CA2075407A1

CA2075407A1 - N-azinyl-n-(2-methylsulphinyl- phenylsulphonyl)-ureas

Info

Publication number: CA2075407A1
Application number: CA 2075407
Authority: CA
Inventors: Hans-Jochem Riebel; Hans-Joachim Santel; Klaus Luerssen; Robert R. Schmidt
Original assignee: Individual
Current assignee: Bayer AG
Priority date: 1991-08-09
Filing date: 1992-08-06
Publication date: 1993-02-10
Also published as: JPH05201998A; BR9203078A; MX9204450A; EP0528211A1

Abstract

N-Azinyl-N'-(2-methylsulphinyl-phenylsulphonyl)-ureas A b s t r a c t The invention relates to new N-azinyl-N'-(2-methyl-sulphinyl-phenylsulphonyl)-ureas of the formula (I) (I) in which A represents nitrogen or a CH group, X represents hydrogen, halogen or, alkoxy or alkyl-thio, each of which has 1 to 3 carbon atoms and each of which is optionally substituted by halogen and Y represents alkyl or alkoxy, each of which has 1 to 3 carbon atoms and each of which is optionally substituted by halogen, and salts of compounds of the formula (I), processes for the preparation of these compounds and their salts, and their use as herbicides.

Le A 28 896-Foreign Countries

Description

2075~07 The invention relates to new N-azinyl-N'-(2-methyl-sulphinyl-phenylsulphonyl)-urea~, processes for their preparation, and their use as herbicides.

It has been disclosed that certain arylsulphonylureas having substituents bonded via sulphur such as, for example, N-(4,6-dimethoxy-s-triazin-2-yl)-N'-(2-propyl-thio-phenylsulphonyl)-urea (cf. US Patent 4,818,277) or N-(4,6-dimethylpyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea (cf. US Patent 4,169,719; cf. also EP-A 101,308, EP-A 35,893) have herbicidal properties.
However, the herbicidal action of these known compounds is not satisfactory in all respect~.

New N-azinyl-N'-(2-methyl~ulphinyl-phenylsulphonyl)-ureas of the general formula (I) ~ 02-NH-CO-NH ~ A (I) in which A represents nitrogen or a CH group, X repre~ents hydrogen, halogen or alkoxy or alkylthio, each of which has 1 to 3 carbon atoms and each of which is optionally sub~tituted by halogen and Le A 28 896 - 1 -207~4~7 Y represents alkyl or alkoxy, each of which has 1 to 3 carbon atoms and each of which is optionally substituted by halogen, and salts of compounds of the formula (I) have now been found.

The new N-azinyl-N'-(2-methylsulphinyl-phenylsulphonyl)-ureas of the general formula (I) are obtained when N-azinyl-N'-(2-methylthio-phenyl~ulphonyl)-ureas of the general formula (II) ~ 502-NH-CO-NH ~ x ~II) in which A, X and Y have the a~ovementioned meanings are reacted with hydrogen peroxide (H202) în the pre~ence of a diluent and, if appropriate, the products obtained in this way are converted into salts by customary methods.

The new N-azinyl-N'-(2-methylsulphinyl-phenylsulphonyl)-ureas o~ the formula (I) are distinguished by a powerful Le A 28 896 - 2 -207~7 herbicidal activity.

Surprisingly, the new compounds of the formula (I) show a considerably more powerful action than the known compounds N-(4,6-dimethoxy-s-triazin-2-yl)-N'-(2-propyl-thiophenylsulphonyl)-urea and N-(4,6-dimethylpyrimidin-2-yl-N'-(2-methylsulphinyl-phenylsulphonyl)-urea, which are comparable in terms of structure and of profile of action.

The invention preferably relates to compounds of the formula (I) in which A represents nitro~en or a CH group, X represents hydrogen, fluorine, chlorine, bromine, or repre~ents alkoxy or alkylthio each of which has 1 or 2 carbon atoms and each of which is optionally substituted by fluorine and/or chlorine, and Y represents alkyl or alkoxy, each of which has 1 or 2 carbon atoms and each of which is optionally substituted by fluorine and/or chlorine.

The invention furthermore preferably relates to salts which are obtained from compounds of the formula (I) and bases such as, for example, sodium hydroxide, sodium hydrite, sodium amide, sodium carbonate, potassium hydroxide, potassium hydride, potassium amide, potassium carbonate, calcium hydroxide, calcium hydride, calcium Le A 28 896 - 3 -, .

207~407 amide or calcium carbonate, ~odium Cl-C4-alkanolate~ or potassium Cl-C4-alkanolates, ammonia, Cl-C4-alkylamines, di-(C,-C4-alkyl)-amines or tri-(Cl-C4-alkyl)-amines.

The invention particularly relates to compounds of the S formula (I) in which A represents nitrogen or a CH qroup, X represents hydrogen, chlorine, methoxy, ethoxy, difluoromethoxy or methylthio and Y represents methyl, ethyl, trifluoromethyl, methoxy, ethoxy or difluoromethoxy.

If, for example, N-(4,6-dimethoxy-pyrimidin-2-yl)-N'-(2-methylthiophenylsulphonyl)-urea is u~ed a~ starting substance, the course of the reaction can be outlined by the following equation:

~02-NH-Co-NH~ $ - H20 Le A 28 896 - 4 -207~07 OCH~
Formula (II) provides a general definition of the N-azinyl-N'-(2-methylthio-phenylsulphonyl)-urea~to be used as starting substances in the process according to the invention for the preparation of compounds of the formula (I)-In formula (II), A, X and Y preferably, or in particular,have those meanings which have already been mentioned above in connection with the de~cription of the compounds of the formula tI) according to the invention as being preferred, or particularly preferred, for A, X and Y.

The starting substances of the formula (II) are known and/or can be prepared by processes known per se (cf. US Patent 4,127,405, US Patent 4,169,719).

The process according to the invention i~ carried out u~ing hydrogen peroxide. The hydrogen peroxide is prefer-ably employed as an aqueou~ solution which preferably contains between 5% and 55%, in particular between 10%
and 50%, of H2O2.

The pr~cess according to the invention is carried out in the pre~ence of a diluent. Diluents which are suitable Le A 28 896 - 5 --- 2075~07 for this purpose are virtually all those which are customary in oxidation reactions. Diluents which are preferred for the proce~s according to the invention are carboxylic acids such as formic acid, acetic acid and S propionic acid, in particular acetic acid.

When carrying out the process according to the invention, the reaction temperatures can be varied within a substan-tial range. In general, the process is carried out at temperatures between 0C and 100C, preferably at temperatures between 10C and 60C.

The process according to the invention is generally carried out under atmospheric pres~ure. However, it is also po sible to carry out the process under increased or reduced pressure.

For carrying out the proce~s according to the invention, between 1.0 and 2.0 moles, preferably between 1.1 and 1.5 moles, of hydrogen peroxide are generally employed per mole of starting compound of the formula (II).

The reactants are preferably reacted as follows:
The ~ulphonylurea of the formula (II) is first mixed with the diluent, and the hydrogen peroxide is slowly metered into this mixture, with stirring. The reaction mixture i~
then stirred until the reaction is complete, if approp-riate at elevated temperature. When the mixture has cooled it may be diluted with water, and the crystalline product is then isolated by filtration with suction.

Le A 28 896 - 6 -207~4~7 If appropriate, salts can be prepared from the compounds of the general formula (I) according to the invention.
Such salts are obtained in a simple manner by customary salt formation methods, for example by dissolving or dispersing a compound of the formula (I) in a suitable diluent such as, for example, methylene chloride, tert-butyl-methyl ether or toluene, and addin~ a suitable base. The salts can then be i~olated by concentration or filtration with suction, if appropriate after prolonged stirring (cf. the Preparation Examples).

The active compounds according to the invention can be used as defoliants, desiccants, agents for destroying broad-leaved plants and, especially, as weed-killers. By weeds, in the broadest sense, there are to be understood all plants which grow in locations where they are un-desired. Whether the substances according to the inven-tion act as total or selective herbicides depends essen-tially on the amount used.

The active compounds according to the invention can be used, for example, in connection with the following plants:

Dicotyledon weeds of the genera: Sinapis, Lepidium, Galium, Stellaria, Matricaria, Anthemis, Galinsoga, Chenopodium, Urtica, Senecio, Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum, Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Solanum, Rorippa, Le A 28 896 - 7 -. . ' 2~75~7 Rotala, Lindernia, Lamium, Veronica, Abutilon, Emex, Datura, Viola, Galeop~is, Papaver~ Centaurea, Trifolium, Ranunculus and Taraxacum.

Dicotyledon cultures of the genera: Go~sypium, Glycine, Beta, Daucus, Phaseolus, Pi~um, Solanum, Linum, Ipomoea, Vicia, Nicotiana, Lycopersicon, Arachis, Brassica, Lactuca, Cucumis and Cucurbita.

Monocotyledon weeds of the aenera: Echinochloa, Setaria, Panicum, Digitaria, Phleum, Poa, Festuca, Eleusine, Brachiaria, Lolium, Bromus, Avena, Cyperus, Sorghum, Agropyron, Cynodon, Monochoria, Fimbristylis, Sagittaria, Eleocharis, Scirpus, Paspalum, Ischaemum, Sphenoclea, Dactyloctenium, AgrDstis, Alopecurus and Apera.

Monocotyledon cultures of the genera: Oryza, Zea, Triticum, Hordeum, Avena, Secale, Sorghum, Panicum, Saccharum, Ananas, Asparagus and Allium.

However, the use of the active compounds according to the invention i3 in no way restricted to these genera, but also extends in the ~ame manner to other plants.

The compounds are suitable, depending on the concen-tration, for the total combating of weeds, for example on industrial terrain and rail tracks, and on path~ and ~quares with or without tree plantings. Equally, the compounds can be employed for combating weeds in peren-nial culture3, for example afforestations, decorative Le A 28 896 - 8 -.

2075~07 tree plantings, orchards, vineyards, citrus groves, nut orchards, banana plantation~, coffee plantations, tea plantations, rubber plantations, oil palm plantations, cocoa plantations, soft fruit plantings and hopfields, in lawns, turf and pasture-land and for the selective combating of weeds in annual cultures.

The compounds of the f ormula (I) according to the inven-tion are particularly suitable for ~electively combating monocotyledon and dicotyledon weeds in monocotyledon cultures, both by the pre-emergence and the post-emergence method.
The active compounds can be converted into the customary formulations, such as solutions, emulsions, wettable powders, suspensions, powders, dusting agents, pastes, soluble powders, granules, suapension-emulsion concen-trates, natural and synthetic materials impregnated with active compound, and very fine capsules in polymeric sùb~tance~.

These formulations are produced in a known manner, for example by mixing th0 active compounds with extenders, that i8 liquid aolvents and/or solid carriers, optionally with the use of surface-active agents, that is emulsify-ing agents and/or dispersing agent~ and/or foam-forming agents .

In the case of the u~e of water as an extender, organic solvents can, for example, also be used as auxiliary solvents. As liquid solvent~, there are suitable in the Le A 28 896 - 9 -207~7 main: aromatics, ~uch as xylene, toluene, or alkylnaph-tha7enes, chlorinated aromatics and chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example petroleum frac-tions, mineral and vegetable oils, alcohol~, such as butanol or glycol as well as their ethers and eRters, ketone , such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, ~trongly polar sol-vents, such as dimethylformamide and dimethyl sulphoxide,a~ well as water.
As solid carriers there are suitable: for exzmple ammonium salt~ and ground natural minerals, ~uch as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth, and ground syn-thetic minerals, such as highly disperse silica, alumina and silicates; as solid carriers for granules there are suitable: for example crushed and fractionated natural rocks such as calcite, marble, pumice, sepiolite and dolomite, as well as synthetic granules of inorganic and organic meals, and granules of organic material such as sawdust, coconut ~hells, maize cobs and tobacco stalks;
aR emulsifying and/or foam-forming agents there are suitable: for example non-ionic and anionic emulsifiers, such aR polyoxyethylene fatty acid esters, polyoxy-ethylene fatty alcohol ethers, for example alkylaryl polyglycol ethers, alkylsulphonates, alkyl sulphates, arylsulphonates as well as albumen hydrolysis products;
as dispersing agents there are suitable: for example lignin-sulphite wa~te liquors and methylcellulose.

Le A 28 896 - 10 -207~

Adhesives such as carboxymethylcellulose and natural and synthetic polymers in the form of powders, granule~ or latexes, such a~ gum arabic, polyvinyl alcohol and polyvinyl acetate, as well as natural phospholipids, such as cephalins and lecithins, and synthetic phospholipids, can be used in the formulations. Further additives can be mineral and vegetable oils.

It is possible to use colorants such as inorganic pig-ments, for example iron oxide, titanium oxide and Prus-sian Blue, and organic dyestuffs, such as alizarindyestuff 8, azo dyestuffs and metal phthalocyanine dye-stuffs, and trace nutrients such as salts of iron, manganese, boron, copper, cobalt, molybdenum and zinc.

The formulation~ in general contain between 0.1 and 95 per cent by weight of active compound, preferably between 0.5 and 90%.

For combating weeds, the active compounds according to the invention, as such or in the form of their formula-tions, can also be used as mixture~ with known herbi-cides, finished formulation~ or tank mixes being possible.

Suitable components for the mixture~ are known herbi-cides, such as, for example, anilides such as, for example, diflufenican and propanil; arylcarboxylic acids such as, for example, dichloropicolinic acid, dicamba and Le A 28 896 - 11 -20754~7 picloram; aryloxyalkanoic acids such as, for example, 2,4 D, 2,4 DB, 2,4 DP, fluroxypyr, MCPA, MCPP and triclopyr; aryloxy-phenoxy-alkanoates such as, for example, diclofop-methyl, fenoxaprop-ethyl, fluazifop-butyl, haloxyfop-methyl and quizalofop-ethyl; azinones such as, for example, chloridazon and norflurazon;
carbamates such as, for example, chlorpropham, desmedipham, phenmedipham and propham; chloroacetanilides such as, for example, alachlor, acetochlor, butachlor, metazachlor, metolachlor, pretilachlor and propachlor;
dinitroanilines such aC, for example, oryzalin, pendimethalin and trifluralin; diphenyl ethers such as, for example, acifluorfen, bifenox, fluoroglycofen, fomesafen, halosafen, lactofen and oxyfluorfen; ureas such as, for example, chlortoluron, diuron, fluometuron, isoproturon, linuron and methabenzthiazuron; hydroxyl-amines such as, for example, alloxydim, clethodim, cycloxydim, sethoxydim and tralkoxydim; imidazolinones such as, for example, imazethapyr, imazamethabenz, imazapyr and imazaquin; nitriles ~uch as, for example, bromoxynil, dichlobenil and ioxynil; oxyacetamides ~uch as, for example, mefenacat; sulphonylureas such as, for example, amidosulfuron, bensulfuron-methyl, chlorimuron-ethyl, chlorsulfuron, cinosulfuron, metsulfuron-methyl, nico~ulfuron, primisulfuron, pyrazosulfuron-ethyl, thifensulfuron-methyl, triasulfuron and tribenuron-methyl; thiocarbamates such a~, for example, butylate, cycloate, di-allate, EPTC, esprocarb, molinate, prosulfocarb, thiobencarb and tri-allate; triazines such as, for example, atrazine, cyanazine, simazine, Le A 28 896 - 12 -.
,. ..

2~7~07 simetryne, terbutryne and terbutylazine; triaæinones such as, for example, hexazinone, metamitron and metribuzin;
others such as, for example, aminotriazole, benfuresate, bentazone, cinmethylin, clomazone, clopyralid, difenzoquat, dithiopyr, ethofumesate, fluorochloridone, glufosinate, glyphosate, i~oxaben, pyridate, quinchlorac, quinmerac, sulphoæate and tridiphane.

Mixture~ with other known active compounds, such as fungicides, insecticides, acaricides, nematicides, bird repellants, plant nutrients and agents which improve soil structure, are al~o possible.

The active compounds can be used as such, in the form of their formulations or in the use form~ prepared therefrom by further dilution, such as ready-to-use solutions, suspensions, emulsions, powders, pastes and granules.
They are used in the customary manner, for example by watering, spraying, atomising or scattering.

The ~ctive compounds according to the invention can be applied either before or after emergence of the plants.
They can aleo be incorporated into the soil before sowing.

The amount of active compound used can vary within a sub~tantial range. It depends essentially on the nature of the desired effect. In general, the amounts used are between 10 g and 10 kg of active compound per hectare of soil surface, preferably between 50 g and 5 kg per ha.

Le A 28 896 - 13 -207s~07 The preparation and use of the active compounds according to the invention can be seen from the following examples.

Le A 28 896 - 14 -- :

2~7~7 Preparation Examples:

Example 1 52 NH-co`NH-~ ~

3.5 ml of a 30% strength aqueous solution of hydrogen peroxide (0.03 mol of H2O2) are added dropwise at 20C
with stirring to a mixture of 10.0 g (0.027 mol) of N-(4-methoxy-6-methyl-pyrimidin-2-yl)-N'-(2-methylthiophenyl-sulfonyl)-urea and 70 ml of acetic acid, and the reaction mixture is stirred for 15 hours at 20C. It is then concentrated, the residue is digested with a little ethanol, and the cryYtalline product is isolated by filtration with suction.

8.1 g (78% of theory) of!N-(4-methoxy-6-methyl-pyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea of melting point 198C are obtained.

Le A 28 896 - 15 -2~7~4~7 Salts of compounds of the formula ! I):
Example la O ~ - Nl I - C O - NH~N~ - s o d i u 0.55 g (0.011 mol) of 80~ ~odium hydroxide powder is added at 20C with stirring to a mixture of 4.0 g (0.011 mol) of N-(4-methoxy-6-methyl-pyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea and 80 ml of toluene, and the mixture is stirred for 15 hours at 20C.
The crystalline product i~ then isolated by filtration with suction.

4.5 g (100% of theory) of the !sodium salt of N-(4-me-thoxy-6-methyl-pyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea of melting point 171C are ob-tained.

Other compounds of the formula (I) or their salt~ which can be prepared analogously to Example 1 or Example la and following the general description of the preparation process according to the invention are, for example, those mentioned in Table 1 below.

Le A 28 896 - 16 -.

207~97 ~ S2 NH-CO-NH

Table 1: Examples of the compounds of the formula (I~
and their salts Ex. A X Y Salt Melting No. point (C) 3a CH OCH3 OCH3 sodium salt 123 6 CH Cl OCH3 7 CH Cl C2H5 14 CH sC~3 CH3 Le A 28 896 - 17 -207~

Table 1 - Continuation Ex. A X Y Salt Melting No. point (C) 17 CH C1 CH~ -Use Examples:

In the use examples which follow, the compounds mentioned below are used a~ comparison substances:

[ ~ 02-NH-CO-NH ~ ~ N
OCH3 (A) N-(4,6-dimethoxy-~-triazin-2-yl)-N'-(2-propylthio-phenyl-sulphonyl)-urea ~ (disclo~ed in US Patent 4,818,277);

Le A 28 896 - 18 -207~a7 S02-NH-CO-NH ~ ~ t~) CH~

N-(4,6-dimethyl-pyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea (disclosed in US Patent 4,169,719).

Le A 28 896 - 19 -2075~7 ~ Example A

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 is mixed with the stated amount of solvent, the stated amount of emulsifier is added and the concentrate is diluted with water to the desired concentration.

Seeds of the test plants are sown in normal soil and, after 24 hours, watered with the preparation of the active compound. It is expedient to keep constant the amount 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 plants is rated in % damage in comparison to the development of the untreated control. The figures denote:

0~ = no action (like untreated control) 100~ = total destruction A clearly superior activity compared with the prior art is shown, in this test, for example by the compounds of the following Preparation Examples: 1, la, 3 and 3a.

Le A 28 896 - 20 -~7~7 Example B

Post-emergenc~ test Solvent: 5 parts ~y weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a æuitable preparation of active compound, 1 part by weight of active compound is mixed with the stated amount of ~olvent, the stated amount of emul~ifier is added and the concentrate is diluted with water to the de~ired concentration.

Test plants which have a height of 5 - 15 cm are sprayed with the preparation of the active compound in such a way as to apply the particular amounts of active compound desired per unit area. The concentration of the spray liquor is 80 chosen that the particular amounts of active compound desired are applied in 1,000 1 of water/ha.
After three weeks, the degree of damage to the plants is rated in % damage in comparison to the development of the untreated control. The figures denote:
0% = no action (like untreated control) 100% = total destruction In this test, the compounds according to the invention show a very potent action against weeds.

Le A 28 896 - 21 -

Claims

1. An N-azinyl-N'-(2-methylsulphinyl-phenylsulphonyl)-urea of the general formula (I) (I) in which A represents nitrogen or a CH group, X represents hydrogen, halogen or alkoxy or alkyl-thio, each of which has 1 to 3 carbon atoms and each of which is optionally substituted by halogen and Y represents alkyl or alkoxy, each of which has 1 to 3 carbon atoms and each of which is optionally substituted by halogen, or salt thereof.

2. A urea of the formula (I) or salt thereof according to Claim 1, characterised in that, in this formula, A represents nitrogen or a CH group, X represents hydrogen, fluorine, chlorine, bromine, or represents alkoxy or alkylthio, each of which has 1 or 2 carbon atoms and each of which is optionally substituted by fluorine and/or chlorine, and Y represents alkyl or alkoxy, each of which has 1 or 2 carbon atoms and each of which is optionally substituted by fluorine and/or chlorine.

3. A urea of the formula (I) or salt thereof according to Claim 1, characterised in that, in this formula, A represents nitrogen or a CH group, X represents hydrogen, chlorine, methoxy, ethoxy, difluoromethoxy or methylthio and Y represents methyl, ethyl, trifluoromethyl, methoxy, ethoxy or difluoromethoxy.

4. The compound N-(4-methoxy-6-methyl-pyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea of the formula

5. The sodium salt of N-(4-methoxy-6-methyl-pyrimidin-2-yl)-N'-(2-methylsulphinyl-phenylsulphonyl)-urea of the formula - sodium salt

6. A compound according to Claim 1 in which A is CH, X is OCH3 and Y is OCH3.

7. A compound of Claim 6 in the form of a sodium salt.

8. A herbicidal composition comprising a herbicidally effective amount of a compound according to any one of Claims 1 to 7 in admixture with a suitable carrier or diluent.

9. A herbicidal composition comprising a herbicidally effective amount of a compound according to any one of Claims 1 to 7 in admixture with a solid diluent or carrier, a liquified normally gaseous diluent or carrier, or a liquid diluent or carrier containing a surface active agent.

10. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a compound according to any one of Claims 1 to 7.

11. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a composition containing a compound according to any one of Claims 1 to 7 in admixture with a suitable carrier or diluent.

12. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a composition containing between 0.1 and 95% by weight of a compound according to any one of Claims 1 to 7 in admixture with a suitable carrier or diluent.

13. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a composition containing between 0.5 and 90 % by weight of a compound according to any one of Claims 1 to 7 in admixture with a suitable carrier or diluent.

14. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a compound according to any one of Claims 1 to 7 wherein the compound is applied as a pre-emergence herbicide.

15. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a compound according to any one of Claims 1 to 7 wherein the compound is applied as a post-emergence herbicide.

16. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a compound according to any one of Claims 1 to 7 wherein the compound is applied to an area of cultivation at a rate of between 10 g and 10 kg/ha.

17. A method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a herbicidally effective amount of a compound according to any one of Claims 1 to 7 wherein the compound is applied to an area of cultivation at a rate of between 50 g and 5 kg/ha.

18. A process for preparing a urea of the formula (I) or salt thereof according to Claim 1, which process comprises reacting an N-azinyl-N'-(2-methylthio-phenylsulphonyl)-urea of the general formula (II) (II) in which A, X and Y have the meanings given in Claim 1, with hydrogen peroxide (H2O2) in the presence of a diluent and, where required, converting a compound so obtained to a salt thereof.

19. A process for preparing a herbicidal composition, which comprises admixing a urea of the formula (I) or a salt thereof according to Claim 1 with an extender or surface-active agent.