IL35356A - 0,0-dialkyl-thionophosphoric acid esters and their use as insecticides - Google Patents

Description

35356/2 Kew 0,O-dialkyl-thionophosphoric acid esters and their use as insecticides 55356/5 - la - The present Invention relates to new and v lu ble O,0-dialkylthiono¾hoephoric esters and insecticides containing these compounds.

It is known from Belgian late t Ho. 609,209 to use dithio hosphoric esters as insecticides? however, their action is not satisfactory.

We have now found that 0, 0-dialkylthionop osphoric esters having the formula A R R1 3( I'-^ «2 - 0 - S (A) " w If C»0 A'" 1 2 where It and E are identical or different and each A denotes a lower alkyl radical, R denotes hydrogen, lower alkyl or aryl and R denotes lower alkyl, lower alkenyl, cycloalkyi, lower alkoxyalkyl, lower alkylthioalkyl, haloalkyl, lower alkoxycarbonyje h l or aryl optionally substi u ed with halogen, trifluoromethyl, nitro and/or alkyljhave a good insecticidal action.

The new active ingredients may "bo prepared by reacting 0,0-di- 55356/2 alkylthionophosphoric ester halides having.the formula where R has the above meanings and Hal denotes a halogen atom, with urazoles having the formula where R "^¾ and R 4 have the above meanings.

T tional manner (v. C.A-.55* 22298 as follows: —NH— Hg + C0(0C2H5)2 R —N—NH2 + C2H50H COOC2H5 -N=C=0 — NH «c c=o II 0 HN C0H,- n> 2"5 R base (CH,ONa) ·.—> ■N——N f 0=C C-ONa + CH,OH + 0 Ηκ0Η III The corresponding hydrazocarboxylic ester, to which isocyanate is added on and which is subsequently cyclized with a suitable base, is thus obtained from the hydrazine component with diethyl carbonate.

The substituted of the hydrazine component denotes 3 lower alkyl or aryl and R in the isocyanate denotes lower - alkyl «ni i n«p ai knyyl . The aromatic may be substituted by severai different groups selected from those listed.

The active ingredients are preferably produced in the presence of acid binding agents; suitable agents are alkali metal carbonates, alkali metal alcoholates, alkali metal hydroxides and organic bases. Another preferred method consists in reacting the alkali metal salts of the urazoles mentioned above with thionophosphoric ester chlorides of the above formula. The reaction is advantageously carried out in an inert organic solvent at a moderate (30° to 100°C) temperature.

Ketones, benzene, dioxane, toluene, nitriles such as acetonitrile, propionitrile, dimethylformamide and esters of organic acids have proved to be particularly suitable as solvent. The yield may be increased by heating and stirring the mixture for a fairly long time at the recommended temperature after the starting materials have been mixed. The thjcnophosphoric ester chlorides used as starting materials are known in the art. Owing to the large number of suitable isocyana-tes and hydrazines, many differently substituted urazoles may be obtained whose phosphoric esters have excellent insecticidal properties.

The new thionophosphoric esters are usually colaless to yellow oils which are insoluble in water and are difficult to distil, even at a substantial subatmospheric pressure, without any decomposition occuring. They have an excellent action on a plurality of insect pests (aphids, mosquits larvae, caterpillars, houseflies), and some of them have a low toxicity on warm bloods. Because of their excellent insecticidal properties the active ingredients are most suitable as pesticides in the plant protection field.

The production of the compounds is illustrates below with reference to examples: The urazoles described in the literature are predominancy those having aromatic substituents . Cyclization in accordance with equation (III) is therefore usually carried out in aqueous systems with caustic with urazoles bearing only aliphatic substituents, as these urazoles ^ dissolve very readily in water.

The process for cyclizing type II compounds has therefore been modified. The sodium salts of the type III urazoles may be obtained directly in pure form by slowly adding a methanolic solution of the stoichiometric amount of technical grade sodium methylate or 50$ aqueous caustic soda solution to a boiling solution of II in 98$ ethanol. After a short reaction time, the urazole salt III is precipitated upon cooling, either directly or after benzene has been added. Where no spontaneous crystallization of the salts occurs, the solution may be concentrated or evaporated to dryness since the reaction proceeds almost quantitatively. The urazole salts obtained by this procedure are usually sufficiently pure for subsequent phosphorylation.

Preparation of the sodium salt of 2-methyl-4-allyl-l,2,4-triazolidine-dione-3, 5 CH-.-N N 0=C C-ONa CH2-CH=CH2 59 parts by weight of ethyl methylhydrazinecarboxylate is dissolved in 150 parts of benzene; 0.5 part of triethylamine is added and 5· 7 parts of allyl isocyanate in 50 parts of benzene is dripped in. The reaction proceeds exothermically and, to complete the reaction, the mixture is stirred for a further hour at 60°C. After removal of the benzene, the oily residue is taken up in 150 parts of ethanol and 85 parts of 3~ % by weight methanolic sodium methylate solution is dripped in. The whole is subsequently stirred for an hour at 60°C, after which the solvent is removed. The powdered product is completely freed from solvent by treatment in a rotary evaporator for an hour at 60°C.

Yield: 95$ of the theory, m.p. 235°-248°C.

The invention is illustrated by way of the following examples EXAMPLE 1 Preparation of 0, 0-diethyl-0- £Ί, 4-dimethyl-l, 2, 4-triazolon- ( 5) -yl-(3)7-thionophosphate 22.6 parts by weight of the sodium salt of l,4-dimethyl-l,2,4-tri-azolidinedione-3, 5 is suspended in 150 parts of acetonitrile. While stirring thoroughly, 284 parts of diethylthionophosphoryl chloride is added at 50°C over a period of 5 to 10 minutes. The mixtures is then boiled under reflux for 5 hours. The end of the reaction is easily detectable by the change from the initial coarse suspension to a very finely divided suspension of precipitated sodium chloride. Without previous separation of the sodium chloride (extremely difficult to filter off as a result of the fine dispersion), the reaction mixture is evaporated at 6o°C in a rotary evaporator using a water jet vacuum and the oily residue is taken up in 300 parts of benzene. The solution is washed once with 50 parts of saturated aqueous sodium hydrogen carbonate solution and twice with 50 parts each time of 3 aqueous sodium hydrogen carbonate solution, after which the solution is dried over anhydrous sodium sulfate. After evaporation in a rotary evaporator under a water jet vacuum and devolatilization for 2 hours under an oil pump vacuum (approx. 0.5 mm) at 90°C, there remains 0 parts (71,>% yield) of a pale yellow oil having a refractive index Analysis (in ) C H P S Calc . % 34.2 5°7 11.0 11.4 Found: 34.Ο 5-9 10.6 11.6 LD = 50 mg/kg of rat EXAMPLE 2 Preparation of 0, O-dimethyl-0- /l,4-dimethyl-l, 2, 4-triazolon- (5) -yl-(3)J -thionophosphate )2 22.6 parts of the sodium salt of l,4-dimethyl-ls2s4-triazolidinedione-3,5 is suspended in 150 parts of anhydrous benzene. After an addition of Ο.26 part of finely powdered C Cl2«2H20, 24.1 parts of dimethyl-thionophosphoryl chloride is added at 50°C over a period of 10 minutes and while stirring thoroughly. The whole is then stirred for 4 hours at 50°C and subsequently boiled for 6 hours under refluy. The reaction mixture is worked up as described in Example 1. After de-volatilization for 2 hours under an oil pump vacuum (0.5 mm) at 90°C, there remains 14.5 parts (a yield of 38.2 ) of a pale yellow oil hav-ing a refractive index nn 2C D = I.506O Analysis (in c H N P S Calc . : 28.4 4.7 I6.6 12.2 12.7 Pound : 28.4 4.9 I7.O 11.5 I2.5 EXAMPLE Preparation of 0, C-diethyl-0- fi-phenyl-1, 2, -triazolon- (5) -yl- (3)]-thionophosphate -4 parts of 4-phenyl-l,2,4-triazolidinedione-3,5 is suspended in 1 0 parts of methanol. While stirring and cooling with ice, 35.4 parts rotary evaporator there remains a crystalline mass of the monosodium salt of 4-phenyl-l, 2, 4-triazolidinedione-3, which is suspended in 200 parts of acetonitrile . While stirring thoroughly, 37-8 parts of dieth lthionophosphoryl chloride is dripped in at room temperature and the whole then boiled under reflux for 5 hours. The reaction mixture is worked up as described in Example 1. There is obtained 42 parts of a turbid oil from which crystals separate out after standing for 3 days. After diluting with 25 ml of benzene, suction filtering and washing twice with benzene, l4„7 parts (a yield of 22.3$) of a crystalline substance having a melting point of 110° to 111°C is obtained. Analysis reveals the substance obtained to be the desired phosphorylation product.

Analysis C H N P S Calc: 3.8 4.9 12.8 9- .9.7 Found: 44.1 5.0 12.9 9-6 9.8 The compounds listed below may be prepared analogously; in all cases the substances are fairly thin oils which even under a high vaccum cannot be distilled without decomposition occuring.

Compounds having the general formula: No. R f R R^ R* nD 1 ~C2H5 CH, H I.497I 3 2 -C2H5 CH, CH, 3 I 3 .4905 3 C2H5 CH, 1.4858 3 4 _C2H5 CH^ 1.4850 C3H7 - _C2H5 CH, 1.4841 iC3H7 3 6 -C2H5 C4H9 CH^ 1.4838 -° H sec-C H H, 4 O.Z. 26,393 I.5 91 -C2H5 3 CH, 1,4802 -C2H5 3 · 1C3H7 1.4755 "C2H5 C2H5 iC3H7 I.4720 _C2H5 1C3H7 iC3H7 1,4750 -C2H5 C4H9 iC3H7 -CH2-C00-C2H5 CH^ 1.4842 -C2H5 CH, CH, CH, I.5060 CH, CH, I.4944 C3H7 ■CH2-CH2C1 CH, 1,4970 C2H5 (CH2)5-0-CH5 CH, 1,4869 C2H5 . . , C2H5 CH, 1.5040 -CH CH, 1.500 C2H5 CH2-C1 CH, t 3 HC≡C-C- CH, 1.4902 C2H5 t CH, 3 CH, » 3 HC=C-C- CH, I.492I C2H5 C2H5 CH, Br-CH C- C2H5 CH, CH, CH C1 C1-H C-C- CH, C2H5 CH2C1 No. R- R CH, I 3 44 H,C-CH-CH-CH -CH, C2H5 3 2 3 51 C2H5 H5C-CH2-?C¾-CH=CH2 CH^ The insecticides according to the invention may be used as solutions, emulsions, suspensions or dusts. The form of application depends entirely on the purpose for which the agents are being used; in any case it should ensure a fine distribution of the active ingredient .

For the preparation of solutions to be sprayed direct, hydrocarbons such as tetrahydronaphthalene, and alkylated anphthalenes may be used as spray liquids.

Aqueous formulations may be prepared from emulsion concentrates, . . , Concentrates which are suitable for dilution with water may be prepared from active ingredient, emulsifying or dispersing agent and possibly solvent.

Dusts may be prepared by mixing or grinding the active ingredients with a solid carrier.

The following examples demonstrate the excellent insecticidal action of the new active ingredients.

For comparison purposes, the compound described in Belgian Patent No. 609, is used.

The active ingredient numbers corre¾)ond to those given inlhe above table.

EXAMPLE 4 Adult oriental cockroaches (Blatta orientalis) are placed in 1 liter jars whose inside walls have been wetted with the solutions of the active ingredients. The action is determined after 48 hours.

Active ingredient Lowest effective amount in mg of active ingredient per jar A 2.5 1 0.5 2 0.1 0.1 4 0.1 0.05 6 0.5 7 0.05 8 0.1 9 0.1 Active ingredient Lowest effective amount in mg of active ingredient per jar 12 1.0 13 0.1 14 0.25 0.05 17 0.1 19 CT.25 0.25 24 0.5 0.5 26 0.5 27 1.0 28 1.0 29 0.25 21 0.25 31 0.25 32 0.25 EXAMPLE 5 Action on mosquito larvae (Aedes aegypti) Mosquito larvae in the fourth larval stage are exposed to the action of aqueous emulsions of the active ingredients. The concentration (in ppm) of the active ingredient in water is the amount achieving a larvae kill rate of more than 90$.

Active ingredient Concentration of the active ingredient in ppm A 1.0 1 0.2 2 0.1 3 0.25 Active ingredient Concentration of the active ingredient in ppm 7 0.25 8 0.25 9 0.25 0.5 11 0.25 12 0.25 13 0.05 0.25 26 0.5 27 0.5 29 0.5 31 0.5 32 0.25 EXAMPLE 6 1 mnr of the acetonic solution of the active ingredients is administered to the ventral abdomen of houseflies (Musca domestica) under C02 narcosis.

The may be calculated from the results obtained by using different concentrations of the active ingredients in acetone. The mortality after 4 hours is taken as a basis.

Active ingredient LD,-A A 1.0 7 fiy 2 0.1 F/fiy 3 0.33 4 0.45 6 0.3 /fly 7 0.3 fiy Active ingredient LD50 0.6 3*/fly 0.45 fly 0.08 ?/fly 0.5 ^fiy 35356/2

Claims (1)

1. CLAIMS Phosphoric esters having the general formula where and 2 are identical or and each denotes a lower denotes lower alkyl or and denotes lower lower lower lower lower or aryl optionally substituted with t nitro An insecticide comprising phosphoric ester of formula in Claim An insecticide a solid or liquid carrier and a phosphoric ester of formula in A process producing an insecticide wherein a solid or liquid carrier is mixed with a phosphoric of formula in Claim A process for controlling insects wherein the insects are treated with an inaecticidal amount of a phosphoric ester of the general formula in insufficientOCRQuality