CA1317220C - Pyrethroidal composition comprising more than one active ingredients - Google Patents

Abstract

ABSTRACT

According to the present invention there is provided an insecticidal composition containing more than one active ingredients which comprises as active ingredient in an amount of 0.001-99% by weight a synthetic pyrethroid of the general Formula I

Description

PYRETHROIDAL COMPOSITION COMPRISING MORE THAN ONE
ACTIVE INGR~DIENTS

Technical field This invention relates -to insecticidal compositions comprising more than one pyrethroide active ingredients, the use thereof, the active ingredients and a process for the preparation of the same.

Backqround Art In the present specification the spatial configuration of the substituen-ts related to the chiral carbon atom denoted with "~" is characterized by "S" and "R" respectively. The des-ignations "cis" and "trans", respectively, mark the position of the substituents attached to carbon atom "3" of the cyclopropane ring related to the spatial configuration of the substituents of carbon atom "1". The absolute spatial configuration of the sub-stituent attached to carbon atom "1" is deno-ted with the prefix "lR" and "IS", respectively.
In the present specification the various enantiomer.s and enantiomer-pairs are designated with the following abbrevia-tions:
Ia mixture of IRcisS and IScisR
Ib mixture of lRtransS and IStransR
Ic mixture of lRcisR and lScisS
Id mixture of lRtransR and lStransS
If lRcisS
Iq lRtransS
Ih lScisR

A3669-77 KY ~ _ Ii lStransR
From the compounds Qf the general Formula I

`;2 ~ ' - la -X

COO I H ~3 ~/I /

the following are commercially available:
- ~Cypermethrine~' of the Formula II

Cl Cl ~ CN ~ ~ /II/

comprising all isomers;
- ~Alphametrine~ of the Formula II comprising only the lRcisS and lScisR isomers;
- "Deltamethrin", of the Formula III

Br Br CO~CH ~ O ~ /III/

5 - ~--comprising only the lRcisS isomer.
Selection of the possible isomers on the basis of insecticidal effect is based on the experimental fact that -particularly according to tests carried out on Musca domestica species - certain isomers proved to be highly and outstandingly toxical on certain insects and it was the obvious trend to put the most active isomers to the market or to synthesize the same [Pest. Sci. 7, 273-(1976)].
- It is known that the pyrethroid of the Formula II
(known under the generic name "cypermethrin") belong to the valuable family of synthetic pyrethroids and is useful as insecticide (Hungarian patent No. 170,866). This compound may be prepared by reacting m-phenoxy-benzaldehyde cyanohydrine with cyclopropane carboxylic acid chloride ln the presence of a base EPestic. Sci _, 537-...(1957)]. The product thus obtained consists of eight stereoisomexs i.e. of a mixture of our en-antiomer-pairs. If a 60 : 40 mixture of trans and cis cyclopropane carboxylic acid chlorides is used, the mixture contains 18-19 ~ of enantiomer-pair Ia, 21-22% of enantiomer-pair Ic, 26-27~ of enantiomer-pair Ib and 33-34% of enantiomer-pair Id.
According to prior art the stereoisomers of cypermethrin show different biological activity. It is generally accepted that the activity of molecules comprising cis cyclopropane carboxylic acids is superior to that of the corresponding trans derivatives EPest. Sci. 7, 273 (1976)].
In the comparative biological tests of various pyrethroids [Pest. Sci. 9, 112-116 (1978)] the cis and trans stereoisomers - including the cypermethrin stereoisomer-pairs -t 3 1 7220 were evaluated together.
The comparative tests were carried out in Musca domestica L. and Phaedon cochleariae Fab species.

- 3a -1 3 1 722() Concerning the chloro derivatives from the trans isomers activity data o~ IRtransS (Iq) and lRtransR were disclosed.
The said data show that - while the IRtransS isomer possesses ~
strong activity - the lRtransR isomer is considerablY less active [according to the test the activity related to bioresmethrin (100) amounts to 1400 and 81, respectively, on Musca domestica and to 2200 and 110, respectively, on Phaedon cochleariae]~ It was disclosed further on that the activity of a mixture of both tested isomers was lower than the calculated value. Thus the isomers showed an antagonism rather than the expected synergism and the rate of antagonism amounted to 1.42 and 1.46 on house fly and mustard beetle, respectively.
As a result of the said tests and publications the trans isomers and mixtures thereof were pushed to the background of biological interest and research was focused to active cis derivatives and mixtures thereof. This led to the development of alphamethrin [isomer mixture of lRcisS and lScisR (Ia) of the chloro derivatives] and decamethrin [comprising the only IRcisS
isomer (Ir) of the bromo derivatives].
For this reason several procedures are known for the preparation of mixtures enriched in the cis isomers from known cypermethrin isomer mixtures.
Disclosure of Invention According to an aspect of the present invention there is provided an insecticidal composition containing more than one active ingredients which comprises as active inyredient in an amount of 0.001-99% by weight a synthetic pyrethroid of the gen-eral Formula I (wherein X stands ~or chlorine or bromine) -namely out of the eight possible lsomers at le~st 95~ o~ a 55 : 45 - 25 : 75 mixture of the enantiomer-pairs la : Ib, wherein -- 4a -1 31 722n I~ is lRcisS -~ lScis~ and Ib is lRtransS ~ lStransR - if desired in admixture with an activator and/or with an amount of up to 100~ of an auxiliary agent, preferably an antioxidant, stabilizer, wetting agent, emulsifying agent, dispersing agent, antifoam agent, diluent, carrier, and/or filler.
The present invention is based on the recognition that the isomeric mixture Ia ~ Ib possesses valuable and advanta~eous biological properties. The said properties are surprising and unforeseen, although extendea research work has already been per-formed in the field of pyrethroids of the general Formula I anda number of publications and patents have been published.
It is known further on that mixtures enriched in cis isomers can be prepared by means o~ crystalIization from solutions comprising other isomers [C.A. 95, 1981; KOKAI No. 57755/81].
A substantially pure 1 : 1 mixture o~ the lRcisS and lScisR
isomers may be separated by using suitable solvents from a mixture comprising the other cis isomers too (Briti'sh pat~nt specification No. 2,064,528). The isomeric mixture Ia is described to be very active. Special, so-called "high cis" syntheses are elaborated for the preparation of cis-cyclopropane carboxylic acid intermed-iates comprising cis isomers above a certain limit (about 50~), but these methods were rather expensive ~Angew. Chem. Ie, 24, (11), 996 (1985)].
The present invention is based on the recognition that when using a combination of the lRtransS isomer Ig (being the most active trans isomer of the compounds of the Formula II) and the lStransR isomer Ii (being ranged among the less active isomers from the remaining seven isomers) no anta~onism characteristic for 1 3~ 72~0 the earlier published isomer-pairs is observed.
Moreover a sy~eryistic effect occurs over the additive effect of the pure Ig and Ii isomers when used -~, ~ - Sa -1 3 1 722() per s~.
The above recognition enables a new type of selection from the isomers of synthetic pyrethroids in order to develop a new active ingredient type having outstanding properties. The said new active ingredient shows various advantages over hith-erto known i~somer selections:
- lower toxicity on a warm-blooded species and humans;
- more economical manufacturing process;
- smaller damages caused to useful parasites and bees.
The new compositions comprising the isomer- mixture Ib are described and claimed in our co-pending~patent application Ser. No. 4.~ 2 ~
The present invention is based on the further recogni-tion that the biological order of succession of biological activity previously observed for the individual isomers and the already known rules described for the isomer-pairs are not absolutely relevant for other isomer-pairs;
Thus we have tried to compare and simultaneously test the lRtransS + lStransR enantiomer-pair Ib - which was found to be active by our experiments - with other isomers~ The comparison has shown that synergism observed between the members of enant-iomer-pair Ib (i.e. Ig and Ii) does not take place between the members of the corresponding cis enantiomer-paix Ia (i.e. If and Ih).
The present invention is based on the further recog-nition that while from the lRcisS (If) and IRtransS (Ig) isomers it is generally the If isomer which is the more active, on certain species the biologicaly activity of the enantiomer-pairs :
~ - 6 -1 31 722~) Ia and Ib proves to be opposite.
As a result o~ the aforesaid we have come to the surprising recognitlon that when using simultaneously the enantlomer-pairs Ia and Ib a synergistic effect is observed, i.e. the effect of the combination is superior 6a -7 23305-1~00 to that of the additional effect oE both enantiomer-pairs when used per se.
It has been found that the synergistic biological effect of mixtures Ia + Ib is not limited to such mixtures in which Ib is more active than Ia. Thus on Colorado potato beetle /Leptinotersa decemlineata/ the use of the two enantiomer-pairs results in a significant synergism. The said results are disclosed in details in the examples.
Based on the above recognitions we have performed a new selection from the already known isomer mixtures and this led to the new composition of the present invention.
In addition to the synergistic effect the composition of the present invention has a number of further advantages too and for this reason it is an outstanding product. It is very important that the compositions of the present invention are less toxical towards mammals than the hitherto known compositions of similar efficiency. This is unambiguously proved by the so-called selectivitY index /517 and 747, respectively/ which is the ~uotient of the approximative LD50 values measured on rats-p.o.
/280 and 355 mg/kg, respectively/ and on house fly topically /0.54 and 0.48 mg/kg, respectively/. The said selectivity index of Ia amounts to 50/0.45=111.
The synergistic effect may be observed Oll mites too /see biological Example No. 19/, thus the compositions are also useful as acaricidal agents. The compositions of the present invention show a low toxicity towards bees and do not damage useful entomophages and parasites /biological Examples 25 and 26/
The said advantageous properties are due to the repellant effect, .r preferable persistence and suitable inherent activity of the active ingredient.
The above properties enable the use of the mixture of the enantiomer-pairs of the present invention in integrated plant protecting technology /IPM = Integrated Pest Management/.
The economical advantages of the compositions of the present invention are at least as important as the biological efficiency. The preparation of a pure cis enantiomer-pair Ia re~uires very expensive synthetic methods or involves the loss of the trans components formed in the reaction mixture. On the other hand the present invention enables the use of practically all the components Ia and Ib from the reaction mixture formed by the most economical syntheses. /The rate of efficiency depends naturally on the particular syntheses used and the ratio of the components Ia and Ib of the mixture/.
The insecticidal compositions of the present invention comprising the isomer-pairs Ia and Ib in admixture with known additives may be formulated in forms suitable for direct use.
The composition of the present invention may be ULV
/ultra-low-volume/ compositions, spray, dispersible powders, granules, wettable and other powders, stable emulsions etc. The said compositions are suitable for the pesticidal treatment of vegetables, grape fields, orchards, fields of cereals and other large scale cultures. Due to the low toxicity the compositions of the present invention are particularly suitable for combating flying insects and pests having a hidden mode of life in households, walls of stables for the treatment of pasture etc.
According to a further aspect of the present invention ~ 31 7220 23305-1~00 8a there is provided the use of the said insecticidal compositions.
It is preferred to use the said compositions under field conditions at a rate of 2-25 g of active ingredient per hectare.
The insecticidal compositions of the present invention may comprise in addition to the isomer-pairs Ia 1 31 722() + Ib activators and further synergists, e.g. piperonyl butoxide.
The said additives increase strengthen the efficiency of the active ingredient without increasing the toxicity on warm-blooded species.
According to a preferred embodiment of the present invention there are provided dispersible granules comprising 1-99% by weight of the active ingredient in admixture with 99-1%
by weight of suitable additives. As auxiliary agent e.g. 0.1-1 by weight of anionic and/or non~ionic surfactants may be used, such as alkali salts of alkyl-aryl sulfonic acids, alkali salts of condensation products of alkyl aryl sulfonic acids and formalde-hyde, alkyl-aryl-polyglycol ether, sulfated long chained alcohols, polyethylene oxides, sulfated fatty alcohols, fatty acid poly-glycol esters and various other commercially available surfactants.
The insecticidal compositions of the present invention may also be formulated in the form of concentrates comprising preferably 5-50% by weight of the active ingredient in admixture with 50-95% by weight of additives which enable the formation of a stable emulsion when emulsifying the emulsion concen-trate in or in the presence of water.
As additive 1-20% by weight of a tenside and/or 0.1-5%
by weight of a stabilizing agent may be used and the mixture may be preferably filled up to 100% with an organic solvent.
It is preferred to use as tenside a mixture of anionic and non-ionic tensides. The following tensides may be preferably applied: calcium salts of alkyl aryl sulfonic acids, mono and diesters of phosphoric acid, nonyl and tributyl phenol polyglycol ethers, adducts of fatty alcohols and ethylene oxide, fatty acid _ 9 _ polyglycol esters, ethyleneoxide - propylene oxide block polymers etc.

- 9a -As solvent preferably mixtures of aromatic hydrocarbons (e.g. xylenes), cyclohexanol, butanol, methyl ethyl ketone, isopropanol etc. may be ùsed.
rrhe compositions of the present invention may also comprise further synergists which enable the reduction of the amount of the active ingredient. For this purpose preferably piperonyl butoxide may be applied.
The invention of the divisional applicatlon provides a process for the preparation oE an insecticidal active ingredient comprising out of the eight possible isomers of synthetic pyrethroides of the general Formula I (wherein X stands for chlorine or bromine) substantially only a 55 : 45 - 25 : 75 mixture of enantiomer-pairs Ia : Ib - wherein Ia is lRcisS and lScisR and Ib is lRtransS and lStransR - which comprises a) preparing from a mixture comprising in additon to the isomer-pairs Ia + Ib other possible isomers too and/or comprising the isomer-pairs Ia + Ib in a ratio other than the desired values a saturated solution with a protlc or apolar aprotic inert organic solvent, seeding the solution;with a seeding crystal consisting of a 55 : 45 - 25 : 75 mixture of enantiomer-pairs Ia and Ib, and isolating the crystals precipitating at a temperature between 30 C and -30 C; or b) seeding a melt of a mixture comprising in addition to the isomer-pairs Ia + Ib other isomers too and/or comprising the isomer-pairs Ia + Ib in a ratio other than the desired value at a temperature between 10 C and 60 C with a seeding crystal comprising a 55 : 45 - 25 : 75 mixture of enantiomer-pairs Ia and Ib, allowing the solution to crystallize at a temperature ~ ' 11 ~3305-1100 between 30 C and -10 C and lf deslred suspending khe mixture thus obtalned at a temperature between -10 C and -20 C ln a protic or apolar aprotlc inert organlc solvent and isolatln~ the preclpltated crystals; or c) adding to a solutlon or a melt of a mlxture comprising in addltlon to the lsomer-palrs Ia ~ Ib other lsomers too and/or comprlsing the isom~r-pairs Ia ~ Ib ln a ratio other than the deslred value an enantiomer-palr Ia or Ib ln such an amount that the solutlon or the melt should contaln the lsomers ln a ratlo of 55 : 45 - 25 : 75 and if desired performing crystallization according to variant a/ or ~ 7 or d) admlxing enantiomer-pairs Ia and Ib in the deslred ratio - if desired in the presence of a protlc or apolar aprotlc organlc solvent - homogenizlng the mixture and performing crystallizaklon - lf deslred after the seedlng step according to variant a).
According to varlant a) of the process one may preferably proceed by using a Cl_l2 hydrocarbon, Cl_6 chlorlnated hydrocarbon, Cl_5 dlalkyl ether or Cl_10 alcohol as organlc solvent. The sald solvents may be straight or branched chained, and cycllc and allcycllc, respectively.
It is preferred to carry out seeding wlth a seedlng crystal in the presence of an antloxl~ant -partlcularly ~ertiary butyl hydroxy toluene or 2,2,4-trimethyl-quinollne - and to use ethanol, lsopropanol petrolether or hexane as solvent.
One may proceed preferably by accompllshing crystalllzatlon under ~low cooling.
Accordlng to a preferred form of realizatlon of the process of the present inven~lon a migture of 60 % of trans and ~,~..

1 31 72~0 lla 23305-1100 40 % of cis cypermethri.ne enantiomer-pairs /18.2 ~ of Ia, 26.8 %
of Ib, 21.8 % of Ic and 33.2 % of Id; referred to further on as Ie is used as starting material. The said mixture is dissolved in isopropanol and the solution is seeded with seeding ;~

. ' ' ' , ;

1 31 722~) 23305~
crystals consisting of a mixture of Ia and Ib in ~he presence o~
0.01~ of 2,2,4-trimethyl-quinoline or tertiary butyl hydroxy toluene. A crystalline product is obtained with an absolute yield of 35-40~, which melts at 63.5-65C, comprises the enan~iomer-pairs Ia and Ib in a ratio of ~0 : 60 and contains enantlomer-pairs Ic and Id as contamination in an amount of 5%. The products thus obtained may be recrystallized as described above. Thuæ the mixture of enantiomer-pairs Ia and Ib can be prepared with a purity abovè 99%.
Similar results are obtained when recrystallizing mixtures of other cis/trans ratio.
The cypermethrins used as starting material ~ay be prepared by esterifying the mixture of cyclopropane carboxyllc acids of suitable cis/trans ratio.
In the following Table the melting points of mixtures of various cis/trans ratio are disclosed.
Ia/Ib 25,75 30,70 40s60 50,50 55,45 m.p.: C 67-71.5 65-68 63.5 65 60.5-62 61.5-64 A preferred form o~ the compound o~ formula I consist~
of at least 95~ of a 5S:45 - 25 5 75 mixture of ~he enantiomer pairs Ia5Ib with a melting point o~ 63-65C.
The practical feaslbility in the desired direc~ion of the crystallization step strongly depends on the purity of the starting cypermethrin mixture. If the active ingredient content is lower than 95~, the yields decrease. Tarry contaminations may even inhibit crystalllzation.
The crystallization o~ the mixture of enantiomer-pairs Ia and Ib according to the present invention may be carried out in the absence of a solvent too. Thus cypermethrin of the composition Ie may be seeded with crystals consisting of Ia and Ib. In a refrigerator the mixture of Ia and Ib precipitates within a week. The crystals are isolated by adding ethanol cooled to -20C to the mixture and filtering the crystals.
The mixture of enantiomer-pairs Ia + Ib according - 12a -.~ .

1 3 1 72~0 to the present invention may also be prepared by a~mixing and/or crystallizing Ia and Ib or various amounts thereof or by admixing and/or crystallizing a mixture of Ia and Ib, or calculated amount Ib, respectivel~.
The biological activity o~ the products according to ; the present invention is tested on various insect species. In the test methods the effect of stereoisomers used as reference standard and prepared by known methods - e.g. by chromatograph-ical separation or by chromatographical separation of cypermethrins prepared from chiral acids - is disclosed as well.

Industrial applicability The insecticidal compositions of the present invention are harmless to environment and can be used particularly in house-hold and stables for combating flying insects and pests having a hidden mode of life and also for the treatment o~ pasture.

Modes of Carrying out the Invention Further details of the present invention are to be found in the following chemical and biological examples without limiting the scope of protection to the said Exa~ples.

Chemical Examples Example l 100 g of cypermethrin (consisting according to gas chromatography of a mixture of 18.2% of Ia, 21.8% of Ic~ 26.8%

- 13 ~

l3l722n of Ib and 33.2% of Id), 0.2 g of potassium hydroxide and 0.2 y of 2,6-di-tertiary butyl-4-methyl-phenol are d~ssolved in 2000 ml of isopropanol under constant stirring at 45.0 C. The solution is - 13a -1 31 722() slowly cooled to 30C, clarified with activated charcoal and filtered at 30C. The colourless solution is seeded with a cr~stal consisting of 60% o~ Ib and 40% of Ia and the mixture is stirred at -10C for 24 hours. The precipitated product is filtered, washed with isopropanol and dried in vacuo. Thus 36.02 g of a snow-white crystalline product are obtained. M.p.:
62-65C (non-corrected value)~ According to GC and TLC analysis the product contains 37% of Ia and 58% of Ib isomers. Yield:
76% (related to the Ia + Ib isomer content of the cypermethrin starting material). Ia isomer Rf = 0.25; Ib isomer Rf = 0.20.
After recrystallization from isopropanol 32 ~ of the product are obtained as first crops. ~.p.: 63.5-65.0C; the product consists of 39.5 6 of Ia and 59.5% of Ib.
IR (KBr) v c=o 1730, 1735 cm NMR (CDC13) ~ (ppm): 1.05-2.45 m (8H); 5.6, d,J =8Hz (=CH trans 0.6H); 6.14, d, J=8Hz (=CH cis 0.4H); 6.35, d, (lH);
6.85-7.60 m, (9H) Example 2 100 g of c~permethrin (27.8% of Ia, 21.8% of Ib, 32.1%
of Ie and 18.2% of Id), 0.2 g of potassium h~droxide and 0.2 g of 2,6~di-tertiary butyl-4-methyl-phenol are dissol~ed in 2000 ml of isopropanol under stirring at 45C. The solution is clarified with activated charcoal and filtered at 30C. The colourless solution is seeded with a seedin~ crystal consisting of 20% of Ib and ~0% of Ia and stirred at -10C for 36 hours. The pre-cipitated product is filtered, washed with isopropanol and dried .~ .

1 31 722(~

in vacuo. Thus 30 g of snow-white crystalline product are obtained, m.p.: 66-73C~ ~ccording to gas chromatography the product contains 77% of Ia + 19% of Ib, purity 96% ~TLC, see Example 1).

la -Af-ter recrystallization from isopropanol as first yeneration 26.5 g of a snow-white crystalline product are obtained, m.p.:
70-73C, containing 81.5 of Ia + 18% of Ib (GC analysis).
IR (KBr) v c O 1730 cm NMR (CDC13) ~ (ppm): 1.05 - 2.45 m (8H); 5.60 d J= 8 (=CH trans 0.2H); 6.14 d J= 8Hz (=CH cis 0.8 H); 6.35 d (ArCH lH) 6.85 - 7.60m(9H).

Example 3 100 g of colourless clearly transparent oily cypermethrin (18.2% of Ia, 21.8% of Ic, 26.8% of Ib and 33.2%
of Id) are seeded with a seeding crystal consisting of 60% of Ib and 40% of Ia and the solution is allowed to crystallize at 7C for a week. The mixture is suspended in 100 ml of a 1:1 mixture of isopropanol and aiisopropyl ether and filtered at -15C. The crystals are washed with isopropanol and dried in vacuo. Thus 40.1 g o a white crystalline product are obtained, containing 37.5% of Ia and 59% of Ib, m.p.: 62.5 - 65C.
Yield 86%. After recrystallization from isopropanol as first generation 36 g of a snow-white crystalline product are obtained, m.p.: 63.5 - 65C, consisting of 40% of Ia and 60% of Ib (GC)~
The IR and NMR are identical with those disclosed in Example 1.

Example 4 100 g of cypermethrin (18.2% of Ia, 21.8% of Ic, 26.8%
of Ib, 33.2% of Id) and 0.05 g of 2,6-ditertiary butyl-4-methyl-phenol are dissolved in 100 ml of diisopropyl ether under constant stirring at 0C and the solution is clari~ied with 2 g of activ-ated charcoal. The solution i.s filtered and seeded at -15~C
with a seeding crystal consisting of 60~ of Ib and 40~ of Ia.
The mixture is allowed to crystallize for - 15a -1 37 722() 72 hours, the crystals are filtered, washed with diisopropyl ether and isopropanol and dried. Thus 38 g of a snow-white crystalline product are obtained, yield 62-65 C, comprising 37.5 % of Ia and 58 % of Ib. Yield 80.6 %. After recrystallization from isopropanol as first genexation 35 g of a snow-white crystalline product are obtained, m.p.: 63,5-65 C, the ratio of the Ia : Ib isomers = 40 : 60. The physical constants are identical with those disclosed in Example 1.
xample 5 10 g of samples of the product obtained according to Example 2 /the ratio of the Ia : Ib isomers = 4:1~ are admixed with 4.60 g, 6 g, 10 g, 16.67 g and 22.0 g of pure seeding crystals of Ib, respectively, and the mixtures thus obtained are recrystallized as described in Example 1 from a 10-fold amount of isopropanol, each. The composition and melting point of the products thus obtained are shown in the following Table.

Ia : Ib M.p.: /C/
55:A5 61.5-64 5:5 60.5-62 4:6 63.5-65 3:7 65-68 25:75 67-71.5 Example 6 10 g samples of pure crystalline isomer-pair Ia are admixed with 8.20 g, 10.00 g and 15.00 g of pure crystalline isomer-pair Ih, respectively, and the mixtures are homogenized.
The crystal mixtures thus obtained comprise the substances Ia + Ib in a ratio of 55:45, 50:50 and 40:60, respectively. m.p.: 61.5--64 C, 60.5-62 C and 63.5-65 C, respectively.

.

1 3 1 722~) Exam~le 7 10 g samples of pure crystalline isomer-pair Ia are dissolved in 10-Eold amount of isopropanol and to each sample 23.34 g and 30.0 g of pure crystalline isomer-pair Ib are added, respectively. The solutions are crystallized. The precipitated white crystalline products /m.p.: 65-68 C and 67-71.5 C, respectively/ comprise the Ia : Ib isomers in a ratio of 30:70 and 25:75, respectively. The product thus obtained can be formulated as plant protecting agent and is a useful insecticidal active ingredient.
Formulatinq examPles Example 8 To 166.2 g of perlite /dmaX - 120 ~m/ 0.8 g of synthetic silicic acid /~erosil 300/ are added in a fluidizing rapid stirrer. 20 g of a cypermethrine mixture of enantiomer-pairs Ia:Ib = 4:6 and 2 g of fatty alcohol polyglycol ether are added so that the mixture is uniformly homogenized. The powder mixture is ground first in a mechanical mill and afterwards in an~air flow mill, whereupon 5 g of octyl phenol polyglycol ether /E0=20/ and 2 g of sulfosuccinate are added in a rapid stirrer. The wettable powder mixture /WP/ thus obtained is subjected to suspension stability test. Wetting time = 23 seconds; floatability = 89 /standard WHO method/.
Exam~le 9 3 g of a mixture of cypermethrine enantiomer-pairs Ia : Ib = 3 : 7 and 0.3 g of fatty alc-ohol polyglycol ether are applied in a homogenizing apparatus onto talc /dmaX ~ 15 ~m/
adjusted to the pH value of 6.5 with a buffer of 0.8 of synthetic silicic acid /Aerosil 200/ and 193.9 g of potassium and sodium phosphate. To the mixture 1 g of dioctyl sulfosuccinate and 1 g of fatty alcohol polyglycol ether sulfonate are added under stirring and the mixture is ground to an average particle size of 20 ~m. Thus a thin flowable powder mixture is obtained.
Example lQ
5 g of a mixture of cypermethrine enantiomer-pairs Ia : Ib = 55 : 45 are dissolved in a mixture of 21.25 g of xylene and g2.5 g of n-propanol under slow stirring. To the solution a mixture of 4 g of ethoxylated alkyl phenol + calcium salt of linear alkyl aryl sulfonate and a mixture of 6 g of ethoxylated amine + alkali salt of linear alkyl aryl sulfonate is added under stirring until all the materials are completely dissolved, whereupon 21.25 g of water are added. Thus a transparent solution is obtained which maintains its properties at a temperature between 0 C and 50 C for long period of time. The solution can be optionally diluted with water at any rate under the forrnation of an emulsion having a droplet-size of 0.8-1.5 ~n-Exam~le 11 5 g of a mixture of cypermethrine enantiomer-pairs Ia : Ib = 25 : 75 are dissolved in a mixture of 75 g of xylene and 10 g of an aliphatic oil whereupon under slow stirring a mixture /17.5 g/ of ethoxylated alkyl phenol + calcium salt of linear alkyl aryl sulfonate and also a mixture /2.5 g/ of ethoxylated fatty acid + linear alkyl aryl sulfonate salt are addedO When measured according to the method of CIPAC the emulsion concentrate proves to be stable after 170 hours.

, .
..~ .~, ` 1 31 72~0 Example 12 In a mechanical granulator a 50: 50 mixture of the Ia and Ib cypermethrine enantiomer-pairs is admixed with 1500 g of polycarboxylate alkali salt, 500 g of sodium dodecyl benzene sulfonate, 500 g of saccharose and 7200 g of China-clay. The powder mixture is admixed with 8300 ml of water by using a stirrer of large shearing strength /v=10 m/sec/ and subjected to spray drying. The distribution of particle size is as follows:
0.1 - 0.4 mm = 95 %. The floatability amounts to 98 % /according 10 to the WHO method/.
Example 13 Emulsifiable concentrates /EC/ are prepared by admixing the following components:

Component Amount, kq/;~
Isomer-pairs Ia:Ib=40-60 0.105 Cyclohexanol 0.290 Atlox 3386 B 0.020 Atlox 3400 B 0.045 Odourless mineral oil 0.540 Component Amoun~
Isomer-pairs Ia:Ib=40:60 0.050 Cyclohexanol 0.290 Atlox 3386 B 0.020 Atlox 3400 B 0.045 Odourless mineral oil 0.595 siolo~ical Examples _ _ Example 14 In Table 1 the activity of various stereoimomexs oE
cypermethrin orl house fly (Musca domestica) is shown.
The test is carried out as follows:
The active ingredient is dissolved in a 1:2 mixture o~
oil and acetone; filter paper discs (Whatman No. 1, diameter 9 cm) are impregnated with the solutions of the corresponding stereo-isomers and enantiomer-pairs, respectively. The acetone is allowed to evaporate, whereupon the insects are exposed to filter paper discs placed in Petri-dishes. Three parallels are used or each dose and 15 insects are placed into each Petri-dish. The percentage mortality is determined after 24 hours. The corrected percentage mortality is calculated by means of the Abbot Formula.

Tab~e 1 Cypermethrin Dose (mg/disc) stereoisomer 0.04 0.11 0.33 1.00 3.00 24 hours' mor-tality (%) . .
If 68 93 100 100 100 Ia 44 84 100 100 100 Ig 48 68 83 100 100 Ib 32 62 95 100 100 Ia:Ib=40:60 41 81 100 100 100 According to this tPst the activity of mixture Ia + Ib corresponds to that of the pure isomer Ia.

1 3l722n Example 15 It appears from Table 2 that the increased activity shown in Example 14 is due to the synergistic e~fect of the trans-isomers to tribolium confusum.

Table 2 .
Active Dose (mg~disc) ingredient 0.11 0.33 1.003.00 24 hours' mortality %

IScisR (Ih) 0 38 80 100 IRcisS (If)80 100 100 100 Ia 22 65 94 100 IStransR (Ii) 0 0 71 90 IRtransS (Ig) 70 92 100 100 Ib 64 89 100 100 Ia:Ib=40:6061 89 100 100 .
In Example 18 it is shown on further insect species -that the enantiomer-pair Ib of the present inven-tiGn is more active than Ia. The increased ac-tivity manifests itselE not only in the 24 hours' mortality but also in the fact that the toxical effect is exhibited more rapidly.

Example 16 In Table 3 the insecticidal effect of mixtures of enantiomer-pairs Ia and Ib of various ratio is shown on flour beetle (Tribolium confusum). The test method is that disclosed in Example 14.
.

~ ~ - 21 -13172~0 Table 3 Ia : Ib Dose (mg/disc) 0.0~ 0.06 0.25 1.00 24 hours' mortality ~
. _ . .
10:0 0 14 54 100 5:5 0 43 100 100 4:6 14 53 100 100 3:7 20 81 100 100 0:10 8 46 100 100 .

The above data clearly proves-the synergism between enantiomer-pairs Ia and Ib.

Example 17 According to a further recognition of the present invention when the mixtures of enantiomer-pairs Ia and Ib are combined with conventional pyrethroid synergists (e.g. piperonyl butoxide, NIA 16388 etc.) the increase of activity is larger than the usual value (see Example 16).
In Table 4 the activity on Colorado pota-to beetle is shown.
The test method is as follows:
The test materials are dissolved in 2-ethoxyethanol (Cellosolve). One 0.3 ~1 drop of the solution is applied to the abdominal sterna of the imago. The treatment is carried out by using 2 parallels and 10 insects for each dose. Mortality is determined after 48 hours.

- 2~ _ Table 4 Active ingredient Dose (~g/beetle) 0.05 0.10 0.20 0.40 24 hours' mortality %
.. --- . .. _ Ia 50 55 75 80 Ib 0 25 75 85 Ia:Ib=4:6 45 60 70 80 Ia:Ib=3:7 45 65 75 85 deltamethrin 45 60 75 85 cypermethrin 0 20 45 75 _ Synergism is observed between enantiomer~pairs Ia and Ib, although on imago of Colorado potato beetle Ia is more active than Ib. Mixtures of enantiomer-pairs Ia and Ib exert the same activity a deltamethrin.

Example 18 .
The comparative test of Ia, Ib and a 40:60 mixture of Ia : Ib is carried out on bean weevil (Acanthoscelides obtectus), flour-beetle (Tribolium confusum), house fly (Musca domestica) and sheep magyot fly (Lucillia sericata). The test method des-cribed is Example 14 is used. The results are summarizèd in Table 5.

1 31 7~2() Table 5 Species Enantiomer Dose (mg/disc) pair 0.020.07 0.22 0.67 2.0 6.0 mortality ~
. _ _ .. . . . _ . _ _ . _ A.obtectus Ia 10 37 63 95 lO0 100 (imago) Ib 32 55 87 lO0 100 lO0 Ia:Ib=4:630 55 90 100 100 100 T.confusum Ia 0 18 51 100 lO0 100 (imago) Ib 14 73100 100 100 100 Ia:Ib=4:616 80100 100 lO0 100 M.domestica Ia 36 63 88 lO0 lO0 100 (imago) Ib 0 18 67 100 lO0 100 Ia:Ib=4:625 45 85 100 100 100 L.sericata Ia 0 30 29 57 60 65 (imago) Ib 22 55 70 75 100 lO0 Ia:Ib=4:618 50 60 75 lO0 100 Example 19 Activity of cypermethrin stereoisomer-pairs as function of time on flour beetle (T. Confusum).
Flour beetle tT. confusum)imagos are exposed in Petri-dishes according to the method described in Example 14.
For each dose 3 parallels are used and 15 animals are applied for each parallel test. In each point of time the insects lying on their backs are counted and the percentage results are expressed in ~able 6.

1 31-~22(3 Table_6 Dose /mg/disc/
Stereoisomer-pairs and Exposition 0.11 0.33 1.00 3.00 enantiomer- time pairs /minutes/ % of lnsects showlng toxlcal symptoms Ib 30 0 0 0 0 If 30 0 0 48 64 Ia 30 0 0 0 33 Ii 30 0 Q 0 15 0 o 0 70 Ig 30 0 0 15 68 120 30 70 100 100 :

..
Ib 30 : 0 0 47 61 0 21 82 1.00 Ia:Ib=4:6 30 0 0 50 55 Example 20 Imagos of flour-beetle /T. confusum/ are treated in an analogous manner to Example 14. As synergist piperonyl butoxide is used in a dose of 0.5 mg/disc.

1 31 7~0 Table 7 cypermethrin Dose ~mg/disc) stereoisomer0.4 0.2 0.1 0.05 0.025 24 hours' mortality %
.
Ia 96 53 12 0 0 Ia + PBO 100 58 16 0 0 Ia+Ib 100 90 57 18 0 Ia+Ib+PBO 100 95 75 43 7 It may be seen that the mixture of enantiomers Ia and Ib can be synergized to a larger extent than enantiomer Ia.
(Ia:Ib=4:6).

; Example 21 The active ingredients are dissolved in 2-ethoxy-ethanol and the solutions are applied in the form of 0.2 ~1 droplets onto the back of ~all webworm (Hyphantria cunea) of L7-L8 larvae stage. The treated worms are placed on strawberry leaves in Petri-dishes The test is carried out by using a doses, 2 parallels and 10 insects for each dose. The ~illed worms are counted after 24 hours and the percentage mortality rate is calculated. The results are summarized in Table 8.

Table 8 Active ingredient Dose (~g/larvae) 0.023 0.0~7 0.094 0.188 0.375 24 hours' mortality %
.. . ... . . . _ Ia 40 60 65 80 90 Ib 10 lS 30 70 80 Ia:Ib=4:~ 40 50 55 65 75 cypermethrin 0 10 25 50 75 1 3l722n Example 22 _ Leaves already infested with mites (Tetranychus urticae) were sprayed under Potter Tower. Mortality after 24 hours on the treated leaves was compared with the control.

Table_9 Active ingredient approx LD50 (ppm) Ia 0.056 Ib 0.340 Ia:Ib=4:6 0.060 cypermethrin 0.120 deltamethrin 0.185 . . .
Example 23 The 5 EC formulations prepared accordi~g to Example 13 are diluted 50x, lOOx, 200x, 400x, 800x and 1600x with water and 0.5 ml doses are sprayed onto glass plates. After drying 10 L.
decemlineata imagos are placed on each glass plate and the insects are covered with Petri-dishes. The tests are carried - out by using 6 doses and 3 parallels for each dose. The killed insects are counted a~ter 48 hours. The results are disclosed in Table 10.
Table 10 5 EC dilution formulation 1600x 800x 400x200x lOOx 50x mortality ~
. . ~
Ia 0 27 53 63 87 97 Ia:Ib=4:6 0 33 53 73 80 93 deltamethrin 7 35 53 67 83 100 cypermethrin 0 17 33 50 67 83 Example 24 _ Glass plates are sprayed wi-th 5 EC formulations prepared according to Example 13 in an analogous manner to Example 23.
After drying 10 bean weevil (Acanthoscelides obtectus) imagos are placed on each plate and the insects are covered with Petri-dishes.
The killed insects are counted after 24 hours. The test is carried out with 6 doses by using 3 parallels for each dose.
The results are summarized in Table 11, Table 11 5 EC dilution formulation1600x800x 400x 200x lOOx 50x mor-tality ~
.
Ia 0 13 27 33 50 70 Ia:Ib=4:6 10 17 30 37 53 70 deltamethrin 7 - 13 20 37 57 75 cypermethrin 0 3 10 20 45 60 .

Example 25 15 bean plants infected with green peach aphids(Myzus persicae) at 6 days' age are cultivated in each pot. At 12 days' age the strongly and uniformly infected plants are selected and sprayed to run-off with emulsions freshly prepared from the formulation according to Example 13. Treatments are carried out with three doses (active ingredient 2.5, 5 and 10 ppm) and four parallels are used (one pot per parallel). The second, fourth and eighth day after treatment the aphids are swept down ~rom the plants to a white paper with a fine brush and the live insects are counted. The results are disclosed in Table 12.

;i ,- .~

1 31 72~n Table 12 Average number oE aphids 5 EC Concentration per pot formulations /ppm/
Days after treatment Ia 2. 5 44 83 245 5 . 0 22 29 90 10 . 0 8 17 30 Ia:I~=4:6 2.5 38 71 251 5 . 0 21 32 82 10.0 10 11 21 deltamethrin 2 . 5 26 47 137 5 . 0 13 19 29 10.0 6 11 23 ___ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ __ __ _ _ _ __ __ _ __ _ _ _ _ __ _ _ _ _ _ _ __ _ _ __ _ _ __ _ _ _ _ __ __ __ __ __ _ __ _ _ _ _ _ _ _ _ _ _ _ control 1850 2780 4120 Example 26 Tomato plants pre-cultivated in pots are sprayed with a suspension of the active ingredient formed with a mixture of acetone and water. The treated plants are placed into lsolators and infected with L3 stage Leptinotarsa decemlineara larvae. The percental ratio of paralysed larvae which fall do~m from the plants is determined after 6 hours. The results are disclosed in Table 13.

. ~

1 3l722n Table 13 ~_ ~
IaIa : Ib = 4 : 6 Concentration /ppm/ % ratio of paralysed larvae .

Exam~le 27 The treatments are performed on a 25 m2 plot strongly infected with Colorado potato beetle. 10 plants per plot are specîally marked on which the Colorado potato beetles were counted previously. /During assessment of the number of pests only adults of the second Summer generation are taken into consideration, because at the point of time of the test the ratio of lavae of stages L3 and L4 is negligible/. Treatment is accomplished on 25 m2 plots at a dose of 10 g of active ingredient/ha with a~ueous suspensions of the formulations according to Example 10 and three parallels are used. The test is evaluated by counting the live insects on the marked plants. The average values of three parallel tests are disclosed in Table 14.

.--~ .,,~

1 31 722() Table 14 5 MEAverage number of live insects/10 plants formulationTime elapsed after treatment /in days/

-Ia 171 11 9 25 Ia:Ib=4:6 213 8 4 22 Deltamethrin 181 7 10 19 Control 211 206 179 183 Example 28 Residual contact test on adults of Aphidinus matricariae. Adults of A. matricariae are exposed to residues of the active ingredients freshly applied on glass plates forming cages, then the survivors are counted.
Treatment: test product/s/ and control treated with water.
Replicates: at least 3. Plot size /net/: 1 cage.
Parasites of known age /24 hours/ are used.
The products are applied at 5.1 ppm concentration, to each of the glass plates.
10 females of A. matricariae are introduced into each cage and supplied with honey as food. The number of females surviving exposure is determined after 1.5 and 24 hours, in independent runs. Total number of survivors is calculated for each cage. ~he results are shown in Table 15.

,, ~

1 3 1 7~2() Table 15 Concentration 5 ppm 1 ppm lh lh lh 24h mortality %
Ia 100 100 100 96 Ia:Ib=4:6 100 50 90 63 deltamethrin 100 20 100 85 .
Example 29 Direct contact test on pupae of A. metricariae Mature pupae of A. matricariae on paprika leaves in Petri-dishes are exposed to a direct spray of the active ingredients. Two or three days before emergence paprika leaves with parasitized pupae are used. The leaves are laid on moistened filter paper in a plastic Petri-dish.
Application of treatment: see Example 28.
The pieces of leaf are transferred after treatment to clean Petri-dish bottoms. The trays are stored in a climatic chamber at 20 C temperature, 70 % relative humidity and a light-dark cycle of 16-8 h. Surviving pupae hatch after 2-3 days.
The numbers of hatched and dead pupae are counted. Results are shown in Table 16.

-32~ 3 1 7 2 2 0 ~3305-1~00 Tabl_ 16 : Active ingredient Concentration 30 ppm10 ppm 5 ppm 1 ppm mortality %
.
Ib:Ia=6:4 14.3 0 0 0 Deltamethrin 75.0 33.0 0 0 Ia 77.0 12.5 0 0 Control 0 0 0 0 .,f~,

Claims (13)

1. Insecticidal composition containing more than one active ingredient, which comprises as active ingredient in an amount of 0.001-99% by weight a synthetic pyrethroid of the general Formula I

(I) (wherein X stands for chlorine or bromine) - wherein out of the eight possible isomers at least 95% of a 55:45 - 25:75 mixture is of the enantiomer-pairs Ia:Ib, wherein Ia is 1RcisS + 1ScisR and Ib is IRtransS - IStransR - if required in admixture with an activator and with the balance up to 100% of an auxiliary agent or filler.

2. Insecticidal composition according to claim 1 wherein said auxillary agent is selected from the group consisting of an antioxidant, a stabilizer, a wetting agent, a dispersing agent, an antifoam agent and a diluent.

3. Insecticidal composition according to claim 1, which comprises as active ingredient a 40:60 mixture of Ia:Ib.

4. Insecticidal composition according to claim 1, which comprises as active ingredient a 30:70 mixture of Ia:Ib.

5. Insecticidal composition according to claim 1, which comprises as active ingredient a 50:50 mixture of Ia:Ib.

6. A method of combating insect pests which comprises applying to the pests or their habitat a pesticidally effective amount of a composition according to any one of claim 1 to claim 5.

7. A method according to claim 6 wherein said composition is applied at a dose of 2g to 25g of active ingredient per hectare.

8. A crystalline synthetic pyrethroid of the general Formula I

(I) (wherein X stands for chlorine or bromine) - consisting of at least 95% of a 55:45 - 25:75 mixture of the enantiomer-pairs Ia:Ib, wherein Ia is 1RcisS + 1ScisR and Ib is 1RtransS + 1 StransR with the melting point 63-65°C.

9. A process for preparing an isomeric mixture of a compound of formula I as defined in claim 1, said isomeric mixture comprising substantially only a 55:45 - 25:75 mixture of enantiomer pair Ia:Ib, wherein Ia is 1RcisS and 1ScisR and Ib is 1RtransS and 1StransR which process comprises a) preparing from a starting mixture comprising in addition to isomer pair Ia:Ib other possible isomers or comprising isomer pair Ia:Ib in a ratio other than 55:45 - 25:75 a saturated solution of said starting mixture in a protic or apolar aprotic inert organic solvent, seeding the saturated solution with a seeding crystal comprising a 55:45 - 25:75 mixture of enantiomer pair Ia:Ib and isolating crystals precipitating therefrom at a temperature between 30°C and -30°C; or b) seeding a melt of a mixture comprising in addition to isomer pair Ia:Ib other possible isomers or comprising isomer pair Ia:Ib in a ratio other than 55:45 - 25:75 at a temperature between

10°C and 60°C with a seeding crystal comprising a 55:45 - 25:75 mixture of enantiomer pair Ia:Ib, allowing the solution to crystallize at a temperature between 30°C and -10°C and, if required, suspending the mixture thus obtained at a temperature between -10°C and -20°C in a protic or apolar aprotic inert organic solvent and isolating the precipitated crystals; or c) adding to a solution or a melt of a mixture comprising in addition to isomer pair Ia:Ib other possible isomers or comprising isomer pair Ia:Ib in a ratio other than 55:45 - 25:75 a sufficient amount of each of the isomer pair Ia:Ib to yield a solution or melt comprising the isomer pair Ia:Ib in a ratio of 55:45-25:75 and then, if required, crystallizing according to step a) or step b) above; or d) admixing enantiomer pair Ia and Ib in a ratio of 55:45 -25:75, if required, in the presence of a protic or apolar aprotic organic solvent, homogenizing the mixture and then crystallizing the enantiomer pair Ia:Ib in a ratio of 55:45 - 25:75, if required after seeding according to step a) above.

10. Process according to claim 9, step a) wherein said organic solvent is a C1-12 hydrocarbon, C1-6 chlorinated hydrocarbon, C2-6 dialkyl ether or C1-10 alkanol, and each said solvent may be a straight or branched chained and cyclic or alicyclic, respectively.

11. Process according to claim 9, step a), c) or d) wherein seeding with a seeding crystal is carried out in the presence of an antioxidant.

12. Process according to claim 11, wherein said antioxidant comprises tertiary butyl-hydroxy-toluene or 2,2,4-trimethyl quinoline.

13. Process according to claim 11 or 12 wherein said solvent is selected from the group consisting of ethanol, petrolether and hexane.