IL34667A - N-isopropyl-o-ethyl-o-phenylphosphoric acid ester amides,their preparation and their use as nematocides - Google Patents

Description

K-is©propyi-0-e hyl- -.phei3ylp¾M5sphori© sold ester aaiaee, their preparation, and their use as nesiatoeides The present invention relates to certain new N-iso-propyl-0-ethyl-O-arylphosphoric acid ester amides which possess outstanding nematocidal properties, and also possess insecticid-al and acaricidal properties, to a process for their preparation, and to their use.

It is known that 0-alkyl-O-phenylphosphoric acid ester amides, for example 0-isopropyl-0-(3-methyl-4-methylmer-captophenyl) -phosphoric acid ester amide, 0-methyl-0-(3-methyl-4-methylmercaptophenyl)-N-methylthiophosphoric acid ester amide and N,N-dimethyl-0-methyl-0-(3-methyl-4-mercaptomethylphenyl)-thiophosphoric acid ester amide are effective as contact and systemic insecticides. On the other hand, 0,0-dialkyl-O-aryl-thionophosphoric acid esters, such as 0,0-diethyl-0-(2,4-di-chlorophenyl)-thiophosphoric acid ester, exhibit a good nemato-cidal activity [cf. DAS (German Published Specification) 1,121,882 and U.S. Patent Specification 2,761,806].

The present invention provides N-isopropyl-O-eth l-O-phenylphosphoric acid ester amides of the formula in which n is 1 or 2.

These compounds have been found to possess strong nematocidal, in particular soil-nematocidal, properties.

The invention also provides a process for the production of a N-isopropyl-O-ethyl-O-phenylphosphoric acid ester amide of the formula (1) in which a N-isopropyl-O-ethylphos-phoric aci is reacted, in the presence of an acid-binding agent, with a 3-meth l-4-meth lsulphoxyl- or -4-methylstilphonyl-phenol of the formula In the above formulae, n has the meaning stated above, while Hal stands for halogen, preferably chlorine or bromine.

Surprisingly, the N-isopropyl-0-eth l-O-phenylphos-phoric acid ester amides of the invention are distinguished by a considerably higher nematocidal activity than the known 0,0-dialkyl-0-(2,4-dichlorophenyl)-thionophosphoric acid esters of analogous constitution and the same direction of activity. The substances according to the invention therefore represent a genuine enrichment of the art.

If N-isopropyl-O-ethylphosphoric acid ester amide chloride and 3-methyl-4-methylsulphonylphenol are used as starting materials, the reaction course can be represented by the following formula scheme: i-C The starting materials to be used according to the process are clearly defined generally by the formulae (2) and (3) The phosphoric acid ester amide halides (2) are known from the literature and are readily accessible, even on an industrial scale, according to customary methods, while 3-methyl-4-methyl-sulphoxyl- or -sulphonyl-phenol (3) can be prepared by oxidation with hydrogen peroxide under suitable reaction conditions.

The preparative process is preferably carried out in the presence of a solvent (this term includes a mere diluent). As such, all inert organic solvents are suitable. Preferred examples include aliphatic and aromatic (possibly chlorinated) hydrocarbons, such as benzine, benzene, toluene, xylene and chlorobenzene ; ethers, such as diethyl ether, dibutyl ether and dioxan; ketones and nitriles, such as acetone, methyl-ethyl ketone, methylisopropyl ketone, meth lisobutyl ketone, acetonitrile and propionitrile.

The reaction temperatures can be varied within a fairly wide range. In general, the reaction is carried out at 20 to 120°C, preferably at 50 to 90°C.

The reaction is, in general, carried out under normal pressure and, as already mentioned, in the presence of an acid acceptor. As such, all customary acid-binding agents are suitable. Particularly suitable have proved to be alkali metal carbonates and alcoholates, such as sodium and potassium carbonate or methylate and eth late; further, aliphatic, aromatic and heterocyclic amines, for example trieth lamine, dimeth laniline, dimeth lbenz lamine and pyridine.

When the process is being carried out, the reactants may be reacted in equimolar proportion in one of the above-mentioned solvents in the presence of the acid acceptor at the stated temperatures. After the reactants have been combined, the mixture is stirred for a further 2 to 4 hours, then poured into water, extracted with an inert hydrocarbon, preferably benzene, the organic phase is separated and dried and the solvent is distilled off.

The products according to the invention are, as already mentioned above, distinguished by outstanding nemato- cidal properties with only slight toxicity to warm-blooded animals. They may therefore he used for the control of nematodes, particularly those of phytopathogenic nature.

These include, in the main, leaf nematodes (Aphelen-choides), such as the chrysanthemum foliar nematode (A. ritze-mabosi), the strawberry nematode (A.fragariae) and rice nematode (A. oryzae); stem nematodes (Ditylenchus) , e.g. the stem nematode (D. dipsaci) ; root gall nematodes (Meloidogyne) , such as M. arenaria and M. incognita; cyst-forming nematodes (Heter-odera), for example the golden nematode of potato (H. rosto-chiensis) and the sugar beet nematode (H. schachtii) ; and free-living root nematodes, e.g. of the genera Pratylenchus, Paratyl-enchus, Rotylenchus, Xiphinema and Radopholus.

In addition, the new compounds of the invention have good insecticidal, acaricidal and systemic properties, with only slight phytotoxicity.

The active compounds according to the present invention can be converted into the usual formulations, such as solutions, emulsions, suspensions, powders, pastes and granulates. These may be produced in known manner, for example by mixing the active compounds with extenders, that is, liquid or solid diluents or carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing agents. In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents.

As liquid diluents or carriers, there are preferably used aromatic hydrocarbons, such as xylenes or benzene, chlorinated aromatic hydrocarbons, such as chlorobenzenes, paraffins, such as mineral oil fractions, alcohols, such as methanol or butanol, or strongly polar solvents, such as dimethyl formamide or dimethyl sulphoxide, as well as water.

As solid diluents or carriers, there are preferably chalk, or ground synthetic minerals, such as highly-dispersed silicic acid or silicates.

Preferred examples of emulsifying agents include non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylarylpolyglycol ethers, alkyl sulphonates and aryl sulphon-ates; and preferred examples of dispersing agents include lignin, sulphite waste liquors and methyl cellulose.

The active compounds according to the invention may be present in the formulations in admixture with other active compounds.

The formulations contain, in general, from 0.1 to 95, preferably 0.5 to 90, per cent by weight of active compound.

The active compounds may be used as such or in the form of their formulations or of the application forms prepared therefrom, such as ready-to-use solutions, emulsifiable concentrates, emulsions, suspensions, spray powders, pastes, soluble powders, dusting agents and granulates. Application may take place in the usual manner, for example by watering, spraying, atomising, vaporisation fumigation, scattering, dusting, etc.

The invention therefore provides a nematocidal composition containing as active ingredient a compound according to the invention in admixture with a solid diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent.

The invention also provides a method of combating nematodes which comprises applying to the nematodes or a habitat thereof a compound according to the invention alone or in the form of a composition containing as active ingredient a compound according to the invention in admixture with a solid or liquid diluent or carrier.

The invention also provides crops protectee from ''ninaf by nematodes by being grown in areas in which, immediately prior to and/or during the time of the growing, a compound according to the invention was applied alone or in admixture with a solid or liquid diluent or carrier.

The invention is illustrated by the following Examples.

Example A.

Critical concentration test Test nematode: Meloidogyne incognita Solvent: 3 parts by weight acetone Emulslfier: 1 part by weight alkylaryl polyglycol ether To produce a suitable preparation of active compound, 1 part by weight of active compound is mixed with the stated amount of solvent, the stated amount of emulsifier is added and the concentrate is diluted with water to the desired concentration.

The preparation of active compound is intimately mixed with soil which is heavily infested with the test nematodes.

The concentration of the active compound in the preparation is of practically no importance; only the amount of active compound per unit volume of soil, which is given in p.p.m. , is decisive. The soil is filled into pots, lettuce is sown in and the pots are kept at a greenhouse temperature of 27 °C. After 4 weeks, the lettuce roots are examined for infestation with nematodes, and the degree of effectiveness of the active compound is determined as a percentage. The degree of effectiveness is 100 when infestation is completely avoided; it is O when the infestation is exactly the same as in the case of the control plants in untreated soil which has been infested in the same manner.

The active compounds, the amounts applied and the results can be seen from Table A.

Example 1, 75 g potassium carbonate and 93 g N-isopropyl-O-ethyl- phosphoric acid amide chloride are added to 85 g 3-ciethyl-4- methylsulphoxylphenol in 500 ml acetonitrile. After 3 hours' stirring at 600C, the mixture is poured into water and extracted with benzene, and the benzene phase is separated and evaporated.

The yield of N-isopropyl-0-ethyl-0-(3-meth l-4-methylsulphoxyl-phenyl)-phosphoric acid ester is 100 g (63° of the theory). The refractive index is 19 = 1.5274.

Example 2. 75 g potassium carbonate and 93 g N-isopropyl-O-ethyl-phosphoric acid amide chloride are added to 93 g 3-methyl-4-methylsulphonylphenol in 500 ml acetonitrile. The mixture is then heated to 60 to 70°C for 3 hours, poured into water and extracted with benzene, and the benzene phase is separated, dried and evaporated. The yield is 140 g. The N-isopropyl- 0-ethyl-0-(3→aethyl-4-methylsulphonylphenyl)-phosphoric acid ester melts at 77°C The 3-methyl-4-methylsulphoxyl- or -sulphonyl-phenols required as starting materials can be obtained for example as follows : hydrogen peroxide are added, at 20 to 40°C, to 462 g 3-methyl-4-methlmercaptophenol dissolved in 1.2 1 of methanol and 15 ml of sulphuric acid.

The mixture is subsequently heated to 60°C for half an hour, and the sulphuric acid is neutralised with calcium carbonate then the mixture is filtered, the solvent is drawn off from the filtrate, and the residue is recrystallised. The yield is 380 g. The product melts at 123°C.

A solution of 200 ml of 35 -strength hydrogen peroxide in 200 ml glacial acetic acid is added, at 50 to 90°C, to 155 3-methyl-4-methylmercaptophenol in 400 ml glacial acetic acid. The mixture is subsequently heated to 90°C for 2 hours, the solvent is then drawn off and the residue is triturated with petroleum ether. The yield is 140 to 145 g. The melting point of the product is 107°C

Claims (14)

1. V/hat we claim is:- 1 . N-isopropyl-O-ethyl-O-phenylphosphoric acid ester amid es of the formula in which n is 1 or 2.

2. The compound of the formula

3. The compound of the formula

4. A process for the preparation of a N-isopropyl-O-ethyl-0-phenylphosphoric acid ester according to any of claims 1 -3 in which a N-isopropyl-O-ethylphosphori c acid ester amide halide of the formula is reacted , in th th a 3- methyl-4-methylsulphoxyl- or -sulphonylphenol of the iornula CH. in which n is 1 or 2, and Hal is halogen.

5. A process according to claim 4 in which Hal is chlorine or bromine.

6. Λ process according to claim 4 or 5 in which the reaction is carried out in the presence of a solvent.

7. A process according to any of claims 4-6 in which the reaction is carried out at 20 - 120°C.

8. A process according to claim 7 in which the reaction is carried out at 50 - 90°C.

9. A process according to any of claims 4 - 8 in which the acid-binding agent is one of those hereinbefore mentioned.

10. A process for the production of a compound accord: r.,- c claim 1 , substantially as hereinbefore described in iixar.ple 1 or 2.

11. Compounds according to claim 1 whenever prepared i>y a proce according to any of claims 4 - 10.

12. A nematocidal composition containing as active ingredient a compound according to any of claims 1 - 3 or 11 in admixture with a solid diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent.

13. A composition according to claim 12 containing from 0.1 to 5 of the active compound by weight.

14. A method of combating nematodes which comprises applying to the nematodes or a habitat thereof a compound accordin to any of claims 1 - 3 or 11 alone or in the form of a composition containing as active ingredient a compound according to rin of claims 1 - 3 or 11 in admixture with a solid or liquid diluent or carrier. 15· Crops protected from damage by nematodes by being grown in areas in which, immediately prior to and/or during the time of the growing, a compound according to any of claims 1 - 3 or 11 was applied alone or in admixture with a solid or liquid diluent or carrier. Le A 12 313 -13-