IL44041A - Heterocyclic-substituted 1,3,4-thiadiazole derivatives their preparation and herbicidal compositions containing the - Google Patents

Description

derivatives;,, their preparation and her cidal cofflposi iong cont ining tem G. 41989 Type la The present invention relates to certain new hetero-cyclic-substituted 1,3,4-thiadiazole derivatives, to a J process for their preparation and to their use as herbicides.

It has already been disclosed that imidazolidin--2-ones, especially imidazolidin-2-one-l-carboxylic acid isobutylamide, can be used for combating weeds (compare German Offenlegungsschrift (German Published Specification) 1*795,117). However, their action against grasses, for example varieties of Echinochloa and Lolium. is not always satisfactory, especially if low amounts and concentrations are used. German patent specification No. 2,123,450 discloses herbicidally active compounds of formula I below wherein n = 1 and the imidazolidinone portion of the compounds is v sr substituted by e.g. halogen in the Z- and position. It has now been surprisingly found that the new compounds according to the invention, which are unsubstituted in the above positions, are also herbicidally active.

The present invention provides heterocyclic-substituted 1, 3,4-thiadiazole derivatives of the formula in which 1 R represents alkyl , haloalkyl, alkylthio, alkylsulphonyl or alkylsulphoxyl . 2 R represents methyl or~¾thyl, and n represents 1 ox 2.

R1 preferably represents straight-chain or branched alkyl with 1 to 5 carbon atoms, especially with 1 to 4 carbon atoms; haloalkyl with 1 or 2 carbon atoms and 2 alkylthio, alkylsulphonyl or alkylsulphoxyl , in each case with 1 to 4 carbon atoms.

The invention also provides a process for the production of a heterocyclic-substituted 1,3,4-thiadiazole derivative of the formula (I) in which a 1,3, -thiadiazolyl (2)-urea of the general formula in which R has the abovementioned meaning, m represents 2 or 3> and Hal represents halogen, especially chlorine, is heated at 50 - 120°C, in the presence of an acid-binding agent and optionally in the presence of a diluent, and the hexahydropyrimidin-2-one or imidazolidin-2-one thus produced, of the general formula Le A 14 811 - 3 in which R1 and n have the abovementioned meanings, is reacted with an alkylating agent, for example dimethyl sulphate, diethyl sulphate, methyl iodide or ethyl iodide, in the presence of an acid-binding agent and optionally in the presence of a diluent, at temperatures of -5 to +100°C.

Surprisingly, the l,3»4-thiadiazole derivatives according to the invention display a better herbicidal activity than the known imidazolidin-2-one-carboxylic acid isobutylamide which is chemically the nearest active compound of the same type of action. The compounds according to the invention thus represent an enrichment of the art.

If l-[5-trifluoromethyl-1, 3,4-thiadiazolyl-(2) ]-3--chloroethyl-urea and dimethyl sulphate are used as starting materials, the course of the reaction can be represented by the following formula scheme: The formula (II) provides a general definition of the l,3»4-thiadiazolyl-(2-ureas which can be used as starting materials in the process of the invention. Some of their compounds are known (compare German Offenlegungsschrift (German Published Specification) 1,770,467 and Swiss Patent Specification 522,681). Those which are not known can be prepared according to processes described there (compare also the preparative Examples below).

The following may be mentioned as examples of the l,3,4-thiadiazolyl-(2^ureas: l-[5-tert.-but l-l,3,4-thiadia- zolyl- (2) ] -3- ( β-chloroethyl) urea , 1- [5-tert.-butyl-l,3 , 4-thiadiazolyl- (2) ] -3- (γ-chloropropyl) urea, 1- [5-trifluoromethyl-1 , 3 , 4-thi<3azolyl- (2) ] -3- (γ-chloropropyl) - urea f 1- [5-methylthio-l , 3 , -thiadiazolyl- (2) ] -3- (β-chloroethyl) urea , 1- [ 5-ethylthio-l , 3 , 4-thiadiazolyl- (2 ) ] -3- ( β-chloroethyl ) urea , 1- [5-methylthio-l , 3 , 4-thiadiazolyl- ( 2 ) ] -3- (γ-chloropropyl ) urea , 1- [ 5-ethylthio-l , 3 , 4-thiadiazolyl- (2 ) ] -3- (γ-chloropropyl) urea , 1- [5-propylthio-l, 3 , 4-thiadiazolyl- (2) ] -3- (g-chloroethyl) urea, 1- [5-propylthio-l , 3 , 4-thiadiazolyl- (2) ] -3- (γ-chloropropyl) urea , 1- [5-butylthio-l , 3 , -thiadiazolyl- ( 2 ) ] -3- (γ-chloropropyl ) urea , 1- [5-butylthio-l, 3, 4-thiadiazolyl- (2) ] -3- (β-chloroethyl) urea, 1- [ 5-sec . -butylthio-1 , 3 , 4-thiadiazblyl-T2) ] -3- (β- chloroethyl) - urea , 1- [5-sec . -butylthio-1 , 3 , 4-thiadiazolyl- (2 ) ] -3- (γ-chloropropyl) - urea, 1- [5-ethylsulphonyl-l, 3 , 4-thiadiazolyl- (2) ] -3- (β-chloroethyl) - urea , 1- [5-ethylsulphonyl-l, 3 , 4-thiadiazolyl- (2) ] -3- (γ-chloropropyl) - 1- [5-methylsulphoxyl-l , 3 , 4-thiadiazolyl- (2) ] -3- (γ-chloro- propyl) urea, 1- [5-ethylsulphoxyl-l, 3, 4-thiadiazolyl- (2) ] -3- (γ-chloro- propyl) urea, 1- [5-ethylsulphoxyl-l, 3 , 4-thiadiazolyl- (2) ] -3- ( -chloro- ethyl) urea , Polar solvents can be used as diluents in the reaction according to the invention to give the imidazolidiones or tetrahydropyrimidinones of the formula (III). Preferred solvents include alcohols such as methanol, ethanol, propanol and butanol, nitriles such as acetonitrile, chlorinated hydrocarbons such as 2 , 4-dichlorobenzene , and/or water.

All customary acid-binding agents can be used as add binders; alkali metal hydroxides, for example sodium hydroxide or potassium hydroxide, alkali metal carbonates, for example sodium carbonate or potassium carbonate, alkaline Le A 14 811 - 6 - earth metal hydroxides, for example calcium hydroxide or magnesium hydroxide, and alkaline earth metal carbonates, for example calcium carbonate or magnesium carbonate, are preferred. The reaction according to the invention to give imidaz-olidinones or tetrahydropyrimidinones of the formula (III) can in general be carried out in a temperature range of 50 to 120°G, preferably of 80 to 120°C.

In carrying out the preparation of compounds of the formula (III), 1 to about 1.1 mols of acid-binder are generally employed per mol of the compounds of the formula (II).

The compounds of the firmula (III) may be isolated as follows: the reaction mixture is hydrolysed and the resulting precipitate is filtered off and optionally purified by recrystallisation.

Polar organic solvents are also preferred as diluents in the reaction of the second stage of the process of the invention, which yields the compounds of the formula (I).

These solvents include halogenated hydrocarbons such as chloroform or methylene chloride, ethers such as diethyl ether, dibutyl ether, tetrahydrofuran or dioxan, and sulphoxides such as dimethyl!sulphoxide.

The acid-binding agents employed may be those already described in connection with the first stage of the process.

The alkylating agents used are generally dialkyl sul-phates, such as dimethyl sulphate and diethyl sulphate, or alkyl halides such as methyl iodide, ethyl iodide or ethyl bromide.

The reaction according to the invention to give compounds of the formula (I) is carried out in a temperature range of -5 to +100°C, preferably at 0 to 50°C. acid binder are generally employed per mol of the compound of the formula (III). Exceeding the stoichiometric ratios to a greater extent does not produce any substantial improvement in yield .

To isolate the compounds according to the invention of the formula (I), the reaction mixture may be poured onto ice and the resulting precipitate filtered off and optionally purified by recastaliisation.

The active compounds according to the invention are distinguished by a high herbicidal potency. They can therefore be employed with good success for destroying weeds.

Weeds in the broadest sense are plants which grow in places where they are not desired. As weeds, there may be mentioned: dicotyledons such as mustard (Sinapis ) , cress (Lepidium) . cleavers (Gali m), chickweed (Stellaria) . camomile (Matricaria) . gallant soldier (Galinsoga) , goosefoot (Chenopodium) , annual nettle (Urtica) and groundsel (Benecio) , and monocotyledons such as timothy (Phleum) . bluegrass (Poa) . fescue (Pestuca), goosegrass (Bleusine) , foxtail (Setaria), ryegrass (Lolium) and barnyard grass (Bchinochloa) .

The active compounds according to the invention are in particular outstandingly suitable for combating grasses such as species of Bchinochloa or Lolium. Furthermore, they can also be employed with particular advantage as selective agents for combating weeds, especially, for example, in crops of cereals or cotton. When used in larger amounts, they are also suitable as total herbicides.

The active compounds according to the present invention can be co er e granulates. These may be produced in known manner, for example by mixing the active compounds with extenders, that is, liquid or solid or liquefied gaseous diluents or carriers optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing agents, and/or foam- forming agents. In the case of the use of water 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, toluene, benzene or alkyl naphthalenes, chlorinated aromatic or aliphatic hydrocarbons, such as chlorobenzenes , chloroethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclo-hexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutjrl ketone or cyclohexanone , or strongly polar solvents, such as dimethyl^formamide, dimethyl sulphoxide or acetonitrile , as well as water.

By liquefied gaseous diluents or carriers are meant liquids which would be gaseous at normal temperatures and pressures, e.g. aerosol propellents, such as halogenated iiydr-Dcarions, e.g..Freon* As solid diluents or carriers, there are preferably used ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorill onite or diatomaceous earth, or ground synthetic minerals, such as highly-dispersed silicic acid, alumina or silicates.

Preferred examples of emulsifying and foam-forming agents include non-ionic and anionic emulsifiers , such as V alcohol ethers, for example alkylaryl-polyglycol ethers, alk l_sulphonates, alkyl sulphates and aryl^ulphonates as well as albumin hydrolyzation products; and preferred examples of dispersing agents include lignin, sulphite waste liquors and methyl cellulose.

The active compounds according to the invention can be used as a mixture with other active compounds.

The formulations in general contain from 0.1 to 95 per cent by weight of active compound, preferably 0.5 to 90 per cent by weight.

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

They can be used either according to the post-emergence method or according to the pre-emergence method; when the active compounds are used as total herbicides, they are preferably applied after emergence of the plants, whilst when they are used as selective agents thejr are preferably applied before emergence. The amount of active compound employed can vary within substantial ranges. It depends essentially on the nature <£ the desired effect. In general, the amounts applied are from 0.1 to 25 kg/ha, preferably 0.5 to 10 kg/ha.

The invention therefore provides a herbicidal composition containing as active ingredient a compound according to the invention in admixture with a solid or liquefied gaseous diluent or carrier or in admixture with a The invention also provides a method of combating weeds which comprises applying to the weeds or their habitat a compound according to the invention alone or in the form of a composition containing as active ingredient a compound according to the invention in admixture with a 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 the growing, a compound according to the invention was applied alone or in admixture with a diluent or carrier. It will be seen that the usual methods of providing a harvested crop may be improved by the present invention.

The compounds according to the invention, and the preparation and use of the compounds according to the invention, are illustrated by the following Examples.

Example A Post-emergence test Solvent: 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a suitable preparation of active compound, 1 part by weight of active compound was mixed with the stated amount of solvent, the stated amount of emulsifier was added and the concentrate was then diluted with water "to the desired concentration.

Test plants which had a height of 5 - 15 cm were sprayed with the preparation of the active compound in such a way as to apply the amounts of active compound per unit area which are indicated in the table. Depending on the concentration of the spray liquor, the amount of water used weeks, the degree of damage to the plants was determined and characterised by the values 0 - 5, which have the following meaning: 0 no effect 1 a few slightly burnt spots 2 marked damage to leaves 3 some leaves and parts of stalks partially dead 4 plant partially destroyed 5 plant completely dead The active compounds, the amounts used and the results can be seen from Table A.

Table A Post-emergence test Amount of active compound used, kg/ha Bchino- Cheno- Sina- Galin- St Active compound chloa podium pis so&a a (known) Example B Pre-emergence test Solvent : 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a suitable preparation of active compound, 1 part by weight of active compound was mixed with the stated amount of solvent, the stated amount of emulsifier was added and the concentrate was then diluted with water to the desired concentration.

Seeds of the test plants were sown in normal soil and, after 24 hours, watered with the preparation of the active compound. It was expedient to keep constant the amount of water per unit area. The concentration of the active compound in the preparation was of no importance, οηΐγ the amount of active compound applied per unit area being decisive. After three weeks, the degree of damage to the test plants was 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 growth 5 heavy damage and only deficient development or only 50$& emerged 4 plants partially destroyed after germination or only 25c/° emerged 5 plants completely dead or not emerged.

The active compounds, the amounts applied and the results obtained can be seen from Table B.

Table B emergence test Amount of active compound Echino- Cheno- Lolium G-alin- Ma Active compound used, chloa podium soga ca kg/ha (known) Example 1: (a) First A mixture of 19.2 g (0.07 mol) of l-[5-trifluoro- methyl-l,5,4-thiadiazolyl-(2)]-3-f-chloroethy)urea 3.92 g (0.07 mol) of potassium hydroxide, 11.2 ml of water and 28 ml of ethanol was heated to the boil under reflux for 10 minutes. After cooling, the reaction mixture was poured into 200 ml of water and the resulting precipitate was filtered off, rinsed with ice water and dried.

Recrystallisation from ethanol yielded 12.6 g (lSc0 of theory) of l-[5-trifluoromethyl-l, 3,4-thiadiazolyl-(2) ]- imidazolidin-2-one of melting point 198°0. (b) Second sta e 42.3 g (0.18 mol) of l-[5-trifluoromethyl-l,3,4- thiadiazolyl-(2) ]-imidazolidin-2-one were slowly added to a suspension of 11.9 g (0.213 mol) of powdered potassium hydroxide in 100 ml of dimethylsulphoxide . 25.2 g (0.18 mol) of methyl iodide were added dropwise thereto at an internal temperature of 5 to 10°0, whilst stirring and cooling externally.

After heating for two hours to 50°C, the reaction resulting precipitate was filtered off, washed with ice water, dried in vacuo and purified by recrystallisation. 33.9 g (75?¾ of theory) of l-[5-trifluoromethyl-1,3,4-thiadiazolyl-(2) ]-3-methyl-imidazolidin-2-one of melting point 176°C (from ethyl acetate) were obtained.

Sxanmle 2 ; (a) First sta^e ( A mixture of 21.8 g (0.08 mol) of l-[5-tert .-butyl-1,3, 4-thiadiazolyl-(2) ]-3-Y-chloropropy])urea, 4.4 g (0.08 mol) of potassium hydroxide and 63 ml of ethanol was heated to the boil under reflux for 10 minutes. After cooling, the reaction mixture was poured into 400 ml of water and the resulting precipitate was filtered off, rinsed with water, dried and recrystallised from ethyl acetate. 17 g (895* of theory) of l-[5-tert.-but l-l,3,4-thiadiazolyl-(2) ]-hexahydropyrimidin-2-one of melting point 3.87°C were obtained, (b) Second sta^e 25.5 e (0.106 mol) of l-[5-tert.-butyl-l,3,4 thia-diazolyl-(2) j-hexahydropyrimidin-2-one were slowly added to a suspension of 7.13 g (0.13 mol) of powdered potassium h droxide in 6 ml of dimeth lsul hoxide 1 at an internal temperature of 5 to 10°C, whilst stirring and cooling.

After heating for two hours to 50°G whilst stirring, the reaction mixture was cooled and poured into 300 ml of water. The resulting precipitate was filtered off, rinsed with water, dried in vacuo and recrystallised from ligroin/ ethyl acetate. 21.5 g (80?o of theory) of l-[5-tert.-butyl-l,3,4-thiadiazolyl-(2 ) ]-3-methyl-hexahydropyrimidin-2-one of melting point 100°C were obtained.

Examples 3 - 16 The compounds of formula (I) identified in Table 2 below were prepared analogously to Examples 1 and 2, each being prepared in two stages (a) and (b).

First, the compounds of the general formula (III), listed in Table 1 below, were prepared analogously to Examples 1(a) and 2(a): Table 1 R1 n Melting point (°C) 3(a) C(GH3)3 1 205 6(a) CP3 2 228 9(a) CH3S 1 180 10(a) G2H5S 1 176 11 (a) C2H5S 2 133 13(a) n-C3H?S 1 115 Table 1 (continued) Melting n point 15(a) C2H5S02 1 175 16(a) C2H5S02 2 2 7 Then the active compounds of the general formula (I), listed in Table 2 below, were prepared analogously to Examples 1(b) and 2(b): Table 2 Melting R1 R2 n point ( °c ) 3(b) C(CH3)3 CH3 1 129 4(b) C(CH3)3 1 75 C2H5 5(b) C(CH3)3 C2H5 2 81 6(b) CH3 2 141 7(b) CP3 1 103 °2H5 8(b) C 3 C2H5 2 66 9(b) CH,S CH3 1 125 3 10(b) C2H5S CH3 1 100 1Kb) C2H5S CH, 2 62 3 12(b) C2H5S 2 60 C2H5 13(b) n-C3H7S CH_ 1 101 15(b) OH. 1 131 C2H5S02 16(b) C2H S02 OH, - 2 150 The preparation of the starting materials the formula (II) is exemplified below: Example (1) 23.5 g (0.15 mol) of 2-amino-5-tert,-fcutyl-l, 3,4- thiadiazol (prepared according to Bulletin de la Societe Chimique de Prance 1959. pages 477-479 ) were suspended in 200 ml of anhydrous ethyl acetate. 15.8 g (0.15 mol) of /chloroethyljisocyanate were added dropwise to this suspension at 40°C internal temperature, with stirring and reflux cooling. In the course of the addition, the temperature gradualD.y rose to 45°C After stirring for ten hours at 40 - 45°C, the reaction mixture was filtered hot and the solvent was dis- tilled off in vacuo. The solid which remained was recrystal- lised from 70 ml of ethyl acetate. 32.8 g (83.5?'' of theory) of l-[5-tert.-butyl-l,3,4- thiadia7.o.lyl-(2) ]-3-¾-chloroethy^urea of melting point 131°C were obtained.

The compounds of Table 3 belowwere prepared analogous^: Table 3 Example R"1" m HeItin»■ No. point ° ) (2) C(CH ) 3 97 Table 5 (continued) Further 2-amino-5-substituted 1, 3,4-thiadiazoles can be prepared in accordance with the information in the following literature. 1) Ber. dtsch. chem. Ges. 29_, 2511 (1896) 2) J. Chem. Soc. (London) 2» 54 (1901) 3) U.S. Patent' 2,422,050, C.A. £1, 59021 (1947) - 4) Helv. Chid. Act.22» !353 (1950) 5) U.S. Patent 2,524,729, CA.45_, 2030 (1951) 6) Can. J. Chem.22» 1121 (1959) 7) JA Pat. 20,944-66, C.A. 66, 46430 f (1967) ) Arch. Pharm. 284_, (1951), page 61 9) J. of Het. Chem. 3. .page 336 (1966) 0) Farmaco Ed. Sci. 18 (8), pages 607-613 (1963) 1) U.S. Patent 2,799,683 of 16.07.1957 (Messrs.

American Cyanamid) ?) U.S. Patent 2,947,825 of 14.02.1950 (Messrs.

Monsanto) 3) Pharmazeutische Zentralhalle, volume 107. issue 9 (1968) a es 656-657 14) Zeitschrift fur Chemie (1969) 12, 450. »

Claims (17)

44041/2 What we claim is:

1. Heterocyclic-substituted 1, 3,4-thiadiazole derivatives of the general formula in which represents alkyl, haloalkyl, alkylthio, sulphonyl or alkylsulphoxyl , 2 R represents methyl or ethyl, and n represents 1 or 2,.

2. Compounds according to claim 1 in which R re-presents alkyl with 1-5 carbon atoms, haloalkyl with 1 or 2 carbon atoms and 2-5 halogen atoms, alkylthio, alkylsulphonyl or alkylsulphoxyl with 1-4 carbon atoms.

3. The compound of the formula 0

4. The compound of the formula 0

5. The compound of the formula 0

6. Each of the compounds according to claim 1 which are hereinbefore specifically identified other than those of claims 3 - 5.

7. A process for the preparation of a heterocyclic-substituted 1 , » 4-thiadiazole derivative according to any of claims 1 - 6 in which a l,3,4-thiadiazolyl-(2)-urea of the general formula in which R^" has the meaning given in claim 1, m represents 2 or 3» and Hal represents halogen is heated at 50 - 120°C in the presence of an acid-binding agent, and the hexahydrop3Timidin-2-one or imidazolidin-2-one thus produced, of the general formula in which R1 and n have the meanings given in claim 1, is reacted with an alkylating agent in the presence of an acid-binding agent at a temperature of -5 to +100°C.

8. A process according to claim 7 in which Hal represents chlorine.

9. A process according to claim 7 or 8 in which one or both stages is or are carried out in the presence of a diluent .

10. A process according to any of claims 7 - 9 in which the first stage of the process is carried out at 80 to 120°C, and the second at 0 to 50°C.

11. A process for the preparation of a compound according to claim 1 substantially as hereinbefore described in any of Examples 1 - 16.

12. Compounds according to claim 1 whenever prepared by a process according to any of claims 7 - 11.

13. A herbicidal composition containing as active ingredient a compound according to any of claims 1 - 6 or 12 in admixture with a solid or liquefied gaseous diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent.

14. A composition according to claim 13 containing from 0.1 to 95 of the active compound by weight.

15. A method of combating weeds which comprises applying to the weeds or their habitat a compound according to any of claims 1 - 6 or 12 alone or in the form of a composition containing as active ingredient a compound according to any of claims 1 - 6 or 12 in admixture with a diluent or carrier.

16. A method according to claim 15 in vhih the active of 0.1 to 25 kg per hectare.

17. Crops protected from damage by weeds by being grown in areas in which, immediately prior to and/or during the time of the growing, a compound according to any of claims 1-6 or 12 was applied alone or in admixture with a diluent or carrier.