced pressure to yield a reqldual oll which was dissolved in chloroform and washed lS wlth saturated sodium bicarbonate solution and then with water. After arying the chloroform solution over anhydrous magnesium sulphate the solvent was removed under reduced pressure and the residual oil sub~ected to preparative thin layer chromatographv using a mixture of chloroform (10% v/v) /

and petroleum ether (boiling range 40-60C; 90% v/v) as eluent. Th~ required product was identified by infra-red and nuclear magnetic spectroscopy.

This Example illustrate~ the preparation of Compound no. 2.
A mixture of dl~3(2,2-dichlorovinyl)2,2-dimethylcyclo-propane carboxylic acid ~80:20, trans:cis; 0.75 g), 3(2,2--dichlorovinyloxy)benzyl bromide (1.0 g), anhydrous po~assium carbonate (0.5 g) and acetone (25 ml) was stirred at the ambient temperature for 18 hours. The product was isolated from the reaction mixture by a procedure similar to that used in Example 1, except that diethyl ether was used in place of chloroform as solvent, and the T.L.C. eluent consisted of 20% v/~ chloroform and 80% v/v petroleum ether (boiling range 40-60C).

This Example lllustrates the preparation of (-~) oC-cyano-3(2,2-dichlorovinyloxy)benzyl (+) cis/trans-2(2,2-dlchlorovinyl)3,3-dlmethylcyclopropane carboxylate, Compound no. 5, (Formula I; Rl, R~, R3, R4 are chlorine radicals, R5 is a cyano radlcal).

. . .

~ ., . ~ . - . .. . :
- ~ , ;
' - .
. ~ :

3~ 5~

2(2,2-Dichlorovinyl)3,3-dimethylcyclopropane carboxylic acid ( ~ (40:60, 1.29 g) is added to thionyl chloride (5.0 g) and the mixture heated at 100C (steam bath) for one hour, after which the excess thionyl chloride is removed by S azeotropic distillation with toluene. The residual acid chloride thus produced is dissolved in n-hexane (3.0 ml) and the solutlon ob~ained added dropwise at the ambient temperature to a solution of 3(2,2-dlchlorovinyloxy) benzaldehyde cyanohydrln (1.5 g) in a mixture of n-hexane (7.0 ml) and pyrldlne tO.5 ml). After completing the addition the mixture is stirr~d for two hours at the ambien~ temperature.
The solid precipitate which forms is then removed by filtration and the filtrate washed with water t2 x 10 ml~, dried over anhydrou~ magnesium sulphate and concentrated by evaporation of the solvent under r~duced pressure. The residual oil is subjected ta preparative thin layer chromatography using ~ a plates and as eluent a mixture of chloroform (2 parts by ~olume) and petroleum ether (boiling range 60-80C, 3 p~rts by volume), to yield substantially pure (+) OC-cyano-3(2,2-dichlorovinyloxy)benzyl (+) cis/trans-2t2,2-dichloro-vinyl)3,3-dimathylcyclopropane carboxylate, consisting of 40% of the ci~ isomer and 60~ of the trans isomer.

. .

Thls Example illustrates the preparation of Compounds No~ 3 and 4.

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The product obtained by ~he process of ~xample 2 (250 mg) was subjected to preparative thin layer chromato-graphy using a silica coated plate and a solvent mixture comprising 35% v/v chloroform - 65% v/v petroleum ether (60-80C). The required products were identified by infra-red and nuclear magnetic spectroscopy as Compound 3 (70 mg; (+) cis-i30mer) and Compound 4 (100 mg; (+) trans-isomer).

. .
EXAMPLE 5 . .

This Example illustrates the preparation of 3~2,2-dichlorovinyloxy)benzyl bromide.
(aJ Preparation of 1(3-tolyloxy)-2,2!2-trichloroethyl aceta~e.
: Tola solution of anhydrous chloral (37.0 gj in dry ether (125 ml) was added meta-cresol (27.0 g) and the mixture was stirred at ~he ambient temperature for 20 minutes, after which it wa~ cooled to 10C and a solution of triethylamine (25.25 g) in dry ether (lO0 ml) was slowly added. Acetyl chlorid (20.0 g) was then care~ully added to the ~tirred mixture and stirr$ng was continued for one hour.
The insoluble material was removed by filtration and the ~lltrate drled over anhydrou~ magnesium ~ulphate. A~ter r~moval of the ether by evaporation under reduced pressure the re~ldual oil was di~tilled under high vacuum and the ,~ - 17 -..

~L5~

fracticn boiling at 132-134/0.5 mm Hg collected. Infra-red and nuclear magnetic spectroscopic analysis indicat~d that this was 1(3-tolyloxy)-2,2,2-trichloroethyl acetate.
(b) ~reparation of 3 tolyI 2,2-dichlorovinyl ether.
(i) By a metallic reductive dehydrohydrogenation method. 1(3-tolyloxy)-2,2,2-trichloroethyl acetate (14.2 g) was dissolved in glacial acetic acid (40 ml) and zinc dust (3.6 g) was slowly added to the solution with stirring at the amblent temperature. The temperature rose to 60~C in respon~e to the exothermic reaction which occurred, after~
which the mixture was heated at 50-60C for 4 hours. The mixture was filtered and the filtrate poured in an excess of water and extracted with chloroform. The extracts we:re wa~hed twice with water, with saturated sodium bicarbonate solut1on, and finally with water. After drying the chloroform extracts over anhydrous magnesium~sulpha~e, the solvent was removed by evapora~ion under reduced pressure and the residual oil distilled to yleld crude 8-tolyl 2,2-dichloro-vinyl ether, collected as a fraction boiling at 92-95C/0.3 mmi, ~0 which was red1stllled and the fraction boiling at 84C/0.2 mm Hg collected.
(ii) By an electrochmical reductive dehydrohalogenation method 1(3-tolyloxy)~2,2,2-trichloroethyl acetate (15.8 g), concentrated ulphurlc acid t98~ w/v, 9.8 g) and methanol ~5 (220 ml) wai~ charged into an electrolytic cell, which was .

.
: ' ' ~ ... ..

~' surrounded by a cooling bath set to maintain the temperature at about 15C, and fitted with a cylindrical diaphragm, stirrer, reference electrode (SCE) and a working electrode.
The cathode was a lead plate (surface axea about 40 cm2).
Us~ng a current density in the range 5 to 10 mA/cm~ the reaction was conducted in the potential range -1100 to 1700 mV (SCE)o When reduction was completed the cathodic elect-rolyte was neutralised with caustlc soda and sxtracted with methylene chloride~ the extracts dried over anhydrous sodium ~ulphate and evaporated to yield a residue of crude 3-tolyl 2,2-dichlorovinyl ether.
(c) Preparation of 3(2,2-dichlorovinyloxy)benzyl bromide.

3-Tolyl 2,2-dichlorovinyl ether (12.2 g) was dissolved in carbon tetrachloride (75 ml), and N-bromosuccinimide ; ~12.0 g) and a trace of wet benzoyl peroxide added, and the mixture refluxed for 3 hours. After ~iltration the solvent was evaporated from the f1ltrate~ and the residue dissolved ln ether and extracted with 1~ w/v sodium hydroxide solution.
The ethereal solution was dried over anhydrous magnesi~m sulphate, the solvent removed by evaporation under reduced pressure, and the residual oil distilled to yield a fraction boiling at 150C/0.5 mm Hg. This fraction was shown by ~MR

to contain about 65% of the required product together with about 30~ of unchanged starting material~ the remainder belng a small proportion of the dibromomethyl compound.

...

.

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This example illustrates the prepa:ration of 3~2,2-dichlorovinyloxy)benzyl alcohol.
A mlxture 3(2,2-dichlorovinyloxy)benzyl bromide (2.8 : g), ~odium p-toluene sulphonate (2.0 g) and methanol (20 ml)iB warmed to 50C or 1 hour, after which water (20 ml) and ~ toluene (20 ml) is added with agitation. The toluene layer ; i~ separated, washed with water and concentrated by evaporation of the ~olvent under reduced pressure. The concentrate is then added dropwl~e to a 15% (w/v) aqueous solution of pota~slum hydxoxide (100 ml) and the mixture warmed to 60C
for 1 hour, cooled to the ambient temperature and extracted with a mixtuxe of toluene (10 ml) and methyl iso-butylketone (10 ml), the extracts dried over anhydrous magnesium sulphate and ~he solvent~ evaporated under reduced pressure to yield 3(2,2~dichlorovinyloxy)benzyl alcohol as a residual pale yellow oil.
' ~ EXA~PLE 7 Thi~ Example illustra~e~ the conver~lon of 3t2~2-dichlorovinyloxy)ben~aldehyde to lts cyanohydrin, via the bisulphite compound.

~ 20 . .
.. ~ .

To a stirred solutlon of sodium metabisulphlte (3.2 g) in a mixture of water (5.2 ml) and methanol (5.2 ml) at the ambient temperature is added 3(2,2-dichlorovinyloxy) benz-; aldehyde (2.0 g). After 30 minutes the white precipitate which forms is collected by filtration/ washed with co~d methanol and dried to yield the bisulphite compound of 3(2~2-dichlorovinyloxy)benzaldehyde (2.5 g). This is suspended in water t5 ml) and to it is added a solution of sodium cyanide (0.4 g) in water (5 ml) at the ambient temperatureO The mixture is stirred for 2 hours and then~
extracted wlth diethyl ether (2 x 10 ml3. The extracts are combined, washed with water (2 x 10 ml)~ dried over an hydrous magnesium sulphate and evaporated under reduced pressure to yield the cyanohydrin of 3(2,~-dichlorov~nyloxy)-benzaldehyde as a yellow oil.

The activity of a number of the compounds was tested against a variety of insect and other invertebrate pests.
The compounds were used in the form of a liquid preparation containing 0.1~ by welght of the compound except in the tests with Aedes ~Ye~ wh~re the preparations contained 0.01~ by weight of the compound. The preparations were made by dissolving each of the compounds ln a mixture of solvents ~.
' ' : ' ~ , :
. . .

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consisting of 4 parts by volume o~ acetone and 1 part by volume of diacetone alcohol. The solutions were th~n diluted with water containing 0.01% by weight of a wetting ~` agent sold under the trade name "LISSAPOL" NX until the liquid preparations contained the requixed concentration of the compound. "Lissapol" is a 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 medlum which WhS usually a host plant or a foodstuff on which the pests feed, and treating either or both the pe~ts and the medlum with the preparations.
The mortality of the pests was then assessed at periods usually varying rom one to three days after the treatment.
~he results of the tests are given below in Table I.
1$ In th~s table the first column indlcates the name of the pest spec~es. Each o the subsequent columns indicates the host plant or medium on which it was supported, the number o~ da~s which were allowed to elapse after the treatment before asqe~sing the mortality o~ the pests, and the results obtained for each of the compounds numbered as abo~e. The a~se~ment is sxpre~sed in integers which range from 0-3.

0 represents less than 30~ kill 1 represents 30 - 49% kill 2S 2 represents 50 - 90~ kill 3 represents over 90~ kill - ~ , 3~3 A dash (-) in Table I indicates that no test was carried out.
In Table I 'contact test' indicates that both the pest~
and the medium were treated and 'residual testl indicates that the medium was treated before infestation with th~
pests .

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~XAMPLE 9 This Example illustrates a dusting powder which may be applied directly to plants or other surfaces and comprises 1~ by welght of Compound no. 1 and 99-~ by weight of talc.

~5 Parts by weight of Compound no~ 2, 65 parts by weight of xylene a~d 10 parts of an alkyl aryl polyether alcohol ~'Tr~ton' X-100; 'Triton' ls a Trade Mark) were mlxed in a sultable mixer. There was thus obtained an emulsion concentrate which can be mixed with water to produ¢e an emulslon suitable for use in agricultural appli-catlons.

10 Parts by weight of Compound no. 2, 10 parts of an ethylene oxide-octylphenol condensate ('Lissapol' NX;
'Li~sapol' is a Trade Mark) and ~0 parts by weight of diacetonP alcohol were thoroughly mixed. There was thus obtained a concentrate which, on mixing with water, gave an aqueous disperRion suitable for application as a spray in the control of insect pests.

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"LISSAPOL" NX is a condensate of 1 mole of nonyl phenol with 8 moles of ethylene ; oxide.

This Example lllustrates the preparation of 3(2~2-dichlorovinyloxy)benzaldehyde.
3(~72-Dichlorovinyloxy)benzyl bromide (2.5 g) was care~ully added to a stirred solution of hexamethylene : t~txamine (2.1 g) in carbon tet.rachloride (20 ml) at the amblent temperatuxe. ~fter five minutes the precipitate was collected by filtration and washed with acetone. The solid ~hu~ o~tained was a~ded to aqueous acetic acid solution (50 by welght, 16 ml) and the mixture r~fluxed for one hour. A
mixture of water (16 ml) and concentrated hydrochloric acid (4.5 ml) was thell added and the mixture refluxed for a lS urther 15 minutes. After cooling the mixture was extracted wlth chloroform, the extracts washed with water (twlce), dried over anhydrous magnesium sulphate and the solvent removed by evaporation under reduced pressure to yield a re~idue o~ ~ubstantially pure 3(2,2-d~chlorovinyloxy)benz-.~0 aldehyde, identification of which was confirmed by infra-red and nuclear magnetic re~onance spectro~copy.

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Claims (17)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1, A compound of formula;- wherein R1 and R2 represent halogen radicals or lower alkyl groups; R3 and R4 represent halogen radicals; and R5 represents a hydrogen atom or the cyano radical.

2. A compound as claimed in claim 1 wherein R1 and R2 are both methyl groups, or both chlorine or both bromine.

3. A compound as clalmed in claim 1 wherein R3 and R4 are either both chlorine or both bromine.

4. A compound as clalmed in claim 1 wherein R1, R2, R3 and R4 are all chlorine.

5. A compound as claimed in any of claims 1 to 3 in the form of the cis isomer in relation to the substitution of the cyclopropane ring.

6. A compound as claimed in any of claims 1 to 3 in the form of the trans isomer in relation to the substitutlon pattern of the cyclopropane ring.

3(2,2-Dichlorovinyloxy)benzyl (?) cis/trans--chrysanthemate.

8. 3(2,2-Dichlorovinyloxy)benzyl (?) cis/trans-2,(2,2-dichlorovinyl)3,3-dimethylcyclopropane carboxylate.

9. 3(2,2-Dichlorovinyloxy)benzyl (?) cis-2(2,2-dichlorovinyl)3,3-dimethylcyclopropane carboxylate.

l0. 3(2,2 Dichlorovinyloxy)benzyl (?) trans-2(2,2-dichlorovinyl)3,3-dimethylcyclopropane carboxylate.

11. (?)- .alpha.-Cyano-3(2,2-dichlorovinyloxy)benzyl (?) cis/trans-2(2,2-dichlorovinyl)3,3-dimethylcyclopropane carboxylate.

12. Process for preparing a compound according to claim 1 which comprises either (a) reacting a compound of formula:
optionally in the form of a metal salt thereof, with a compound of formula:- wherein X is a halogen atom and R1, R2, R3, R4 and R5 are as defined in claim 1; or (b) reacting a compound of formula:- with a compound of formula:- wherein Y is a halogen atom and R1, R2, R3, R4 and R5 are as defined in claim 1.

13. A process as claimed in claim 12 in which X is chlorine or bromine.

14. A process as claimed in claim 12 in which Y is chlorine.

15. A process for the preparation of a compound according to claim 1 which comprises heating the mixture of a lower alkyl ester of the acid of formula:- with a compound of formula:- in a solvent or diluent, and in the presence of a base.

16. A process as claimed in Claim 15 wherein the base is a lower alkoxide.

17. A method of combating insect pests at an agricultural or horticultural locus which comprises applying to the locus a composition comprising as an active ingredient a compound as claimed in Claim 1 in association with an agriculturally or horticulturally acceptable diluent.

C1 18 A compound of the formula wherein:
R6 and R7 represent halogen or lower alkyl R8 represents hydrogen or cyano R9 and R10 represent halogen.

C2 19 A process for the preparation of a compound of the formula wherein:
R6 and R7 represent halogen or lower alkyl R8 represents hydrogen or cyano R9 and R10 represent halogen which comprises reacting a compound of the formula:

or a reactive derivative thereof at the carboxyl function and wherein R6 and R7 are as defined above, with a compound of formula:

wherein:
R8, R9 and R10 are as defined above R11 represents halogen or hydroxyl, C3 20 A method of combatting pests at a locus which comprises applying to the locus a compound of the formula:
wherein:
R6 and R7 represent halogen or lower alkyl R8 represents hydrogen or cyano R9 and R10 represent halogen.