DE2541388A1 - (2)-Rhodane-methyl-mercapto (1,3,4)-oxadiazoles and-thiadiazoles - are fungicides, used in seed disinfection - Google Patents

Abstract

Novel 2-rhodanemethylmercapto-1,3,4-oxadiazoles and -thiadiazoles are of formula (I): (where R is H or opt. branched 1-12 (1-4)C alkyl, X is O or S. (I) have broad fungicidal activity against fungi in cultures, esp. against real mildew species in cereals, etc. (I) are also active as seed-disinfectants against helminthosporiosis and hve also bactericidal activity; they may be used as technical bactericides and fungicides. (I) are prepd. by reacting salts of 2-mercaptooxadiazoles or thiadiazoles with halorhodanides. (I) are very active against the commercially most important fungi in barley; Helminthosporium gramineum and Ustilago nuda; they can replace the very toxic mercury derivs. used as seed disinfectants at present.

Description

2-Rhodanmethylmercapto-1,3,4-oxidazole and -1,3,4-thiadiazole,

Process for their preparation and their use as fungicides The invention relates to 2-rhodanemethylmercapto-1,3,4-oxdiazoles and -thiadiazoles of the general formula in which R is hydrogen or a linear or branched alkyl group having 1-12, preferably 1-4, carbon atoms, and X is oxygen or sulfur.

The new compounds are produced in a manner known per se by reacting salts of 2-mercapto-1,3,4-oxdiazoles or thiadiazoles with halo-rhodanides or by reacting 2-halomethylmercapto-1,3,4-oxidazole or thiadiazoles with salts of hydrothodic acid produced, where Hal is a halogen radical, preferably chlorine or bromine and B is a cation of an inorganic or organic base.

The salts of the formula II are either used as such or - preferably - formed in the reaction mixture 1. For this purpose, the free 2-thio-1,3,4-oxdiazoles are used or thiadiazoles in aqueous or alcoholic solution with an organic or organic base. Suitable inorganic bases are preferably alkali (Na, K), Alkaline earth (Ca, Ba) or ammonium hydroxide or alkali (Na, K) alcoholates, as organic bases such as pyridine and triethylamine. Be used as a solvent preferably water, methanol or ethanol or aqueous-alcoholic mixtures are used.

The new compounds show a broad spectrum of fungicidal activity against fungal diseases on cultivated plants, especially against real powdery mildew species such as z. B. wheat or cucumber powdery mildew, rust fungi such. B. Wheat brown rust, Tilletia tritici, Phoma betae, Pythium ultimum, Ustilago avenae, Piricularia oryzae, Plasmopara viticola, Cercospora beticola and Cladosporium fulvum.

The compounds obtained by the process according to the invention of Formula I can already be used as crude products for this fungicidal application or, if desired, by customary methods, in particular chromatographically, further cleaned.

The effectiveness of the new compounds against fungal diseases of the seeds grouped under the designation helminthosporioses, those hitherto only extremely toxic and environmentally hazardous because of their ability to accumulate Mercury compounds can be effectively combated. The new connections can thus as a substitute for seed dressings containing mercury in the fight against Helminthosporium can be used. Connections previously used as replacements such as Manganese ethylene-1,2-bis-dithiocarbamate, 1,4-dichloro-2,5-dimethoxybenzene, 5-acetyl-8-hydroxy-quinoline do not show the efficiency required for practice, like some of the following biological comparative examples can be taken.

The compounds according to the invention can be in the usual forms as powder, wettable powder, emulsion concentrates, dispersions and ULV concentrates formulate and use on the green plant or as a seed dressing agent. About that In addition, the claimed compounds are also bactericidal and can be therefore also use as technical bactericides and fungicides.

The invention therefore also relates to fungicides and built cides Means which, as active ingredient, compounds of the formula I, optionally in a mixture with other fungicidal active ingredients in addition to customary formulation auxiliaries and / or Contains inert substances.

The invention also relates to seed dressings, in particular for barley, which by a content of a compound of the formula I in addition to usual Formulation aids and inert materials are marked.

to achieve a sufficient effect against helmet minthosporium gramineum, 25 g of active ingredient of a compound I are required for 100 kg of seeds. Larger amounts are possible, but in general without any particular advantage.

In order to widen the spectrum of activity of the compounds, it is advantageous in many cases to add a component which is effective against Ustilago nuda to the compounds of the formula I. The following are particularly suitable: a) 5,6-Dihydro-2-methyl-1,4-oxathiine-3-carboxylic acid aureanilide (US Pat. No. 3,249,499): and / or b) 2,5-dimethyl-furan-3-carboxylic acid cyclohexylamide (BE-PS 734.808): and / or c) 2,5-dimethyl-furen-3-carboxylic acid-cyclohexylamide and / or d) 2-methyl-5,6-dihydro-4H-pyran-carboxylic acid-meta-ethoxy-anilide (DT-OS 2.416.431): and / or e) (C12-C18) -alkanesulfonic acid salt of benzimidazole carbamic acid methyl ester (DTOS 2.320.529): and / or f) 1-methoxycarbonyl-3-exo-endo-norbonylmethyl-S-hexahydrotriazino-benzamidazole (DR-OS 2.349.911): and / or g) methyl benzimidazole carbamate (US-PS 3 olo 968): The seed dressing compositions according to the invention can contain the active substance I alone or in a mixture with one or more compounds a - g in a total concentration of 10 to 90% by weight, preferably 4c to 8c% by weight. The remainder generally consists of one or more of the customary inert materials which, in a manner known per se, are intended to prevent the grist from sticking together or to support its good distribution over the seed. Talc, silica, kieselguhr or kaolin can preferably be used as such inert materials.

Customary adhesives and wetting agents can also be added to the seed dressings can be added. The agents can be prepared in a manner known per se by grinding of the components are manufactured.

The ratio of components I to a - g in the mixture can be im Vary the range from 1: 2 to 2: 1. The seeds are treated by intensive mixing of seed dressing and seed z. B. in dry pickling plants or Mixing drums.

The treatment time varies with the intensity of the mixing.

In the usual systems, a period of 3 - 10 minutes is sufficient.

The seed dressings according to the invention have an excellent effect against the economically most important harmful fungi of barley, Helminthosporium gramineum and Ustilago nuda, a combination effect that so far has only been achieved with dressing agents containing Hg could be achieved. They are sufficient for the long-established, but not so far meetable requirement for a mercury-free seed dressing.

The comparison substances used in the biological examples have the following chemical names: Manganese-ethylene-1,2-bis-dithiocarbamate = A (Maneb) (pyracarbolide) 2-methyl-5,6-dihydro-4H-pyran-3-carboxylic acid anilide = (oxathiine dioxide) 2-methyl-5,6-d-Hydro-3-carboxanilido-1,4-oxathiin saioxide = U (benomyl) 1-butylcarbamoyl-2-methoxycarbonylamino-benzimidazole = Combination preparation of tetramethyl-thiuram disulfide and 2-methoxy-carbamoylamino-benzimidazole = B Combination preparation of 2-methyl-5,6-dihydro-3-carbonxanilido-1,4-oxathiine and methoxyethyl-Hg-silicate = F methoxyethyl-Hg-silicate = G 2,4-dinitro-6- (1-methylhepthyl) -phenyl-crotonate = H PREPARATION EXAMPLES Example 1: 2-Rhodanmethylmercapto-5-methyl-1,3,4-oxdiazole 93 g of 2-mercapto-5-methyl-1,3,4-oxdiazole (0.8 mol) are dissolved in 400 ml of ethanol and mixed with a solution of 18.6 g of sodium in 400 ml of ethanol. After addition of 88 g of chloromethylrhodanide (0.82 mol) the reaction mixture is under for one hour Stirring heated to boiling and then by distilling off the ethanol in a rotary evaporator concentrated at about 100 torr. The residue that remains is dissolved in 300 ml of methylene chloride recorded.

The resulting methylene chloride suspension is extracted by shaking with 200 ml of water freed from inorganic salts. After distilling off the methylene chloride The residue remaining from the organic phase is at 0.1 torr for half an hour heated to 1000C.

11 g of unreacted chloromethylrhodanide distill off.

What remains: 120 g of 2-rhodanemethylmercapto-5-methyl-1,3,4-oxdiazole (85% of theory) as an orange-brown oil with the following analytical data: N 21.2%; S 34.2 0 found: N 21.4%; S 34.0% Example 2: 2-Rhodanmethylmercapto-5-ethyl-1,3,4-oxdiazole 26 g of 2-mercapto-5-ethyl-1,3,4-oxdiazole are in a solution of 8 g of sodium hydroxide dissolved in 200 ml of ethanol. After adding 22 g of chloromethylrhodanide, the mixture is Heated under reflux to 80 ° -900 ° C. for half an hour.

The work-up described under Example (1) gives 36 g of 2-rhodanemethylmercapto-5-ethyl-1,3,4-oxdiazole (90, d. Th.) As an orange-colored oil with the following analytical data: N 20.9%: S 31.8% found: N 20.5%; S 31.4 70 Example 3: 2-Rhodanmethylmercapto-5-isopropyl-1,3,4-oxdiazole In the reaction of 29 g of 2-mercapto-5-isopropyl-1,3,4-oxdiazole carried out analogously to Example (1) and 14 g of sodium ethylate with 22 g of chloromethylrhodanide in 200 ml of ethanol are 35 g 2-Rhodanmethylmercapto-5-isopropyl-1,3,4-oxdiazole (81.4% of theory) as a red-orange Oil with the following analytical data: N 19.5; S 29.8% found: N 19.3; S 29.9% example 4: 2-Rhodanmethylmercapto-5-methyl-1,3,4-thiadiazole 21 g of 2-mercapto-5-methyl-1,314-thiadiazole are dissolved in a solution of 3.7 g of sodium in 180 ml of ethanol. After addition the reaction mixture is refluxed for 1 hour with 16 g of chloromethylrhodanide.

The work-up described in the preceding examples resulted 30 g of 2-rhodanemethylmercapto-5-methyl-1,3,4-thiadiazole (93% of theory) as red-brown Oil with the following analysis data calculated: N 20.7%; S 47.3% found: N 20.3%; S 46.9 ffi BIOLOGICAL EXAMPLES Example 1: Wheat plants were im 3-leaf stage with conidia of wheat powdery mildew (Erysiphe graminis) heavily inoculated and in a greenhouse at 200C and a relative humidity of 90 - 95% set up. 3 days after inoculation, the plants were given watery suspensions the compound from example (1) in the active ingredient concentrations of 500, 250, 120, 60 and 30 mg / liter of spray liquid are sprayed drip-snap. The experiment was repeated four times. Compound H was used as a comparison agent.

After an incubation period of 10 days, the plants were infected examined with wheat powdery mildew. The degree of infection was expressed in% more infected Leaf area based on untreated, infected control plants (= 100%). That The result of the experiment in Table I shows a clear superiority to that according to the invention Connection to the commercially available comparison medium.

Table I. Leaf surface infested with wheat powdery mildew Preparation in d10 at mg active ingredient / liter spray liquid 500 250 120 60 30 Connection according to Example (1) 0 0 0 0 5 Comparison agent HO 0 5 10 # 15 untreated infected 100 plants Example II: Wheat plants were treated with aqueous suspensions of the compound according to Example (4) at the rates of application of 500, 250, 120 and 60 mg / liter of spray liquor. Compounds B and C in the same concentrations were used as comparatives.

After the active ingredient coating had dried on, the plants became spore of the brown rust rust (Puccinia triticina) and inoculated for 24 hours in a climatic chamber with 100% relative humidity and 200C. Afterward card the plants in a greenhouse and were here 14 days after inoculation examined for infestation with brown rust of wheat.

Table II Leaf areas infested with brown rust in% Preparation at mg active ingredient / liter spray liquid 5000 250 120 60 link according to 0 0 0 3 Example (4) Compare mean B 0 0 3 10 Compare mean C 0 5 10 25 untreated infected 100 plants The clear superiority of the compound according to the invention over the comparative agents B and C can be seen from Table II.

Example III: Sugar beet plants were in the 6-leaf stage with aqueous Suspensions of the compound according to example (4) in the quantities of 500, 250, 120, 60 and 30 mg / liter spray liquor treated. The compound served as a means of comparison A in the same application rates.

After the active substance coating had dried on, the plants became conidiae of the pathogen causing leaf spot disease in the beet (Cercospora beticola) was heavily inoculated and drip in a climatic chamber with approx. 100% relative humidity and 250C. 48 hours later, the plants were returned to a greenhouse. 14 days later were they examined for infestation with leaf blotch disease. The degree of infestation was in ffi infected leaf area based on untreated, infected control plants (= 100%) expressed.

Table III leaf infested with Cercospora beticola Preparation area in. ° S at mg active ingredient / liter spray broth 500 250 120 60 30 Connection according to 0 0 0 0 3 Compare mean A 0 0 3 15 60 untreated infected 100 plants As can be seen from Table III, the compound from Example (4) is considerably superior to the comparative agent.

In the following example, the compounds from Example (1) and (4) Tested against organisms that are used in technical areas, e.g. during decomposition of dispersion, emulsion and ship paints, car paints, textiles, paper, wood etc. play an important role. In the present investigations, as representative organisms are the fungi Pullularia pullulans, Aspergillus niger, Penicillium funiculosum, Chaetomium globosum, Alternaria consortiale and Poria monticola as well a mixture of bacteria consisting of E. coli, Bacterium prodigiosum and Bacterium pyocyaneum selected.

Example IV: 0.02 ml each of a spore or bacterial suspension were placed in Petri dishes on nutrient media (Biomalz agar for mushrooms; Standard-I-NElragar for bacteria) applied drop-shaped; the agar were previously in the liquid state the claimed compounds according to example (1) or (4) in the in Table IV specified concentrations have been added. 6 days after inoculating the plates the diameter of the fungal colony on the agar was measured and the Preparations according to the invention caused growth inhibitions expressed in ß based on the control (= inoculated agar without addition = 0 inhibition).

The plates inoculated with bacteria were evaluated after 4 days; the inhibition of growth compared to the control (= inoculated Agar without addition = 0 r inhibition) rated.

Table IV Fungi% inhibition at mg of active ingredient per liter of agar Bacteria preparation 100 50 10 5 1 0.5 Connection Alternaria consortiale 100 70 50 according to Penicillium furniculosum 100 40 20 Example (1) Aspergillus niger 100 90 60 Chaetomium globosum 100 25 10 Pullularia pullulans 100 95 90 Poria monticola 100 60 Bacteria 100 50 25 Connection Alternaria consortiale 100 85 60 according to Penicillium furniculosum 100 60 40 Example (4) Aspergillus niger 100 30 Chaetomium globosum 100 30 - Pullularia pullulans 100 80 40 Poria monticola 100 75 50 - Bacteria 100 50 Table IV (continued) Mushrooms 1000 500 100 50 10 5 1 0.5 Preparation bacteria Compare means E Alternaria 100 27 consotiale Penicillium 100 75 funiculosum Aspergillius 100 74 Niger Chaetomium 100 95 74 globosum Pullularia 100 95 pullulans Poria 44 monticola Bacteria 50 Table IV shows the effect of the compounds according to the invention, which is essentially superior to the comparative agent E.

Example V: Winter barley seeds naturally infected with Helminthosporium gramineum with a degree of infestation of 30%, the compounds from example (1) or (4) Dressed in concentrations of 100, 50, 25 and 12.5 g of active ingredient / 100 kg of seed. The sowing took place in the middle of November in such a way that 20 g of the dressed Seeds were planted in 2 m2 plots. Each attempt was quadrupled created.

A commercial mercury preparation was used as a comparison agent (G), a mercury-carboxin combination preparation (F) and Maneb (A) in the commercially available Application rates of 300, 250 or 200 g of preparation per 100 kg of seeds.

At the beginning of June, after the development of the typical leaf symptoms in the untreated, Helminthosporium-infected plots, the evaluation of the Try. In the treated and untreated test members, both the Plants infested with He1minthsporium as well as healthy plants are counted, the respective The degree of infestation is determined and finally the degree of effectiveness is calculated, which is shown in the table V is reproduced.

Table V Pickling agent efficiency in% with g preparation / 100 kg Seeds 300 250 200 150 100 50 25 Connection off Example (1) - - 100 - 100 100 100 50% Connection off Example (4) - - 100 - 100 100 100 50% See means G (1.75% Hg) - - 100 - - - - Compare mean F - 100 -. - - - - 50% - 100 - - - - - See mean A 75 - 55 - 50 - - 80 Soig un e an ee infected plants 0 Example VI: Helminthosporium-infected spring barley seed (natural infection with a degree of infection of approx. 15%) was treated with the compounds from example (1) and (4) in concentrations of 100, 50, 25 and 12.5 g of active ingredient dressed per 100 kg of seed. The tests were carried out and evaluated in accordance with the BBA guidelines.

Table VI Efficiency in% with g preparation / 100 kg Seed dressing 300 250 200 150 100 50 25 Connection off Example (1) - - 100 - 100 100 100 50% Connection off Example (4) 50% - - 100 - 100 100 100 See means G (1.5% Hg) - - 100 - - - - See mean F. 50% - 100 - - - - - untreated infected 0 plants The results in Tables V and VI show that even with 12.5 and 25 g of active ingredient per 100 kg of seed, the compounds according to the invention achieve the efficiency of over 95 ffi required for mercury-free Helminthosporium seed dressings and are therefore suitable as a substitute for Hg preparations .

Claims (5)

Claims 1) 2-Rhodanmethylmercapto-1,3,4-oxdiazoles and thiadiazoles of the general formula in which R is hydrogen, a linear or branched alkyl group having 1-12, preferably 1-4, carbon atoms, and X is oxygen or sulfur. 2) Process for the preparation of compounds of formula 1 in claim 1, characterized in that a) salts of 2-mercapto-l, 3,4-oxdiazoles or thiadiazoles of the formula with halo-rhodanides of the formula HalCH2SCN III or b) 2-halomethylmercapto-1,3,4-oxdiazoles or thiadiazoles of the formula is reacted with salts of hydrofluoric acid of the formula BSCN V in a manner known per se, Hal being halogen, preferably chlorine or bromine, and B being the cation of an inorganic or organic base. 3) Fungicidal and bactericidal agents, characterized by a content on a compound of the formula I in addition to customary formulation auxiliaries and / or Inerts. 4) Seed dressing, especially for barley, gekennzeiehrjet through a content of a compound of formula 1 in addition to customary formulation auxiliaries and inert materials. 5) Seed dressing for barley, characterized by a GÆ content of a compound of the formula I in combination with a compound of the formula: a) 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxylic acid anilide (carboxin) : and / or b) 2,5-dimethyl-furan-3-carboxylic acid anilide; and / or c) 2,5-dimethyl-furan-3-carboxylic acid cyclohexylamide: and / or d) 2-methyl-5,6-dihydro-4H-pyran-carboxylic acid meta-ethoxyanilide: and / or e) (C12-C18) -alkanesulfonic acid salt of benzimidazole carbamic acid methyl ester: and / or f) 1-methoxycarbonyl-3-exo-endo-norbornylmethyl-S-hexahydrotriazino-benzimidazole: and / odQls g) Benzimidazole carbinic acid methyl ester: in addition to the usual formulation auxiliaries and inert materials.