CA1094952A - Stabilized insecticide formulation - Google Patents

Abstract

ABSTRACT
Insecticide formulations containing an organo-phosphorous insecticide on clay carriers are stabilized by incorporating a lactone in said formulation, preferably in an amount of from 0.5 to 10 weight percent.

Description

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STABILIZED INSECTICIDE FORMULATIONS

This invention concerns stabilized insecticide formulations.

To permit effective application of many pesticides by airborne or ground spreading equipment, the active pesti-cide is impregnated on a solid carrier material which may be diluted to field strength prior to application. The physical properties of the solid formula~ion, such as ease of fiow and retention on the plant, are of the essence. ~lays are frequently preferred as the carrier material because of the desirable physical properties o~ solid pesticide formulations which are based on clay carriers. Some of the clay mat~rials that have been found to be especially suitable as carriers for organic pesticides are the attapulgite and montmorillonite clays. The calcined clays have been consider,ed to possess excellent physical properties as carrier material for organic compounds. Although the above clays possess excellent flow properties after impregnation with organic pesticides and are readily amenable to impregnation with organic pesticides, the calcined clays unfortunately tend to cause certain types of pesticides, such as thiophosphate ester toxicants, to decompose chemically and to lose their potency when the solid composi-tions are stored for long periods in temperate climates or for shorter periods in the tropics. Improvements in stabi-lizing the clay formuLations are continuously being sought.

18,466B-F
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The present invention provides a stabilized insecticidal composition comprising an organophosphorous insecticide, a granular solid clay carrier, which carrier, during storage, causes deterioration of said organophos-phorous insecticide mixed therewith, and from 0.5 to 10percent by weight of the ultimate formulation of a lactone.

One object of this invention is to increase the active life of insecticides and to provide a means for more effective insect control. A further object is to provide for prolonged activity of the insecticide during storage and to enable a more uniform reproducible control of insects.

For several years it has increasingly become the practice to put active insecticides onto solid carriers, especially those which are in granulated form. Because of the use of solid carriers, instead of liquid carxiers, it is possible to save work, such as preparation immedi~tely be~ore use, and in some cases additional mixing of spraying liquids as well as the undesirable transportation of large quantities of water. In addition, less expensive carriers are normally employed for solid formulations.

Typically, a granular formulation may contain from about 2 percent to about 40 percent of the active insecticide by weight. This type of formulation is generally used as such without further dilution.

The insecticidal ingredients which are stabilized by the present invention are the phosphorus containing insecticides.

18,466B-F

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~OC~9~2 -2a-Phosphorus compounds usable with the present invention include compounds selected from the class of halopyridyl phosphates set forth in U.S. Patent 3,244,586 which are of the formula 18,466B-F

, :' -~ " ' ~, . '. ' ~0~9~Z

R-O-P-(R') wherein R represents halopyridyl, z represents oxygen or sulfur and each R' represents loweralkoxy of 1 to 8 carbon atoms, amino or loweralkylamino of 1 to 8 carbon atoms. ..

Additionally, phosphoramidates set forth in U.S.
Patent 2,929,762 which are of the formula Cl ,~ O <R

wherein Y represents alkyl of 1 to 5 carbon atoms, R repre-sents alkyl of 1 to 4 carbon atoms and R' represents amino or alkylamino of 1 to 4 carbon atoms.

Also included are compounds taught in U.S. Patent

2,599,516 which are of the formula ~ Cl Cl ~ OP-(OR)2 wherein R is methyl or ethyl.

Additional examples of phosphorus compounds which can be stabilized according to the present invention are O,O-diethyl -S-(ethylthio)ethylphosphorodithioate, O,O-diethyl O(and S)-2-(ethylthio)ethyl phosphorothioates, O,O-diethyl S-(ethylmercaptomethyl) dithiophosphate, S-(1,2-dicarboethoxy-ethyl) O,O-dimethyl dithiophosphate, O,O-dimethyl S-2(ethyl-18,466B-F

10~9';2 sulfinyl)ethyl phosphorothioate, O,0-dimethyl S-2-(ethyl-thio)ethyl phosphorothioate, O,O-dimethyl S-2-(ethylsulfinyl)-isopropyl phosphorothioate, 0,O-dimethyl S-2-(ethylsulfinyl)-ethyl phosphorodithioate, O,O-dimethyl 0-(4-methylthio-m--tolyl phosphorothioate, O,O-dimethyl S-2-(ethylthio)ethyl phosphorothioate, O,O-diethyl O-(p-nitrophenyl) phosphoro-thioate, O,O-dimethyl 0-(p-nitrophenyl) phosphorothioate, S-tertiary-butylmercaptomethyl O,O-diethyl dithiophosphate, S-secondary-amylmercaptomethyl O,O-diethyl dithiophosphate, S-n-butoxymethyl 0,0-bis(2-chloroethyl) dithiophosphate, S--tertiary-butylmercaptomethyl O,O-bis(2-chloroethyl) dithio-phosphate, S-(l,l-dimethylethylthiomethyl) O,O-diethyl phos-phorodithioate, 0-~4-bromo-2,5-dichlorophenyl) O,O-dimethyl phosphorothioate, O,O-diethyl 0-(2,4-dichloro-5-methylthio-phenyl) thionophosphate and other such phosphorus compounds.

The carriers or diluents generally used withihese insecticides, when mixed therewith, are solids o the class consisting of kaolin clays such as Kaolinite, dickite, nacrite, anauxite, halloysite, endellite or barden clay;
montmorillonite clays such as beidellite, nontromite, montmorillonite, hectorite, saponite, savconite or bentonite;
attapulgites such as fuller's earth, attapulgite or sepiolite;
diatomaceous earths such as diatomite or kieselguhr; vermicu-lite such as biotite;.synthetic silicates; and talc.
.

While the solid carriers above discussed are veryuseful in formulating the herein defined insecticides -` for reasons of their inexpensiveness, availability, ease of handling, absorbency characteristics, durability, and other desirable physical properties, they have the disadvantageous property, to varying degrees, of degrading or decomposing the insecticide when intimately mixed therewith.- This degradation process is significant and troublesome, since dry formulations are often prepared as concentrates or even field 18,466B-F

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strength materials and then stored for periods which may be as long as a year or more. Duxing storage, the effect of the carrier or diluent on the insecticide ingredient may reduce its effectiveness to the point where satisfactory insect control under field conditions is no longer obtainable.

The nature of the reaction or effect of the carriers on the insecticide has never been fully elucidated.
The rate of deterioration may vary by the action of different carriers or diluents.

To solve the present problem, it has been found necessary to neutralize the activity of the solid carriers and diluents so that they are inert to the insecticide and will allow protracted storage of dry insecticide formulations without deterioratio~ of insecticidal activity of such formu-lation.

Since the formulations herein concerned are used preponderantly in agriculture, any treatment of the ca'rriers and diluents used must necessarily not render the formulation unfit for agricultural use on food and fora~e crops at time of harvest. Thus, the treatment must not render the ~ormulation phytotoxic. The treatment must likewise not be hazardous from a warm-blooded animal toxicity standpoint, or otherwise increase the hazard in the utilization of insecti-cide formulations. Also, of primary importance, and con-sidering the economics involved, the ~reatment must not - involve expensive materials, nor can the process of treatment be complex. Another consideration in the present problem is that the treatment must not affect the insecticidal activity of the toxicant employed.
.
It has now been found that the solid carriers and diluents which were previously described and which are 18,466B-F
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~09~9S2 active in deteriorating the classes of insecticides herein concerned can be made substantially inert by the addition of from 0.5 to 10 percent by weight based on the weight of the carrier and toxicant contained in the formulation of a lactone. A preferred concentration of the lactone to dry insecticide formulation is 2 percent to 4 percent by weight of the ultimate formulation.

Lactones useful in preventing or reducing deterioration include, for example, butyrolactone, 2-acetyl-r-butyrolactone, Y-valerolactone, ~-valero-lactone, Y-octanoiclactone and ~-caprolactone~ These lactones are all well known and can be obtained commer-cially.

The art of blending materials with solid carriers and diluents of the class described is well known, and the liquid lactone additives employed in the present invention can be blended with these solid materials by any known means. For example, the use of commercial type mixers or blenders is adequate. The lactone can be added to and blended with the solid carriers either alone or in combina-tion with an inert, relatively volatile solvent which can be removed after blending. The lactone can be added to and blended with the solid carriers prior to blending the insect toxicant therewith.

In the alternative, the lactone can be added to the solid carriers during the same blending operation wherein mixing of the insecticide and carrier is achieved.

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, ~0"1~9~;2 It is preferred to dissolve the insecticide in the lactone and to blend this mixture with the solid carrier. By employing this preferred blending technique, a saving is achieved in that only one blending step is needed.

~ In addition, it has been found that the use of lactones as stabilizers overcomes the caking problem associated with many stabilizers in that product does not cake but is rather a free flowing material and allows for a more marketable product.

The following examples serve to illustrate the practice of the present invention but are not intended to be limitations upon the overall scope of the same.
Example I
Formulations containing about 15 percent chlorpyrifos [O,O-diethyl O-t3,5,6-trichloro-2-pyridyl) phosphorothioate]
and from 0 to 4 percent by weight of the ultimate composition of butyrolactone and one of the hereinafter set forth clays were prepared and held under accelerated storate conditions at a temperature of 125F (52C) for up to 70 d~ys. At 0 day, 14 days (equal to 1 year of storage at room temperature), 30 days (equal to 2 years of storage at room temperature) and 70 days (equal to 3 ye,ars of storage at room temperature) after storage, the formulations were analyzed to determine the percentage of the active phosphate compound remaining and the percent pyridinol present (a decomposition product formed during storage). The results of these analyses are set forth below in Table I.

18,466B-F

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110~9S2 Example II
Formulations containing about 15 percent chlor-pyrifos [O,O-diethyl 0-(3,5,6-trichloro-2-pyridyl) phosphoro-thioate] and from O to 4 percent by weight of the ultimate composition of butyrolactone and montmorillonite clay were prepared and held under accelerated storage conditions at a te~perature of 125F (52C) for up to 70 days. At O day, 14 days (equal to 1 year of storage at room temperature), 30 days (equal to 2 years of storage at room temperature) and 70 days (equal to 3 years of storage at room temperature) after storage, the formulations were analyzed to determine the percentage of the active phosphate compound remaining and the percent pyridinol. present (a decomposition product formed during storage). The results of these analyses are set forth below in Table II.

18,466B-F

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1~9~9~2 Example III
Formulations containing about 15 percent chlor-pyrifos-methyl [O,O-dimethyl 0-(3,5,6-trichloro-2-pyridyl) phosphorothioate] and from O to 4 percent by weight of the ultimate composition of butyrolactone and montmorillonite clay were prepared and held under accelerated storage con-ditions at a temperature of 125F (52C) for up to 30 days.
At O day, 14 days (equal to 1 year of storage at room temper-ature) and 30 days (equal to 2 years of storage at room temperature) after storage, the formulations were analyzed to determine the percentage of the active phosphate compound remaining and the percent pyridinol present (a decomposition product formed during storage). The results of these analyses are set forth below in Table III.

18,466B-F

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~09 1.~S2 Example IV
Formulations containing about 15 percent ronnel [0,0-dimethyl 0-(2,4,5-trichlorophenyl) phosphorothioate]
and from 0 to 4 percent by weight of the ultimate composition of butyrolactone and montmorillonite clay were prepared and held under accelerated storage conditions at a temprature of 125F (52C) for up to 30 days. At 0 day, 14 days (equal to 1 year of storage at room temperature) and 30 days (equal to 2 years of storage at room temperature) after storage, the formulations were analyzed to determine the percentage of the active phosphate compound remaining. The results of these analyses are set forth below in Table IV.

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18, 466B-F

10~ 19.~2 Example V
Formulations containing ~14.2 percent ronnel [0,0-dimethyl 0-(2,4,5-trichlorophenyl) phosphorothioate]
and 0 and 4 percent by weight of one of the hereinafter set forth lactones and montmorillonite clay were prepared and held under accelerated storage conditions at a temperature of 122F (50~C) for up to 60 days. At 0 days, 14 days (equal to ~1 year of storage at room temperature), 30 days (equal to 2 years of storage at room tem~erature) and 60 days (equal to ~3 years of storage at room temperature) after storage, the formulations were analyzed to determine the percentage of the active phosphate compound remaining. The results of these analyses are set forth below in.Table V.

18,466B-F

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Claims (10)

1. A stabilized insecticidal composition com-prising an organophosphorous insecticide, a granular solid clay carrier, which carrier, during storage, causes deterioration of said organophosphorous insecticide mixed therewith, and from 0.5 to 10 percent by weight of the ultimate formulation of a lactone.

2. A stabilized insecticidal composition as defined in Claim 1 wherein the solid clay carrier is a montmorillonite clay or an attapulgitic clay.

3. A stabilized insecticidal composition as defined in Claim 1 wherein the lactone stabilizer is pres-ent in an amount of from 2 to 4 percent by weight of the ultimate formulation.

4. A stabilized insecticidal composition as defined in Claim 3 wherein the organophosphorous insecti-cide is 0,0-diethyl 0-(3,5,6-trichloro-2-pyridinyl) phosphorothioate, 0,0-dimethyl 0-(3,5,6-trichloro-2--pyridinyl) phosphorothioate or 0,0-dimethyl 0-(2,4,5--trichlorophenyl) phosphorothioate.

5. A stabilized insecticidal composition as defined in Claim 4 wherein the lactone stabilizer is butyrolactone.

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6. A stabilized insecticidal composition as defined in Claim 4 wherein the lactone stabilizer is .delta.-valerolactone.

7. A stabilized insecticidal composition as defined in Claim 4 wherein the lactone stabilizer is .gamma.-valerolactone.

8. A stabilized insecticidal composition as defined in Claim 4 wherein the lactone stabilizer is .gamma.-octanoiclactone.

9. A stabilized insecticidal composition as defined in Claim 4 wherein the lactone stabilizer is .epsilon.-caprolactone.

10. A stabilized insecticide composition as defined in Claim 4 wherein the lactone stabilizer is 2-acetyl-.gamma.-butyrolactone.

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