GB2058570A - Pesticidal compositions - Google Patents

Abstract

A liquid pesticidal composition contains amitraz and a carbodiimide. Preferred carbodiimides are di-(2,6-di - isopropylphenyl) carbodiimide and dicyclohexyl carbodiimide. The carbodiimide acts as a stabiliser for the composition to prevent degradation of the amitraz. The composition shows insecticidal and acaricidal properties.

Description

SPECIFICATION Pesticidal compositions This invention relates to pesticidal compositions and in particularto compositions containing the pes ticidal compound, amitraz.

X Amitraz has the chemical formula 1,5-di-(2,4- dimethylphenyl)-3-methyl 1,3,5-triazapenta-l ,4- diene and has a wide range of insecticidal and acaricidal properties as described in British Patent Specifi cation 1,327,935.

The present invention provides a liquid pesticidal composition comprising a solution of amitraz and a carbodiimide of the formula R-N =C =NR' where R and R' may be the same or different and may be aliphatic, cyclic aliphatic, aromatic or substi tuted aromatic groups.

The composition may contain from 0.5 to 35% of amitraz and conveniently contains from 5 to 25% of amitraz. All percentage compositions given in this specification are expressed as weight/volume per centages that is the weight of material in grams per 100 millilitres of solution.

The carbodiimide acts as a stabilizer for the com positions of the present invention and may be pres ent in an amount from 0.5 to 5%. The preferred car bodiimides are dicyclohexyl carbodiimide and di (2,6diisopropylphenyl) carbodiimide.

One form of composition containing amitraz which is supplied for use on both plants and animals is an emulsifiable concentrate which is mixed with water to form an emulsion which may be used as a pesticidal spray, dip or "pour-on" preparation for animals or a pesticidal spray for crops. An emulsifi able concentrate comprises a solution of the active ingredient along with one or more emulsifying agents in a suitable solvent e.g. a water-immiscible solvent.

The emulsifying agents employed in an emulsifi able concentrate composition may be any of those commonly used in the art and are preferably nonionic surfactants, anionic surfactants or a blend of nonionic and anionic surfactants. The amount of emulsifier present may be up to 30 /O of the total composition.

Nonionic compounds include for example, ethoxyslated alkylphenols such as nonylphenol ethoxylates; ethoxylated aliphatic alcohols; ethoxylated amines; ethoxylated esters; ethoxylated alkylolamides; block polymers/copolymers of ethylene oxide and prop ylene oxide; or alkylolamides. One material which has been found to be particularly advantageous is an ethoxylated nonylphenol with an ethoxy content of 9.5 motes per mole.

Anionic compounds include for example, sulpho nates such as alkylaryl sulphonates or petroleum sulphonates; sulphates such as alcohol sulphates or ether sulphates; phosphate esters; or sulphosucci nates.

The components of an emulsifiable concentrate are dissolved in a water-immiscible solvent. Suitable solvents include for example, aromatic hydrocar bons such as alkylbenzenes incorporating the various trimethylbenzenes, methylethylbenzenes, dimethylethylbenzenes, diethylbenzenes, tetramethylbenzenes, trimethylethyl benzenes, methyldiethyl benzenes, pentamethylbenzenes, naphthalene and various methylnaphthalenes and mixtures thereof; chlorinated hydrocarbons such as chlorinated alkanes, chlorinated alkenes and chlorinated benzene and chlorinated alkylbenzenes; ketonic solvents such as cyclohexanone, isophorone, N-methyl-pyrrolidone, diisobutylketone and methylisobutylketone.

In addition to emulsifiable concentrates other liquid compositions containing amitraz may be stabilized by the inclusion of carbodiimides. For example, a ULV (ultra-low volume) formulation comprising a solution of amitraz and the carbodiimide in a suitable solvent may be prepared for direct spraying without dilution or a pour-on formulation may be prepared for the direct application to animals by dissolving amitraz and the carbodiimide in an oil medium which may optionally contain a co-solvent.

Other components which may be included in the emulsifiable concentrates ofthe present invention include additional pesticides.

The invention will be illustrated by the following examples of pesticidal compositions which are given by way of example only.

Example 1 An emulsifiable concentrate was prepared by dissolving amitraz (5009), di-(2,6-di-isopropylphenyl)- carbodiimide sold under the trade name Stabaxol 1 by Bayer (1209) and a nonylphenol ethoxylate having an ethoxy content of 9.5 mole per mole sold under the trade name Ethylan KEO by Diamond Shamrock Europe Ltd. (800g) in a solvent comprising naphthalene and substituted naphthalenes sold under the trade name Esso 200. The solution was made up to 4 litres, filtered and dried using molecular sieve.

The solution was split into two parts for stability testing. The first part was stored at a constant temperature of 50"C. The second part was loaded with 0.2% w/v of water and stored in the same manner as that of the first part. After six months portions were removed from each of the samples and the amitraz concentration in the portions was determined by gas-liquid chromatography (glc). Within the limits of experimental error no loss of amitraz was observed.

By way of comparison samples of a similar composition but containing no carbodiimide were stored alongside the above samples and were subjected to the same analytical procedures. The samples of concentrate with no added water showed that after 3 months there had been a 3% loss of amitraz and after 6 months a 9% loss of amitraz. In the samples with 0.2% added water the loss of amitraz was 10% after 3 months and 25% after 6 months.

From these results it can be seen that at 50"C there was a significant loss of amitraz after six months storage in concentrates containing no carbodiimide.

Example 2 The experiment described in Example 1 was repeated with compositions containing 1 and 2% of di (2,6-di-isopropylphenyl)-carbodiimide (Stabaxol 1) respectively. The compositions showed no loss of amitraz after 6 months storage at 50"C.

Example 3 An emulsifiable concentrate containing amitraz (200 g which is nominally 5.0 /O w/v) di-(2,6-diisopropylphenyl)-carbodiimide (120 g) and a nonylphenolethoxylate having an ethoxy content of 9.5 mole per mole (Ethylon KEO 800 g) was made up by dissolving the components in an aromatic solvent sold underthetrade name Naphtha 21199 by Carless Chemicals Ltd., and making the solution up to 4 litres with the solvent. The solvent is a 99% aromatic solvent prepared by distilling a heavy naphtha Cg feed stock in the range 1600C to 250"C. The solution was filtered and dried and subjected to stability testing in similar way to that described above for Example 1.

After one years storage at a constant temperature of 50"C samples containing carbodiimide showed no loss of amitraz within the limits of experimental error whereas similar compositions with no carbodiimide present showed a loss of amitraz of 26% when no water had been added and 64% when 0.2% w/v of water had been added.

From the results given above it can be seen that the presence of the carbodiimide effectively stabilizes the emulsifiable concentrate against the breakdown of amitraz which occurs in the concentrate with no carbodiimide present.

Example 4 An emulsifiable concentrate was prepared by dissolving amitraz (nominally 20%), dicyclohexylcar bodiimide (3%), and a blend of calcium dodecylbenzene sulphonate and a nonylphenol ethoxylate hav ing an ethoxy content of 14 mole per mole (10%) (sold underthe trade name Agrilan B.M. by Diamond Shamrock Europe Ltd.) in xylene. The solutions were tested as described in Example 1 and afterthree months storage at 50"C showed no loss of amitraz.

Claims (7)

1. A liquid pesticidal composition comprising a solution of amitraz and a carbodiimide of the formula R-N = C = NR' where R and R' may be the same or different and may be aliphatic, cyclic aliphatic, aromatic or substituted aromatic groups.

2. A pesticidal composition as claimed in claim 1 wherein the composition comprises 0.5 to 35% w/v of amitraz.

3. A pesticidal composition as claimed in claim 2 wherein the composition comprises 5 to 25% w/v of amitraz.

4. A pesticidal composition as claimed in any one of the preceding claims wherein the composition comprises 0.5 to 5% carbodiimide.

5. A pesticidal composition as claimed in any one ofthe preceding claims wherein the carbodiimide is dicyclohexylcarbodiimide or di-(2,6-di- isopropylphenyl) carbodiimide.

6. A pesticidal composition as claimed in any one of the preceding claims wherein the composition is in the form of an emulsifiable concentrate.

7. A pesticidal composition substantially as hereinbefore described with reference to Example 1 or Example 2.