HRP921364A2 - Stabilized pesticidal composition - Google Patents

Description

The invention relates to stabilized pesticide preparations and, more specifically, to stabilized pesticide preparations containing dimethoate.

Dimethoate. o.o-dimethyl-S-methylcarbamoylmethyl-phosphorodithioate is a well-known and widely known systemic and contact insecticide. It is described together with procedures for its preparation, for example. in UK Patent No. 791,824 and US Patent Nos. 2,996,531. The problem with dimethoate is that it is thermally unstable and at temperatures of 50°C or more, it can undergo uncontrolled thermal decomposition, leading to explosions. This is clearly a major potential disadvantage in hot climates, particularly in developing countries where storage facilities do not allow products to be protected from the sun's rays, and where there is a tendency for products to be transported in open trucks and temporarily stored outdoors. space.

Under such conditions, unprotected storage, or storage for very long periods of time, can easily lead to products that are unstable and cause problems during disposal, and in some cases fires can occur due to self-ignition of stored products.

It has now been unexpectedly found that when dimethoate is stored in a mixture with an oil containing some cyclopropene fatty acid, a significant reduction in thermal degradation is observed.

Therefore, the present invention provides a pesticide preparation comprising, as an active ingredient, dimethoate together with at least one inert carrier for it, which is characterized in that the preparation contains, as a stabilizer, some cyclopropane fatty acid or oil containing at least 1% by weight some cyclopropane fatty acids.

Typical examples of cyclopropane fatty acids are malvalic acid (2-octyl-1-cyclopropene-1-heptanoic acid) (otherwise also known as malvinic acid or halfenic acid) and sterculic acid (2-octyl-1-cyclopropene-1-octanoic acid) ) (also known as sterculinic acid). Oils containing these acids can be extracted from the seeds of the kapok tree (Cieba petandra) (namely kapok seed oil) and from Sterculia species, especially Sterculia foetida. These acids are also found in other plants, eg durian (Durio zibethinus), gnomen (Gretum gnemon) and species of the Malvacea family.

Preferably, the stabilizer in the preparation of the invention comprises malvalic or sterculinic acid or oil from the seeds of the kapok tree or from Sterculia species. The stabilizer can very conveniently be kapok seed oil.

It is preferable that the weight ratio of cyclopropene-fatty acid(s) dimethoate in the preparation from the invention is in the interval from 0.1:1 to 1.5:1, more preferably from 0.4 to 1:1, suitable from 0.5:1 to 0.7 : 1.

When the stabilizer in the preparation of the invention is kapok seed oil, the weight ratio of kapok seed oil: dimethoate is preferably in the interval from 1:1 to 10:1, more preferably from 4:1 to 6:1.

The invention also provides a process for stabilizing a pesticide with a preparation that includes, as an active ingredient, dimethoate together with at least one inert carrier for it, wherein the process includes introducing cyclopropene-fatty acid or oil containing at least 1% by weight of cyclopropene-fatty into the preparation as a stabilizer. acid.

The preferred methods of the invention use the same stabilizers and mastics as indicated above in connection with the preparations of the invention.

Pesticide preparations comprise at least one active ingredient together with at least one inert carrier for it, preferably at least two carriers, wherein at least one of them is a surface-active agent.

The carrier may be a solid or liquid material, which may be inorganic or organic or of synthetic or natural origin. Typical solid supports include natural and synthetic clays and silicates, for example, natural silicas, for example, diatomaceous earths and aluminosilicates, coalinites, montmorillonites and micas. Typical liquid carriers are ketones, for example, methylnaphthalenes, petroleum fractions, for example, petroleum xylenes and light mineral oils, and chlorinated hydrocarbons, for example, carbon tetrachloride, are often suitable liquid mixtures.

One or more surfactants can be included in the pesticide preparation. The surface active agent can be an emulsifying agent or a dispersing agent or a wetting agent; it can be non-ionic or ionic. Any of the surfactants commonly used in the formulation of insecticides can be used. Examples of suitable surfactants are sodium and calcium salts of polyacrylic acids and ligninsuironic acids: condensation products of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide fatty acid esters of glycerol, sorbitan, sucrose or pentaerythritol, condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohols or alkylphenols, for example, p-octylphenol or p-octylcresol with ethylene oxide and/or propylene oxide; sulfates or sulfonates of these condensation products of alkali and alkaline earth metal salts, preferably sodium salts, esters of sulfuric III sulfonic acids containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulfate, sodium secondary alkyl sulfates, sodium sulfonated castor oil and sodium alkyl aryl sulfonates, such as which is sodium dodecylbenzenesulfonate: and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The pesticide preparation can, for example, be formulated as a wet powder, as microcapsules, powder, as granules, as a solution, as a suspension concentrate or as an aerosol. Preparations may have properties of controlled release or may be suitable for use as bait.

Wettable powders usually contain 25, 50 or 75% by weight of the active ingredient and may contain, in addition to the inert solid material, 3-10% by weight of dispersing agents and, when necessary, 0-10% by weight of a penetrant stabilizer and/or a thickener. The powder is usually formulated as a powder concentrate that has a similar composition to that of wet powder but without dispersant, and is diluted in the field with a still solid carrier so that a preparation containing 1/2-10% is obtained. by weight of the active ingredient.

Granules typically range in size from 10 to 100 BS mesh (1,676-0,162 mm) and can be produced by agglomeration or impregnation techniques. Generally, the granules will contain from 1/2 to 25% by weight of the active ingredient and 0-10% by weight of additives, for example, stabilizers, slow release modifiers and/or binding agents.

Emulsifying concentrates usually contain, in addition to a solvent, and when necessary, a solvent. 10-50 % by weight/abbr. active ingredient. 2 to 20 wt. order emulsifier and 0-20 % wt./vol. other additives. for example some stabilizer, penetrant and/or corrosion inhibitor. The suspension concentrate is a stable, non-sedimenting, liquid product and usually contains 10-75% by weight of the active ingredient. 0.5-15% by weight of dispersing agents, 0.1-10% by weight of suspending agents, for example some protective colloid and/or thixotropic agent and 0-10% by weight of other additives including, for example, some defoamer, corrosion inhibitor, stabilizer, penetrant and/or a thickener, and, as a dispersant, water or some organic liquid in which the active ingredient is essentially insoluble; certain organic additives and/or inorganic salts may be dissolved in the dispersant to help prevent sedimentation or as a water antifreeze.

Aqueous dispersions and emulsions, which are formed by diluting a wet powder or an emulsifying concentrate, are pesticide preparations in themselves. Such emulsion preparations can be of the water-oil or oil-in-water type, and can have a thick "mayonnaise" consistency.

The pesticidal preparations may also contain other ingredients, for example, one or more other compounds having pesticidal, herbicidal or fungicidal properties or attractants, for example, pheromones or nutrients for use in bait or trap formulations.

The invention also includes a site pest control method comprising site application of a pesticidal composition according to the invention.

The invention will be further understood on the basis of the following illustrative Examples.

Example 1

The dimethoate formulation is made by mixing the components according to the following composition

I %wt./wt.

Dimethoate 11

Cyclohexanone 34

Kapok seed oil (equivalent to 6-7% wt.

cyclopropane-fatty acids)

In order to compare the storage stability of formula 1, it was monitored together with the stability of comparative formulation A, which consisted of 55.4% w/w. Dimethoate and 44.6% wt./wt. Cyclohexanone in the temperature interval with the duration of the experiment up to 36 months. The results are shown in the following Table 1.

Table I

[image]

* strong exothermic decomposition

The results, which are presented in Table I, show a significantly higher thermal stability, which is given to the formulation of dimethoate and cyclohexanone by the inclusion of an oil (kapok seed) containing cyclopropene fatty acids.

Claims (8)

1. Pesticide preparation, which includes, as an active ingredient, dimethoate together with at least one inert carrier for it, characterized by the fact that the preparation contains, as a stabilizer, cyclopropene fatty acid or oil containing at least 1% by weight of cyclopropene fatty acid. 2. The preparation according to Claim 1, characterized in that the stabilizer includes malvalic or sterculinic acid or oil from the seeds of the kapok tree or from Sterculia species. 3. Preparation according to Claim 1 or 2, characterized in that the weight ratio of cyclopropene-fatty acid(s): dimethoate is in the interval from 0.1:1 to 1.5:1. 4. The preparation according to Claim 1, 2 or 3, characterized in that it contains kapok seed oil as a stabilizer, whereby the weight ratio of kapok seed oil: dimethoate is in the interval from 1:1 to 10:1. 5. A process for stabilizing a pesticide preparation, which includes, as an active ingredient, dimethoate together with at least one inert carrier for it, indicated by the fact that it includes introducing into the preparation, as a stabilizer, cyclopropene-fatty acid or oil containing at least 1% by weight of cyclopropene -fatty acids. 6. The method according to claim 5, characterized in that the stabilizer comprises malvalic or sterculinic acid or oil from kapok tree seeds or Sterculia species. 7. The method according to claim 5 or 6, characterized in that the weight ratio of cyclopropene-fatty acid: dimethoate is in the interval from 0.1:1 to 1.5:1. 8. The method according to Claim 5, 6 or 7, indicated by the fact that it includes adding to the preparation, as a stabilizer, kapok seed oil in such an amount that the weight ratio of kapok seed oil: dimethoate is in the interval from 1:1 to 10:1.