WO2015107540A2

WO2015107540A2 - Insecticide compound and the compositions thereof

Info

Publication number: WO2015107540A2
Application number: PCT/IN2014/000768
Authority: WO
Inventors: Kalyanaraman RAMASWAMY; Amit Ramaswamy KALYANARAMAN; Mangesh Vasudeo HANDE; Yuvraj Hanamant GHARGE
Original assignee: Shogun Organics Limited
Priority date: 2013-12-30
Filing date: 2014-12-10
Publication date: 2015-07-23
Also published as: WO2015107540A3; MY183491A; AP2016009305A0

Abstract

The invention disclosed herein relates to insecticide compound and the compositions thereof. Particularly the invention provides insecticidal isomeric composition of 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl 3-(2,2-dichlorovinyl)-2,2-dimefhylcyclopropanecarboxylate comprising total trans isomers ranging from 90% to 99.90% and rest being cis isomers. Further it describes process for preparation of said isomeric composition and its use, as insecticide/pesticide.

Description

"INSECTICIDE COMPOUND AND THE COMPOSITIONS THEREOF"

TECHNICAL FIELD:

The present invention relates to insecticide compound and the compositions comprising the same. Particularly the invention provides insecticidal isomeric composition of 2,3, 5,6- tetrafluoro-4-(methoxymethyl)benzyl3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylate comprising total trans isomers ranging from 90% to 99.90% and rest being cis isomers.

Further it describes efficient process for preparation of said isomeric composition and its use, as insecticide/pesticide.

BACKGROUND AND PRIOR ART:

In the recent age, environmental friendly biologically active pesticides, insectcides has drawn increasing attention. Various mosquito and insect repellent products formulations based on pyrethroid compounds are useful in households. Pyrethroids usually can have 2 to 8 optical isomers and biological activity between the isomers varies greatly and therefore need for preparation of highly bioactive insecticides. Some of the optically active insecticides such as Transfluthrin, Prallethrin, Metofluthrin, Meperfluthrin, Dimefluthrin, d-trans allethrin, d-Allethrin are known in the art.

JP2005298476 and CN 1669429 provide pesticidal compositions comprising a compound of formula (1), and di (2,3,3,3 -tetrachloro -propyl) ether.

(1) wherein R^l is preferably 'Ή

The process for preparation of insecticide Transfluthrin is reported in 898/MUM/2007 and 322/MUM/2005.

The China Patent CN101580471(B) and Indian Patent Application No.8431/DELNP/201 1 discloses pyrethroid compound Meperfluthrin, i.e. 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl ( 1 R,3 S)-3 -(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxyl ate, having (1R,3S) trans single optically active isomer of dextrorotation. According to CN101580471 the preparation of Meperfluthrin comprises only one of the four isomers of Cypermethric Acid Chloride. Insecticide compound Transfluthrin also contains the same (1R,3S) trans isomer.

(1 fl,3S)-3-(2,2-dichlorovinyl}-2,2- dimethy!cyclopropanecarbonyf chloride

or

(1R,3S trans Cypermethric Acid Chloride)

Indian Patent Application No.8431/DELNP/2011 discloses preparation of insecticidal incense. It further states that Meperfluthirn may contain only two isomers 1R Trans ( i.e. 1R,3S trans ) and 1R Cis ( i.e. 1R,3R Cis ) 3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylate.

US 4370346 relates to cyclopropane derivatives useful as insecticides and processes for preparation and compositions thereof, particularly US'346 discloses 4- methoxymethyltetra fluorobenzyl ester of (+)-cis-3-(Z-2-chloro-3,3,3-tri chloroprop-l-en- yl)-2,Z-dimethyl cyclopropane carboxylic acid, which is believed to have the (1R,3R) configuration in the cyclopropane ring.

Indian Patent Application No. 115/CHE/2004 discloses insecticidal composition in the form of emulsion comprising of chemical compound 2,3,5,6-tetrafluoro-4- (methoxymethyl)benzyl (EZ)-( 1 RS ,3 RS ; 1 RS ,3 SR)-2,2-dimethyl-3-prop- 1 - enylcyclopropanecarboxylate, i.e. "Metofluthrin" along with calcium alkylbenzene sulfonate, polyoxyalkylene alkyl ether and other base.

In view of the foregoing, it is evident that many of the prior art documents suggest the use of pyrethroid compounds in specific isomeric form, the isolation of which is cumbersome and expensive. In some cases these isolated isomer compounds also require higher dosage to achieve the desired efficacy in knock down time (KT₅₀ value). Therefore highly stable, bio-active insecticides, obtained by simple and cost-effective process that eliminates the separation of individual isomers, are desirable.

In accordance with the above need, the inventors provide novel insecticidal isomeric composition containing trans and cis isomers in a specific ratio, which gives better bio- efficacy than the existing mosquito repellent formulations.

SUMMARY OF THE INVENTION:

The present invention provides isomeric composition of 2,3,5,6-tetrafluoro-4- (methoxymethyl)benzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate with specific ratio of all cis and trans isomers, wherein total trans isomers range from 90% to 99.90% and rest being cis isomers, hereinafter said isomeric composition called as "Renofluthrin" having better insect repellency or mosquito repellent activity.

In another aspect, the invention provides efficient process for the preparation of 'Renofluthrin' without isolation/separation of any specific cis or trans isomer, using Cypermethric Acid in native form with all isomers present.

Further the invention provides evaluation of Renofluthrin for mammalian Toxicology and bio-efficacy of 'Renofluthrin' towards mosquitoes.

Abbreviations:

CM A: Cypermethric Acid

HTCMA: High Trans Cypermethric Acid

HTCMAC: High Trans Cypermethric Acid Chloride

TFMBA: 2,3,5,6-Tetrafluoro-4-(methoxymethyl)benzyl Alcohol

DETAILED DESCRIPTION OF THE INVENTION:

The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated. The invention provides an insecticidal isomeric composition of 2,3,5,6-tetrafluoro-4- (methoxymethyl)benzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate with total trans isomers ranging from 90% to 99.90% and rest being cis isomers.

Renofluthrin

For the purpose of this invention, the expression 'novel insecticide' or 'Renofluthrin' or 'isomeric composition of 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl 3-(2,2- dichlorovinyl)-2,2-dimethylcyclopropane carboxylate having total trans isomers ranging from 90% to 99.90% and rest being cis isomers' or 'mosquito repellent' or 'insect repellent' are used interchangeably throughout the specification and the same may be appreciated as such by the person skilled in the art.

The Renofluthrin as used in the specification intends to refer isomeric composition of 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropane carboxylate, comprising ;

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lR,3S)-3-(2,2-dichlorovinyl)-2,2-dimethyl cyclopropanecarboxylate;

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lS,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate;

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lR,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate; and

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lS,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate;

wherein total trans isomers (1R,3S and 1S,3R ) are present in range of 90% to 99.90%, rest being cis isomers (1R,3R and 1S,3S). In a preferred embodiment, the isomeric composition of Renofluthrin is a racemic mixture of 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lR,3S)-3-(2,2-dichlorovinyl)- 2,2-dimethyl cyclo propanecarboxylate;

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lS,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl; with both the trans isomers in the range of 90% to 99.90% , and the rest being cis isomers. The cis isomers preferably present in an amount of 0.1 to 10%.

The isomeric composition of 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl 3-(2,2- dichlorovinyl)-2,2-dimethylcyclopropane carboxylate, having total trans isomers in the range of 90% to 99.90 % and the rest being cis isomers, which may be obtained in free base or agrochemically acceptable salt form.

In another preferred embodiment, the isomeric composition of 2,3,5,6-tetrafluoro-4- (methoxymethyl)benzyl3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate having minimum 98% of total trans isomers and maximum 2% of cis isomers.

In another embodiment, the invention provides novel insecticide 'Renofluthrin' having better bio-efficacy, which is prepared using sequential process. The process for synthesis of Renofluthrin starts with available form of Cypermethric Acid (CMA) having total trans isomers minimum 50% or above. Further process steps involves increasing total trans isomers up to the range of 90% to 99.90% (HTCMA), then its chlorination to obtain (HTCMAC), followed by reaction of (HTCMAC), with 2,3,5,6-Tetrafluoro-4- (methoxymethyl)benzyl alcohol (TFMBA). No specific individual trans or individual cis isomers are separated in the process.

The Cypermerthric Acid having total cis isomers 40% and total trans isomers 60%, which is converted to Cypermerthric Acid having cis isomer at least about 10%; preferably < 2%, and the trans isomers preferably in the range of 90% to 98%) more preferably 90% to 99.90 % by known process and subsequently converted into Cypermerthric Acid Chloride (HTCMAC) with the same trans and cis ratio, wherein, the total trans Cypermerthric Acid Chloride present in the range of 90% to 99.90%, the rest being cis isomers in the range of O.l % to l0%.

The high trans Cypermethric Acid Chloride (HTCMAC) in the specification intends to refer the isomeric composition of (lR,3S)-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarbonyl chloride; (lS,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride; (lR,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride and (lS,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride, wherein total trans isomers i.e. (1R,3S) and (1S,3R), are in the range of 90% to 99.90 % and rest being cis isomers, preferably 0.1% to 10%.

The isomeric composition of Cypermethric Acid Chloride is a racemic mixture of (lR,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride; (lS,3R)-3- (2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride; (lR,3R)-3-(2,2- dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride and (lS,3S)-3-(2,2- dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride.

The high-trans Cypermethric Acid Chloride having four isomers as shown below:

Trans

(T«,3fli.3-(2,2-dlcfilar<}vinyl).¾a. dim€itiyi^dopropanecart3on dimetn !cyctopcopar>e

carbonyi ehtoricte

(1:S,3f¾-3-C¾2-dic toroviRyl|-2,2- {1S_t3S)-3-(2,2-dic torov!riyi)-2,2- d!meihyteycl^opsnecarfcon c tortde dlmethyleyctopropanecarbonll ehtorWe In another specific embodiment, the invention provides isomeric composition of Cypermethric Acid Chloride which comprises minimum 98% of total trans isomers and maximum 2% of cis isomers.

In another embodiment, the invention provides economically efficient process for ' preparation of highly pure, stable 'Renofluthrin'. The invention describes the known process to increase total trans isomers in CMA from 60% to minimum 90% and then further to minimum 98%. CMA, where 60% total trans is processed with acid anyhydride such as formic anyhydride, acetic anyhydride, organic solvent such as toluene, cyclohexane, other hydrocarbon solvents and non-oxidising strong organic acid such as sulfonic acid. The said isomerisation process reduces the total cis isomers and increases total trans isomers.

Further the process comprises chlorination of this high trans Cypermerthric Acid in presence of thionyl chloride (TC) to obtain highly pure high trans Cypermerthric Acid Chloride (HTCMAC), wherein trans isomers and cis isomers of Cypermerthric Acid Chloride is present in specific ratio, particularly total trans isomers are present in the range of 90% to 99.90% and cis isomers are in the range of 0.1%) to 10%.

Moreover, the process for the preparation of isomeric composition of 2,3,5,6-tetrafluoro- 4-(methoxymethyl)benzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylase comprises, reaction of 2,3,5, 6-tetrafluoro-4-(methoxymethyl) benzyl alcohol and high trans Cypermethric Acid Chloride, in presence of organic solvent, and alkali salt at lower temperature. This is followed by further purification to obtain active Renofluthrin with high purity, along with its related manufacturing impurities and entire chemical composition. Purification is performed by the known techniques such as vacuum distillation, filtration, crystallization, charcoal filtration and the like thereof.

In further embodiment, formulations of 'Renofluthrin' insecticide active ingredient having concentration of Renofluthrin between 2.5% to 25%, to be used as intermediate 'manufacturing use product' in preparations of lower concentration formulations of household mosquito repellents and insect repellents. Such 'manufacture use products' (MUP) enable better stability, safety and easier handling of Renofluthrin to prepare mosquito repellent products.

In further embodiment, the invention provides chemical composition for insect repellent/ mosquito repellent comprising lower concentration of the active ingredient 'Renofluthrin' additionally containing chemically acceptable additives, adjuvants, solvents, perfumes, aromatic compounds, carriers, fillers, stabilizers, preservatives, other inactive ingredients and like thereof,

In another embodiment the intermediate "manufacture use product" (MUP) formulations can be made of Renofluthrin, containing 2.5% to 25% of Renofluthrin active ingredient which can then be used to make end product mosquito repellent and insect repellent for household use, which provides better stability and safety in handling of the product. The target insects according to the invention include housefly, mosquito, cockroach and other flying and crawling pests. The manufacturing use product containing Renofluthrin can be used in preparation of end use formulations or home insecticide product forms like coils, mats, sprays, vaporizers, liquid, oils, aerosols, paper, and many other product forms.

According to the invention, vapourising liquid formulation containing 'Renofluthrin' shows better efficacy than presently marketed liquid formulations in India. Renofluthrin 0.6% concentration liquid formulation is more effective when compared to insecticide Transfluthrin 0.88% concentration liquid, and insecticide Prallethrin 1.6% concentration liquid. In liquid formulations, the active ingredient insecticide is diluted in deodourised kersoene or isoparaffins or aromatic / aliphatic solvents. Two or more solvents can be used for the dilution. Some of the liquid formulations also may contain additives, perfume, stabilisers etc.

In yet another embodiment, the invention provides bio-efficacy of Renofluthrin on target pests. Mosquito species 'Culex quinquefasciatus ' is seen all over India in and around human dwellings. It is major vector of various virus and diseases. Mosquito species 'Aedes aegypti ' is a major vector of dengue fever, chikungunya and yellow fever viruses, and other diseases. The effectiveness / efficacy of mosquito repellent formulation is normally measured in "Knock-down time" (KT) in minutes of percentage of the test population of mosquitoes i.e. KT₅₀ values, referring to knock down time of 50% of the test insects quantity. Lower the time in minutes required for KT50, higher the effectiveness of the insecticide. Results can vary based on study conditions, mosquito species, and protocols.

Particularly the bio-efficacy lab study of instant active ingredient is performed in Peet Grady chamber on 'Aedes aeg pti ' mosquitoes. Transfluthrin 0.88% liquid formulation is widely available in the market. In accordance with the efficacy study, KT50 of 12 minutes requires concentration of 0.88% of Transfluthrin liquid. However KT50 of 12 minutes is achieved at 0.6% Renofluthrin liquid. At around 30% lower dosage, Renofluthrin gives same effect as that of Transfluthrin liquid formulation already available in market.

The insecticidal compound mentioned in Patent 8431/DELNP/2011 requires seperation of single isomers, making the process more difficult and expensive compared to manufacture process of Renofluthrin.

The Comparison of bio efficacy study between 'Renofluthrin' and the compound mentioned in 8431/DELNP/2011 referred as 'Meperfluthrin' was conducted, wherein liquid formulation 0.5% Renofluthrin and liquid formulation 0.5% Meperfluthrin was compared for efficacy study in Peet Grady chamber on 'Culex quinquefasciatus' species mosquitoes. Renofluthrin 0.5% liquid showed KT50 around 22.50 minutes compared to Meperfluthrin 0.5% liquid KT50 around 24 minutes against 'Culex quinquefasciatus' in this study.

Renofluthrin 0.5% liquid showed around 5% better KT50 values than Meperfluthrin 0.5% liquid. Additionally the instant formulations of Renofluthrin are cost-effective as Renofluthrin has simpler process devoid of cumbersome isolation of trans isomer, unlike the compound mentioned in 8431/DELNP/201 1 which requires seperation of single isomers. Renofluthrin insecticide according to the invention effectively controls mosquitoes particularly, effective against 'Culex quinquefasciatus ' as well as 'Aedes aegypti '. This helps to reduce the incidence of diseases such as malaria, dengue fever, chikungunya and yellow fever and other diseases transmitted through mosquitoes. Also, Renofluthrin is simpler to produce as compared to Transfluthrin, Meperfluthrin and other insecticidal compounds that require specific isomer separation. Moreover, Renofluthrin requires relatively lesser dosage to achieve better effect on mosquitoes with lower KT50 values. Such features make the invention industrially viable and cost-effective.

In an insecticide / pesticide compound, toxicity and efficacy play a vital role. New insecticide compounds are based on their effect on target pests and their Toxicology profile. Two main mammalian toxicology studies considered for insecticide compounds are Acute Oral Toxicity and Acute Inhalation toxicity.

Acute Oral Toxicity is measured in 'Lethal Dose' LD50 values. LD₅₀ is a standard measurement of toxicity that is stated in milligrams (mg) of an insecticide per kilogram (kg) of body weight. Lower the LD50 value, the more toxic the insecticide. Compounds are classified in cateogories based on the LD50 values. As per "Globally Harmonized System of Classification and Labelling of Chemicals" (GHS), GHS Category 1 is the most toxic and category 5 is least toxic:

Category 5 has many criteria along with anticipated oral LD50 between 2000 and 5000 mg/kg.

Efficacy of the compound, as stated hereinabove, is measured in KT50 values i.e. Knock down time of 50% of the test population of target insects. The invention will now be illustrated with help of examples. The aforementioned embodiments and below mentioned examples are for illustrative purpose and are not meant to limit the scope of the invention. Various modifications of aforementioned embodiments and below mentioned examples are readily apparent to a person skilled in the art.

Experimental / Examples:

The invention discloses specific embodiments that details isomeric compositions of Renofluthrin having variable trans/cis ratio, and further compared the same with regard to oral toxicity and efficacy. '

3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylic acid ( Cypermethric Acid / CMA ) native form has two trans and two cis isomers. It is commonly available with isomer composition of around 60% total trans and 40% total cis isomers.

Higher the LD50 value, lower the oral toxicity of the compound. Lower oral toxicity means safer the product. Therefore, to lower the acute oral toxicity, total trans isomers in the instant isomeric mixtures were increased, concurrently cis isomers were reduced.

The isomeric composition of Renofluthrin comprising minimum 98% total trans isomers is preferable, which gives higher efficacy and lower actute oral toxicity.

Organization for Economic Co-operation and Development (OECD) Guidelines are internationally agreed test methods used by government, industry and independent laboratories to determine the safety of chemicals and chemical preparations, including pesticides and industrial chemicals. Acute Oral Toxicity study in all the compounds / compositions mentioned below, was performed on 'Sprague Dawley^'' Rats. The studies were conducted on Rats, according to OECD guidelines No. 423.

The comparison of different isomeric compositions of Renofluthrin is described herein below: a) The 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride having total trans isomers in an amount of 60% and total cis isomers in an amount of 40% when reacted with 2,3,5,6-tetrafluoro- 4-(methoxymethyl)benzyl (TFMBA) gives a chemical compound (Renofluthrin) having total trans isomers in amount of 60% and cis isomers in amount of 40% which shows efficacy on Aedes ageypti mosquitoes. KT50 around 17 minutes for 0.5% concentration liquid. But this isomeric composition has high acute oral toxicity GHS category 2 , where LD50 is > 5 and < 50 mg/kg body weight. b) The 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarbonyl chloride with increased total trans isomers minimum 90%), balance being cis isomers, when reacted with TFMBA, the product (Renofluthrin) gives better efficacy on Aedes ageypti mosquitoes. KT50 around 13 to 14 minutes for 0.5% concentration liquid. Also, this composition has lower acute oral toxicity GHS category 3, where LD50 is >50 < 300 mg/kg body weight.

Increasing total trans isomers and reducing cis isomers reduced the oral toxicity, while maintaining efficacy on mosquitoes. c) The 3-(2,2-dichlorovinyl)-2 2- dimethyl cyclopropanecarbonyl chloride with total trans isomers further increased to minimum 98%, rest of cis isomers i.e. maximum 2% , when reacted with TFMBA, the product, Renofluthrin gives impressive efficacy on Aedes aegypti mosquitoes. KT50 around 12 to 13 minutes for 0.5% concentration liquid. Acute oral toxicity was in GHS category 3, where LD50 is >50 < 300 mg/kg body weight. Within this category LD50 showed lower toxicity.

In view of above examples, studies, experiments and analysis it proved that higher total trans content gives better efficacy with reduction in the toxicity of the product. Hence Renofluthrin total trans isomers ranging from 90 to 99.9% is required, rest being cis isomers. Renofluthrin with minimum 98% total trans and maximum 2% total cis isomers are preferable.

Toxicity study of compound mentioned in patent 8431/DELNP/2011 referred as Meperfluthrin was conducted on Rats, as per the same OECD guideline. Acute oral toxicity was in GHS category 3, wherein LD50 is >50 < 300 mg/kg body weight. This compound known as Meperfluthrin requires isolation / seperation of specific isomer i.e. (1R,3S) trans isomer.

On the contrary, Renofluthrin of the present invention avoids the need for specific isomer isolation, yet possess Oral toxicity in GHS category 3, wherein LD50 is >50 < 300 mg/kg body weight.

Acute Inhalation Toxicity:

In mosquito repellent and flying insect repellent products, Inhalation toxicity is very important. Most flying insect repellent products are based on evaporation and vapours of the active ingredient. Household insecticide product forms like coils, mats, aerosol sprays, liquid evaporators, other forms of burning and vapourising formulations are based on evaporation of the active ingredient. Concentration in air of the insecticide and its evaporation are the most important aspects in flying insect repellent product.

Inhalation toxicity is measured in 'Lethal concentration' LC50 values. LC₅₀ (lethal concentration) is expressed as weight of test substance per standard volume of air (i.e. mg / L). Higher the mg/L value of LC50, lower the inhalation toxicity and safer the product.

Known insecticide compounds have the following reported LC50 values:

• Insecticide 'Prallethrin' LC50 is 0.658 mg/L ( reported in literature in unit of measurement 658 mg/m³ which in mg/L is 0.658)

• Insecticide 'Transfluthrin' LC50 is 0.513 mg/L ( reported in literature in unit of measurement 513 mg/m³ which in mg/L is 0.513)

• Insecticide 'Metofluthrin' LC50 is reported as > 1.08 and < 1.96 mg/L

These results are published and reported for the respective insecticides.

Acute Inhalation Toxicity Study of Renofluthrin was performed in Rats as per OECD guideline No. 403. In Globally Harmonized System of Classifications and Labelling of Chemicals (GHS), for Dust & mists (mg/1), the insecticide 'Renofluthrin' of the present invention falls in category 4 which is > 1.0 and < 5 mg/L.

The insecticide 'Renofluthrin' of the present invention has LC50 greater than 3.81 mg/L. which shows that Renofluthrin has the lowest Inhalation toxicity among all the compounds commonly used as active ingredient in household insecticide products.

Examples :

Example 1: Preparation of Renofluthrin (minimum 90% trans isomers and maximum 10% cis isomers)

a) CMA 40% cis and 60% trans isomers, to HTCMA maximum 10% cis and minimum 90% trans isomers:

In glass RBF, charged minimum 3200 ml solvent like Toluene or Xylene with stirring. 1600 gms CMA having 40% cis and 60% trans isomer was charged into the RBF and stirred for 1-2 hours, then charged 377 to 393 gms acetic anhydride and 9 to 12 gms Sulfonic acid into the RBF and stirred for 30 to 45 mins. The reaction mass was heated to temperature above 140 degrees C. Stirred the mass for more than 12 hours followed by filtration of reaction mass and removal of solvent by distillation. The reaction mass was then cooled to room temperature to yield HTCMA in an amount of 1150 gms, having maximum 10% cis isomers and minimum 90% trans isomers. b) HTCMA to HTCMAC havinn maximum 10% cis isomers and minimum 90% trans isomers :

HTCMA 1150 gms was charged in new glass RBF Thionyl chloride (TC) 720 gms dropping was started under heating and stirring. After completion of TC dropping, maintained the temperature between 42 to 50 degrees C for minimum 45 minutes The HTCMA conversion was checked by known technique and then vacuum was applied to remove TC which gave HTCMAC in an amount of 1235 gms having maximum 10% cis isomers and minimum 90% trans isomers.

The purity of the isomers was evaluated by using known techniques such as HPLC, TLC, and GC. c) Synthesis of RENOFLUTHRIN, having maximum 10% cis isomers and minimum 90% trans isomers:

4400 to 4500 ml solvent like Xylene or Toluene along with minimum 935 gms of 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl alcohol and 4-dimethylaminopyridine 5.60 to 7.25 grams were charged in glass reactor at room temperature. The temperature was maintained between 10 to 15 degrees C and 274 to 281 gms sodium hydroxide along with water was added dropwise to reaction mass followed by drop wise addition of 1230 gms of HTCMAC (having maximum 10% cis isomers and minimum 90% trans isomers). After completion of reaction 1300 ml of Toluene and more than 3000 ml water was charged for washing mass. Further the reaction mass was washed with 35 to 40 gms HCL and water. Further the mass was washed with water to get neutral pH. Distilled out solvent to obtain Renofluthrin with output around 1645 gms, having maximum 10% cis isomers and minimum 90% trans isomers.

Example 2: Preparation of Renofluthrin ( minimum 98% trans isomers and maximum 2% cis isomers)

a) CM A 40% cis and 60% trans isomers, to HTCMA maximum 2% cis isomers and minimum 98% trans isomers:

1400 gms CMA having 40% cis and 60% trans isomer, was treated like in example 1 above , to give HTCMA maximum 10% cis and minimum 90% trans isomers. Further treatment was done on this mass before removal of solvent. The reaction mass was cooled to around 40 degrees C, then sodium hydroxide flakes in an amount of 339 to 352 gms was added to the RBF and stirred for minimum 30 mins. The reaction mass was then filtered and removed the solvent by distillation. The reaction mass was cooled to 5 degree C or lesser. The mass was filtered, along with chilled water circulation, to get High Trans CMA (HTCMA) with around 980 grams having minimum 98% trans isomers and maximum 2% cis isomers. b HTCMA to HTCMAC having maximum 2% cis isomers and minimum 98% trans isomers : 980 gms of HTCMA having maximum 2% cis isomers and minimum 98% trans isomers, was treated like in example 1 above, to give output HTCMAC 1055 gms having maximum 2% cis isomers and minimum 98% trans isomers. c Synthesis of RENOFLUTHRIN, having maximum 2% cis isomers and minimum 98% trans isomers :

Treatment and process were same as in example 1 above. Around 4000 ml solvent, 800 gms of 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl alcohol and 4-dimethylamino pyridine 4.84 to 6.14 grams were charged in glass reactor at room temperature. The temperature was maintained between 10 to 15 degrees C and dropwise addition of 235 to 241 gms sodium hydroxide along with water was added to reaction mass followed by dropwise addition of 1052 gms HTCMAC having maximum 2% cis isomers and minimum 98% trans isomers to obtain Renofluthrin with an output around 1410 gms,. having maximum 2% cis isomers and minimum 98% trans isomers.

Analysis :

Analysis of isomers of HTCMAC (High trans Cypermethric Acid Chloride) of Example 1 and 2 above, was performed by GC. Sample 1 ml of HTCMAC mixed with alcohol like ethyl alcohol 3 ml, and lgm Potassium carbonate. GC capillary column (30mt. length), Detector temperature: 320 Deg C, Air (300 ml/min.), Carrier Helium, Injection Volume : 0.5μ1.

Results at retention time between 16 to 17 minutes :

Characterization of Renofluthrin by HPLC :

The purity of synthesized Renofluthrin was evaluated by using HPLC technique.

HPLC, Column C 18, 250 mm length,

Mobile phase Acetonitrile 75: Water 25,

Detector: UV 210 nm,

Flow rate: 1.4 ml/min, Injection Volume: 20μ1,

Mixture of mobile phase and Renofluthrin sample,

Identification of Renofluthrin, purity area percentage 93% minimum, at retention time between 13 to 14 minutes.

Industrial Advantages of the invention:

The cumbersome and expensive methods to separate out single isomers to make insecticide compounds as mentioned in prior art is avoided in the instant invention and therefore the instant process is cost-effective and simple.

Further 0.5% Renofluthrin liquid showed better efficacy than 0.5% Meperfluthrin liquid against mosquito species 'Culex quinquefasciatus ' , with similar oral toxicity GHS category 3.

The use of Renofluthrin comprising total trans isomers in the range of 90% to 99.90% rest being cis isomers, obviates the separation of isomers and thus makes the product cost effective.

Renofluthrin 0.6% liquid formulation is more effective and shows better KT50 values as compared to Transfluthrin 0.88% liquid, against mosquito species ^Aedes aegypti '. Compared to Transfluthrin, Renofluthrin gives efficacy at much lower concentration.

From the above, it is evident that Renofluthrin possesses enhanced bio-efficacy with good KT50 value against mosquitoes such as Aedes aegypti, Culex quinquefasciatus at lower concentration.

Also, Renofluthrin has the lowest Inhalation toxicity compared to the known, and marked insecticide compounds and therefore safer for domestic use.

Simple composition without isolation of single isomers, combined with high efficacy at lower concentrations, and low mammalian inhalation toxicity, make the invention innovative and advantageous.

Claims

We Claim:

1. An insecticidal isomeric composition of 2,3,5,6-tetrafluoro-4- (methoxymethyl)benzyl3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate i.e. Renofluthrin, wherein total trans isomers ranging from 90% to 99.90% and total cis isomers ranging from 0.1% to 10% , having structure :

2. The insecticidal isomeric composition according to claim 1, wherein the isomers are selected from the group consisting of;

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lR,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate;

2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (lS,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate.

3. The insecticidal isomeric composition according to claim 1, wherein 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl (lR,3S)-3 -(2,2-dichlorovinyl)-2,2- dimethyl cyclopropane carboxylate; and 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1S,3R)- 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate are present in range of 90% to 99.90%,

4. The insecticidal isomeric composition according to claim 1, wherein 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl (lR,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropane carboxylate; and 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1S,3S)- 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate are present in range of 0.1% to 10%,

5. The insecticidal isomeric composition according to claim 1, wherein 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl (lR,3S)-3 -(2,2-dichlorovinyl)-2,2- dimethyl cyclopropane carboxylate; and 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1S,3R)- 3-(2,2-dichlorovmyl)-2,2- dimethyl cyclopropanecarboxylate are present, preferably in amount of minimum 98%,

6. The insecticidal isomeric composition according to claim 1, wherein 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl (lR,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropane carboxylate; and 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1S,3S)- 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate are present, preferably in amount of maximum 2%,

7. The insecticidal isomeric composition according to claim 1, wherein 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl (lR,3S)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropane carboxylate; and 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1S,3R)- 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate are present, preferably in amount of 99.90%,

8. The insecticidal isomeric composition according to claim 1, wherein 2,3,5,6- tetrafluoro-4-(methoxymethyl)benzyl (lR,3R)-3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropane carboxylate; and 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1S,3S)- 3-(2,2-dichlorovinyl)-2,2- dimethyl cyclopropanecarboxylate are present, preferably in amount of 0.1%,

9. The insecticidal isomeric composition according to claim 1, wherein the acute inhalation toxicity LC50 is greater than 3.81 mg/L.