DE1176653B - Process for the production of (thiono) phosphonic (- in -) - acid esters - Google Patents

Description

Process for the preparation of (thiono) phosphonic (- in -) - acid esters It has been found that (thiono) phosphonic (- in -> acid 4-nitrophenyl ester of the general formula which is substituted by a methyl group in the 3-position of the phenyl radical) have excellent insecticidal effectiveness and are therefore extremely suitable as pesticides.

In the above formula, R1 denotes a lower alkyl radical; R2 stands represents a lower alkyl or alkoxy group, where R1 and R2 are the same as or from one another can be different.

These (thiono) phosphonic (- in -) - acid esters are prepared in a manner known per se by reacting alkylphosphonic acid or thionophosphonic acid O-alkyl ester halides or dialkylphosphinic acid or dialkylphosphinic acid halides of the general formula in which R1 and R2 have the meaning given above, while Hal stands for a halogen, preferably a chlorine atom, with 3-methyl4-nitrophenol in the presence of acid-binding agents, e.g. B.

Alkali carbonates, or with a corresponding alkali or ammonium phenate.

The reaction is expediently carried out in inert organic solvents carried out. As such, aromatic hydrocarbons such. B. benzene, toluene or chlorobenzene and aliphatic ketones, especially methyl ethyl ketone proven.

Furthermore, it is advantageous to achieve good yields that Reaction according to the invention at a slightly to moderately elevated temperature, preferably 50 to 100 "C, to perform and then the reaction mixture about 2 to Post-heating to the stated temperature for 3 hours.

The products of the process are generally colorless to pale colored viscous parts, some of which distill in a high vacuum without decomposition permit. In some cases, however, solid crystallized compounds with sharp Melting point obtained by recrystallization from suitable solvents or solvent mixtures can easily be further purified.

From the German patent specification 1 026 323 are already those according to the invention Compounds analogous 0,0-dialkylthiono - thiolphosphoric acid-S-phenyl ester known. Furthermore, in German Patent 1,050,768, phenylthionophosphonic acid O-alkyl-O-phenyl esters described whose phenyl radical is substituted by halogen atoms and / or nitro groups is.

Compared to the thiophosphoric acid or thiophosphonic acid derivatives known from the publications mentioned, however, the process products are distinguished by significantly better insecticidal properties. This unexpected technical superiority of the (thiono) phosphonic (- in -) - acid esters which can be prepared according to the process is evident from the results of comparative experiments compiled in the following table: Comparative experiments Biological effectiveness Active ingredient constitution Active ingredient killing Application against application against concentration of pests in 01o in 0! o Aphids 0.0001 40 1 NO2 4 OP aphids 0.0001 40 oC2115 spider mites 0.001 100 CH3 (according to the invention, example 3) 5 2 || xOC2H5 aphids 0.1 90 2 to \ O {0 NO, spider mites 0.01 Cl (known from German exposition 1 050 768, example 3) 5 3 o2.N / \ o {I ZCH3 Aphids 0.001 80 XF \ OC2H5 spider mites 0.0001 100 CH (according to the invention, example 2) 5 4 OzN - 1) / OCzHs 4 02N <P - \ OC2H5 spider mites 0.1 100 (known from German exposition 1 026 323, example 1) Due to their excellent insecticidal effectiveness, the (thion o) phosphon - (- in -) - acid 3-methyl-4-nitrophenyl esters which can be prepared according to the invention are, as already mentioned above, mainly used as pesticides in crop protection.

example 1 A mixture of 30.5 g (0.2 mol) of 3-methyl-4-nitrophenol (melting point 1300C), 56 g (0.4 mol) of powdered potassium carbonate and 200 ml of methyl ethyl ketone is heated to 60 to 70 for 30 minutes with stirring "C., 29 g (0.2 mol) of M ethyl-thionophosphonic acid-O-methyl ester chloride are then added dropwise at this temperature to the reaction mixture, which is then heated to 70 to 80 ° C. for 2 hours to complete the reaction. After the mixture has cooled the precipitated salts are suctioned off and washed with 250 ml of benzene. The filtrate is washed with water until the former is no longer yellow in color. After drying the benzene solution over sodium sulfate and distilling off the solvent, 26 g (500 in theory) of the methyl thionophosphonic acid are obtained. O - methyl - O - (3 - methyl-4-nitrophenyl) ester in the form of a light brown ole.

The mean toxicity of the compound is per os in rats (DL .; ") about 5 mg per kilogram of animal.

Example 2 As described in the previous example, 30.5 g (0.2 mol) of 3-methyl-4-nitrophenol (melting point 130 ° C.) are heated together with 56 g (0.4 mol) of powdered potassium carbonate in 200 ml of methyl ethyl ketone for 30 minutes 60 to 70 ° C., 32 g (0.2 mol) of methyl thionophosphonic acid O-ethyl ester chloride are then added dropwise to the reaction mixture at this temperature and the latter is then heated to 70 to 80 ° C. for a further 2 hours. After working up in the manner described in the preceding example, 47 g (85.5% of theory) of methylthionophosphonic acid O-ethyl-0- (3-methyl-4-nitrophenyl) ester are obtained as a pale yellow UI of bp. o, ol 105 "C. The mean toxicity of the compound on the rat per os is 2.5 mg per kilogram of animal.

Example 3 A mixture of 46 g (0.3 mol) of 3-methyl-4-nitrophenol, 46 g (0.33 mol) of potassium carbonate and 300 cc of methyl ethyl ketone is heated to 50 to 60 ° C. for half an hour. Then it is added dropwise at this temperature Add 52 g (0.3 mol) of ethylthionophosphonic acid-O-ethyl ester chloride to the reaction mixture and heat it to 50 to 600 ° C. for 2 hours. It is then dried over sodium sulfate until it is colorless, the solvent is distilled off and the residue is fractionated "C as a light yellow ul over. Yield 50 g, corresponding to 86.30 / 0 of theory.

Average toxicity: 2.5 mg per kilogram rat after oral administration. 0.001% solutions of the ester kill aphids and spider mites 1000%.

Example 4 46 g (0.3 mol) of 3-methyl-4-nitrophenol are heated together with 46 g (0.33 mol) of potassium carbonate in 300 cc of methyl ethyl ketone for half an hour at 60 ° C. The mixture is then added dropwise at this temperature 53 g (0.3 mol) of ethylthionophosphonic acid O-methyl ester chloride. After the reaction mixture has been heated to 50 ° C. for 2 hours, it is allowed to cool, the precipitated salts are filtered off with suction and the latter is washed with 250 cc of benzene. The filtrate is first washed with water, then washed once with 2N sodium hydroxide solution and finally again with water until it reacts neutral. The organic phase is then dried over sodium sulfate and finally the solvent is distilled off. 75 g (90.80% of theory) of the ethylthionophosphonic acid O-methyl-043-methyl-4-nitrophenyl ester remain in the form of a red-brown, viscous ole.

The ester has an average toxicity of 5 mg per kilogram of rat, applied orally. Aphids and spider mites are with 0.01%, caterpillars with 0.1 Above solutions of the compound 1000% killed.

Example 5 A mixture of 30.5 g (0.2 mol) of 3-methyl-4-nitrophenol, 56 g (0.4 mol) of potassium carbonate and 500 cc of chlorobenzene is heated to 80 to 90 ° C. for half an hour, then added dropwise at this point Temperature 26 g (0.2 mol) of methyl-phosphonic acid-O-methyl ester chloride to the reaction mixture and then heated to 90 ° C. for a further 2 hours. After the mixture has cooled down, the precipitated salts are filtered off with suction. The solvent is distilled off from the filtrate in vacuo, the UI that remains is taken up in benzene, the benzene solution is first washed with water, then with sodium bicarbonate solution, and finally with water again until the reaction is neutral, it is dried over sodium sulfate and obtained after the solvent has been distilled off 27 g (55% of theory) of the methyl-phosphonic acid-O-methyl-O- (3-methyl4-nitrophenyl) ester as a yellow, viscous Ul.

Average toxicity of the compound: 2.5 mg per kilogram of rat oral application. Aphids are treated with 0.01% solutions of the ester 1000% killed and spider mites destroyed with 0.00010% solutions to 600/0.

Example 6 76 g (0.5 mol) of 3-methyl-4-nitrophenol are dissolved together with 45 g of finely powdered potassium carbonate in 250 cc of methyl ethyl ketone. 65 g (0.5 mol) of dimethylthionophosphinic acid chloride are added to this solution at 60 ° C. with stirring, the reaction mixture is then stirred for a further 1 hour at 60 to 70 ° C. and then poured into 300 cc of ice water. The oily product which has separated out is taken up in benzene, the benzene solution is separated off and dried with sodium sulfate. After the solvent has been distilled off, the O- (3-methyl-4-nitrophenyl) dimethylthionophosphinic acid solidifies to give colorless crystals of melting point 68 ° C. Yield 60 g (490/0 of theory).

The mean toxicity of the compound in the rat orally is 1000 mg per kilogram of animal.

Aphids are destroyed with 0.01 above, spider mites and caterpillars with 0.1 above solutions of the ester 1000 / oig. Example 7 In a mixture of 76 g (0.5 mol) of 3-methyl-4-nitrophenol, 75 g of finely powdered potassium carbonate and 250 ccm of methyl ethyl ketone, 79 g (0.5 mol) of ethylphosphonic acid O-ethyl ester chloride are added dropwise at 50 ° C. with stirring , the reaction mixture is then heated to 50 ° C. for 1 hour, the precipitated salts are then filtered off with suction and the mixture is poured into 400 cc of ice water. The deposited oily fraction is taken up in 200 cc of benzene, the benzene solution is washed several times with water and dried over sodium sulfate. In the subsequent fractional distillation, after evaporation of the solvent, 55 g (430/0 of theory) of ethyl-phosphonic acid-O-ethyl-O- (3-methyl-4-nitrophenyl) ester of boiling point 118 ° C. are obtained .

The mean toxicity of the compound (Das) is in the rat orally 10 mg per kilogram of animal.

Example 8 76 g (0.5 mol) of 3-methyl-4-nitrophenol are suspended in 250 cc of methyl ethyl ketone with the addition of 75 g of potassium carbonate. 87 g (0.5 mol) of ethylthionophosphonic acid O-ethyl ester chloride are added dropwise to this suspension with stirring at 60.degree. C., the mixture is then heated to 60 to 65.degree. C. for a further hour and then worked up as described in the previous example. Yield : 65 g of ethylthionophosphonic acid O-ethyl-O- (3-methyl - 4 - nitrophenyl) ester.

The compound has a moderate toxicity in the rat per os of 10 mg per kilogram of animal.

Claims (1)

Claim: Process for the production of (thiono) phosphonic (- in -) - acid esters, d a d u r c h e k e n n n -z ei c h n e t that alkylphosphonic acid resp. - thionophosphonic acid - 0 - alkyl ester halides or dialkylphosphinic acid or thionophosphinic acid halides of the general formula in which R1 is a lower alkyl radical and R2 is a lower alkyl or alkoxy group, while Hal stands for a halogen atom, with 3-methyl-4-nitrophenol in the presence of an acid binder or with a corresponding alkali metal or ammonium phenolate in a manner known per se Compounds of the general formula converts, where R, and R2 have the meaning given above. Considered publications: German Patent Specifications No. 814 152, 1,768; U.S. Patent Nos. 2,503,390, 2,668,845; Recueil des Travaux Chimiques des Pays-Bas, 78, 1959, pp. 271-274.