NO166044B - TERMOPLAST-POLYMER BLEND. - Google Patents

Description

Fungicide containing pyrrole derivatives as active substance.

The invention relates to a fungicidal agent for combating fungi and scab attacks on plants, the agent being characterized in that it consists of or contains as an active ingredient one or more compounds with the general formula

or salts thereof, wherein

R-^ means a hydrogen atom, a straight or branched Cfr. at 12p-2 and 45 1-21/00 alkyl residue, a cycloalkyl residue with 5-8 carbon atoms, a benzyl residue or a phenyl residue optionally substituted with a halogen atom or an alkyl group or a lower alkyl residue substituted with a hydroxy group or amino group,

R2 and ^r both mean the thiocyano group or one of these, a thiocyano group and the other a hydrogen atom or an acetyl group

and

R^ and R^ mean hydrogen atoms or methyl groups.

Compounds or mixtures of compounds with the above formula have been shown to be very effective against fungal growth on trees and plants. Positive effects have also been achieved in the treatment of seeds, and the compounds or mixtures of the compounds have in this connection a wide range of advantages over mercury. The reason for this is that the compounds are far less toxic.

Very good results have been obtained with N-phenyl-oc,a'-dithio-cyanopyrrole and its corresponding N-para-chlorophenyl homologue. These compounds and especially the N-p-chlorophenyl derivative are active against Venturia inaequalis, Fasarium culmorum and against Podosphaera leucotricha. No similar compounds with fungicidal action are known from the literature.

Depending on the circumstances under which the preparations are used, the salts or compounds can be mixed with a suitable carrier, which can either be solid, semi-solid or liquid. The carrier material itself can of course consist of a wide range of different components.

In the preparation of substituted thiocyanopyrroles, one or two thiocyano groups are added to a substituted or unsubstituted pyrrole ring, whose substituents are not thiocyano groups, and this can be done by allowing free thiocyanogen to react with the pyrrole ring. The free thiocyanogen can be obtained by a reaction between an alkali metal thiocyanate or an ammonium thiocyanate and a suitable oxidizing agent, such as e.g. halogen, a monochlorourea or a dichlorourea. Electrolytic oxidation can also be used. Another alternative for producing free thiocyanogen is to decompose a heavy metal cyanate, e.g. copper cyanate. In such a decomposition, it is advantageous to use a catalyst, such as e.g. aluminum trichloride or aluminum tricyanate. The formation of the free cyanogen should preferably take place in a solvent such as e.g. formic acid, acetic acid, methyl acetate, chloroform, carbon tetrachloride, methanol or hydrochloric acid.

The thiocyano groups can also be added to the pyrrole ring using Sandmeyer's method, or by treating a pyrrole derivative

with a halothiocyanogen.

In the following, various examples of methods for producing the substituted thiocyanopyrroles will be described.

Example 1.

N- metvl- oco^- dithiocyanopyrrole.

300 g of potassium thiocyanate and 500 ml of methanol were placed in a flask equipped with a mechanical stirrer and a thermometer and were then cooled in a dry ice-acetone bath to approx. -65°C. The mixture was stirred and kept below -55°C while a cooled bromine solution containing 74.5 ml of bromine in 200 ml of methanol was added from a dropping funnel. As quickly as possible, to the above solution was then added a solution of 48.6 g of freshly distilled N-methylpyrrole (boiling point 114-117°C) in 200 ml of methanol and cooled to -65°C. After further stirring for approx. 40 minutes, the temperature in the reaction mixture was approx. -40°C. The mixture was then poured into 100 ml of water and stirred for approx. 30 minutes. The precipitate of N-methyl-<q>,<q>'-dithiocyanopyrrole was collected in a Biichner funnel, washed with water, dried and recrystallized from. alcohol to 91 g, m.p. Il8 - 120°C. By evaporation of the mother liquor, a further crude product weighing 18 g was obtained.

Example 2.

q, q'- dithiocvanopyrrole.

The method from example 1 was used with the exception that the following chemicals were used: 150 g of potassium thiocyanate was dissolved in 200 ml of methanol, 34 ml of bromine was dissolved in 50 ff of methanol and 24.8 g of pyrrole was dissolved in 100 ml of methanol.

The reaction mixture was poured over 200 g of crushed ice and the α,<q>'-dithiocyanopyrrole was collected in a Biichner funnel, washed with water, dried and recrystallized from water. Sm.p. 114 - ll6C.

Example 3.

N-butvl-q,a'-dithiocvanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 25 g of potassium thiocyanate dissolved in 100 ml of methanol, 6.5 ml of bromine dissolved in 50 ml of methanol and 6.1 g of N-butyl-pyrrole, boiling point at 15 mm and Hg 62 - 70°C, dissolved in 50 ml methanol.

The reaction mixture was poured over 200 g of crushed ice, and the N-butyl-α,α'-dithiocyanopyrrole was extracted with two portions of chloroform, each of 50 ml. The solution was dried, filtered and evaporated under reduced pressure. The residue was a thick oil that solidified after a certain period of time in a refrigerator. The substance had a melting point of 24 - 28°C.

Example 4.

N-(B-hydroxyethyl)-α,α'-dithiocyanopyrrole.

The procedure from example 1 was used with the exception that the following chemicals were used: 25 g potassium thiocyanate dissolved in 100 ml methanol, 6.5 g bromine dissolved in 50 ml methanol and 5>5 g N-(B-hydroxyethyl)-pyrrole boiling point at 3 mm Hg, 66 - rjS°G, dissolved in 50 ml of methanol.

The reaction mixture was worked up as described in example 2. N-(B-hydroxyethyl)-α,α'-dithiocyanopyrrole was recrystallized in alcohol. Melting point 78 - 80°C.

Example 5.

N-cyclohexyl-q,α'-dithiocyanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 25 g of potassium thiocyanate dissolved in 100 ml of methanol, 6.3 ml of bromine dissolved in 50 ml of methanol, 7"! g N-cyclohexylpyrrole, boiling point at 3 mm Hg 68 - 74°C > dissolved in 50 ml methanol

The reaction mixture was worked up as described in example 3. The residue was recrystallized in alcohol and had a melting point of 66 - 68°C.

Example 6.

N-benzyl-α,α'-dithiocyanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 18 g of potassium thiocyanate dissolved in 50 ml of methanol, 5>9 g of bromine dissolved in 50 ml of methanol and 5.7 g of N-benzyl-pyrrole, boiling point at 15 mm Hg 123 - 130°C, dissolved in 5° ml of methanol.

The reaction mixture was worked up as described in example 2. The product was recrystallized in benzene-ligroine. Sm.p.

93 - 96°C

Example 7.

N- f envl-oc, a' - dithiocvanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 25.2 g potassium thiocyanate dissolved in 50 ml methanol, 6.2 ml bromine dissolved in 5 ml methanol and 7.2 g N-phenyl-pyrrole, boiling point at 15 mm Hg 110 - 115°C and m.p. 60 - 61°C, dissolved in 50 ml of methanol.

The reaction mixture was worked up as described in example 2. The product was recrystallized in benzene-ligroine. Sm.p. 162 - 164°C.

Example 8.

q-thiovano-q'-acetylpyrrole.

The procedure in example 1 was used, with the exception that the following chemicals were used: 24 g potassium thiocyanate dissolved in 50 ml methanol, 5.8 ml bromine dissolved in 50 ml methanol and 8.5 g methyl-q<->pyrryl ketone, m.p. . 92 - 93°C» dissolved in 50 ml of methanol.

The reaction mixture was worked up as described in example 2. The product was recrystallized in benzene-ligroine, m.p. 110 - 138°C. The sulfur content agrees with the calculated one. There is, however, a possibility that the product is a mixture of isomers. After repeated recrystallization, however, the melting point rose to 142 - 143°c«

Example Q.

N-methyl-q-thioquanopyrrole.

75 g of potassium thiocyanate and 150 ml of methanol were placed in a flask equipped with a mechanical stirrer and a thermometer, and were then cooled in a dry ice-acetone bath to approx. -60°C. The mixture was stirred and kept below r55°C, while a cooled bromine solution containing 16.5 ml of bromine in 50 ml of methanol was added from a dropping funnel. Stirring was continued for an additional 10 minutes, after which the reaction mixt

was added a solution of 24.3 g of N-methylpyrrole (boiling point 114 - 117°C) in 200 ml of methanol which had previously been cooled to -65°C. After stirring for approx. 50 minutes, the temperature in the reaction mixture had risen to approx. -30°C, and it was then poured into 200 ml of saturated saline solution. After the solution was extracted with two 50 ml portions of chloroform, the latter was dried, filtered and distilled. The boiling point of the solution was 108 - 110°C at 13 mm Hg.

Example 10.

2, 5- dimethyl- 3, 4- dithiocyanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 60 g of potassium thiocyanate dissolved in 75 ml of methanol, 13.8 ml of bromine dissolved in 50 ml of methanol and 14.1 g of 2,5-dimethylpyrrole, boiling point 129 - 131° C, dissolved in 40 ml of methanol.

The reaction mixture was worked up as in example 2. The product was recrystallized from ether-naphtha and then from benzene-naphtha, m.p. 134 - 136°C.

Example 11.

N-ethyl-2,5-dimethyl-3,4-dithiocyanopyrrole.

The procedure from example 1 was used with the exception that the following chemicals were used: 20 g of potassium thiocyanate dissolved in 25 ml of methanol, 8.1 ml of bromine dissolved in 25 ml of methanol and 7% g of N-ethyl-2,5-dimethylpyrrole, boiling point at 10 mm Hg 6l°C, dissolved in 25 ml methanol.

The reaction mixture was worked up as described in example 2. The product was recrystallized in benzene, m.p. 132 - 133°C.

Example 12.

N- propyl- 2, 5- dimethyl- S. 4- dithiocyanopyrrole.

The procedure from example T was used with the exception that the following chemicals were used: 20 g of potassium thiocyanate dissolved in 25 ml of methanol, 8.1 ml of bromine dissolved in 25 ml of methanol and 7.0 g of N-propyl-2,5-dimethylpyrrole, boiling point at 15 mm Hg 78 - 83°C, dissolved in 25 ml methanol.

The reaction mixture was prepared as described in

/in

example 2. The product was recrystallized in benzene-ligroine, m.p. 55

- 58°c.

Example 13.

N-Butyl-2,5-Dimethyl-Ci,4-Dithiocyanopyrrole.

The procedure from example 1 was used with the exception that the following chemicals were used: 20 g of potassium thiocyanate dissolved in 25 ml of methanol, 8.1 ml of bromine dissolved in 25 ml of methanol and 7.5 g of N-butyl-2,5-dimethylpyrrole, boiling point at 13 mm Hg 83 - 85°C, dissolved in 5° ml methanol.

The reaction mixture was worked up as described in example 3. The residue was recrystallized in benzene-ligroin, m.p. 82

- 83°C.

Example 14-.

N-(B-hydroxyethyl)-2,5-dimethyl-3,4-dithiocyanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 20 g of potassium thiocyanate dissolved in 25 ml of methanol, 8.1 ml of bromine dissolved in 25 ml of methanol, 7.0 g of N-(B-hydroxyethyl)-2, 5-dimethylpyrrole, boiling point at 7 mm Hg 112 - 113°C, dissolved in 50 ml of methanol.

The reaction mixture was worked up as described in example 2. The product was crystallized in benzene, m.p. 153 - 156°c-

Example 15.

N-carbmethoxymethyl-2,5-dimethyl-3,4-dithiocyanopyrrole.

The procedure from example 1 was used, with the exception that the following chemicals were used: 25 g of potassium thiocyanate dissolved in 100 ml of methanol, 6.2 ml of bromine dissolved in 50 ml of methanol and 8.3 g of N-carb-methoxy-2,5- dimethylpyrrole, boiling point at 12 mm Hg 126°C, m.p. 42 - 46°C, dissolved in 50 ml of methanol.

The reaction mixture was worked up as described in example 2. The product was recrystallized in benzene-ligroine, m.p. 131 - 135°C.

Example 16^

NT (B- aminoethyl)- 2, 5- dimethyl- 3, 4- dithiocyanopyrrole..

The procedure from example 1 was used with the exception that the following chemicals were used: 20 g of potassium thiocyanate dissolved in 25 ml of methanol, 8.1 ml of bromine dissolved in 25 ml of methanol and 7.0 g of N-((3-amino-ethyl)- 2,5-Dimethylpyrrole, boiling point at 10 mm Hg 106°C dissolved in 50 ml of methanol.

The reaction mixture was worked up as described in example 2. The product was recrystallized in alcohol.

Example 17.

N-p-chlorophenyl-q,a'-dithiocyanopyrrole.

The procedure from Example 1 was used with the following exceptions: chemicals: 8.5 g potassium thiocyanate in $0 ml methanol, 2.7 ml bromine in 25 ml methanol and 3 g N-p-chlorophenylpyrrole in 75 ml methanol. Reaction temperature: -25 - -30°C.

The reaction mixture was prepared as in example 2.

The product was recrystallized from alcohol. Sm.p. 133 - 135°C

Example 18.

In this example, the connections were tested

. effect. Each compound was ground for 15 minutes.

3 mg of a surface-active agent and 10 ml of water were added to the ground compounds. A few drops of a suspension of the compounds were placed on two glass plates. A few drops of spores of Fusarium culmorum (grown on agar) or Venturia inaequalis (collected from infected apple leaves) were mixed with the compounds.

These mixtures were then incubated for 48 hours. The negative logarithms of the concentration that produced complete inhibition of germination are given in the following table:

As can be seen from this table, the compounds with the general formula indicated at the beginning, in which R^ and R^ are hydrogen atoms and Rg and R^ are both thiocyano groups in positions 2 and 5, have a better effect, and the most interesting effect has the compounds N-methyl -α,α'-dithiocyanopyrrole and N-para-chlorophenyl-α,α'-dithiocyanopyrrole or a salt thereof.

Example 19.

Suspensions (prepared as described in Example 18) of various compounds were sprayed on the underside of three tomato leaves (cultivar Bonny Best), placed in water (50 ml bottles). Three bottles were used for each concentration. After drying, the underside of the leaves was infected by spraying them with a suspension, of zoospores (100.00 ml) of Phytophtora infestans, obtained from sporangia grown on potatoes.

The bottles with the leaves were then placed in a climate room where for the first 24 hours there was a temperature of 15°C and a relative humidity of 95% and complete darkness, after which for 48 hours it was 18°C, a relative humidity of 85% and a continuous illumination at 3000 - 6000 lux. The results were obtained by estimating the incipient growth of dark mycelium on the leaves. The results are expressed in the following table as a percentage of infection on control leaves that were not treated with chemicals.

Example 20.

Apple cuttings M II with one or two 20 cm shoots were infected with suspensions of conidia spores of Venturia inaequalis collected from infected leaves. Cherry juice was added to the suspensions. The chemicals were sprayed on immediately before the infection (preventive test) or 24 hours after the infection (curative test). They used approx. 3 ml of a suitably diluted suspension per shot.

The plants were kept moist for 24 h after infection, then planted and protected from rain during the experiment. After two to three weeks of growth, the mycelium on the leaves was estimated and is expressed in the next table as a percentage of the mycelium growth on shoots that were infected in the same way but not treated with chemical.

Example 21.

The leaves of approx. 10 cm tall and young celery plants (cultivar Balder) were sprayed with suitably diluted suspensions of the compounds. Each concentration was applied to 6 plants. After the treatment, the plants were infected by being sprayed with a suspension of spores (150,000/ml) of Septoria apii, collected from infected leaves. The plants were incubated for 14 days in a climate room (18°C, 16 hours of light, 8 hours of darkness, high humidity).

The results were obtained by estimating the number of spots per

leaf and express this number as a percentage of what was observed on infected control leaves that had not been treated.

The results obtained are indicated in the following table

Example 22.

10 g of N-methyl-α,α'-dithiocyanopyrrole together with 10 g of talc were ground in a glass mill. 20 mg of this preparation was mixed with 5 g of bean seeds naturally infected with Thoma betae. The seeds were sown in sterilized soil that was kept at 10°C for 12 days in an ice box and then for 12 days in a Wisconsin tank in a greenhouse (soil temperature 10°C). Two experiments showed that 97 °g 100% respectively, of the seedlings were protected against Thoma betae.

Example 2^.

10 g of α,α'-dithiocyanopyrrole were ground in a glass mill together with 10 g of talc. 10 g of maize seeds with relatively low vitality were treated with 50 mg of this preparation. The treated seeds (hundred per experiment) were sown in a soil naturally infected with earthworm (Pythium spee.) and kept at 10°C in closed boxes for 10 days. The cans were then opened and kept at 25 - 3°C for 1 three days.

In three experiments, 91, 98 and 100%, respectively, of the seeds germinated.

In examples 24 and 25, it will be described how powder preparations according to the present invention can be produced.

Example 24.

A wettable powder of N-methyl-ct,α'-dithiocyanopyrrole was

prepared by mixing 500 g of this chemical, 440 g of kaolin, 50 g of a lignin sulfonate (Polyfon H) and 10 g of oleyl-N-methyl sodium taurate.

The mixture was ground in an air mill until 95% of the particles measured

less than 325 mesh.

Example 25.

In this example, 250 g of a,a'-dithiocyanopyrrole were used

which was mixed and ground together with 650 g of kaolin, 70 g of lignin sulfonate ("Polyfon H") and 30 g of a fatty alcohol sulfate ("Nifapon").

Claims (2)

1. Fungicidal agent for combating fungal and scab attack on plants, characterized in that the agent consists of or as an active ingredient contains one or more compounds with the general formula or salts thereof, in which R^ means a hydrogen atom, a straight or branched alkyl residue, a cycloalkyl residue with 5-8 carbon atoms, a benzyl residue or a phenyl residue optionally substituted with a halogen atom or an alkyl group or a lower alkyl residue substituted with a hydroxy group or amino group, R2 °S R5 means both the thiocyano group or one of these a thio- cyano group and the other a hydrogen atom or a acetyl group, and and R. means hydrogen atoms.or methyl groups. 2. Fungicidal agent according to claim 1, characterized in that and R. are hydrogen atoms and Rg and Rc are both thiocyano groups in positions 2 and 5*3" Fungicidal agent according to claim 1, characterized in that the active substance contains N-methyl-α,α<»->dithiocyanopyrrole or a salt of this compound. 4- Fungicidal agent according to claim 1, characterized in that it contains as active substance N-parachlorophenyl-a,a<*->dithiocyanopyrrole or a salt of this compound.