NO140938B - METHOD AND DEVICE FOR FORMING A CONTINUOUS MATERIAL PATH OF FIBROSE PARTICLES - Google Patents

Description

Insecticide preparation.

The present invention relates to insecticidal preparations which contain a new,

slightly toxic organophosphoric acid ester. The organophosphoric acid ester used is 0,0-dimethyl-0-(4-cyanophenyl)-thiophosphate, which has

following formula:

The above compound can be prepared

in that 0,0-dimethylchlorothiophosphate is condensed with 4-cyanophenol or an alkali metal salt thereof. The preparation according to the invention can be used for the eradication of agriculturally harmful insects, especially rice borers such as e.g. rice stalk borer (Chilo sup-pressalis W ALKER), rice husk borer (Schoe-nobius incertellus WALKER), rice stalk borer

(Sesamia inferens WALKER), and others

(such as CHILO plejadellus ZINK, Chi-lotra polychrysa MEYR., Scirpophaga albi-nella CRAMER, Scirpophaga innota WAL-KERS, Eldana dichromellus WALKER, and

Elasmopalpus lignosellus ZELLER), and sanitary harmful insects, especially houseflies

(Musea domestica LINNE), and their larvae

and such.

The purpose of the present invention therefore consists in obtaining a new insecticidal preparation which is suitable for agricultural and sanitary use, which is very

slightly toxic towards warm-blooded animals,

but has very high insecticidal activity, compared to ordinary insecticides.

It is known that organic forphosphoric acid esters containing a 4-nitrophenyl radical, e.g. parathion and methyl parathion, have significant insecticidal activity and can therefore form useful, effective constituents in agricultural chemicals. But at the same time they are very toxic to warm-blooded animals, and therefore many attempts have been made by American and German scientists to find similar compounds that are less toxic and have greater insecticidal activity, and as a result substances such as "Chlorthion" and dicaptone. But these so-called low-toxic insecticide compounds are really so low-toxic that their insecticidal activity is also reduced to some extent.

A researcher at the Farbenfabriken Bayer A. G. has given notices of the synthesis of a thiophosphate containing a cyanophenyl radical, namely 0,0-diethyl-O-(4-cyanophenyl) thionephosphate, as well as of the results of insecticidal trials with this compound (G. Schrader : Die Entwicklung neuer Insectizide auf Grundlage organischer Fluor und Phosphor-Verbindungen, page 59, 1952). However, this compound has a high oral toxicity towards warm-blooded animals which does not differ much from parations, while its insecticidal activity towards harmful insects is lower than parations. No notification has been given of further attempts in this connection.

The present inventors have made various studies to find a compound that is low in toxicity but at the same time has great insecticidal activity; such a connection is strongly desired in rice-producing districts. They thereby found the type of compounds to which the patent relates and which fulfill the aforementioned requirements. Substances such as parathion, methyl parathion "EPN" and "Dipterex" have been used as exterminators for rice borers. Admittedly, the first three substances are very active against rice borers, but at the same time they are very toxic to warm-blooded creatures, including humans. For example, paration's LDr„, value for oral use in mice is 6-10 mg/kg body weight, which is why great caution is required when using preparations containing these compounds. "Dipterex" is indeed significantly less toxic to warm-blooded creatures, but the substance has less insecticidal activity compared to the above three compounds. Broadly speaking, it can be said that 2 or 3 times as much of the first-mentioned compounds are needed to achieve the same result against rice borers as when using the latter compound. Such a large consumption would be uneconomical. The consequence is that, despite its very high toxicity towards warm-blooded creatures, parathion has so far been commonly used as an extermination agent for rice borers. The compound to which the present invention relates has, as very precisely explained below, approx. 100 times less toxic than parathion, and several times less than the toxic effect of "Dipterex" (for example for oral toxicity to mice the LDr„ value is 900-1000 mg/kg body weight) so that it can be said that the compound is practically not toxic. But as explained below in connection with numerical indications, the compound's effectiveness against rice borers is not at all less than that of parations, which is why it must be said that the present invention provides a good solution to the question of counteracting rice borers.

The 0,0-dimethyl-O-(4-cyanophenyl)thiophosphate which the invention is about is a new substance, which has not been described in any literature so far. It can be produced according to the following reaction scheme

(where M denotes hydrogen or an alkali metal atom), 0,0-dimethylchlorothiophosphate (I) is thus condensed with 4-cyanophenol or an alkali metal salt thereof (II).

The 0,0-dimethylchlorothione phosphate used as starting material in the present process is a known liquid compound which boils at 66° C. at 16 mm Hg. The other starting material, 4-cyanophenol, can also be prepared by known methods, e.g. that described in J. Chem. Soc, 1942, 113, and melts at 110° C, this compound can easily be converted into a salt by reaction with e.g. caustic alkali, alkali carbonate, alkali metal and alkali metal alcoholate, in water or in an organic solvent. It is preferable to an-

turn sodium or potassium as alkali.

Condensation of the starting materials can be successfully carried out by mixing them in a molecular ratio or possibly with an excess of 0,0-dimethylchlorothione phosphate. In this case, it is generally preferable to carry out the reaction in an inert organic solvent using approximately equimolar amounts of the two substances. That is to say, when 0,0-dimethylchlorothione phosphate is mixed with alkali metal 4-cyanophenolate in an inert organic solvent and then heated, the compound to which the present invention applies can be obtained as a product. If free 4-cyanophenol is used instead of the aforementioned alkali metal 4-cyanophenolate, the reaction takes place after the so-called dehydrogen chloride reaction, and in that case this reaction is preferably carried out in the presence of a deacidifying agent known per se, e.g. organic bases such as pyridine and diethylamine or alkali metal carbonates or bicarbonates. The inert organic solvent used can be of any kind known per se, as long as it does not affect the reaction, e.g. a hydrocarbon, a chlorinated hydrocarbon, an alcohol, a ketone or the like. The reaction can only take place by allowing the reaction mixture to stand at room temperature for a long time, but as a rule it is preferable to heat the mixture, e.g. to a certain temperature below the boiling point of the solvent. Furthermore, the reaction is preferably carried out in the presence of a catalyst such as e.g. copper powder or copper salts, and then gives a good yield.

When the reaction is finished, the precipitated alkali metal chloride or the hydrochloride of the organic base is filtered off, or possibly enough water is added to dissolve the by-product salts, after which the aqueous layer is separated, and the organic layer is evaporated in vacuo, so the desired compound available as leftovers. In the above-mentioned manner, a product can be obtained that is sufficiently purified for most practical purposes, but if necessary, the product can be further purified by distillation in vacuum, by chromatography in columns, and/or by recrystallization at a lower temperature. As the compounds to which the invention relates usually decompose somewhat when heated, it is preferably used without such purification.

The obtained 0,0-dimethyl-O-(4-cyano-phenyl)thiophosphate) is a light yellow, oily product, with a refractive index n^'^- 1-5457

and kp. 119—120° C/0.09 mm Hg (accompanied by some decomposition) and this compound is very soluble in alcohols, ethers, ketones and aromatic hydrocarbons, and very slightly soluble in aliphatic hydrocarbons and insoluble in water.

In the following, an overview is given of the toxicity of 0,0-dimethyl-O-(4-cyanophenyl)thiophosphate to which the invention relates. The toxicity (LD-„, value) towards mice is here compared with parations, under different application conditions, as indicated in table 1.

The following table 2 shows the toxic value and of EPN when applied dermally (LDr>(1, of substance according to the invention and of parathion mg/mouse).

That the preparation according to the invention has the same toxicity towards mice and a beneficial effect - a prominently low toxicity - will be apparent from the substance according to the invention and from the following table 3, where known and used insecticides are indicated.

0,0-Dimethyl-O-(4-cyanophenyl)thiophosphate used according to the present invention occupies a completely unique position among other isomers, homologues and analogues of the substance, due to its correlation of toxicity and insecticidal activity, which will appear from the following table 4.<*>) Local test method was carried out by treating overwintering larvae of rice stem borers in the following way: Each individual compound to be examined was dissolved in acetone, so that a series of acetone solutions containing from 0.067 to 2% of the compound in question (g/cm<3>). Portions of each 1/1000 cm<3> of the relevant solution were applied to the larval body using a microsyringe, and after the preparation had been kept for 3 days at 25° C, it was observed how many had died and how many had survived . The larvae used in this experiment had approximately the same weight, varying from 80 to 90 mg. and each portion of solution was added to a group of 20 larvae, to determine the mean percentage killed. The following table 5 shows in more detail the effectiveness of the compound according to the invention against the rice stem borer, compared to parathion.

Pot trial against second generation of rice stem borer larvae.

(showering of borers that bore into a rice plant).

The following table 7 shows the effectiveness of the preparation according to the invention against pests other than those mentioned above.

("50.E." denotes an emulsifiable concentrate containing 50% by weight of active substance according to the invention, 10 parts by weight of xylene and 40 parts by weight of "Triton X-100" [a polyethylene glycol nonyl phenyl ether].

For the use of the substance, i.e. 0,0-dimethyl-0-(4-cyanophenyl)thiophosphate to which the invention relates, in practice, different inert carriers can also be used, so that an insecticidal preparation is obtained, which contains a toxic amount of the substance. The preparation can take the form of an emulsion, suspension, dust or oil preparation.

An emulsified preparation can e.g. is prepared by mixing the substance with an organic solvent and a surface-active agent in suitable proportions to obtain an emulsifiable concentrate, which is then diluted appropriately with water when it is to be used in practice. An aromatic hydrocarbon can advantageously be used as a solvent, e.g. benzene or xylene, and almost all kinds of non-ionic surfactants can be used as surfactants. The mixing ratio between these materials can be chosen freely, depending on the nature of the materials and the purpose of the preparation. As a rule, 50 parts by weight of active substance mixed with 10 parts by weight of solvent and 40 parts by weight of a surfactant will give a good emulsifiable concentrate. In some cases, according to the invention, the active substance can be mixed only with a non-ionic surface-active material and give an emulsifiable concentrate. For use in practice, the concentrate is diluted with a suitable amount of water, so an emulsion is formed which is showered out directly.

For the production of wettable powder, the substance is mixed with a non-ionic

surface-active material, and further with a powdered carrier. Almost any non-ionic surface-active substance can be used as a surface-active material here, and as a powdered carrier it can be used, e.g. talc, kaolin, bentonite, diatomaceous earth and acidic Japanese clay. The powdered carrier material should have a particle size of over 200 mesh. The mixing ratio can advantageously be 5-25 parts by weight. substance according to the invention, 5-10 weight percent surface-active material and the remaining weight percent is made up of the powdered carrier, but these ratios can otherwise be varied freely depending on the purpose of use. A suitable suspension for use in practice is easily obtained by simply stirring the wettable powder into water.

By mixing a suitable amount of active substance with a powdered carrier, a pollination preparation can be prepared. This can be done by mixing the components directly with each other, but preferably the active substance is dissolved in a solvent that has a low boiling point, and the solution is mixed with the carrier, after which the solvent is removed by distillation. The dust preparation obtained should preferably contain 1-5% by weight of the substance according to the invention. As a solid carrier, such materials as have already been mentioned for the production of wettable powder are advantageously used.

Furthermore, the active substance can be dissolved in e.g. deodorized the kerosene and thereby give an oil preparation of suitable concentration. The active substance is usually so poorly soluble in kerosene that an auxiliary solvent must be used at the same time. As such, benzene, xylene or methylnaphthalene can be used with advantage.

For the production of insecticidal preparations according to the invention, in addition to the aforementioned production methods, any other known method for the production of organic phosphorus insecticides can be used. Furthermore, insecticidal preparations according to the present invention can be mixed with other material, e.g. with an active insecticidal component of a different type, a fungicide or herbicide type, depending on the conditions.

When an insecticidal preparation according to the invention is used in practice to kill harmful insects, the preparation is added to the insects in such a way that an insecticidal quantity of 0,0-dimethyl-O-(4-cyanophenol)-thiophosphate is brought into contact with the harmful insects. If, for example, a 50% emulsifiable concentrate is used, for complete eradication of rice borers it may be sufficient to use 70-80 liters of an emulsion diluted to 1/2000 in 10 years against the first developed larvae and then use 90-180 liters of 1/1000 diluted emulsion per 10 years against the second generation of larvae. If a dust preparation according to the invention is used which contains 1.5% active substance, 3-4 kg of this dust can be applied with advantage per 10 years above the first developed larvae of rice borers, and then from 5 to 6 kg per 10 years should be sufficient for treatment of the second larval generation. If wettable powder according to the invention is used which contains 25% active substance, 70-80 liters of 1/1000 aqueous suspension per 10 years be suitable for use against the first generated larvae and 90-180 liters of 1/500 aqueous suspension per 10 years against the second generation of rice borer larvae.

The invention is explained in more detail by the following examples. Unless otherwise stated, all parts given are parts by weight.

Example 1

To a mixture of 32.8 g of 4-cyanophenol and 27.6 g of anhydrous potassium carbonate in 200 ml of isobutyl ketone, 32.2 g of 0.0-dimethylchlorothiophosphate was added dropwise at 60° C. and with stirring. After the addition, the mixture was further stirred for 8 hours at 60-80° C, to complete the reaction. Water was added to dissolve the precipitated inorganic compound, the organic layer was separated, washed with water and dried over anhydrous sodium sulfate. After distilling off the methyl isobutyl ketone in vacuum, a reddish-brown oily product was left, which weighed 45.2 g. For further purification, this crude product was chromatographed in a column using activated carbon and activated aluminum oxide, whereby a light- yellow oily product, the refractive index of which was nD' = 1.5457.

21 2

Analysis

Calculated (for CH.JSKXPS):

P = 12.8; S = 13.2; N = 5.76 percent.

Found:

P = 12.7; S = 13.0; N= 5.68 percent.

Example 2

To a mixture of 23.8 g of 4-cyanophenol, 32.2 g of 0.0-dimethylchlorothiophosphate and 0.1 g of cuprous chloride in 100 ml of toluene, which had been heated to 60° C, was added in small portions 27.6 g anhydrous potassium carbonate. The water formed by the reaction was removed azeotropically together with the toluene, and in addition the carbon dioxide formed escaped. After the reaction was complete, the reaction product was treated in the same manner as in Example 1, yielding approximately the same amount of effective product.

Example 3

The procedure in example 1 was repeated, with the difference that instead of 4-cyanophenol and anhydrous potassium carbonate, the corresponding amount of sodium 4-cyanophenolate was used, and that chlorobenzene was used as solvent instead of methyl isobutyl ketone. The same result was achieved as in the above examples.

Example 4

50 parts of 0,0-dimethyl-0-(4-cyanophenyl.i-thiophosphate) were combined with 40 parts of "Triton X-100" (a polyethylene glycol nonylphenyl ether) and 10 parts of xylene, in the order indicated, whereby a smooth, emulsifiable ,concentrate. Rice plants were, 20 days after their sowing, transferred to Wagner pots with a surface area of 1/50,000 of 10 ar, with 4 plants in each pot. After 2 months these plants were infested with rice stem borers, and 3 days after these pests had developed, 10 ml of an emulsion diluted to 1/1000 was showered on each pot

of the above-mentioned 50 percent concentrate. Practically 100 per cent of the borers that tried to crawl into the stems were killed within 3 days.

Example 5

1 1/2 parts of 0,0-dimethyl-O-(4-cyanophenyl)-thiophosphate was dissolved in acetone and the solution was thoroughly mixed with 98.5 parts of talc of 200 mesh particle size. By evaporating the solvent, a pollination preparation was obtained which contained 1.5 percent active substance. On rice plants, rice borer eggs were applied under the same conditions as in example 1 and 3 days after the development of the eggs, the pot was placed in the pollination apparatus, showered with 0.2 g of the relevant dust, taken out again after 30 minutes, and given then hold off. Practically 100 percent of the larvae that tried to crawl into the stem were killed within 3 days. Example 6 30 parts of 0,0-dimethyl-O-(4-cyanophenyl)-thiophosphate and 10 parts of "Triton X-100" were mixed thoroughly and the mixture was added dropwise to 60 parts of talc of 200 mesh particle size in a ball mill, whereby a wettable powder was obtained. In a similar way as in example 1, eggs of the rice stem borer were applied to rice plants, and 3 days after the eggs had developed, per pot on-showered 10 ml of a 1/600 aqueous suspension of the aforementioned wettable powder. Practically 100 per cent of the borers, which tried to crawl into the stems, were killed within 3 days. Example 7 1 1/2 parts of 0,0-dimethyl-O-(4-cyanophenyl)-thiophosphate was dissolved in 20 parts of "Versicol AR-50" (an aromatic hydrocarbon solvent) and to the mixture was added 78.3 parts "Deobase" (deodorized hydrocarbon solvent) whereby an oily preparation was obtained. When 66 ml of this oil was showered on 1 m2 of a favorable fly hatching site, e.g. on a waste heap, almost 100 per cent of the fly larvae at this site were killed within 48 hours.

Claims (1)

Insecticidal preparation containing an inert carrier, characterized in that it contains 0,0-dimethyl-O-(4-cyanophenyl)thiophosphate as the essential active ingredient.