IE860193L - Pyrethroid insecticide composition. - Google Patents

Description

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

In the present specification the spatial configuration of the substituents related to the chiral carbon atom denoted with "dL" is characterized by "S" and "R" respectively. The designations "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 substituent attached to carbon atom "1" is denoted with the prefix "1R" and "IS", respectively.

In the present specification the various enantiorcers and enantiomer-pairs are designated with the following a ctreviat.i or.s: la mixture of IReisS and IScisR lb mixture of IRtransS and IStransR Ic mixture of IReisR and IScisS Id mixture of IRtransR and IStransS If IReisS Ig IRtransS Ih IScisR Ii IStransR From the compounds of the general Formula I 3 0 /I/ the following are commercially available: - "Cypermethrin " of the Formula IT.

/II/ comprising all isomers; "Alphamethrln" of the Formula II comprising only the IReisS and IScisR isomers; "Deltamethrin" of the Formula. Ill /III/ COOCH comprising or.ly the IRc icS isomer.

Selection of the possible isomer:-, 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 toxic., on certain insects and it was the obvious trend to put the most active isomers to the market or to synthetise the same /"Pest. Sci. /7, 273- /1976/J.

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 Mo. 170,866/. This compound may be prepared by reacting m-phenoxy--benzaldehyde cyano'nydrin with cyclopropane carboxylic acid chloride in the presence of a base _/~Pestic. Sci 6, 537-... /1975/_7. The product thus obtained consists of eight stereoisomers i.e. of a mixture of four 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 la, 21-22 % of en-antiomer-pair Ic, 26-27 % of enantiomer-pair lb 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 /"Pest. Sci. 7, 273 /1976/_7.

In the comparative biological tests of various pyrethroids /"Pest. Sci. _9, 112-116 /1978/_7 the cis and trans stereoisomers - including the cypermethrine stereoisomer-pairs - were evaluated together.

The comparative tests were carried out in Musca domestica L. and Phaedon cochleariae Fab species.

Concerning the chloro derivatives from the trans isomers activity data of IRtransS / Ig/ and IRtransR were disciosed. The said data show that - while the IRtransS isomer possesses a strong activity - the IRtransR isomer is 5 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_7. It was disclosed further on that the activity of a mixture of 10- 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 alphametrine /"isomer mixture of 20 IReisS and IScisR /la/ of the chloro derivatives_7 and decametrine /"comprising the only IReisS isomer /If/ of the bromo derivatives_7.

For this reason several procedures are known for the preparation of mixtures enriched in the cis isomers 25 from known cypermethrine isomer mixtures.

According to an aspect of the present inven tion there is provided an insecticidal composition containing more than one active ingredient which comprises as active ingredient in an amount of' 0.001-99 % by weight 30 a synthetic pyrethroid of the genera] Formula I (wherein X stands for chlorine or bromine) - namely out of the eight possible isomers at least 95 % of a 55 : 45 -25 : 75 mixture of the enantiomer-pairs la : lb, wherein I.-a is IReisS + IScisR and lb is IRtransS + IStransR -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 a/rent, dispersing agent, antifoam agent, diluent, carrier, and/or filler.

The present invention is based on the recognition that the isomeric mixture la + lb possesses valuable and advantageous biological properties. The said properties are surprising and unforeseen, although extended research work has already been performed in the field of pyrethroids of the general Formula I and a number of publications and patents have been published.

It is known further on that mixtures enriched in cis isomers can be prepared by means of crystallization from solutions comprising other isomers /~C.A. 95, 1981; KOKAI No. 57755/81_7. A substantially pure 1 : 1 mixture of the IReisS and IScisR isomers may be separated by using suitable solvents from a mixture comprising the other cis isomers too /British patent specification No. 2,064,528/. The isomeric mixture la is described to be very active. Special, so-called "high cis" syntheses are elaborated for the preparation of cis-cyclopropane carboxylic acid intermediates comprising cis isomers above a certain limit /about 50 %/, but these methods were rather expensive /"Angew. Chem. Ie, 24, /ll/, 996 /1985 /J.

The present invention is based on the recognition that when using a combination of the IRtransS isomer Ig /being the most active trans isomer of the compounds of the Formula II/ and the IStransR isomer Ii /being ranged among the less active isomers from the remaining seven isomers/ no antagonism characteristic for the earlier published isomer-pairs is observed.

Moreover a synergistic effect occurs over the additive effect of the pure Ig and Ii isomers when used 7 per s e.

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 5 outstanding properties. The said new active ingredient shows various advantages over hitherto known isomer 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 lb are described and claimed in our Patent Specification No. • The present invention is based on the further 15 recognition that the biolqgical 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-paire.

Thus we have tried to compare and simultaneously test the IRtransS + IStransR enantiomer-pair lb - which was found to be active by our experiments - with other isomers. The comparison has shown that synergism observed between the members of enantiomer-pair lb /i.e. Ig and Ii/ 25 does not take place between the members of the corresponding cis enantiomer-pair la /i.e. If and Ih/.

The present invention is based on the further recognition that while from the IReisS /If/ and IRtransS /Ig/ isomers it is generally the If isomer which is the 30 more active, on certain specii the biological activity of the enantiomer-pairs la and lb proves to be opposite.

As a result of the aforesaid we have come to the surprising recognition that when using simultaneously the enantiomer-pairs la and lb a synergistic effect is 35 observed, i.e. the effect of the combination is superior t.o that, of the: additional effect of both enan t iomer-- pa ire- when n:;oil per so.

It has been found that the synergistic biological effect of mixtures la + lb is not limited to such mixtures in which lb is more active than la. 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 detail, 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 inven tion.

In addition to the synergistic effect the compos i-tion 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 toxic 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 quotient of the approximative LDj-0 values measured on rats p.o. /280 and 355 ng/kg, respectively/ and on house fly topically /0.54 and 0.48 mg/kg, respectively/. The said selectivity index of la amounts to 50/0.45=111.

The synergistic effect may be observed on 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, 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 la requires 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 la and lb 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 la and lb of the mixture/.

The insecticidal compositions of the present invention comprising the isomer-pairs la and lb 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 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 la + lb activators and further synergists, e.g. piperonyl butoxide. The said additives increase 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 10 and/or non-ionic surfactants may be used, such as alkali metal salts of alkyl-aryl sulfonic acids, alkali metal salts of condensation products of alkyl aryl sulfonic acids and formaldehyde, alky1-aryl-polyglycol ether, sulfated long chained alcohols, polyethylene oxides, sulfated 15 fatty alcohols, fatty acid polyglycol 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 20 ingredient in admixture with 50-95 % by weight of additives which enable the formation of a stable emulsion when emulsifying the emulsion concentrate in or in the presence of water.

As additive 1-20 % by weight of a tenside and/or 25 0.1-5 % by weight of a stabilising 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 30 iuay 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 polyglycol esters ,-ethylene oxide - propylene oxide block polymers 35 etc.

• As solvent preferably mixtures of aromatic hydrocarbons /e.g. xylenes/, eyelohexanol, butanol, methyl ethyl ketone, ioopropanol etc. may be used.

The compositions of the present invention may 5 also comprise further synergists which enable the reduction of the amount of the active ingredient. For this purpose preferably piperonyl butoxide may be applied.

According to a further aspect of the present 10 invention there is provided a process for the preparation of an insecticidal active ingredient comprising out of the eight possible isomers of synthetic pyrethroids of the general Formula I /wherein X stands for chlorine or bromine/ substantially only a 55 : 45 - 25 : 75 15 mixture of enantiomer-pa irs la : lb - wherein la is IReisS and IScisR and lb is IRtransS and IStransR -which comprises a/ preparing from a mixture comprising in additon to the isomer-pairs la + lb other possible isomers too 20 and/or comprising the isomer-pairs la + lb in a ratio other than the desired values a saturated solution with a protic or apolar aprotic inert organic solvent, seeding the solution with a seeding crystal consisting of a 55 : 45 - 25 : 75 mixture of enantiomer-pairs la 25 and lb, 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 la + lb other isomers too and/or comprising the isomer-pairs la + lb in a ratio 30 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 la and lb, allowing the solution to crystallize at a temperature between 30 °C and -10 °C and if desired suspending 35 the mixture thus obtained at a temperature between -10 °C 1 n - 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 the isomer-pairs la + lb 5 other isomers too and/or comprising the isomer-pairs la + lb in a ratio other than the desired value an enantiomer-pair la or lb in such an amount that the solution orthe melt should contain the isomers in a ratio of 55 : 45 - 25 : 75 and if desired performing crystalliza-10 tion according to variant a/ or b/; or d/ admixing enantiomer-pairs la and lb in the desired ratio - if desired in the presence of a protic or apolar aprotic organic solvent - homogenizing the mixture and performing crystallization - if desired 15 after the seeding step according to variant a/.

According to variant a/ of the process of the present invention one may preferably proceed by using a C, -^2 hydrocarbon, ^ chlorinated hydrocarbon, C-^ ^ dialkyl ether or C-^ alcohol as organic solvent. 20 The said solvents may be straight or branched chained, and cyclic and alicyc]ic, respectively.

It is preferred to carry out seeding with a seeding crystal in the presence of an antioxidant -particularly tertiary butyl hydroxy toluene or 2,2,4-25 -trimethyl-quinoline - and to use ethanol, isopropanol petrolether or hexane as solvent.

One may proceed preferably by accomplishing crystallization under slow cooling.

According to a preferred form of realization 30 of the process of the present invention a mixture of 60 % of trans and 40 % of cis cypermethrin enantiomer--pairs /18.2 % of la, 26.8 % of lb, 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 35 isopropanol and the solution is seeded with seeding 1 3 crystals consisting of a mixture of la and lb in the presence of 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' 5 at 63.5-65 °C, comprises the enantiomer-pairs la and lb in a ratio of 40 : 60 and contains enantiomer-pairs Ic and Id as contamination in an amount of 5 %. The products thus obtained may be recrystallized as described above.

Thus the mixture of enantiomer-pairs la and lb can be 10 prepared with a purity above 99 %.

Similar results are obtained when recrystallizing mixtures Of other cis/trans ratio.

The cypermethrins used as starting material may be prepared by esterifying the mixture of cyclopropane 15 carboxylic 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 40:60 50:50 55:45 m.p. :°C 67-71.5 65-68 63.5-65 60.5-62 61.5-64 The practical feasibility in the desired direction 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 crystallization. 25 The crystallization of the mixture of enantiomer- -pairs la and lb 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 la and lb. In a refrigerator the 30 mixture of la and lb precipitates within a week. The crystals are isolated by adding ethanol cooled to -20 °C to the mixture and filtering the crystals.

The mixture of enantiomer-pairs la + lb according 14 to the present, invention may also be prepared by admixing and/or crystallizing la and lb or various amounts thereof or by admixing and/or crystallizing a mixture of la and lb, or calculated amount of lb, 5 respectively.

The biological activity of the products according to the present invention is tested on various insect specii. In the test methods the effect of stereoisomers used as reference standard and prepared by known 10 methods - e.g. by chromatographical separation or by chromatographical separation of cypermethrines prepared from chiral acids - is disclosed as well.

The insecticidal compositions of the present invention are harmless to environment and can be used 15 particularly in households and stables for combating fly ing insects and pests having a hidden mode of life and also for the treatment of pasture.

Further details of the present invention are to be found in the following chemical and biological 20 examples without limiting the scope of protection to the said Examples.

Chemical Examples Example 1 100 g of cypermethrin /consisting according to 25 gas chromatography of a mixture of 18.2 % of la, 21.8 % of Ic, 26.8 % of lb and 33.2 % of Id/, 0.2 g of potassium hydroxide and 0.2 g of 2,6-di-tertiary butyl--4-met.hyl-phenol are dissolved in 2000 ml of isopropanol under constant stirring at 45.0 °C. The solution is slowly cooled to 30 °C, clarified with activated charcoal and filtered at 30 °C. The colourless solution is seeded with a crystal consisting of 60 % of lb and 40 % of la and the mixture is stirred at -10 °C 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.: 62-65 °C /non-corrected value/. According to GC and TLC analysis the product contains 37 % of la an 58 % of lb isomers. Yield: 76 % /related to the la + lb isomer content of the cypermethrine starting material/.

Ia isomer = 0.25; lb isomer R^. = 0.20.

After recrystallization from isopropanol 32 g of the product are obtained as first crops. M.p.: 63.5-65.0 °C; the product consists of 39.5 % of Ia and 59-5 % of lb. IR /KBr/ C_Q: 1730, 1735 cm"1 NMR /CDC13/ <f* /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, /1H/; 6.85-7.60 m, /9H/ Example 2 100 g of cypermethrin /27.8 % of Ia, 21.8 % of lb, 32.1 % of Ie and 18.2 % of Id/, 0.2 g of potassium hydroxide and 0.2 g of 2,6-di-tertiary butyl-4-methyl--phenol are dissolved in 2000 ml of isopropanol under stirring at 45 °C. The solution is clarified with activat ed charcoal and filtered at 30 °C. The colourless solution is seeded with a seeding crystal consisting of 20 % of lb and 80 % of Ia and stirred at -10 °C for 36 hours. The precipitated product is filtered, washed with isopropanol and dried in vacuo. Thus 30 g of snow-white crystalline product are obtained, m.p.: 66-73 °C. According to gas chromatography the product contains 77 % of Ia + 19 % of lb, purity 96 % /TLC, see Example 1/ 1 a After recrystallization from isopropanol as first generation 26.5 g of a snow-white crystalline product are obtained, m.p.: 70-73 °C, containing 81.5 of Ia + 18 % of lb /GC analysis/.

IR /KBr/ Vc^Q: 1730 cm"1 NMR /CDC13/ ^/ppm/: 1.05 - 2.45 m /8H/; 5.60 d J= 8HZ /=CH trans 0.2H/; 6.14 d J= 8Hz /=CH cis 0.8 H/; 6.35 d /ArCH 1H/ 6.85 - 7-60m/9H/.

Example 3 100 g of colourless clearly transparent oily cypermethrin' /13.2 % of Ia, 21.8 % of Ic, 26.8 % of lb and 33.2 % of Id/ are seeded with a seeding crystal consisting of 60 % of lb and 40 % of Ia and the solution is allowed to crystallize at 7 °C for a week. The mixture is suspended in 100 ml of a 1:1 mixture of isopropanol and diisopropyl ether and filtered at -15 °C. The crystals are washed with isopropanol and dried in vacuo. Thus 40.1 g of a white crystalline product are obtained, containing 37.5 % of la and 59 % of lb, m.p.: 62.5 - 65 °C. Yield 86 %. After recrystallization from isopropanol as first generation 36 g of a snow-white crystalline product are obtained, m.p.: 63.5 - 65 °C, consisting of 40 % of Ia and 60 % of lb /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 lb, 33.2 % of Id/ and 0.05 g of 2,6-di--tertiary buty1-4-methyl-phenol are dissolved in 100 ml 30 of diisopropyl ether under constant stirring at 0 °C and the solution is clarified with 2 g of activated charcoal. The solution is filtered and seeded at -15 °C with a seeding crystal consisting of 60 % of lb and 40 % of Ia. The mixture is allowed to crystallize for 1 5 i 7 72 hours, the crystals arc 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 % 5 of lb. Yield 80.6 %. After recrystallization from iso propanol as first generation 35 g of a snow-white crystalline product are obtained, m.p.: 63,5-65 °C, the ratio of the Ia : lb isomers = 40 : 60. The physical constants are identical with those disclosed in Example 1. 1o Example 5 g of samples of the product obtained according to Example 2 /the ratio of the Ia : lb 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 lb, respectively, and the 15 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 lb 55:45 :5 4:6 3:7 :75 M.p.: / C/ 61.5-64 60.5-62 63.5-65 65-68 67-71.5 Example 6 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 lb, respectively, and the mixtures are homogenized. The crystal mixtures thus 30 obtained comprise the substances Ia + lb in a ratio 1 8 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.

Example 7 g samples of pure crystalline isomer-pair Ia are dissolved in 10-fold amount of isopropanol and to each sample 23.34 g and 30.0 g of pure crystalline isomer-pair lb 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 : lb 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.

Formulating examples Example 8 To 166.2 g of perlite /dmax = 120 /um/ 0.8 g of synthetic silicic acid /Aerosil 300/ are added in a fluidizing rapid stirrer. 20 g of a cypermethrin 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/.

Example 9 3 g of a mixture of cypermethrin enantiomer--pairs Ia : lb r 3 : 7 and 0.3 g of fatty alcohol poly- 1 9 glycol ether are applied in a homogenizing apparatus onto talc /d = 15 ,um/ adjusted to the pH value max / of 6.5 with a buffer of 0.8 of synthetic silicic acid /Aerosil 200/ and 193.9 g of potassium and sodium 5 phosphate. To the mixture 1 g of dioctyl sulfosuccinate an 1 g of fatty alcohol polyglycol ether sulfonate are added under stirring and the mixture is ground to an average particle size of 20 ^um. Thus a thin flowable powder mixture is obtained.

Example 10 g of a mixture of cypermethrin enantiomer--pairs Ia : lb = 55 : 45 are dissolved in a mixture of 21.25 g of xylene and 42.5 g of n-propanol under slow stirring. To the solution a mixture of 4 g of et'noxylat-ed 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 materia.Is 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 formation of an emulsion having a droplet-size of 0.8-1.5 ^um.

Example 11 g of a mixture of cypermethrin enantiomer--pairs Ia : lb = 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 /7.5 g/ of ethoxylat-30 ed 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 added. V.'hen measured according to the rr.ethod of CIPAC the 1 5 emulsion concentrate proves to be stable after 170 hours.

In a mechanical granulator a 50 : 50 mixture of the'Ia and lb 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 shear ing 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 to the WHO method/.

Example 13 Emulsifiable concentrates /EC/ are prepared by admixing the following components: Example 12 EC Component Amount, kg/kg Isomer-pairs Ia:Ib=40-60 0.105 0.290 0.020 0.045 0.540 Cyclohexanol Atlox 3386 B Atlox 3400 B Odourless mineral oil EC Component Amount, kg/kg Isomer-pairs Ia:Ib=40:60 0.050 0.290 0.020 0.045 0.595 Cyclohexanol Atlox 3386 3 Atlox 3400 B Odourless mineral oil 2 1 Biological Examples Example 14 In Table 1 the activity of various stereoisomers of cypermethrin on house fly /Musca domestica/ is shown.

^ The test is carried out as follows: The active ingredient is dissolved in a 1:2 mixture of oil and acetone; filter paper discs /Whatman Mo. 1, diameter 9 cm/ are impregnated with the solutions of the corresponding stereoisomers and enantiomer-pairs, respectively. The acetone is allowed to evaporate, where upon 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 percental mortality is determined after 24 hours.

The corrected percental mortality is calculated by means of the Abbot Formula.

Table 1 Cypermethrin Dose /mg/disc/ stereoisomer 0.04 0.11 0.33 1.00 3.00 24 hours' mortality /%/ If 68 93 100 100 100 Ia 44 84 100 100 100 is 48 68 83 100 100 lb 32 62 95 100 100 Ia:Ib=40:60 41 81 100 100 100 According to this test the activity of mixture Ia + lb corresponds to that of the pure isomer Ia. 22 K I'![) 1 1'; '|v. rj {■ pen r:; I'rum Table 2 that, the i nc roamed activity ;:hown in Example 14 ic duo t. o the synergistic effect of the trans-isomers to Tribolium confusum.

Table 2 Active Dose /mg/disc/ ingredient 0.11 0.33 1.00 3.00 24 hours' mortality IScisR /Ih/ 0 • 3c 80 100 1 0 IReisS /If/ 60 100 100 100 I a 22 65 94 100 IStransR /Ii/ 0 0 71 90 IRtransS /Ig/ 70 92 100 100 lb 64 89 100 100 1 5 Ia:Ib=40:60 61 89 100 100 In Example 18 it is shown on further insect species that the enantiomer-pair lb of the present invention is more active than Ia. The increased activity manifests itself not or.ly in the 24 hours' mortality but also in 20 the fact that the toxical effect is exhibited more rapidly.

Example 16 In Table 3 the insecticidal effect of fixtures of enantiorer-pa irs Ia and lb of various ratio is s':owr. 25 on flour beetle /Tribolium confusum/. The test method is that disclosed in Example 1*».

Table 3 Ia : lb 0.02 Dose 0.06 /mg/d isc/ 0.25 1.00 24 hours' mortality % :0 0 14 54 100 :5 0 43 100 100 4:6 14 53 100 100 3:7 81 100 100 0:10 8 46 100 100 The above data clearly prove the synergism between enantiomer-pairs Ia and lb.

Example 17 According to a further recognition of the present invention when the mixtures of enantiomer-pairs Ia and lb 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 potato beetle is shown.

The test method is as follows: The test materials are dissolved in 2-ethoxyethanol /Cellosolve/. One 0.3 ^ul 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. 24 Table 4 Active ingredient 0.05 Dose /j 0.10 24 hours' ug/beetle 0.20 mortality 0.40 % Ia 50 55 75 80 lb 0 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 45 75 Synergism is observed between enantiomer-pairs Ia and lb, although on imago of Colorado potato beetle Ia is more active than lb. Mixtures of enantiomer-pairs Ia and lb exert the same activity a deltamethrin.

Example 18 The comparative test of Ia, lb and a 40:60 mixture of Ia : lb is carried out on bean weevil /Acanthoscelides obtectus/, flour-beetle /Tribolium confusum/, house fly /Musca domestica/ and sheep maggot fly /Lucillia sericata/. The test method described is Example 14 is used. The results are summarized in Table Table 5 Species Enantiomer- Dose /nig/disc/ pair ' 0.02 0.07 0.22 0.67 2.0 6.0 mortality % A.obtectus Ia 37 63 95 100 100 /imago/ lb 32 55 87 100 100 100 Ia:Ib=4:6 55 90 100 100 100 T.confusum Ia 0 18 51 100 100 100 /imago/ lb 14 73 100 100 100 100 Ia:Ib=4:6 16 80 100 100 100 100 M.domestica Ia 36 63 88 100 100 100 /imago/ lb 0 18 67 100 100 100 Ia:Ib=4:6 45 85 100 100 100 L.sericata Ia 0 29 57 60 65 /imago/ lb 22 55 70 75 100 100 Ia:Ib=4:6 18 50 60 75 100 100 Example 19 Activity of cypermethrin stereoisomer-pairs as function of time on flour beetle /T. Confusum/. 20 Flour beetle /T. 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 25 counted and the percentage results are expressed in Table 6.

P 26 Table 6 Stereoisomer-pairs Exposition Dose /mg/disc/ and enantiomer- time /minutes/ 0.11 0.33 1.00 3.00 pairs % of insects shewing toxical symptoms Th 0 0 0 0 60 0 0 0 8 120 0 0 0 67 180 0 0 0 88 If 0 0 48 64 60 0 84 100 120 0 40 100 100 180 39 61 100 100 Ia 0 0 0 33 60 0 0 16 88 120 0 14 66 100 180 49 100 100 Ii 0 0 0 60 0 o 0 70 120 0 0 0 100 180 0 0 0 100 Ig 0 0 68 60 18 34 98 100 120 70 100 100 180 34 84 100 100 lb 0 0 47 61 60 0 21 82 100 120 28 100 100 100 180 56 100 100 100 Ia:Ib=4:6 0 0 50 55 60 85 85 100 120 100 100 100 180 55 100 100 100 Example 20 Imagos of flour-beetle /T. confusu::/ are treated in an analogous manner to Example 14. As synergist piperonyl butoxide is used in a dose of C.5 mg/disc. 27 Table 7 cypermethrin Dose /mg/disc/ stereoisomer 0.4 0.2 ■ 0.1 0.05 0.025 24 hours' mortality % Ia 96 53 12 0 0 Ia + PB0 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 10 Ia and lb 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 15 0.2 /ul droplets onto the back of fall webworm /Hyphantria cunea/ of L^-Lq 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 for each dose. The killed worms are 20 counted after 24 hours and the percentage mortality rate is calculated. The results are summarized in Table 8.

Table 8 Active ingredient 0.023 Dose / 0.047 .ug/larvae/ 0.094 0.188 0.375 24 hours' mortality % Ia 40 60 65 80 90 lb 70 ' 80 Ia:Ib=4:6 40 50 55 65 75 cypermethrin 0 50 75 2 8 Example 22 Leaves already infested with mites /Tetranychus urticae/ were sprayed under Potter Tower. Mortality ifter 24 hours on the treated leaves was compared with the control.

Table 9 Active ingredient approx /ppm/ Ia 0.056 lb 0.340 Ia:Ib=4:6 0.060 cypermetrine 0.120 deltametrine 0.185 Example 23 The 5 EC formulations prepared according to Example 15 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 20 3 parallels for each dose. The killed insects are counted after 48 hours. The result are disclosed in Table 10.

Table 10 EC dilution formulation 1600x 800x 400x 200x lOOx 50x mortality % la 0 27 53 63 87 97 Ia:Ib = 4 : 6 0 33 53 73 80 93 deltamethrin 7 53 67 83 100 cypermethrin 0 17 33 50 67 83 29 Example 24 Glass plates are sprayed with 5 EC formulations prepared according to Example 13 in an analogous manner to Example 23. After drying 10 bean weevil /Acanthos-5 celides 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 EC dilution formulation 1600 x 800x 400x 200x lOOx 50x mortality % Ia 0 Ia:Ib=4:6 10 deltamethrin 7 cypermethrin 0 13 27 33 50 70 17 37 53 70 13 37 57 75 3 45 60 Example 25 bean plants infected with green peach aphids 20 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 25 /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 from the plants to a white paper with a fine brush and the live insects are counted. The results are disclosed in 30 Table 12. ao Table 12 EC Concentration Average number of aphids formulations /ppm/ per pot Days after treatment 5 2 4 8 Ia 2.5 44 83 245 .0 22 29 90 o o 1—1 8 17 Ia:Ib=4:6 2.5 38 71 251 .0 21 32 82 .0 11 21 deltametrine 2.5 26 47 137 .0 13 19 29 .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 20 are placed into isolators and infected with stage Leptinotarsa decemlineara larvae. The percentage ratio of paralysed larvae which fall down from the plants is determined after 6 hours. The results are disclosed in Table 13. 31 Table 13 Concentration Ia la : lb = 4 : 6 /ppm/ % ratio of paralysed larvae 1000 100 100 200 100 100 40 46 75 8 18 60 Example 27 2 The treatments are performed on a 25 m plot 10 strongly infected with Colorado potato beetle. 10 plants per plot are specially 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, 15 because at the point of time of the test the ratio of lavae of stages and is negligible/. Treatment is accomplished on 25 plots at a dose of 10 g of active ingredient/ha with aqueous suspensions of the formulations according to Example 10 and three parallels 20 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.

Table 14 ME Average number of live insects/10 plants formulation Time elapsed after treatment /in days/ 0 13 9 Ia 171 11 9 Ia : I'd=4 : 6 2*13 8 4 22 Deltametrine 181 7 19 Control 211 206 179 183 3 2 Example 28 Residual contact test on adults of Aphidinus matricariae. Adults of A. matricariae are exposed to residues of the active ingredients freshly applied 5 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. 10 Parasites of known age /24 hours/ are used.

The products are applied at 5.1 ppm concentration, to each of the glass plates. females of A. matricariae are introduced into each cage and supplied with honey as food. The 15 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. The results are shown in Table 15.

Table 15 Concentration ppm 1 ppm lh lh 5h 24h mortality % la 100 100 100 96 la:Ib=4:6 100 50 90 63 deltamethrin 100 20 100 85 Example 29 Direct contact test on pupae of A. matricariae Mature pupae of A. matricariae on paprika leaves 30 in Petri-dishes are exposed to a direct spray of the active ingredients. Two or three days before emergence 33 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.

Table 16 Active ingredient Concentration ppm 10 ppm 5 ppm 1 ppm 15 mortality % lb:la=6:4 Deltamethrin Ia control 14.3 0 0 0 75.0 33.0 0 0 77.0 12.5 0 0 0 0 0 0 3 4 1 0

Claims (11)

CLAIMS :

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 (wherein X stands for chlorine or bromine) - namely out of the eight possible isomers at least 95 % of a 55:45 -- 25:75 mixture of the enantiomer-pairs Ia:Ib, wherein Ia is IReisS + IScisR and lb is IRtransS + IStransR -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.

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

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

4/ Insecticidal composition according to Claim 1, X /I/ 3 5 which comprises as active inuredinet a 50:50 mixture of la:lb.

5/ Process for the preparation of 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 IReisS and IScisR and lb is IRtransS and IStransR - , which comprises a/ preparing from a mixture comprising in addition to the isomer-pairs la + lb other possible isomers too and/or comprising the isomer-pairs Ia + lb in a ratio other than the desired value a saturated solution with a protic or apolar aprotic inert organic solvent, seeding the solution with a seeding crystal consisting of a 55:45 - 25:75 mixture of enantiomer-pairs la and lb, 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 + lb other isomers too and/or comprising the isomer-pairs Ia + lb 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 lb, allowing the solution to crystallize at a temperature between 30 °C and -10 °C and, if desired, 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 the isomer-pairs Ia + lb other i somers too and/or comprising the isomer-pa irs Ia + lb in a ratio other than the desired value an enantiomer--pair Ia or lb in such an amount that the solution cr the melt should contain the isomers in a ratio of 55:45 - 3 6 - 25:75 and, if desired, performing crystallization according to variant a/ or b/\ or d/ admixing enantiomer-pairs Ia and lb in the desired ratio - if desired, in the presence of a protic 5 or apolar aprotic organic solvent - homogenizing the mixture and performing crystallization - if desired, after the seeding step according to variant a/.

6/ Process according to variant a/ of Claim 5, which comprises using as organic 10 solvent a hydrocarbon, chlorinated hydro carbon, C2_£ dialkyl ether or alkanol, whereby the said solvents may be a straight or branched chained and cyclic or alicyclic, respectively.

7/ Process according to variant a/, c/ or d/ 15 of Claim 5, which comprises carrying out seeding with a seeding crystal in the presence of an antioxidant.

8/ Process according to Claim 7, which comprises using as antioxidant tertiary butyl-20 -hydroxy-toluene or 2,2 ,4-trimethyl quinoline.

9/ Process according to any of Claims 7 and 8, which comprises using as solvent ethanol, petrolether or hexane.

10/ Use of an insecticidal composition according 25 to Claim 1 to combat insect pests at a dose of 2.0-25 g of active ingredient/ha.

11/ An insecticidal composition according to Claim 1, substantially as hereinbefore described and exemplified. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS.