IL30586A - N-substituted 5-amino-1,3,4-thiadiazoles - Google Patents

Description

fpjna D'loman β'1ητκ*·,ικ»ητ4»3»1"-ι J»»R-5 N-substItuted 5-amino-l, 3, 4-thladiazolee FARBENFABRIKEN BAYER AKTIENGESELLSCHAUT C. 28815 30586/2 The present invention relates to certain new N-substituted 5-amino-l,3t4-thiadiazoleo, to a process for their production and to their use as herbicides* It is known that thiazolyl ureas, e.g. ( -(4-ne thyl-l,3-thiazolyl-2)-N*-methyl urea, can be used as herbicides (Belgian Patent Specification 679138)· The invention provides new N-substituted 5-aminoj 3»4-thiadiasoles of the formula:- in which R is hydrogen, alkyl, alkenyl or alkylthio# R is hydrogen or alkyl, and R,e is alkyl* The invention also provides a process for the production of the compounds of Formula (1) in which a 5-amino-l,3,4-thiadiazole of the formula:- in whic R has the meaning stated above (a) is reacted in tho presence of a solvent with an iso-oyanate of the formula:- R« -N =G=0 (3) in which 30586/2 acid chloride of the formula in which R1 and R,n have the meaning stated above, and Hal is halogen. .

The process may be carried out in an inert solvent; the term solvent including mere diluents.

It ds decidedly surprising that the new 1,3»4-thiadiazoles exhibit a stronger herbicidal activity, and, in particular, also better selective herbicidal effects, than the previously known thiadiazoles.

The new 1,3»4-thiadiazoles are clearly characterized by the formula (l) stated above.

In the above formulae if R is alkyl it has preferably 1 - 4 carbon atoms; if alkenyl it has preferably 3 carbon . · atoms; and if alkylthio it has preferably 1 - 4 carbon atoms.

R' if not hydrogen, is preferably alkyl with 1 - 4 carbon atoms; R"! is preferably alkyl with 1 - 4 carbon atoms.

If 3-propyl-5-amino-l,3»4-thiadiazole and methyl isocyanate are used as starting materials, the reaction according to (a) can be represented by the following formula scheme: C5H7- (7) If dimethylcarbamic acid chloride is reacted with the same thiadiazole, the reaction according to (b) can be 30586/2 represented by the following formula scheme: 0 (8) Some of the aminothiadiazoles of formula (2) are known.' New thiadiazoles can be prepared in the same manner as those already known, for example by reaction of the appropriate l-acylthiosemicarbazides with agents which split off water, such as acetic anhydride (Chemische Berlchte J22, 2511 (1896)). and The starting materials (3)7(4), are also known.

Examples of the preferred isocyanates which can be used are methyl isocyanate,- ethyl isocyanate and isopropyl isocyanate.

As solvents, all inert organic solvents are suitable. Preferred solvents include hydrocarbons, such as benzene, toluene; ethers, such as diethyl ether, dioxan, tetrahydro-furan, chlorinated hydrocarbons, such as methylene chloride, chloroform, carbon tetrachloride, ketones, such as acetone; esters, such as ethyl acetate and acetonitrlle, and dimethyl formamide.

As acid binders, all customary acid-binding agents can be used. Preferred agents include the alkali metal hydroxides, alkali metal carbonates and tertiary amines.

Particularly suitable are sodium hydroxide, sodium carbonate, triethyl amine and pyridine. 30586/2 The reaction temperatures can be varied within a fairly wide range. In general, the work is carried out from 0° to 140°C, preferably from 10° to 120°C.

When carrying out the process, approximately equi-molar amounts of starting materials are generally Used. The working up of the reaction mixture is carried out in the usual manner.

The active compounds according to the invention influence plant growth and can therefore be used for defoliation or for desiccation of the green parts of plants. in this case they serve as harvest auxiliaries to facilitate harvesting. They are, however, quite particularly suitable for the control of weeds. By weeds in the widest sense are meant all plants which grow in places where they are not desired.

Whether the substances according to the invention act as total or selectiv herbicides depends essentially on the amount applied. . ; The substances according to the invention can be used for example in the case of the following plants: dicotyledons, such as mustard (Sinapis), cress (Lep'idium), cleaver (Galium), common chickweed (Stellaria), mayweed (Matricaria) , small-flower Galinsoga (Galinsoga), fathen (Chenopodium) , stinging nettles (Urtica), groundsel (Senecio), cotton (Gossypium), beets (Beta), beans (Phaseolus), carrots (Daucus), potatoes (Solanum), coffee. (Coffea); monocotyledons, such as timothy (Phleum) ,. bluegrass (Poa) , fescue (Pestuca), goosegrass (Eleu-sine), foxtail (Setaria), ryegrass (Lolium), cheat (Bromus), barnyard grass (Echinochloa) , maize (Zea), rice (Oryza), oats (Avena), barley (Hordeum), wheat (Triticum), millet (Panicum), and sugar cane (Saccharum).

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 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 used round natural minerals , such as kaolins, clays, talc or Preferred examples of emulsifying agents include non-ionic and anionic emulsifiers , such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alk larylpolyglycol ethers, alkyl sulphonates and aryl sulphonates; and preferred examples of dispersing agents include lignin, sulphite waste licuors and methyl cellulose.

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

The formulation's contain, in general, from 0.1 to 951 preferably 0.5 to 90-, per cent by weight of active compound.

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

The active compounds according to the invention can. be used according to both the pre-emergence method and the post-emergence method, that is, before or after emergence of the plants.

When the active compounds are used according to the pre-emergence method, the amount applied can be varied within fairly wide ranges. In general, it lies from 1 to 50 kg per hectare. When used according to the post-emergence process, the concentration of active compound can also be varied within fairly wide ranges. In general, it lies from 0.01 to 5%t preferably from 0.25 to 1$ by weight.

Thus the invention also provides a herbicidal composition containing as active ingredient a thiadiazole of the formula (l) in admixture with a solid diluent or carrier The invention also provides a method of combating weeds which comprises applying to the weeds or to a weed habitat a thiadiazole of the. formula (l) alone or in the form of a composition containing as active ingredient a. thiadiazole of the formula (1) in admixture with a solid or liquid diluent or carrier.

The invention also provides crops protected from damage by weeds by being grown in areas in which immediately prior to and/or during the time of growing a thiadiazole of the formula (1) was applied alone or in admixture with a solid or liquid diluent or carrier.

The invention also provides a method of defoliating plants which comprises applying to the plants a thiadiazole of the formula (l) alone or in admixture with a solid or liquid diluent or carrier whereby the leaves of the plants are caused to fall off or die.

The effectiveness of the new thiadiazoles according to the formula (1) is demonstrated by the tests in Examples A and B.

The process of the invention is demonstrated in the following Examples 1-4.

Example A Pre-emergence test Solvent: 5 parts by weight acetone Emulsifier: 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 then diluted with water to the desired concentration.

Seeds of the test plants are sown in normal soil of water per unit area. The concentration of the active compound in the preparation is of no importance, only the amount of active compound applied per unit area being decisive. After three weeks, the degree of damage to the test plants is determined and characterised by the values 0-5, which have the following meaning: 0 no effect ' 1 slight damage or delay in growth 2 marked damage or inhibition of gr.owth heavy damage and only deficient - . · · development or only 50# emerged 4 plants partially destroyed after germination or only 25 emerged . plants completely dead or not ; . emerged. ' - The active compounds, the amounts applied ' and the results obtained can be seen from the following Table l r Table 1 pre-emergence test νoθ Active compound Amount of active Echino- Cheno-CTv co >mmppound applied chloa podium kg/hectare CH,-C N 40 4-5 5 3 II II (10). 20 4 5 HC-S-C-NH-CONHCIL 10 4 5 3 4 (known) 2.5 2 2-3 H o Example Β Post-emergence test Solvent: 5 parts by weight acetone Emulsifier: 1 part by weight alkylaryl poly lycol ether.

To produce a suitable preparation of active compound, 1 part by weight of active compound is mixed with the stated amoun of solvent, the stated amount of emulsifier is added and the concentrate is then diluted with water to the desired concentration.- ..

Test plants which have, a height of about 5-15 cm. are sprayed with the preparation of the active compound until just dew moist. After three weeks, the degree of damage to the plants is determined and characterised by the values 0-5, which have the following meaning: 0 no effect ■ , l a few slightly burnt spots 2 marked damage to leaves some leaves and parts of stalks, partially dead plant partially destroyed plant completely dead The active compounds, their concentrations and the results obtained can be seen from the following Table 2:^ Table 2 (Contd) post-emergence test H O Active compound Concentration . Echino- of active cos- c loa pound —N 0.2 5 n-c4H9S -S-&H-CO-NK-C !Hj (14) 0.1 5 0.05 5 0.025 4-5 30586/2

Claims (3)

1. CLAIMS 1. ϊϊ-substituted 5-amino-l,3»4-thiadiazoles of the formula in which R is hydrogen, alkyl, alkenyl or alkylthio; R' is hydrogen or alkyl, and R" is alkyl.

2. Thiadiazolea according to Claim 1, in which R is alkyl with 1 - 4 carbon atoms, alkenyl with 3 carbon atoms or alkylthio with 1 - 4 carbon atoms; R' is hydrogen or alkyl with 1 ~ 4 carbon atoms; R' is hydrogen or alkyl with 1 - 4 carbon atoms; and R" is alkyl with 1 - 4 carbon atoms. 3. The thiadiazole of the formula 4, The thiadiazole of the formula IT—if 5. The thiadiazole of the formula 6. The thiadjazoje of the formula n-C.HQ-S-C-S-C-HH-CO-NH-CH_ 4 9 3 (14) ■3 v 30586/2 The thiadiazole of the formula 17. The thiadiazole of the formula 18. * A process for the production of thiadiazoles accord ing to any of Claims 1 to 17 in which a 5-amino-l, »4-thiadiazole of the formula in which R has the same meaning as in Claim 1 (a) is reacted with an isocyanate of the formula R«_N=C=0 (3) in which R' has the same meaning as in Claim 1, or (b) is reacted, in the presence of an acid binder, with an acid chloride of the formula K"0 in which R" and R" have the same meaning as in Claim 1, and Hal is halogen. 19. A process according to Claim 18 (a) in which the isocyanate is methyl isocyanate, ethyl isocyanate or iso-propyl isocyanate. - Ϊ7 - 30586/2 20* A process according to Claims 18 or 19 in which the reaction is carried out at 0° to 140°C . 21. A process according to Claim 20 in which the reaction is carried out at 10° to ¾20°C. 22·· A process according to any of Claims 18 to 21 in which the reaction is carried out in the presence of an inert solven .

3. Processes for the production of thiadlazoles according to Claim 1 substantially as hereinbefore described with reference to the Examples. 24· Herbicidal compositions containing as aotivo ingredient a thiadiazole according to any of Claims 1 to 17 in admixture with a solid diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent, 25. A composition according to Claim 24 containing from 0,1 to 95 per cent by weight, of the active compound. 26. A method of combating weeds which comprises applying to the weeds or to a weed habitat a thiadiazole according to an of Claims 1 to 17 by itself or in the form of a composition according to Claims 24 or 25. 27. A method according to Claim 26 in which a composition is used containing from 0.01 to 5 of the active compound, by weight. 28. A method according to Claim 27 in which a composition is used containing from 0.25 to 1$ of the active compound, by weight, 30566/2 29. A method according to any of Claims 26 to 28 in which the thiadiazole is applied to an area of weeds in an amount of 1 to 50 kg per hectare. 30* A method according to any of Claims 26 to 29 in which the thiadiazole is One Of those hereinbefore mentioned in Example A or B. 31e Crops protected from damage by weeds by being grown in areas in which immediately prior to and/or during the time of growing a thiadiazole according to any of Claims 1 to 17 was applied by itself or in admixture with a solid or liquid diluent or carrier. 32. A method of defoliating plants which comprises applying to the plants a thiadiazole according to any of Claims 1 to 17 by itself or in admixture with a solid or liquid diluent or carrier. RC/rb