NO139605B - THIADIAZOLYLURE COMPOUNDS WITH HERBICID EFFECT - Google Patents

Description

The present invention relates to new 5-alkylsulfonyl and 5-alkylsulfinyl-1,3,4-thiadiazol-2-ylurea derivatives with herbicidal action.

1,3,4-thiadiazol-2-ylureas are known as herbicidal active substances. The best-known compound is m-ixifethyl-1-(5-trifluoro-methyl-1,3,4-thiadiazol-2-yl)-3-methylurea (German

No. 1 816 696). However, this active substance is less suitable as a selective weed control agent as it does not exhibit

some marked compatibility with cultivated plants.

The herbicidal effect of such alkylsulfonyl-thiadiazolyl ureas, which contain an alkyl group with 1-3 carbon atoms, is further revealed from German specification no. 2,044,442. However, these compounds do not show satisfactory selectivity towards cultivated plants.

In addition, 1,3,4-thiadiazolyl-ureas are known from German publication no. 1186568, among which 1,3-dimethyl-3-(5-n-butylsulfonyl-1,3,4-thiadiazol-2-yl)- urea. However, these compounds do not have good compatibility with cultivated plants, especially potatoes.

The purpose of the present invention is to provide an agent which does not exhibit the disadvantages of the known agents, and, in addition to good weed-fighting action, exhibits better compatibility with cultivated plants than known agents. According to the invention, this aim is achieved by means which are characterized by the fact that they contain at least one compound of the general formula:

in which means an alkyl group with 4-8 carbon atoms and n has the meaning 1 or 2.

The object of the present invention is therefore compounds of the general formula (I), with herbicidal action.

By means in the general formula (I) alkyl groups such as n-butyl, isobutyl, n-pentyl, n-hexyl, n-heptyl and n-octyl, tert. butyl, sec. butyl, neopentyl, 1-methylbutyl, 1,3-dimethylbutyl, 1,2-dimethylpropyl or 1-ethylpropyl.

The compounds according to the invention have a special position as a result of their herbicide-selective properties, which due to their analogous structure to known active substances could not be expected. It is therefore surprising that the active substances according to the invention exhibit significantly better selective properties.

The distinctive compounds are further distinguished by a broad soil and foliar herbicide effect. They can be used to control mono- and dicotyledonous weeds.

By using them, either before leaf emergence or after leaf emergence, arable weeds such as Sinapis ssp., Stellaria media, Senecio vulgaris, are combated. Matricaria chamomilla, Ipomea purpurea, Chrysanthemum segetum, Lamium amplexicaule, Centaurea cyanus, Amaranthus retroflexus, Alopecurus myosuroides, Echinochloa crus galli, Setaria italica and Lolium Perenne.

For the control of seed weeds, a spread rate of 1 - 5 kg of active substance/ha is usually used. In this way, the active substances according to the invention exhibit a selectivity in useful plant cultures such as potatoes, maize, peanuts, soybeans, peas and other legumes, cereals and tree species, ornamental plants and plantation cultures.

The active substances can be used either alone or as a mixture with several other active substances. Optionally, depending on the desired target, other plant protection or pest control agents can be added, such as fungicides, nematicides or other agents. The addition of fertilizers, for example, is also possible. In the event that an improvement of the spectrum of action or eradication of an open field flood is intended, other herbicides can also be added. For example, active substances from the group of triazines, aminotriazoles, anilides, diazines, uracils, aliphatic carboxylic acids and halocarboxylic acids, halogenated benzoic acids and phenylacetic acids, alkyloxycarboxylic acids, hydrazides, amides, nitriles, esters of such carboxylic acids, carbamic acid and thiocarbamic acid esters are suitable as herbicide active admixture compounds. , ureas, 2,3,6-trichlorobenzyloxypropanol and thiocyanogel-containing agents, as well as other additives. Other additives are, for example, non-phytotoxic additives which give the herbicides a synergistic effect, such as wetting agents, emulsifiers, solvents and oily additives. The active substances are preferably used in the form of preparations such as powders, flow agents, granules, solutions, emulsions or suspensions during addition of liquid and/or solid carriers, respectively diluents and possibly the addition of wetting, binding, emulsifying and/or dispersing aids.

Suitable liquid carriers are, for example, water, aliphatic or aromatic hydrocarbons such as benzene, toluene, xylene, cyclohexanone, isophorone and further mineral oil extracts.

Soil minerals are suitable as solid carriers, for example tonsil, silica gel, talc, kaolin, attack clay, limestone, silicic acid,

and vegetable products such as flour.

As surface-active agents can be mentioned: for example calcium lignosulphonate, polyoxyethylene-octylphenol ether, naphthalene sulphonic acids, phenol sulphonic acids, formaldehyde condensates, fatty alcohol sulphates and alkali and alkaline earth salts of fatty acids.

The proportion of the relevant active ingredient(s) in the product can vary within wide limits. For example, the agent can contain 20-80% by weight of active ingredient, 80-20% by weight of liquid or solid carriers, and possibly up to 20% by weight of surfactants.

The hitherto unknown compounds of the formula (I) can be prepared, for example, by the action of oxidizing agents on a compound of the general formula:

For the preparation of the compound according to formula (I), if n has the meaning 1, organic hydrogen peroxides, such as tert-butyl hydrogel peroxide or peracids such as m-chloroperbenzoic acid and others, or N-haloamide such as N-bromosuccinimide or inorganic compounds can preferably be used as oxidizing agent such as hydrogen peroxide, sodium m-periodate, etc. Preferably two oxidation equivalents of oxidizing agents or a small excess over one mole of the thio compound are added for this at a temperature in the range 0 - 60°C.

For the preparation of the compounds according to formula (I) where n has the meaning 2, inorganic compounds such as chlorine or potassium permanganate, chromic acid or their salts or nitric acid in a temperature range of 0 - 120° C can be used in addition to the previously mentioned oxidizing agents.

To 1 mol of the thio compound is preferably added for this purpose four oxidation equivalents or, if desired, an excess thereof, i.e. at least twice as much as for the sulfoxidation described above to produce the desired compound where n is 1.

Organic solvents such as carboxylic acids, for example acetic acid, ethers such as dioxane, ketones such as acetone, acid amides such as dimethylformamide, nitriles such as acetonitrile, etc., can preferably be used as reactants, which solvents can be used alone or in mixture with water.

The compounds according to the general formula (I) can also be prepared by reacting a compound of the general formula: with a carbaraoyl halide of the general formula:

in the presence of an acid-binding agent.

Another method consists in reacting a compound of the formula (III) with carboxylic acid halides or with phosgene in the presence of an acid-binding agent to obtain derivatives of carbamic acid which are then reacted with dimethylamine of the formula:

for obtaining the desired product.

As carboxylic acid ester halide, carboxylic acid phenyl ester chloride and thiocarboxylic acid S-phenyl ester chloride are preferably used, whereby, for example, N-(5-alkylsulfonyl-1,3,4-thiadiazol-2-yl)-thiocarbamic acid S-phenyl ester is obtained, which is then reacted with dimethylamine.

In methods where hydrohalic acid is formed, another organic base is added for binding, such as tertiary amines, for example triethylamine or dimethylaniline, pyridine bases or suitable inorganic bases, such as oxides and hydroxides of alkali and alkaline earth metals.

The reaction with carboxylic acid chlorides is carried out between -10° C and 150° C and a subsequent reaction with dimethylamine of the formula (V) between -10° C and 100° C, usually at room temperature.

Solvents that are inert to the reactants serve as reactants. Of these, for example, the following can be mentioned: aliphatic and aromatic hydrocarbons and halogenated hydrocarbons, such as benzene, toluene, xylene, methylene chloride, chloroform, carbon tetrachloride, chlorinated ethylenes, ketones, ether-like compounds, N,N-dialkylated amides and nitriles, etc. .

A further preparation option for 5-alkylsulfonyl-1,3,4-thiadiazolylureas comprises a reaction of 5-carbamoylamino-1,3,4-thiadiazol-2-yl-sulfinic acid salts of the general formula: with alkylating agents of the general formula:

In addition to compounds according to the general formula (VII), other alkylating agents can also be used, such as esters of sulfuric acid or esters of aromatic sulphonic acids, for example dimethyl sulphate.

In the previously mentioned general formulas (II - VII), R^ and n have the meanings defined for the general formula (I), Hal means chlorine, bromine or iodine and B stands for hydrogen, a monovalent metal ion, preferably alkali or alkaline earth metal or a tertiary organic base.

The starting materials used in carrying out the described methods are known in and of themselves or can be produced by methods known in and of themselves.

The following examples illustrate the preparation of the compounds according to the invention.

1. 1. 3- trimethyl- 3-( 5- butylsulfinyl- 1, 3, 4- thiadiazol- 2- yl)- urea

To a solution of 300 g of 1,1,3-trimethyl-3-(5-butylthio-1.3.4-thiadiazol-2-yl)-urea in 1.9 liters of acetic acid, 136 g of perhydrol are added dropwise at room temperature and with stirring, whereby a temperature rise of 28° C occurs. After a 5-day standstill, the excess of perhydrol is destroyed with the heat, the acetic acid is distilled off as much as possible under vacuum, the residue is taken up in methylene chloride and treated twice with active carbon and the solvent is distilled off and the remaining oil is dried under high vacuum.

Yield: 305.5 g (96% of theoretical)

20

n^° = 1.5617

1,1,3-trimethyl-3-(5-butylsulfonyl-1,3,4-thiadiazol-2-yl)-urea

41.1 g of 1,1,3-trimethyl-3-(5-butylthio-1,3,4-thiadiazol-2-yl)-urea are dissolved in 150 ml of acetic acid and 50 ml of water. 33.6 g of finely powdered potassium permanganate is introduced into this solution at 70 - 80° C, stirred for 1 hour and finally the precipitated rudder is reduced

in dsn to 0° C cooled mixture, by the dropwise addition of a solution of 30 g of sodium metabisulphite in 50 ml of water. The separated oil is taken up in methylene chloride and the methylene chloride solution is shaken several times with a sodium carbonate solution and water, after which the organic phase is dried over magnesium sulphate, treated with active carbon and evaporated under vacuum. The residue obtained is recrystallized from isopropyl ether, m.p. 49° C, yield: 16.2 g (35% of theory).

By the methods described, the compounds according to the invention listed in the following table are produced.

The compounds according to the invention are colorless and odorless,

oily or crystalline substances, which are for example insoluble in water and petrol and which are soluble in acetone, methylene chloride, tetrahydrofuran, dimethylformamide, cyclohexanone and isophorone.

The following examples illustrate the herbicidal and selective properties of the compounds according to the invention, in comparison with known active substances.

Example 1

In greenhouses, the listed plants were treated before leaf emergence with the agents in the indicated application quantities. For this purpose, the agents were evenly applied to the soil in the form of aqueous suspensions in a quantity of 500 litres/ha. The results obtained 3 weeks after the treatment showed that the agents according to the invention, in contrast to known compounds, exhibited a good selectivity.

Example 2

In greenhouses, the listed plants were treated after leaf emergence with the agents in the specified application quantity. For this purpose, the agents were evenly sprayed on the plants in the form of aqueous suspensions in a quantity of 500 l/ha. In this case too, the results obtained after 3 weeks showed that the agents according to the invention exhibited a better selectivity in relation to the comparison compounds.

In field trials, which were repeated twice, plots (clay containing sand) with potatoes were treated before leaf emergence with the agent listed in the table. The agent was sprayed on as an aqueous suspension in a quantity of 500 l/ha, where the application amount continuously decreased from 2.0 kg of active substance/ha to 0.0 kg of active substance/h.

Even 6 weeks after the treatment, when the potatoes were completely spared, the plot was practically free of weeds at doses in the range of 2 - 0.3 kg of active ingredient/ha, while the untreated control plot shows an extremely strong overgrowth with Polygonum lapathifolium, Thlaspi arvense, Chenopodium album as well as with Matricaria inodora. An assessment after a total of 8 weeks gave even more effect and the treated parcel with 0.2 kg of active substance/ha was still practically free of weeds. The potatoes did not show any damage there either.

The following table shows average values for the minimum application amount that is necessary for a very good weed-fighting effect.

Example 4

. In a further open field trial (repeated 2 times), potatoes, before leaf emergence, in humus-containing sand were applied in

the agents listed in the table, suspended in 500 liters of water/ha.

At the time of the first assessment, untreated sections were heavily infested with Chenopodium album, Spergula arvensis and Polygonum convolvulus (soil cover 40%).' The assessment followed

6 and 10 weeks after application when determining the swidden value for cultural compatibility and weed control. The table shows the minimum dose for complete weed freedom for each compound, as well as the selectivity indices obtained from the swelling days. This shows the superior selectivity for the compounds used according to the invention.

On a potato field, 1,1,3-trimethyl-3-(5-n-butylsulfonyl-1,3,4-thiadiazol-2-yl)-urea, as well as 1,1,3-tr ±methyl-3-(5-ethylsulfonyl-1,3,4'-thiadiazol-2-yl)-urea suspended in 500 liters of water/ha.

At the time of treatment, the potato plants had developed 6-10 leaves. The strong weed cover consisted mainly of Chenopodium album and Polygonum convolvulus, which respectively had developed 2 - 10 and 2 - 4 true leaves. As a result of the fact that the weeds were shielded by the potato grass during the spraying, an almost 100% destruction of the weeds was only achieved at relatively high doses. The table indicates the swelling value for the weed effect and the selectivity index (assessment 4 weeks after application). Despite this, the inventive compound proved to be selective, while the known compound under these difficult conditions was not selective.

Claims (2)

1. Thiadiazolyl urea compounds with herbicidal action, characterized in that they have the general formula: where is alkyl with 4-8 carbon atoms and n is 1 or 2. 2. Compound according to claim 1, characterized in that it is 1,1,3-trimethyl-3-(5-butylsulfonyl-1,3,4-thiadiazol-2-yl)-urea.