JPH0523241B2 - - Google Patents

Description

Claim 1 Formula [In the above formula, R ₁ is a straight or branched alkyl containing 1 to 5 carbon atoms, R ₂ is a straight or branched alkyl, and R ₃ is a straight or branched alkyl containing 1 to 5 carbon atoms.
straight-chain or branched-chain alkyl containing 5 carbon atoms, provided that the total number of carbon atoms in R ₁ and R ₂ does not exceed 8]. In the method, such insecticide comprises:
A method for retarding or inhibiting the thermal decomposition of pesticides, comprising intimately mixing 0.01 to 2% by weight of inorganic phosphate type compounds to obtain a solid mixture substantially free of water. 2 (a) Formula [In the above formula, R ₁ is a straight or branched alkyl containing 1 to 5 carbon atoms, R ₂ is a straight or branched alkyl containing 1 to 5 carbon atoms, and R ₃ is a straight or branched alkyl containing 1 to 5 carbon atoms. straight-chain or branched-chain alkyl containing carbon atoms, provided that the total number of carbon atoms in R ₁ and R ₂ does not exceed 8] in an insecticidal effective amount, and ( b) Contains 0.01 to 2% by weight of an inorganic phosphate type compound,
Moreover, the solid insecticide composition contains substantially no water. 3. The insecticide composition according to claim 2, wherein R ₁ , R ₂ and R ₃ are methyl. 4. The insecticide composition according to claim 2, wherein the inorganic phosphate type compound is a sodium or potassium monobasic phosphate, a hexametaphosphate, phosphoric acid, or a mixture thereof. 5 (a) Formula [In the above formula, R ₁ is a straight or branched alkyl containing 1 to 5 carbon atoms, R ₂ is a straight or branched alkyl containing 1 to 5 carbon atoms, and R ₃ is a straight or branched alkyl containing 1 to 5 carbon atoms. from 2 to 98% by weight of an organic compound straight or branched alkyl containing carbon atoms, provided that the total number of carbon atoms in R ₁ and R ₂ does not exceed 8; (b) A wettable powder or dispersible granular insecticide composition comprising: 0.01 to 2% by weight of an inorganic phosphate type compound; (c) 0.01 to 20% by weight of a wetting agent; and (d) 1 to 12% by weight of a dispersing agent. . 6. The insecticide composition according to claim 5, wherein the organic compound is thiodicarbamate. 7 Alkali metal salts of aliphatic alkyl or alkenyl sulfates or sulfonates in which the wetting agent contains 8 to 20 carbon atoms, the alkyl chain being 8
Alkali metal salts of alkylbenzyl or alkylnaphthylsulfonates containing ~12 carbon atoms, ethoxylated alkylphenols where the alkyl group contains from 8 to 20 carbon atoms, dialkyl containing from 5 to 10 carbon atoms The insecticide composition according to claim 5, which is a dialkyl ester of sodium sulfosuccinic acid containing atoms, or a polyalkylene oxide-modified dimethylpolysiloxane in which the alkylene group is ethylene or propylene or a hybrid group of both. . 8 The dispersant is starch, an alkali metal or alkaline earth salt of lignin sulfonate, or an alkali metal alkylnaphthalene sulfonate and 1 to 3
6. The insecticide composition according to claim 5, which is a condensate with an organic compound containing at least one carbon atom and at least one oxygen atom. 9. The insecticide composition according to claim 5, which also contains an antifoaming emulsifier. 10. The insecticide composition according to claim 9, wherein the defoaming emulsifier is a polymerized dimethylsiloxane or a mixture of an alkaline earth stearate and a polyalkylene glycol ether or a sugar-free sodium sulfonate of kraft lignin. 11. The insecticide composition according to claim 5, which also contains a compatibilizer. 12 The compatibilizer is a compound of an alkylene oxide made by condensing an alkylene oxide with an alkylene glycol (where all alkyl substituents contain 2 to 4 carbon atoms) and a hydrophobic base. The insecticide composition according to claim 11, which is a condensate. 13. The insecticide composition according to claim 12, wherein the condensate comprises ethylene oxide prepared by condensing propylene oxide with propylene glycol and a hydrophobic base. 14 70 to 95% by weight of thiodicarbamate, 2 to 3% by weight of sodium salt of sulfonated lauric acid, 8 to 15% by weight of sulfonated naphthalene formaldehyde condensate, 1% of dimethylpolysiloxane
6. The insecticide composition according to claim 5, containing 0.5 to 1.5% by weight of sodium or potassium monobasic phosphate or phosphoric acid. 15. The insecticide composition of claim 14, which also contains a nonionic condensate of ethylene oxide and a hydrophobic base prepared by condensing propylene oxide with propylene glycol. FIELD OF THE INVENTION This invention relates to the thermal stabilization of alkylthioalkyliminocarbamate pesticides. especially,
The present invention relates to retarding or preventing the thermal decomposition of these pesticides by incorporating inorganic phosphate-type compounds into formulations containing sulfur-bridged bisalkylthioalkyliminocarbamates. Background of the invention sulfur-bridged bisalkylthioalkylimino-N
- Alkyl carbamate insecticides have a wide range of uses in the control of insects and other agricultural and horticultural pests. The active compounds exhibit extremely high levels of insecticidal activity and substantially reduced mammalian toxicity when compared to other insecticidal compounds having a comparable range of activity against the pests mentioned above. These compounds are thermally unstable in the presence of various contaminants. Heavy metals and their salts, especially chloride salts, are particularly undesirable. Decomposition is copper metal,
It is particularly severe in the presence of copper chlorides, ferrous metals, iron chlorides and iron oxides in the form of rust. Other metals of concern include cobalt, nickel and aluminum. Concentrations as low as 10 ppm are effective, provided sufficient time is allowed at temperatures of 60° C. or higher. Sulfur and sulfide salts may also induce decomposition, even at rates slower than those of chloride-containing systems. Also, pyridine, pyridine hydrochloride, di- and trisulfides, amines, peroxides and acids (e.g.
Several organic decomposition initiators have been identified, including (acetic acid and citric acid). The presence of more than 5% methomyl or its oxime can also induce further degradation. The main objective of the present invention is to suppress the thermal decomposition processes that can occur when large amounts of sulfur-bridged bisalkylthioalkylamino-N-alkyl pesticides are dried at elevated temperatures or stored for long periods of time, especially in warm climates. Or to provide a method for delaying it. Yet another object is to provide stable wettable powder and dispersion granular compositions of these insecticides. DETAILED DESCRIPTION OF THE INVENTION The present invention is based on the formula [In the above formula, R ₁ is a straight or branched alkyl containing 1 to 5 carbon atoms, R ₂ is a straight or branched alkyl containing 1 to 5 carbon atoms, and R ₃ is a straight or branched alkyl containing 1 to 5 carbon atoms. Straight-chain or branched-chain alkyl containing atoms, provided that the total number of carbon atoms in R ₁ and R ₂ is 8
The present invention provides a method for retarding or inhibiting the thermal decomposition of an insecticide of not more than This is accomplished by incorporating from about 0.01 to about 2% by weight of an inorganic phosphate type compound containing at least two oxygen atoms bonded to the atom. The present invention also provides an inorganic phosphate-type compound containing (a) an insecticidal compound of the above formula in an insecticidal effective amount, and (b) at least two oxygen atoms bonded to a polyvalent cation atom. from about 0.01 to about 2% by weight. A. DEFINITIONS The term "powdered or granular compositions" refers to fine powders (e.g., those that pass through US sieve screens No. 400 to No. 100) with a maximum dimension of 5 mm.
It includes all solid formulations ranging in size from substantial particles of moderate size (eg, those that pass through a No. 4 US sieve screen). The term "inorganic phosphate-type compounds" means phosphorous acids, alkali metal monobasic phosphates or metaphosphates, and mixtures thereof. "Thiodicarbamate" is the common name for an insecticide having the formula shown below. The term "compatibilizer" includes additives that allow different pesticides to be combined in a single liquid composition. Such agents can be incorporated into solid or liquid compositions containing one or all of the insecticides to be combined. B Pesticides The organic compounds of the present invention are alkylthioalkylimino-N-alkyl carbamates. These are widely used to control various insects and pests. These can be made by well known methods such as those shown in US Pat. No. 4,004,031 and US Pat. No. 4,382,957. In preferred compounds of the invention R ₁ , R ₂ and R ₃
is alkyl. Thiodicarbamate compounds are particularly preferred for the practice of this invention. C Thermodynamic Stability Typical decomposition times of thiocarbamates in the presence of various contaminants are shown in the table. These data were collected using the following procedure. A 1 g sample of thiocarbamate was intimately mixed with the indicated weight percent contaminant. This solid was placed in a test tube, which was then covered with a rubber septum cap and heated to 100°C.
immersed in a constant temperature bath maintained at . An uncontaminated standard test was conducted under similar conditions. Degradation was shown in various forms. Some samples showed a rapid change from solid to dark liquid. Dark yellow smoke was usually observed. Others underwent gradual discoloration and moisture absorption. In these experiments, the decomposition time was the point at which the sample became a dark brown semi-solid. The values reported were the average of several replicates for each sample.

[Table] Oxide
3% 3-5 days

[Table] The destabilizing effects of methomyl and other sulfur compounds are
This is clear from section B of the table. Thiodicarbamate is stable at low concentrations (1% by weight or less) of methomyl, one of its major decomposition products. However, as the concentration of methomyl increases, the rate of degradation increases significantly. Similarly, the effects of methomyloxime are significant. Also, as the amount of other decomposition products such as dimethyl trisulfide and dimethyl disulfide increases, the rate of decomposition is substantially accelerated. Section C of the table contains the results of studies using contaminants that may be introduced during preparation or storage of pesticide materials. As mentioned above, heavy metal ions, especially copper and iron, are particularly harmful. If possible, the use of production equipment or storage containers made from these metals in a manner where they may corrode and produce harmful salts should be avoided. Other organic materials are also included to illustrate the effect that such compounds may have on the product when present. This is because, for example, they are found in the solvents used in the manufacturing process. The ability of certain silicon-based supports to inhibit the decomposition of contaminated thiocarbamates is evident from the table. In these experiments, 1 g of thiocarbamate
The samples were first contaminated with the indicated weight percentages of cupric chloride and ferric chloride and then intimately mixed with various silicas and silicates. The samples were then placed in test tubes and immersed in a water bath at 50°C, 70°C and 100°C until decomposition was observed. Decomposition time was measured when the solid turned into a dark brown liquid.
All values represent the average of several replicates. In some cases, several orders of magnitude stabilization was observed compared to standard tests containing no silica.

TABLE Thermodynamic instability was accurately and reproducibly assessed by detecting the heat release in a dual thermocouple test performed as follows. The test mixture was prepared by intimately mixing the pesticide standard and the desired amount of stabilizer (the pesticide standard was a thiodicarbamate containing sulfur as an impurity during synthesis, and an additional No contaminants were added). A thermocouple was placed into the 2 g dry sample in the measurement bottle. I put the second thermocouple in the bottle,
This was placed 1 inch above the surface of the mixture. The bottle was then placed in a heating block and heated to 160°C as quickly as possible. Heating rate was not critical as long as it was reproducible and the mixture reached 160°C before exotherm occurred with untreated insecticide.
The exotherm time of the mixture was compared to that of an untreated standard, ie, containing only pesticide. Measurements on a single mixture of additives and pesticides were typically performed 5 to 10 times to ensure reproducibility. In all cases, the pesticides were taken from the same batch to avoid differences in contamination levels that are often observed from batch to batch. The time to exotherm was directly proportional to the thermal stability of the mixture. As a group, inorganic phosphate-type compounds containing at least two oxygen atoms bonded to a polyvalent cationic atom are effective in delaying or suppressing the appearance of exotherm in sulfur-bridged carbamate pesticides such as thiodicarbamates. is surprisingly effective. This group includes phosphorous acids and alkali metal monobasic phosphates or metaphosphates. Compounds that are particularly effective in retarding exotherm are sodium or potassium monobasic phosphates, hexametaphosphates and phosphoric acid. Mixtures of these compounds are also effective. The ability of some of the preferred stabilizers to retard exotherm in thiodicarbamates as measured by the dual thermocouple test described above is evident from the results shown in the table. These results indicate that monobasic potassium phosphate is a particularly preferred stabilizer for thiodicarbamates. Table Exotherm times for stabilized thiodicarbamates Additive exotherm times (min) − − 54 (standard) 4% Molecular Sieve 4A 91 1% Na ₂ SO ₃ 75 5% Na ₂ SO ₃ 117 5% NaHSO ₃ 94 0.5% KH ₂ PO ₄ >300 3% Na ₂ HPO ₄ 58 Decomposition of thiodicarbamate and increasing concentration of methomyl at 100°C in the presence of monobasic sodium phosphate.
I monitored it. Samples of untreated thiodicarbamate and thiodicarbamate treated with various amounts of monobasic sodium phosphate were monitored for several days at 100°C. These were periodically analyzed for thiodicarbamate and methomyl by standard HPLC methods. As the thiodicarbamate concentration decreased, the methomyl concentration increased. However, results show that other products are also formed as the decomposition process continues. The sum of the weight percentages of methomyl and thiodicarbamate becomes progressively smaller as the degradation progresses.
Increasing the amount of monobasic phosphate appears to stabilize the thiodicarbamate as the decomposition reaction progresses. Degradation products (particularly methomyl) accelerate this process. These results also support the hypothesis that bisalkylthioalkylamino-N-alkyl carbamates, including multiple sulfide species, undergo an autocatalytic decomposition process and also catalyze the process. Sulfur-bridged bisalkylthioalkylamino-N
- Stabilization of alkyl carbamates can be achieved by incorporating the stabilizers of the invention in amounts ranging from 0.01 to 2% by weight of the total mixture.

Table D Formulations The compositions of the invention can be applied both to fields and lawns as solids or as liquid dispersions or solutions to control pests. The application is
This is done by methods readily known to those skilled in the art.
Effective amounts range from about 0.05 to about 0.05 active insecticide per acre.
201b. Formulations useful in the practice of this invention are solids as wettable powders or dispersible granules, and liquids as solutions or dispersions. Preferred wettable powder and dispersible granular formulations include (a) about 1 to about 98% by weight bisalkylthioalkylamino-N-alkyl carbamate insecticide; (b) at least from about 0.01 to about 2% by weight of an inorganic phosphate-type compound containing two oxygen atoms; (c) from about 0.01 to about 20% by weight of a wetting agent; and (d) from about 1 to about 12% by weight of a dispersing agent. . Preferred liquid formulations contain (a) from about 0.01 to about 75% by weight of a bisalkylthioalkylamino-N-alkyl carbamate insecticide; (b) at least two oxygen atoms bonded to a polyvalent cationic atom. from about 0.0001 to about 2% by weight of an inorganic phosphate type compound, (c)
Wetting agent: about 0.01 to about 20% by weight; (d) dispersing agent: about 0 to about 20% by weight.
10% by weight, and (e) an inert liquid carrier from about 5% to about 10% by weight;
Contains 80% by weight. Suitable carriers include water, unsubstituted aliphatic and aromatic hydrocarbons or analogs containing e.g. alkyl, halo or hydroxy substituents, fatty acids, and oils derived from natural extracts such as linseed oil and cottonseed oil. Can be mentioned. Among the insecticides useful in this invention, preferred compounds are thiodicarbamates. Preferred inorganic phosphate type compounds are phosphoric acid and sodium or potassium monobasic phosphates or metaphosphates. Many wetting agents, anionic, cationic or nonionic, are useful in these formulations. Exemplary wetting agents are alkali metal salts of aliphatic alkyl or alkenyl sulfates or sulfonates containing from 8 to 20 carbon atoms, alkyl benzyl or alkyl where the alkyl chain contains from 8 to 12 carbon atoms. an alkali metal salt of naphthylsulfonate, an ethoxylated alkylphenol in which the alkyl group contains 8 to 12 carbon atoms, a dialkyl ester of sodium sulfosuccinic acid in which the dialkyl group contains 5 to 10 carbon atoms, or It is a polyalkylene oxide modified dimethylpolysiloxane in which the alkylene group is ethylene or propylene or a mixture of both. Other suitable wetting agents may also be used. Dispersants are substances that interact with the solid components in a formulation and the liquid medium used to suspend these solids for application purposes. They must be soluble in their liquid phase and they usually behave as binders for solid powders or granules. Typical dispersants useful in the practice of this invention include starch, alkali metal or alkaline earth salts of lignin sulfonates, and alkali metal alkylnaphthalene sulfonates and
Condensates with organic compounds containing 3 carbon atoms and at least one oxygen atom, such as formaldehyde and sodium naphthalene sulfonic acid, may be mentioned. Particularly useful additional ingredients in the formulations of the invention are antifoam agents. This prevents or reduces foam during the preparation of the powder or granules and during the dispersion and application of the composition. This also stabilizes the resulting dispersion and allows rapid redispersion if agglomeration of solids occurs in the dispersion. Particularly useful antifoam agents are dialkylpolysiloxanes. Particularly effective are dimethylpolysiloxanes formulated as emulsions or pastes. Such additives do not act as stabilizers for pesticides. Pesticide compositions containing multiple insecticides are popular for obvious reasons of convenience, ie, only one application is required to deposit all of the active ingredients. Although many multiple formulations are easily prepared by simply mixing all of the active ingredients, the formulations of the present invention prevent agglomeration of the final solution or dispersion applied to the target plant. The presence of a compatibilizer may be required.
The presence of additional chemically unrelated pesticides such as parathion can destabilize dispersions prepared for spray applications. Preferred compatibilizers for these compositions are alkylene oxides and alkylene glycols made by condensing alkylene oxides and alkylene glycols in which all alkyl substituents contain 2 to 4 carbon atoms. It is a condensate with a hydrophobic base. A particularly effective agent is a paste condensate of ethylene oxide and a hydrophobic base formed by condensing propylene oxide with propylene glycol. The wettable powders and dispersible granules of the present invention may optionally contain a number of other well-known ingredients, provided that they do not depend on the ability of the inorganic compound to stabilize the insecticide or the ability of the powder or granules to stabilize the insecticide. Needless to say, it should not affect stability, dispersibility or wettability. These additives include buffers, carriers or diluents, dyes, fragrances,
Humectants, thickeners, biocides and anti-evaporation agents may be mentioned. The solid compositions of the present invention can be manufactured by a variety of methods well known in the art such as pan granulation, fluidized bed mixing and drying, spray drying, intensive mixing agglomeration, extrusion, compression or pelletizing. . In pan granulation and fluidized bed methods, a mixture of dry ingredients is prepared and transferred to a mixing/drying chamber containing water and all liquid ingredients. The slurry is then thoroughly mixed and dried. The particles are then ground to the desired size. If spray drying methods are used, grinding of the mixture of dry ingredients or slurry is preferred. Each method yields solids with a range of particle sizes and moisture contents. Useful products are those that meet the particle size requirements for the particular application, contain less than 5%, preferably less than 2%, water by weight, and are well dispersed in water or oil. For granular compositions, good dispersibility is US Screen No.100
(149 microns) and optimum particle stability is obtained with moisture below 2%. Any particles that are too small, too large, or too wet can be returned to the production or drying equipment and recycled. Preparation of the liquid compositions of the present invention can be accomplished by methods known in the art. Useful dispersion formulations do not separate into liquid and solid phases during extended storage at ambient temperatures. To increase stability, the size of the dispersed particles can be reduced by techniques known in the art such as air and wet milling. The following examples are provided to illustrate useful formulations of the invention and to illustrate the effects of various stabilizers. Example 1 To illustrate the effect of phosphate stabilizers in dispersible granules, the following two formulations were prepared (mixing each component in an aqueous slurry and spray drying to less than 2% moisture). ) and their thermal stability was compared (all values are in weight % of dry ingredients).

Table: It is clear that as little as 0.5% NaH ₂ PO ₄ greatly improves the thermal stability of the formulations of the invention. Formulation B at elevated temperature (approximately 45 to
55° C.) can be stored for a significantly longer time than Formulation A, and Formulation B is much less prone to decomposition during drying than Formulation A. Example 2 A thiodicarbamate containing in water the following components (all weights are based on the weight of the components excluding water): 5% sulfur and 1.0% silica.
86.1%, dispersant (sodium salt of sulfonated naphthalene formaldehyde condensate) 10.1%, wetting agent (sodium salt of sulfonated lauric acid) 2.5%,
A highly stable sample containing two stabilizers was prepared by slurrying 0.6% antifoaming emulsifier (dimethylpolysiloxane emulsion) and 0.7% heat stabilizer (KH ₂ PO ₄ ). The slurry was wet milled to pass through a No. 325 screen (US sieve size) and spray dried to a moisture content of less than 2%. Approximately 95% of the resulting granules have a particle size distribution over a narrow range of -14 to +100 mesh (US sieve size). Granules within this size range had the following properties: CIPAC suspension 90% Time to exotherm >120 minutes.