IL46427A - Phosphorothioates process for preparing the same and a soil fungicidal composition containing the same - Google Patents

Description

onianV ι·νπη #ο» τπ o»oK R»nliieeis OMK nV'aan nvnoa n oip ηοτκ nantfni NOVEL PHOSPHOROTHIOATES, PROCESS FOR PREPARING THE SAME AND A SOIL FUNGICIDAL COMPOSITION CONTAINING THE SAME This invention relates to a novel organic phosphoric acid ester compound represented by the formula, wherein and R^, which may be same or different, are individually a chlorine or bromine atom,, and^R^ is a methyl or ethyl group; to a. process for preparing the same; and to a soil fungicide containing said compound as an active ingredient.

Plant diseases derived from plant pathogenic fungi, which exist in soil to give great damage to agricultural and horticultural crops by infection, have heretofore been feared as a kind of the most difficultly controllable dieseases. Although several soil fungicides are being actually used to control said diseases, these fungicides have no sufficient controlling effects.

On the other hand, environmental pollution due to agricultural chemicals has come to be a serious problem in recent years, and there has strongly been desired the advent of agricultural chemicals which are less toxic to mammals and fishe-s-, do not show phytoto-xicity to crops, do not remain in crops and have sufficient controlling effects.

In consideration of the above-mentioned points the present inventors conducted extensive examinations from various viewpoints on organic phosphoric acid ester compounds. As the result, the inventors have been successful in developing entirely novel soil fungicides which show sufficient controlling effects, are markedly less toxic to mammals and fishe-s-, show no phytotoxicity to crops and do not remain in crops.

The compounds of the present invention have markedly excellent controlling effects on1 substantially all of soil-borne plant diseases such as damping-off and "Bakanae" disease of rice plants, damping-off of seedlings, and damping-off, Fusarium wilts, yellows, Verticillium wilts, southern blight, rot, late blight of agricultural and horicultural crops. At the same time, the compounds have actions to promote the spread of root portions of crops to make the growth of the crops vigorous, and particularly show prominent effects against damping-off of seedlings and foot rot of crops which are diseases derived from fungi belonging to the genus Rhizoctonia. It is needless to say that they have no phytotoxicity on every crop.

On the other hand, the compounds of the present ■ invention are extremely low in toxicity to warm-blooded animals such as mice, rats, dogs and chickens, and fishes. such as carps and gold-fishe-s-. Furthermore, the compounds scarcely remain in crops.

The above-mentioned facts indicate that the compounds of the present invention are ideal soil fungicides capable of promoting the growth of agricul- tural cro s without causin an environmental ollution.

The present inventors sufficiently examined in detail the soil-borne disease-controlling effects of many organic phosphoric acid ester compounds, but no effects of controlling soil-borne diseases could be seen even in those which were quite similar in structure to the present compounds.

The compounds disclosed in Australian Patent 29^·, 07? , which is a. prior art to the present invention, are relatively similar in chemical structure to the present compounds, but did not show any soil-borne disease-controlling effects (refer to Test Examples 1 , 2 and 3 ) · Further, 0-2 , ½ , 6-trichlorophenyl 0 , 0-dimethyl thiophosphate disclosed in United States i Patent 2 , 599 , 512 as parasiticides, which compound is quite similar to the present compounds, shows strong neurotoxicity to chickens, and hence cannot be a suitable soil fungicide. On the other hand, the present compounds show no neurotoxicity to chickens at all, and are extremely high in safety.

The excellent controlling effects and low toxicity of the present compounds are ascribable to such specific structure and substituents thereof as represented by the formula (I). the fact that In spite of/ there existing many organic phosphoric acid ester compounds hitherto, the present inventors ' have found that only the compounds represented by the formula (I) can show excellent effects of preventing soil-borne diseases. Thus, the present invention, which is based on the above finding, is not onl extremel hi h in inventive idea, but a s / entirely different from the prior art.

The present compounds can be prepared with ease and in high yields by reacting a 2,1+,6-trisub-stituted phenol represented by the formula, wherein R^ and R , which may be same or different, a.re individually a chlorine or bromine atom; M is a hydrogen atom, an alkali metal or an ammonium group; and R^ is a methyl or ethyl group, with 0 ,0-dimethylthiophosphoryl chloride preferably in the presence of an acid binding agent, or by reacting a. salt of said 2 ,*+,6-trisubstituted pnenol with 0 ,0-dimethylthiophosphoryl chloride.

The above-mentioned reaction is preferably carried out in an inert organic solvent, which may be any of, for example, aliphatic or aromatic hydrocarbon (including halides) such as benzene, toluene and chloroform; ethers such as diethyl ether, dioxane and tetrahydrofuran; and aliphatic alcohols and ketones such as methanol, acetone and methylisobutylketone .

Examples of the acid binding agent are sodium hydroxide; potassium hydroxide; alkali metal carbonates and bicarbonates such as potassium carbonat and sodium carbonates; sodium or potassium methylates and ethylates; and aliphatic, aromatic or heterocyclic tertiary ba.'ses such as pyridine, triethylamine and - Alternatively, the said reaction may be effected by converting the aforesaid 2,l+,6-trisubstituted phenol into a. salt, preferably an alkali metal or ammonium salt, and then reacting the said salt with 0 ,0-dimethylthiophosphoryl chloride.

Each of the above-mentioned reactions may be carried out at a temperature in a considerably broad range, but is ordinarily effected at 20° to 110°C. , preferably 70° to 100°C. The reactions may be represented by the following reaction scheme 1: Reaction scheme 1: wherein ^, R^, ^ and M are as defined previously.

Alternatively, the present compounds may be prepared by reacting the aforesaid 2,1+,6-trisubstituted phenol with phosphorus trichloride at an elevated temperature in the presence of an acid binding agent and an inert solvent, and then with thiophosphoryl trichloride at about room temperature in the presence of an inert solvent to form a 2,k ,6-trisubstituted phenyl thiophosphoryl dichloride., and then reacting the said dichloride with sodium or potassium methyla.te, or with methanol in the presence of a.n acid binding agent, in the presence of an inert solvent at a. temperature ranging from room temperature to the represented by the following reaction scheme Reaction scheme 2: + 2M'C1 wherein R- .^ and R^ are as defined above, and M' is a hydrogen atom or an alkali metal.

Further, the present compounds may be obtained also by reacting the a.foresaid 2 ^^-trisubstituted phenol with thiophosphoryl trichloride in the presence of an acid biding agent under cooling conditions to form a dichloride, and then reacting the said dichloride with sodium or potassium methylate, or with methanol in the presence of an acid binding agent, in the presence of an inert solvent at a temperature ranging from room temperature to the boiling point of the solvent. This reaction may be represented by the following reaction scheme 3: Reaction scheme 3* wherein R^, R^, R^ and M' are as defined in the reaction scheme 2.

Chemical structures and physical constants of the present compounds are as shown in Table 1.

Table 1 Compound Chemical Physical No. . structure constant S Cl CH 0 II \ (1) CHj0 -°-fo)-CH3 m-P- 79-79.5°C 3 Cl ' In actual application, the present compounds may be used as they are or in the form of any conventional prepa.rations such as granules ,' dusts , fine granules, . wettable powders and emulsifiable concentrates. In these, preparations , the present compounds may be contained, as active ingredients in an amount of 0.1 to about 90%, preferably 5 to 60%. It is desirable that these preparations are used properly according to their application purposes. The preparations may be applied by any such procedure as sprinkling, dusting, spraying, granule-sprinkling, soil-mixing, injection, irrigation, seed dressing and dipping, and prominent fungicidal effects of the prepa.rations can be displayed by adoption of suita.ble application procedure.

In formulating the above-mentioned preparations, there may be used any of solid carriers, liquid carriers and emulsifiers. Examples of the solid carriers include talc, bentonite, cla , kaolin, diatomaceous earth, vermiculite and slaked lime; examples of the liquid carriers include benzene, alcohols, acetone, xylene, dioxane, methylnaphthalene and cyclohexanone ; and examples of the emulsifiers include alkyl sulfuric acid esters, alkyl sulfonates, aryl sulfonates, polyethylene glycol ethers and polyhydric alcohol esters.

When the present compounds are used in admixture with one or more of other fungicides and the resulting compositions are applied in proper forms to soil, effects of controlling soil-borne diseases can be far more increased. Chemicals which can greatly increase the controlling effects when used in admixture with the present compounds a.re N-trichloro-methylthio tetrahydrophthalimide, sodium p-dimethyl-aminophenyl .diazosulfonate , 5-ethoxy-3-trichloromethyl-1,2 j^-thiadiazole, 5-methyl-3-hydroxy-l , 2-oxazole and l,'+-dichloro-2, 5-dimethoxybenzene. It is needless to say that the present compounds can be used in admixture also with fungicides other than those mentioned above, insecticides, nematocides, herbicides and fertilizers, and the resulting compositions can greatly contribute to the simultaneous control of diesases and injurious insects and to the promotion of growth oJT crops.

The detail below with reference to examples, but the examples are by way of illustration and not by way of limitation.

Example 1 (Compound No. 1): To a solution of 17-7 g. of 2,6-dichloro-l~ methylphenol in 50 ml. of toluene was added 6.9 β· of potassium carbonate. Into the resulting mixture, 16.0 g. of 0 ,0- dimethylthiophosphoryl chloride was dropped at 0° to 60°C. with stirring. After completion of the dropping, the .stirring was further continued at 80° to 85°C. for 3 hours. Thereafter, the reaction liquid was cooled to 20° to 25°C. and then charged with water to separate the liquid into water and toluene layers. The toluene layer was dried with .5 g. of Glauber's salt. Subsequently, the Glauber's salt was separated by filtration, and the toluene was removed by distillation, whereby a solid residue was formed. This residue was recrystallized . from methanol to obtain 20.3 g. of white crystals of 0 ,0-dimethyl-0-2 , 6-dichloro-1+-methylphenyl phosphoro-thioate having a. melting point of 79° to 79.5°C Example 2 (Compound No. 2): To a solution of 22.0 g. of 2-bromo-1+-methyl-6-chlorophenol in 50 ml. of methyl isobutyl ketone was added 5-3 g. of sodium carbonate. Into the resulting mixture, 16.0 g. of 0 ,0-dimethylthiophosphoryl chloride was dropped at 70° to 75°C. After completion of the dropping, the mixture was heated with stirring at 100° to 105°C. for 2 hours. Thereafter, the reaction liquid was allowed to cool, and then charged isobutyl ketone layers. Subsequently, the methyl iso-butyl ketone was removed by distillation, and the residue was quickly cooled to- form a solid. This solid was recrystallized from n-hexa.ne to obtain 18.0 g. of white crystals of 0 ,0-dimethyl-0-2-bromo- phosphorothioate having a melting point of 73° to 71+°C Example 3 (Compound No. 3): To a sodium methylate prepared by reaction of Ί.6 g. of metallic sodium wi'th 100 ml. of methanol'' was added 26Λ g. of 2 , 6-dibromo-1+-methylphenol .

From the resulting mixture, the methanol was removed by distillation to form a sodium salt of 2,6-dibromo-^-methylphenol . This sodium salt was gradually added to a solution of 16.0 g. of 0 ,0-dimethylthiophosphoryl chloride in 100 ml. of toluene. After stirring at said temperature for 2 hours, the reaction liquid was , charged with water to separate the liquid into water and toluene layers. The toluene layer was dried with Glauber's salt. Subsequently the Glauber's salt wa>s separated by filtration and the toluene was removed by distillation, whereby a. solid residue was formed.

This residue wa.s recrystallized from methanol to obtain I8.O g. of white crystals of 0,0-dimethyl-0-2,6-dibromo -methylphenyl phosphorothioate ha/ving a melting point of 81° to 83°C Example '+ (Compound No. -) : In the sa.me manner as in Example 1, 0,0-dimethyl-0-2,6-dichloro-l+-ethylphenyl phosphorothioate 8,0 Example 5 (Compound No. 5): In the same manner as in Example 2 , 0 , 0-dimethyl-0-2-bromo-6-chloro-^--ethylphenyl phosphoro- , thioate was obtained, η^'^ = 1. 5620.

Example 6 (Compound No. 6 ) : In the same manner as in Example 3 ? 0 , 0-dimethyl-0-2 , 6-dibromo- -ethylphenyl phosphorothioate was obtained, ^0,0 = 1. 5672.

(Provided that no recrystallization was required in each- of Examples h, 5 and 6. ) Example 7 ( Compound No . 1 ) : 17.7 Grams of 2 , 6-dichloro-1+-methylphenol was added to 27. 5 g. of phosphorus trichloride with stirring at 20° to 25°C. The resulting mixture was allowed to stand at 75° to 80°C. for 3 hours, and then subjected to fractionation to collect 19 g. of fra.ctions having a boiling point of 120° to 12 °C at 0.6 mmHg. The collected fraction was mixed with I6.9 g-of thiophosphoryl trichloride, and' the resulting mixture was refluxed for 2 hours. Thereafter, the mixture was fractionated to obtain 28.2 g. of fractions having a. boiling point of 90° to 92°C at 0.01 mmHg. To a. solution of said fractions in 300 nil. of toluene, 10.0 g. of sodium methylate was gradually added at.20 to 25 C.

After stirring at said temperature for 3 hours, the reaction liquid was charged with water to separate the liquid into water and toluene layers. The toluene' layer was dried with Glauber's salt. Subsequently, the Glauber's salt was separated by filtration, and the residue was formed. The residue was recrystallized from methanol to obtain 23.0 g. of white crystals of 0 ,0-dimethyl-0-2,6-dichloro- -methyl-phenyl phosphoro-thioate having a. melting point of 79° to 79.5°C.

Example 8 (Compound No. 1): Into a solution of 28.0 g. of thiophosphoryl trichloride and 17-7 g. of 2 , 6-dichloro-^-methylphenoi in 50 g. of toluene was dropped at 0° to 5°C. 13· 3. g» of triethylamine. The resulting mixture was maintained at 20° to 25°C. for 2 hours, and then charged with 50 ml. of a 5 % aqueous HCl solution to separate the reaction liquid into water and toluene layers. After washing twice with 50 g. of water, the toluene layer was dried with Glauber's salt. Subsequently, the Glauber's salt was separated by filtration and the toluene was removed by distillation, whereby a. solid residue was formed.

This residue was subjected to fractionation to collect 2 .Ο g. of fractions ha.ving a boiling point of 90° to 92°C at 0.01 mmHg. To a. solution of said fractions in 300 ml. of toluene, 8.7 g. of sodium methylate was gradually added at 20° to 25°C. After stirring at said temperature for 3 hours, the reaction liquid was charged with water to separate the liquid into water and toluene layers. The toluene layer was dried with Glauber's salt. Subsequently, the Glauber's salt was separated by filtration, and the toluene was removed by distillation, whereby a. solid residue was formed. This residue was recrystallized from methanol to obtain 1^.6 g. of white crystals of 0 ,0-dimethyl-0-2, 6-dichloro-'+-methyl- hen l hos horothioate ha.vin a. meltin oint of ° to 79.5°C Procedures for compounding the present compounds into fungicidal compositions are explained in detail below with reference to compounding examples, but the kinds and proportions of additives for the present compounds are va.riable within broad scopes without being limited to those shown in the examples. In the examples, all the parts are by weight.

Compounding Example 1 Dust: A mixture comprising .10 parts of the present compound (1) and 90 parts of clay was sufficiently pulverized to obtain a. dust containing 10% of active ingredient. In application, the dust was dusted as it was or thoroughly kneaded with soil.

Compounding Example 2 Wettable powder: A mixture comprising 50 parts of the present compound (h) , parts of a. wetting agent ( alkylbenzene-sulfonate type) and -5 parts of diatomaceous earth was sufficiently pulverized to obtain a. wetta.ble powder containing 50% of active ingredient. In application, the wet.table powder was diluted with water, and the resulting dilution was irrigated into water.

Compounding Example 3 Emulsifiable concentrate: A mixture comprising 20 parts of the present compound (3), 60 parts of xylene and 20 parts of an emulsifier (polyoxyethylene phenylphenol polymer type) was sufficiently kneaded to obtain an emulsifiable concentrate containing 20% of active ingredient. In application, the concentrate was diluted with water, and the resultin emulsion was irri ated into soil.

Compounding Example h Granule: A mixture comprising 10 parts of the present compound ( 5) > 85 parts of silica, powder, h.95 parts of calcium lingnin sulfate and 0.05 parts of sodium alkyl-benzenesulfona.te was sufficiently pulverized, kneaded with water, gra^lated, and then dried to obtain a. granule containing 10% of active ingredient. In application, the granule was sprinkled as it was or kneaded with soil.

Compounding Example Compounded dust: A mixture comprising 2 parts of the present compound (1), 3 parts of N-trichloromethylthio tetra-hydrophthalimide and 95 parts of talc was sufficiently pulverized to obtain a. compounded dust containing 5% of active ingredient.

Compounding Example 6 Compounded dust: A mixture comprising 2 parts of the present compound (6), 3 parts of sodium paradimethylaminophenyl diazosulfonate and 95 parts of cla was sufficiently pulverized to obtain a compounded dust containing 5% of active ingredient.

Compounding Example 7 Compounded dust: A mixture comprising 2 parts of the present compound ( ) , 3 parts of 5-ethoxy-3-trichloromethyl-l , 2 ^-thiadiazole and 95 parts of clay was sufficiently pulverized to obtain a. compounded dust containing 5% of active ingredient.

Compounding Example 8 Compounded dust: A mixture comprising 2 parts of the present - - - - - and 97 parts of cla.y was sufficiently pulverized to obtain a compounded dust containing 3 of active ingredient.

■ Compounding Example 9 Compounded dust: A mixture comprising 2 parts of the present compound (5)? 8 parts of 1,*+-dichloro-2, 5-dimethoxy- benzene and 90 parts of clay was sufficiently pulverized to obtain a compounded dust containing 10 of active ingredient.

In order to substantiate excellent soil fungicidal effects of the present compounds, typical test results are described below with reference to test examples, but the test examples are part of typical tests, and it is needless to say that the present compounds have extremely broad application scopes as soil fungicides.

Test Example 1 Cucumber da.mping-off-controlling effect (Pot test): Farm soil was filled in 9 cm-dia.meter flower pots. On the surface of said soil was uniformly spread and inoculated .10 ml. per pot of pathogenic soil in which Rhizoctonia solani had been cultured.

Subsequently, each of aqueous dilutions of test chemicals in the form of emulsifiable concentrates was irrigated into the thus treated soil in a proportion of 15 ml. per pot. After 2 hours, 10 seeds per pot of cucumber (variety: Kaga-Aonagafushinari ) were sowed in the soil and, 5 days thereafter, the disease severity of cucumber seedlings was investigated to calculate the percentage . of healthy seedlings. The said percentage was calculated according to the following formula: Percentage of Number of healthy seedl- ings in treated area healthy Number of germinated seeds in non-treated and non- inoculated area As the result, the present compounds showed markedly excellent effects over the control similar compounds as shown in Table 2.

Table 2 - Cont'd - ' Notes: * Control compounds synthesized for comparison by the present inventors.

** Compounds disclosed in Australian Patent 29^, 072.

*** Compound disclosed in Belgian Patent 6^8 , 813. **** Commercially available soil fungicide.

(The same shall apply hereinafter. ) Test Example 2 Cucumber damping-off controlling effect (Vat test): Farm soil was filled in plastic-made vats 2 of 0.1 m in size. On the surface of said soil was uniformly spread and inoculated pathogenic soil in which Rhizoctonia. sola.nl had been cultured, and the pathogenic soil was sufficiently mixed with the farm soil to a depth of 3 to 5 cm from its surface. Subsequently, each of aqueous dilutions of test chemicals in the form of emulsifiable concentrates was irrigated into the thus treated soil in a. proportion of 300 ml. per vat. After 2 hours, 30 seeds per vat of cucumbe (variety: Kaga-Aonagafushinari ) were sowed in the soil and, one month thereafter, the disease severity of cucumber seedlings was investigated to calculate the percentage of healthy seedlings. The said percentage was calculated according to. the same formula as in Test Example 1.

As the results, the present compounds showed markedly excellent controlling effects over the control similar compounds as shown in Table 3· Table 3 Active Percentage Compound ingredient of healthy concentration seedlings (p.p.m.) (%) S CI (CH30)2P-0-^-CH3 20,0 98 CI Compound No. (1) S CI (CH30)2P-0-^-CH3 200 98 Br Compound No. (2) - Cont'd - Test Example 3 Japanese raddish Fusarium wilt-controlling effect (Vat test): Farm soil was filled in lastic-made vats of 0 „ 1 m in size. Subsequently, pathogenic soil, in which Fusarium oxy.sporum f . raphani had been cultured, was mixed with and inoculated into the farm soil to a depth of cm. from the surface thereof. On the thus treated soil, 30 seeds per pot of Japanese ra.ddish (variety: Wase D-nichi) were sowed, and the seeds were covered with soil. After 3 hours, each of aqueous dilutions of test chemicals in the form of emulsifiable concentrates was irrigated into the soil in a proportion of 300 ml. per vat. After -culturing the raddish for one month in an air-controlled greenhouse at 26° to 28°C, the disease severity of raddish seedlings was investigated to calculate the percentage of healthy seedlingSo The said percentage was calculated according to the same formula as in Test Example 1 .

As the result, the present compounds showed markedly excellent controlling effects over the control compounds as shown in Table k.

Table 1+ - Cont'd - - Cont'd -

Claims (2)

1. WHAT WE CLAIM IS: 1. A phosphorothioate of the formula, wherein and R^ are each chlorine or bromine and is methyl or ethyl group.

2. A phosphorothioate of the formula, wherein R-^ and R^ are as defined in Claim 1. 3· A phosphorothioate of the formula, A phosphorothioate of the formula 5. A phosphorothioate of the formula, 6. A process for preparing a phosphorothioate of the formula given and defined in Claim 1 which includes (1) reacting 2,l+,6-trisubstituted phenol derivative of the formula, wherein R^, and R^ are as defined in Claim 1 and M is hydrogen, an alkali metal or ammonium group, with 0 ,0-dimethylthiophosphoryl chloride ; (2) reacting 2,1+,6-trisubstituted phenol of the formula (II) with phosphorus trichloride in the presence of an acid-binding agent and then with thiophosphoryl trichloride, and reacting 2,1+,6-trisubstituted phenyl-thiophosphoryl dichloride thus obtained with an alkali metal alcoholate or reacting said dichloride with methanol in the presence of an acid binding agent; or (3) reacting 2 ^-^-trisubstituted phenol with thiophosphoryl trichloride in the presence of an acid binding agent, and reacting the dichloride thus obtained with an alkali metal alcoholate or reacting said dichloride with •methanol in the presence of an acid binding agent. 7. A soil fungicidal composition including an inert carrier and, as an active ingredient, a fungici- dally effective amount of a phosphorothioate of the formula given and defined in Claim 1. 8. A soil fungicidal composition according to Claim 7> wherein the composition is in the form of a granule, dust, fine granule, wettable powder or emulsifiable concentrate. 9. A method for controlling soil fungi which comprises applying a phosphorothioate of the formula given and defined in Claim 1 to the soil fungi. 10. A method according to Claim 9? wherein the soil fungi are Rhizoctonia species. g i ven an ti ri p. f i n prl i Γ1 n i m 1 i η nni 1 f nrt i n i r\ n*. Attorney for Applicants