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AU2002312741A1 - Insecticidal composition having improved storage stability - Google Patents

Insecticidal composition having improved storage stability

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Publication number
AU2002312741A1
AU2002312741A1 AU2002312741A AU2002312741A AU2002312741A1 AU 2002312741 A1 AU2002312741 A1 AU 2002312741A1 AU 2002312741 A AU2002312741 A AU 2002312741A AU 2002312741 A AU2002312741 A AU 2002312741A AU 2002312741 A1 AU2002312741 A1 AU 2002312741A1
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AU
Australia
Prior art keywords
weight
dimethoate
insecticidal composition
maleic anhydride
parts
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
AU2002312741A
Other versions
AU2002312741B2 (en
Inventor
Vita Nielsen
Anita Wengel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cheminova AS
Original Assignee
Cheminova AS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DK200100708A external-priority patent/DK174660B1/en
Application filed by Cheminova AS filed Critical Cheminova AS
Publication of AU2002312741A1 publication Critical patent/AU2002312741A1/en
Application granted granted Critical
Publication of AU2002312741B2 publication Critical patent/AU2002312741B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Description

Insecticidal composition having improved storage stability
The present invention relates to an insecticidal composition having improved storage stability and containing Dimethoate as an active compound as well as to a process for the control of insects. The insecticidal composition according to the invention is particularly useful for the control of insect pests, such as sucking and chewing insects, within areas cultivated with agricultural crops and plantation crops .
Dimethoate, chemically termed as 0,0-dimethyl S- methyl carbamoyl methyl phosphorous dithioate, is a well-known compound for the control of undesired insects. It is primarily used to control chewing and sucking insects attacking agricultural and plantation crops, and it works both systemically and by contact. When using Dimethoate, a mayor disadvantage is that the compound is thermally unstable and, at temperatures above approximately 50° C, it may decompose uncontrollably and, at worst, result in explosions. Even at lower temperatures, Dimethoate will decompose and lead to its activity dropping. Therefore, it is essential to be able to stabilize Dimethoate formulations so as to withstand even long-term storage without loss of activity, particularly in warm climatic surroundings .
On standing, Dimethoate will degrade into the corresponding S-methyl isomer according to the following mechanism:
S-methyl isomer has proven toxic to mammals and, hence, it is undesirable in the end product. Several formulations wherein Dimethoate has been stabilized with various stabilizers are described in the prior art. Thus, US Patent No. 3,090,719 discloses stabilizing Dimethoate formulations with aromatic hydrocarbons, aliphatic ketones, cyclic ketones (also known as cycloparaffinic ketones) , acetates of primary alcohols, glycol ether acetates and tri-alkyl phosphoric esters .
US Patent No. 5,234,919 discloses stabilized formulations containing Dimethoate, in which a solvent system comprising a lower alkyl alcohol and a lower alkyl acetate ester is used.
In US Patent No. 4,892,866, cyclopropene fatty acids are used as stabilizers for Dimethoate and, in GB Patent No. 2050170-A the use of various organic acids in Dimethoate formulations is described, whereas GB Patent No. 1043006 relates to the use of various anhydrides, acetic anhydrides, propionic anhydrides and butyric anhydrides in particular, for the stabilization of formulations comprising Dimetho- ate.
US Patent No. 3,278,369 discloses emulsion concentrates of Dichlorvos, an organophosphate insecticidal, stabilized with for instance acetic anhydride or maleic anhydride. As it appears from Example 2 of said publication, acetic anhydride results in a better stabilizing effect than maleic anhydride.
The object of the present invention is to provide insecticidal compositions having improved storage stability even at temperatures above normal ambient temperature. Sufficient storage stability is essential in connection with commercial pesticides, and reduced degradation of the products on standing before the final use is financially very advantageous. It has now been established that it is possible to stabilize Dimethoate against thermal degradation by means of maleic anhydride. Thus, the present invention relates to an insecticidal composition in which Dimethoate has been stabilized with maleic an- hydride.
The invention also relates to a process for the control of insects, said process being characterized in that an insecticidal composition according to the invention, possibly following a dilution, is appor- tioned to an area, in which crops are grown, in an amount adequate to at least impede the growth of insects.
As shown in the following examples, maleic anhydride has a considerably better stabilizing effect than acetic anhydride. In view of the technical teaching derivable from US 3,278,369 in connection with a related compound, it must be considered surprising that maleic anhydride has a significantly better stabilizing effect on Dimethoate in comparison with a corresponding amount of acetic anhydride. Compared to acetic anhydride, maleic anhydride may therefore be used in smaller amounts to stabilize Dimethoate formulations without jeopardizing the stability in connection with long-term standing, even at high temperatures. In addition to the improved stabi- lizing effect of maleic anhydride, also the degree of obnoxious smell is lower both during the manufacturing process and when in use than is the case with acetic anhydride.
The insecticidal composition according to the invention preferably contains 0.1 to 20 parts by weight maleic anhydride, calculated on the basis of 100 parts by weight Dimethoate. The use of maleic anhydride in a quantity below 0.1 parts by weight may be appropriate in certain formulations, since no lower limit for the stabilizing effect of maleic anhydride has been established. However, usually a concentration above 0.1 parts by weight maleic anhydride is preferred to ensure a sufficiently stabilized durability. In certain cases, it may be appropriate to use a quantity of maleic anhydride in a formulation above 20 parts by weight, since no upper limit for the stabilizing effect has been established. Generally, however, a maleic anhydride content of up to 20 parts by weight for each 100 parts by weight Dimetho- ate should be sufficient to ensure a high storage stability. More preferably, the insecticidal composition contains 1 to 15 parts by weight maleic anhydride and, most preferably, the insecticidal composition contains 2 to 10 parts by weight maleic anhy- dride, calculated on the basis of 100 parts by weight Dimethoate .
The insecticidal composition according to the invention may be formulated in many different ways to obtain the storage stability effect. For instance, the insecticidal composition may be formulated as a solid, preparation containing particulate Dimethoate and maleic anhydride only.
However, usually it is preferred to formulate Dimethoate and maleic anhydride together with at least one further component. Said at least one component may be another biologically active compound or a compound that is inert in relation to Dimethoate. Inert components may be solid or liquid and either organic or inorganic. Whenever the component is inert in relation to Dimethoate, the at least one further component is particularly suitable to dissolve, disperse or emulsify Dimethoate.
The insecticidal compositions according to the invention may be prepared for instance in the form of water or oil based solutions, powders, dusting materials, pastes, aqueous or oil based suspensions, emulsifiable concentrates, micro emulsions, micro capsules, granules and water-dispersible granules. The choice of formulation type highly depends on the forthcoming application. In one embodiment of the present invention, the insecticidal composition is formulated as a concentrate to be diluted by a suitable diluent before use. Particularly, it is preferred to formulate the insecticidal composition as an emulsifiable concentrate.
A list of typical components for a liquid formulation would include inter alia mineral oils, aliphatic, cyclic, and aromatic carbon hydride compounds, e.g. xylene, paraffin, tetra-hydro naptha- lene, alkylated napthalenes or derivative compounds thereof, alkylated benzenes as well as derivative compounds thereof, aliphatic, cyclic, and aromatic alcohols, cyclo-hexanon or highly polar solvent s. For certain formulation types it is desirable to add one or more surface-active compounds foreseen to ensure the physical stabilization of the formulations and to make sure that the formulations are being quickly absorbed by the crops/plants on which they are to be used. The surface-active compounds may be either ionic or non-ionic. A list of suitable surface-active compounds would include salts of alkali metal, alkaline earth metal, and ammonium salts of aromatic sulphonic acids, e.g. ligno acid, phenol acid, naphthalene acid, or dibutyl napthalene sulphonic acid as well as fatty acids; alkyl acids, alkyl aryl sulphonic acids; salts of fatty alcohol sulphates; condensates of sulphonated naphthalenes and derived compounds comprising formaldehyde; condensates of naphthalene or naphthalene ' sulphonic acids with phenol and formaldehyde as well as fatty alco- hol/ethylene oxide condensates and sorbitol esters.
Powders and dusting materials may be obtained by mixing or grinding Dimethoate and maleic anhydride, possibly together with one or more solid excipients, or by saturating solid excipients with solutions of maleic anhydride and Dimethoate in volatile solvents, evaporating the solvents and, possibly, grind the products into powders. Granules may be obtained by granulating powders prepared as described above or by having Dimethoate and maleic anhydride be absorbed on solid excipients. Examples of suitable solid excipients are alumino-silicate, talcum, calcinated magne- sium oxide, diatomite and clay types, such as kaolin and bentonite. If desired, the insecticidal compositions according to the invention may also contain anti-foam agents, protective colloids, thickenings, UV- absorbants, dyes, corrosion inhibitors, and other pesticide-active compounds.
The insecticidal compositions according to the invention comprise solid and liquid formulations for immediate use by being spread onto an area, for which insect control is wanted, and highly concentrated liquid formulations that are usually diluted before use.
The concentrates may contain up to 95% by weight Dimethoate based on the weight of the formulation, preferably, between 10 and 70% by weight and, more preferably, between 20 and 60% by weight. Following a dilution with a suitable composition, usually water, which will often be chosen, before use, the Dimethoate content will vary depending on the relevant purpose, typically, however, the dosage will correspond to an apportion of up to 1 kg Dimethoate a hectare, preferably, up to 0.5 kg a hectare.
The formulations according to the invention are applicable for the control of quite a number of insects, primarily sucking and chewing insects, in ar- eas grown with agricultural and plantation crops in particular, but may advantageously be used in other places infected with undesired insects, e.g. areas where insects live or their eggs hatch.
The following examples illustrate methods of car- rying out the invention but do in no way represent delimitations thereof: Example 1
Three emulsifiable concentrates (la, lb and Ic) containing Dimethoate were prepared by mixing the components listed below in the amounts stated. Said amounts are parts by weight .
The formulation la does not contain any compound for the stabilization of Dimethoate, whereas in for- mulation lb acetic anhydride is used as a stabilizer. The formulations la and lb are not according to the invention but serve as comparison examples to formulation Ic (according to the invention) .
The formulations were stored at different tem- peratures for various periods of time, whereupon the pro rata share of Dimethoate degradation was determined. The results are shown in Table 1. Table 1
The results of Table 1 show that after having been stored for 14 days at 54°C, Dimethoate had been stabilized twice as effectively with maleic anhydride as with acetic anhydride. When stored for 3 months at 40°C, the storage stability obtained was more than 5 times better with maleic anhydride as with acetic anhydride. After having been stored for 1 year at 30°C, the product still shows a low degradation in comparison with the product without any stabilizer.
Example 2 A number of formulations were prepared by the same process as in Example 1 but having various anhydride contents, viz. 0.5% by weight, 1% by weight, 2% by weight, and 3% by weight based on the weight of the formulation. Said concentrations of maleic anhy- dride correspond to a content of 1.2 parts by weight, 2,5 parts by weight, 4.9 parts by weight and 7.4 part by weight maleic anhydride, respectively, for 100 parts by weight Dimethoate. For stability comparison reasons, corresponding formulations were prepared in which the maleic anhydride had been replaced by acetic anhydride. The results appear from Table 2. Table 2
The results of Table 2 show that a stabilizing effect is demonstrable already at a maleic anhydride content of 0.5% by weight. In comparison with acetic anhydride, the stabilizing effect of maleic anhydride in the low concentration of 0.5% by weight when stored for 3 months at 40°C is particularly evident. The stabilizing effect of maleic anhydride improves upon an increased concentration in the formulations until an apparently complete degradation inhibition is obtained after a relatively short-term storage for 14 days at 54°C. Upon storage for 3 months at 40°C a maximally possible stabilizing seems obtainable with a maleic anhydride concentration of 2% by weight, since adding an increased amount of maleic anhydride does not result in a further lowering of the amount of degraded Dimethoate.
Example 3
A concentrate without any emulsifier was prepared by initially dissolving 547 g Dimethoate in 444 g cyclo- hexanon. Subsequently, as a stabilizer, 1% by weight maleic anhydride was admixed, corresponding to 1.6 parts by weight maleic anhydride based on 100 parts by weight Dimethoate . Comparable compounds containing 3% by weight and 5% by weight maleic anhydride were prepared, corresponding to 4.9 part by weight and 8.2 parts by weight maleic anhydride, respectively, based on 100 parts by weight Dimethoate. For stability comparison reasons also a compound without any stabilizer was prepared.
The compounds prepared were stored for 14 days at 54°C, whereupon the pro rata share of degradation was determined. The results are shown in Table 3.
Table 3
As it appears from Table 3, if the stabilizer content is increased, a liquid composition containing Dimethoate, a solvent (cyclo-hexanon) and a stabilizer (maleic anhydride) shows a lower degradation and thus prolonged durability. No upper limit for the maximally obtainable stabilizing has been established.

Claims (12)

P A T E N T C L A I M S
1. An insecticidal composition having improved storage stability and containing Dimethoate, c h a r a c t e r i z e d in that the Dimethoate is stabilized by maleic anhydride.
2. An insecticidal composition according to claim 1, wherein the composition contains 0.1 to 20 parts by weight of maleic anhydride, calculated on the basis of 100 parts by weight of Dimethoate.
3. An insecticidal composition according to claim 1, wherein the composition contains 1 to 15 parts by weight of maleic anhydride, calculated on the basis of 100 parts by weight of Dimethoate.
4. An insecticidal composition according to claim 1, wherein the composition contains 2 to 10 parts by weight maleic anhydride, calculated on the basis of 100 parts by weight of Dimethoate.
5. An insecticidal composition according to any one of the preceding claims, wherein the composition is prepared as a concentrate to be diluted with a suitable diluent before use.
6. An insecticidal composition according to claim 5, wherein the concentrate contains an emulsi- fier and a solvent so as to obtain an emulsifiable concentrate .
7. An insecticidal composition according to claim 5 or 6, wherein the content of Dimethoate is up to 95% by weight based upon the weight of the formu- lation.
8. An insecticidal composition according to any one of the claims 5 to 7, wherein the content of Dimethoate is between 10 and 70% by weight based upon the weight of the formulation.
9. An insecticidal composition according to any one of the claims 5 to 8, wherein the content of Di- methoate is between 20 and 60% by weight based upon the weight of the formulation.
10. A process for the control of insects, c h a r a c t e r i z e d in that an insecticidal composition according to any one of the claims 1 to 9, possibly following a dilution, is apportioned to an area, in which crops are grown, in an amount adequate to at least impede the growth of insects.
11. A process according to claim 10, wherein the insecticidal composition is apportioned to the area, in which crops are grown, in an amount of up to 1 kg Dimethoate a hectare.
12. A process according to claim 10 or 11, wherein the insecticidal composition is apportioned to the area, in which crops are grown, in an amount of up to 0.5 kg Dimethoate a hectare .
AU2002312741A 2001-05-07 2002-05-02 Insecticidal composition having improved storage stability Ceased AU2002312741B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DK200100708A DK174660B1 (en) 2001-05-07 2001-05-07 Insecticidal agent with increased storage stability as well as insect control method
DKPA200100708 2001-05-07
PCT/DK2002/000285 WO2002089574A1 (en) 2001-05-07 2002-05-02 Insecticidal composition having improved storage stability

Publications (2)

Publication Number Publication Date
AU2002312741A1 true AU2002312741A1 (en) 2003-05-01
AU2002312741B2 AU2002312741B2 (en) 2004-12-02

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AU2002312741A Ceased AU2002312741B2 (en) 2001-05-07 2002-05-02 Insecticidal composition having improved storage stability

Country Status (28)

Country Link
US (1) US7282492B2 (en)
EP (1) EP1385375B8 (en)
JP (1) JP4101660B2 (en)
KR (1) KR100867450B1 (en)
CN (1) CN1262184C (en)
AR (1) AR033317A1 (en)
AT (1) ATE366043T1 (en)
AU (1) AU2002312741B2 (en)
BG (1) BG66147B1 (en)
BR (1) BRPI0209423B1 (en)
CA (1) CA2443814C (en)
CO (1) CO5540269A2 (en)
CY (1) CY1108518T1 (en)
DE (1) DE60221001T2 (en)
DK (1) DK174660B1 (en)
EA (1) EA005858B1 (en)
ES (1) ES2290310T3 (en)
HU (1) HU228740B1 (en)
ME (1) MEP44208A (en)
MX (1) MX245226B (en)
PH (1) PH12003501081B1 (en)
PL (1) PL204332B1 (en)
PT (1) PT1385375E (en)
RS (1) RS50711B (en)
SI (1) SI1385375T1 (en)
TW (1) TWI306737B (en)
UA (1) UA74642C2 (en)
WO (1) WO2002089574A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8110608B2 (en) 2008-06-05 2012-02-07 Ecolab Usa Inc. Solid form sodium lauryl sulfate (SLS) pesticide composition
MX336009B (en) * 2009-04-30 2016-01-07 Cheminova As Dimethoate low voc formulations.
US8968757B2 (en) 2010-10-12 2015-03-03 Ecolab Usa Inc. Highly wettable, water dispersible, granules including two pesticides

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL130008C (en) 1960-04-28
NL300590A (en) 1962-11-16
CH437907A (en) 1963-12-13 1967-06-15 Sandoz Ag Process for stabilizing anhydrous, emulsifiable active ingredient concentrates based on phosphoric acid esters and thiophosphoric acid esters
US4147781A (en) * 1977-11-25 1979-04-03 Rohm And Haas Company O,s-dialkyl o-benzamidophenyl phosphorothiolates and phosphorodithioates and pesticidal methods
IT1113947B (en) 1979-05-04 1986-01-27 Montedison Spa LIQUID FORMULATIONS OF PHOSPHORIC AND THIOPHOSPHORIC Pesticides STABLE OVER TIME AND THAT RESIST TO LOW AND HIGH TEMPERATURES
DE3726339C2 (en) 1987-08-07 1996-02-29 Shell Int Research Thermal stabilization of insecticidal phosphoric acid esters or insecticidal preparations containing phosphoric acid esters
JP2606324B2 (en) * 1988-10-14 1997-04-30 住友化学工業株式会社 Stable pesticide composition
US5234919A (en) 1990-05-31 1993-08-10 Helena Chemical Company Water soluble, highly active dimethoate formulations in an alcohol/ester solvent system
GB9102757D0 (en) 1991-02-08 1991-03-27 Albright & Wilson Biocidal and agrochemical suspensions

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