WO1996008488A1

WO1996008488A1 - Herbicidal heterocyclyl-1,2,4-oxa- or thia-diazolyloxyacetamides

Info

Publication number: WO1996008488A1
Application number: PCT/EP1995/003411
Authority: WO
Inventors: Heinz Förster; Ulrich Heinemann; Hans-Joachim Santel; Markus Dollinger
Original assignee: Bayer Aktiengesellschaft
Priority date: 1994-09-13
Filing date: 1995-08-31
Publication date: 1996-03-21
Also published as: DE4432552A1; AU3519195A

Abstract

The invention concerns novel heterocyclyl-1,2,4-oxa- or thiadiazolyloxyacetamides of formula (I), in which R1 stands for hydrogen or for in each case optionally substituted alkyl, alkenyl, alkinyl or aralkyl, R2 stands for in each case optionally substituted alkyl, alkenyl, alkinyl, cycloalkyl, cycloalkenyl, aralkyl, aryl, alkoxy, alkenyloxy or alkinyloxy, or R?1 and R2¿ together with the nitrogen atom to which they are bonded form an optionally substituted, saturated, or unsaturated nitrogen heterocyclic ring which can contain further heteroatoms and to which a benzo group can be annelated, Q stands for oxygen or sulphur, and Het stands for an optionally substituted heterocyclyl. The invention further concerns a method of preparing these substances and their use as herbicides.

Description

HERBICIDE HETEROCYCLYL-1, 2, 4-OXA- BZW. -THIADIAZOLYLOXYACETAMIDE

The invention relates to new heterocyclyl-1,2,4-oxa- or -thiadiazolyloxyacetamides, a process for their preparation and their use as herbicides.

It is already known that certain thienyl-1,3,4-thiadiazolyloxyacetamides have herbicidal properties (cf. JP-A-05-286 969). The effectiveness of these previously known compounds, however, is not entirely satisfactory in all fields of application, in particular at low application rates and concentrations.

The new heterocyclyl-1,2,4-oxa- or thiadiazolyloxyacetamides of the general formula (I) have now been found,

in which.

R ^{1 represents} hydrogen or represents optionally substituted alkyl, alkenyl, alkynyl or aralkyl, R ² represents optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aralkyl, aryl, alkoxy, alkenyloxy or alkynyloxy, or

R ¹ and R ² together with the nitrogen atom to which they are attached form an optionally substituted, saturated or unsaturated nitrogen heterocycle which can contain further heteroatoms and to which a benzo group can be fused, Q stands for oxygen or sulfur and

Het represents optionally substituted heterocyclyl.

It was further found that the new heterocyclyl-1,2,4-oxa- or -thiadiazolyloxyacetamides of the general formula (I) are obtained if alkylsulfonyl-1,2,4-oxa- or -thiadiazoles of the general formula (II)

in which

Q and Het have the meaning given above and R represents alkyl or arylalkyl, with hydroxyacetamides of the general formula (III)

in which

R ¹ and R ^{2 have} the meaning given above, if appropriate in the presence of a diluent, if appropriate in the presence of an acid binder and if appropriate in the presence of a catalyst.

Finally, it was found that the new heterocyclyl-1,2,4-oxa- or -thiadiazolyloxyacetamides of the general formula (I) have interesting herbicidal properties. The invention preferably relates to compounds of the formula (I) in which

R ^{1 represents} hydrogen, C ₁ -C ₈ alkyl (which may be replaced by fluorine, chlorine,

Cyano or C ₁ -C ₄ alkoxy is substituted) for C ₂ -C ₈ alkenyl (which is optionally substituted by fluorine and / or chlorine), for C ₂ -C ₈ -

Alkynyl or for benzyl (which may be replaced by fluorine, chlorine, C ₁ -

C ₄ alkyl and / or C ₁ -C ₄ alkoxy is substituted),

R ² for C ₁ -C ₈ alkyl (which is optionally substituted by fluorine, chlorine, cyano or C ₁ -C ₄ alkoxy), C ₂ -C ₈ alkenyl (which is optionally substituted by fluorine and / or chlorine) , for C ₂ -C ₈ - alkynyl, for C ₃ -C ₆ -

Cycloalkyl (which is optionally substituted by chlorine and / or C ₁ -C ₃ alkyl), for C ₅ - or C ₆ cycloalkenyl, for benzyl (which is optionally substituted by fluorine, chlorine, C ₁ -C ₄ alkyl and / or C ₁ -C ₄ alkoxy is substituted) for phenyl (which is optionally substituted by fluorine, chlorine, bromine, iodine, cyano, nitro, C ₁ -C ₄ alkyl, trifluoromethyl, C ₁ -C ₄ alkoxy and / or C. ₁ -C ₄ -

Alkylthio is substituted), represents C ₁ -C ₈ -alkoxy (which is optionally substituted by C ₁ -C ₄ -alkoxy), or represents C ₃ -C ₄ -alkenyloxy, or

R ¹ and R ² together with the nitrogen atom to which they are attached form a saturated or unsaturated five- to seven-membered nitrogen heterocycle which is optionally mono- to trisubstituted by C ₁ -C ₃ -alkyl and which is optionally benzene-fused,

Q stands for oxygen or sulfur and

Het stands for saturated or unsaturated, optionally benzannellated heterocyclyl with 2 to 8 carbon atoms and 1 to 4 heteroatoms - in particular nitrogen, oxygen and / or sulfur atoms - and the possible substituents are preferably selected from the following group:

Halogen, cyano, nitro, carboxy, (each optionally substituted by halogen) C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₁ -C ₄ alkylthio, C ₁ -C ₄ alkylsulfinyl, C ₁ - C ₄ alkylsulfonyl, C ₁ -C ₄ alkylcarbonyl, C ₁ -C ₄ alkoxycarbonyl.

The invention relates in particular to compounds of the formula (I) in which R ^{1 is} methyl, ethyl, n- or i-propyl, n-, i- or s-butyl, n-, i- or s-pentyl (which are each optionally substituted by fluorine, chlorine, cyano, methoxy or ethoxy) , stands for propenyl, butenyl, propynyl or butynyl, R ² for methyl, ethyl, n- or i-propyl, n-, i- or s-butyl, n-, i- or s-pentyl, n-, i- or s-hexyl (which are each optionally substituted by fluorine, chlorine, cyano, methoxy or ethoxy), for propenyl, butenyl, pentenyl, propynyl, butinyl or pentynyl, for cyclopentyl or cyclohexyl (which are each optionally substituted by methyl and / or ethyl for cyclohexenyl, for benzyl (which may be replaced by fluorine,

Chlorine and / or methyl is substituted) or for phenyl (which is in each case optionally substituted by fluorine, chlorine, bromine, cyano, nitro, methyl, ethyl, trifluoromethyl, methoxy or ethoxy), for methoxy, ethoxy, n- or i -Propoxy, n-, i- or s-butoxy, n-, i- or s-pentyloxy (which are each optionally substituted by methoxy or ethoxy), or

R ¹ and R ² together with the nitrogen atom to which they are attached, for piperidinyl optionally substituted one to three times by methyl and / or ethyl, for pyrrolidinyl optionally substituted once or twice by methyl and / or ethyl, for perhydroazepinyl or for 1,2,3,4-

Tetrahydro (iso) -quinolinyl,

Q stands for oxygen or sulfur and

Het for optionally substituted furyl, benzofuryl, tetrahydrofuryl, thienyl, pyrrolyl, benzopyrrolyl, tetrahydropyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, pyridyl, pyrimidyl,

Pyrazinyl, pyridazinyl, triazinyl or tetrahydropyranyl, the possible substituents being selected in particular from the following group

Fluorine, chlorine, bromine, cyano, (each optionally substituted by fluorine and / or chlorine) methyl, ethyl, n- or i-propyl, n-, i-, s- or t-butyl,

Methoxy, ethoxy, n- or i-propoxy, methylthio, ethylthio, n- or i-propylthio, methylsulfinyl, ethylsulfinyl, n- or i-propylsulfinyl, methylsulfonyl, ethylsulfonyl, n- or i-propylsulfonyl. A very particularly preferred group of compounds according to the invention are those in which R ¹ and 2 ^{1 have} the meaning given above as being particularly preferred, Q is sulfur and Het is furyl, thienyl or pyridyl. The general or preferred radical definitions given above apply both to the end products of the formula (I) and correspondingly to the starting materials or intermediates required in each case for the preparation.

These radical definitions can be combined with one another as desired, that is to say also between the specified ranges of preferred compounds.

Examples of the possible meanings of grouping

in formula (I) are listed in Table 1 below

If, for example, 3-furyl-5-methylsulfonyl-1,2,4-thiadiazole and N-methyl-hydroxyacetic anilide are used as starting materials, the course of the reaction in the process according to the invention can be outlined using the following formula:

Formula (II) provides a general definition of the alkylsulfonyl-1,2,4-oxa- or thiadiazole derivatives to be used as starting materials in the process according to the invention for the preparation of the compounds of the general formula (I). In the formula (II), Het preferably or in particular has the meaning which has already been mentioned above in connection with the description of the compounds of the formula (I) as preferred or as particularly preferred for Het; R preferably represents methyl, ethyl or benzyl and Q preferably represents oxygen or sulfur.

The starting materials of the formula (II) are known and / or can be prepared by processes known per se (cf. DE-A 4239727 / LeA 29431, DE-A 4341066 / LeA 29687, WO-A 94/10159). The alkylsulfonyl-1,2,4-oxa- or -thiadiazole derivatives of the formula (II) are obtained if alkylthio-1,2,4-oxa- or -thiadiazole derivatives of the general formula (IV))

in which

Het, Q and R have the meaning given above, with an oxidizing agent such as e.g. Hydrogen peroxide, optionally in the presence of a catalyst, e.g. Sodium molybdate, and optionally in the presence of a diluent, such as water and formic acid, at temperatures between -20 ° C and + 100 ° C (see DE-A-4239727).

Formula (III) provides a general definition of the hydroxyacetic acid amides to be used as starting materials in the process according to the invention for the preparation of compounds of the formula (I).

In formula (III), R ¹ and R ² preferably or in particular have those meanings which have already been mentioned above in connection with the description of the compounds of the formula (I) according to the invention preferably or as particularly preferred for R ¹ and R ² .

The hydroxyacetic acid amides of the formula (III) are known and / or can be prepared by processes known per se (cf. US-P 4509971 and US-P 4645525, furthermore US-P 4334073, DE-OS 3038598, DE-OS 3038636, EP -A 37526, EP-A 348737, DE-OS 3819477).

The process according to the invention for the preparation of the new heterocyclyloxa- or thiadiazolyloxyacetamides of the formula (I) is preferably carried out using diluents. These preferably include hydrocarbons, such as toluene, xylene or cyclohexane, halogenated hydrocarbons, such as methylene chloride, ethylene chloride, chloroform or Chlorobenzene, ethers, such as, for example, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether, glycol dimethyl ether, tetrahydrofuran and dioxane, alcohols, such as, for example Methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol or tert-butanol, ketones, such as, for example, acetone, methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone, esters, such as, for example, methyl acetate and ethyl acetate, amides, such as, for example, dimethylformamide, dimethylacetamide and N- Methylpyrrolidone, nitriles such as acetonitrile and propionitrile, sulfoxides such as dimethyl sulfoxide and water or aqueous salt solutions.

The salts used here are preferably chlorides or sulfates of alkali or alkaline earth metals, such as sodium chloride, potassium chloride or calcium chloride. Sodium chloride is particularly preferred. The process according to the invention is advantageously carried out using acid binders. As such, strongly basic alkali and alkaline earth metal compounds, e.g. oxides such as e.g. Sodium, potassium, magnesium and calcium oxide, hydroxides such as e.g. Sodium, potassium, magnesium and calcium hydroxide, alcoholates such as e.g. Sodium and potassium tert-butoxide and / or carbonates, e.g. Sodium, potassium, magnesium and calcium carbonate used.

The addition of 0.01 to 10% by weight (based on the glycolic acid amide of the formula (III) used) of a phase transfer catalyst may prove advantageous in some cases. Examples of such catalysts are: tetrabutylammonium chloride, tetrabutylammonium bromide, tributylmethylphosphonium bromide, trimethyl-C ₁₃ / C ₁₅ -alkyl-ammonium chloride, dibenzyl-dimethylammonium-methylsulfate, dimethyl-C ₁₂ / C ₁₄ -alkyl-benzylammonium-chloride, tetrabutylammonium chloride Krone-6, triethylbenzylammonium chloride, trimethylbenzylammonium chloride, tetraethylammonium bromide. The reaction temperatures can be varied within a wide range in the process according to the invention. In general, temperatures between -50 ° C and +1 10 ° C, preferably at temperatures between -20 ° C and + 80 ° C.

The process according to the invention is generally carried out at normal pressure; but it can also be carried out at elevated or reduced pressure, for example between 0.1 and 10 bar. To carry out the process according to the invention, generally 0.5 to 5 mol, preferably 0.8 to 1.5 mol, of hydroxyacetic acid amide of the formula are employed per mol of alkylsulfonyl-1,2,4-oxa- or thiadiazole of the formula (II) (III) a. The reaction components can be combined in any order. In each case, the reaction mixture is stirred until the end of the reaction and worked up by customary methods (cf. the preparation examples).

The active compounds according to the invention can be used as defoliants, desiccants, haulm killers and in particular as weed killers. Weeds in the broadest sense are all plants that grow in places where they are undesirable. Whether the substances according to the invention act as total or selective herbicides depends essentially on the amount used.

The active compounds according to the invention can e.g. used in the following plants: dicot weeds of the genera: Sinapis, Lepidium, Galium, Stellaria, Matricaria, Anthemis, Galinsoga, Chenopodium, Urtica, Senecio, Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum, Sesbania, Ambrosia, Cirs Carduus, Sonchus, Solanum, Rorippa, Rotala, Lindernia, Lamium, Veronica, Abutilon, Emex, Datura, Viola, Galeopsis, Papaver, Centaurea, Trifolium, Ranunculus, Taraxacum.

Dicotyledon cultures of the genera: Gossypium, Glycine, Beta, Daucus, Phaseolus, Pisum, Solanum, Linum, Ipomoea, Vicia, Nicotiana, Lycopersicon, Arachis, Brassica, Lactuca, Cucumis, Cucurbita.

Monocotyledon weeds of the genera: Echinochloa, Setaria, Panicum, Digitaria, Phleum, Poa, Festuca, Eleusine, Brachiaria, Lolium, Bromus, Avena, Cyperus, Sorghum, Agropyron, Cynodon, Monochoria, Fimbristylis, Sagittaria, Iochasumirumum, Scalumumum, Scalumumum , Sphenoclea, Dactyloctenium, Agrostis, Alopecurus, Apera.

Monocot cultures of the genera: Oryza, Zea, Triticum, Hordeum, Avena, Secale, Sorghum, Panicum, Saccharum, Pineapple, Asparagus, Allium. However, the use of the active compounds according to the invention is by no means restricted to these genera, but extends in the same way to other plants.

Depending on the concentration, the compounds are suitable for total weed control, e.g. on industrial and track systems and on paths and squares with and without tree cover. Likewise, the compounds for weed control in permanent crops, e.g. Forest, ornamental wood, fruit, wine, citrus, nut, banana, coffee, tea, rubber, oil palm, cocoa, berry fruit and hop plants, on ornamental and sports turf and pasture land and for selective weed control in annual cultures are used.

The compounds of formula (I) according to the invention are particularly suitable for the selective control of monocotyledon weeds in dicotyledon crops, especially in the pre-emergence process.

The active compounds can be converted into the customary formulations, such as solutions, emulsions, wettable powders, suspensions, powders, dusts, pastes, soluble powders, granules, suspension emulsion concentrates, active substance-impregnated natural and synthetic substances and very fine encapsulations in polymeric substances.

These formulations are prepared in a known manner, e.g. B. by mixing the active ingredients with extenders, ie liquid solvents and / or solid carriers, optionally using surface-active agents, ie emulsifiers and / or dispersants and / or foam-generating agents.

If water is used as an extender, organic solvents can, for example, also be used as auxiliary solvents. The following are essentially suitable as liquid solvents: aromatics, such as xylene, toluene, or alkylnaphthalenes, chlorinated aromatics and chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chlorethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example petroleum fractions, mineral and vegetable oils, Alcohols such as butanol or glycol and their ethers and esters, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, strongly polar solvents, such as dimethylformamide and dimethyl sulfoxide, and water.

The following are suitable as solid carriers:

e.g. Ammonium salts and natural rock powders, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth and synthetic rock powders, such as highly disperse silicic acid, aluminum oxide and silicates, are suitable as solid carriers for granules: e.g. broken and fractionated natural rocks such as calcite, marble, pumice, sepiolite, dolomite and synthetic granules from inorganic and organic flours and granules from organic material such as sawdust, coconut shells, corn cobs and tobacco stems; as emulsifying and / or foaming agents are possible: e.g. non-ionic and anionic emulsifiers such as polyoxyethylene fatty acid esters, polyoxyethylene fatty alcohol ethers, e.g. Alkylaryl polyglycol ethers, alkyl sulfonates, alkyl sulfates, aryl sulfonates and protein hydrolyzates; Possible dispersants are: e.g. Lignin sulfite liquor and methyl cellulose.

Adhesives such as carboxymethyl cellulose, natural and synthetic powdery, granular or latex-shaped polymers, such as gum arabic, polyvinyl alcohol, polyvinyl acetate, and natural phospholipids such as cephalins and lecithins and synthetic phospholipids can be used in the formulations. Other additives can be mineral and vegetable oils.

Dyes such as inorganic pigments, e.g. Iron oxide, titanium oxide, ferrocyan blue and organic dyes such as alizarin, azo and metal phthalocyanine dyes and trace nutrients such as salts of iron, manganese, boron, copper, cobalt, molybdenum and zinc can be used. The formulations generally contain between 0.1 and 95 percent by weight of active compound, preferably between 0.5 and 90%.

The active compounds according to the invention, as such or in their formulations, can also be used for combating weeds, in a mixture with known herbicides, finished formulations or tank mixes being possible. Known herbicides are suitable for the mixtures, for example anilides, such as, for example, diflufenican and propanil; Aryl carboxylic acids, such as dichloropicolinic acid re, Dicamba and Picloram; Aryloxyalkanoic acids such as 2,4-D, 2,4-DB, 2,4-DP, fluroxypyr, MCPA, MCPP and triclopyr; Aryloxy-phenoxy-alkanoic acid esters, such as, for example, diclofop-methyl, fenoxaprop-ethyl, fluazifop-butyl, haloxyfop-methyl and quizalofop-ethyl; Azinones such as chloridazon and norflurazon; Carbamates such as chlorpropham, desmedipham, phenmedipham and propham; Chloroacetanilides such as alachlor, acetochlor, butachlor, metazachlor, metolachlor, pretilachlor and propachlor; Dinitroanilines such as oryzalin, pendimethalin and trifluralin; Diphenyl ethers such as acifluorfen, bifenox, fluoroglycofen, fomesafen, halosafen, lactofen and oxyfluorfen; Ureas such as chlorotoluron, diuron, fluometuron, isoproturon, linuron and methabenzthiazuron; Hydroxylamines such as alloxydim, clethodim, cycloxydim, sethoxydim and tralkoxydim; Imidazolinones such as imazethapyr, imazamethabenz, imazapyr and imazaquin; Nitriles such as bromoxynil, dichlobenil and ioxynil; Oxyacetamides, such as, for example, mefenacet, sulfonylureas, such as, for example, amidosulfuron, bensulfuron-methyl, chlorimuronethyl, chlorosulfuron, cinosulfuron, metsulfuron-methyl, nicosulfuron, primisulfuron, pyrazosulfuron-ethyl, thifensulfuronmethyl, trifurium sulfuronmethyl, Thiol carbamates such as butylates, cycloates, dialallates, EPTC, esprocarb, molinates, prosulfocarb, thiobencarb and triallates; Triazines such as atrazine, cyanazine, simazin, simetryne, terbutryne and terbutylazine; Triazinones such as hexazinone, metamitron and metribuzin; Others such as aminotriazole, benfuresate, bentazone, cinmethylin, clomazone, clopyralid, difenzoquat, dithiopyr, ethofumesate, fluorochloridone, glufosinate, glyphosate, isoxaben, pyridate, quinchlorac, quinmerac, sulphosate and tridiphane.

A mixture with other known active compounds, such as fungicides, insecticides, acaricides, nematicides, bird repellants, plant nutrients and agents which improve soil structure, is also possible.

The active compounds can be used as such, in the form of their formulations or in the use forms prepared therefrom by further dilution, such as ready-to-use solutions, suspensions, emulsions, powders, pastes and granules. They are used in the usual way, e.g. by pouring, spraying, spraying, sprinkling.

The active compounds according to the invention can be applied both before and after emergence of the plants. They can also be worked into the soil before sowing. The amount of active ingredient used can vary over a wide range. It essentially depends on the type of effect desired. In general, the application rates are between 10 g and 10 kg of active ingredient per hectare of soil, preferably between 50 g and 5 kg per ha. The preparation and use of the active ingredients according to the invention can be seen from the examples below.

Preparation Examples:

example 1

A mixture of 2.41 g (10 mmol) of 3- (4-pyridyl) -5-methylsulfonyl-1,2,4-thiadiazole, 2.11 g (10 mmol) of N- (4-fluorophenyl) -N -isopropyl-hydroxyacetamide and 50 ml of acetone are cooled to 0 ° C. to + 5 ° C. and a solution of 0.48 g (1.2 mmol) of sodium hydroxide in 2 ml of water is added dropwise at this temperature. The reaction mixture is stirred for 15 hours at 0 ° C to 20 ° C and then diluted with water to about three times the volume. The product obtained in crystalline form is isolated by suction.

3.0 g (80% of theory) of N- (4-fluorophenyl) -N-isopropyl-α- [3- (4-pyridyl) -1,2,4-thiadiazol-5-yl-oxy are obtained ] -acetamide with a melting point of 160 ° C.

Analogously to Example 1 and in accordance with the general description of the production process according to the invention, it is also possible, for example, to prepare the compounds of the formula (I) listed in Table 2 below.

Examples of use:

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. After about 24 hours, the active ingredient preparation is poured onto the floor. The amount of water per unit area is expediently kept constant. The concentration of active substance in the preparation is irrelevant, the only decisive factor is the amount of active substance applied per unit area. After three weeks, the degree of damage to the plants is rated in% damage compared to the development of the untreated control. It means:

0% = no effect (like untreated control)

100% = total annihilation

In this test, for example, the compounds according to Preparation Examples 1, 9, 20, 37 and 56 show good activity against weeds with good tolerance to cultivated plants, such as barley and soy.

Claims

claims

1. Heterocyclyl-1,2,4-oxa- or thiadiazolyloxyacetamides of the general

Formula (I),

in which R ^{1 represents} hydrogen or represents optionally substituted alkyl, alkenyl, alkynyl or aralkyl, R ² represents optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aralkyl, aryl, alkoxy, alkenyloxy or alkynyloxy, or

R ¹ and R ² together with the nitrogen atom to which they are attached form an optionally substituted, saturated or unsaturated nitrogen heterocycle which can contain further heteroatoms and to which a benzo group can be fused.

Q stands for oxygen or sulfur and

Het represents optionally substituted heterocyclyl.

2. Compounds of formula (I) according to claim 1, characterized in that therein

R ¹ for hydrogen, C ₁ -C ₈ alkyl (which is optionally substituted by fluorine, chlorine, cyano or C ₁ -C ₄ alkoxy), for C ₂ -C ₈ alkenyl (which is optionally substituted by fluorine and / or chlorine is substituted), for C ₂ -C ₈ alkynyl or for benzyl (which may be replaced by Fluorine, chlorine, C ₁ -C ₄ alkyl and / or C ₁ -C ₄ alkoxy is substituted),

R ² for C ₁ -C ₈ alkyl (which is optionally substituted by fluorine, chlorine, cyano or C ₁ -C ₄ alkoxy), C ₂ -C ₈ alkenyl (which is optionally substituted by fluorine and / or chlorine) , for C ₂ -C ₈ ¬

Alkynyl, for C ₃ -C ₆ -cycloalkyl (which is optionally substituted by chlorine and / or C ₁ -C ₃ -alkyl), for C ₅ - or C ₆ -cycloalkenyl, for benzyl (which is optionally substituted by fluorine, chlorine, C ₁ -C ₄ alkyl and / or C ₁ -C ₄ alkoxy is substituted) for phenyl (which is optionally substituted by fluorine, chlorine, bromine, iodine, cyano, nitro, C ₁ -C ₄ ¬

Alkyl, trifluoromethyl, C ₁ -C ₄ alkoxy and / or C ₁ -C ₄ alkylthio is substituted), for C ₁ -C ₈ alkoxy (which is optionally substituted by C ₁ - C ₄ alkoxy), or for C ₃ -C ₄ alkenyloxy, or

Q represents oxygen or sulfur and Het represents saturated or unsaturated, optionally benzannellated

Heterocyclyl with 2 to 8 carbon atoms and 1 to 4 heteroatoms - in particular nitrogen, oxygen and / or sulfur atoms - and the possible substituents are preferably selected from the following group:

Halogen, cyano, nitro, carboxy, (each optionally by

Halogen substituted) C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₁ -C ₄ alkylthio, C ₁ -C ₄ alkylsulfinyl, C ₁ -C ₄ alkylsulfonyl, C ₁ -C ₄ alkylcarbonyl , C ₁ -C ₄ alkoxycarbonyl.

3. Compounds of formula (I) according to claim 1, characterized in that therein

R ^{1 is} methyl, ethyl, n- or i-propyl, n-, i- or s-butyl, n-, i- or s-pentyl (which are each optionally substituted by fluorine, chlorine, cyano, Are substituted methoxy or ethoxy), stands for propenyl, butenyl, propynyl or butynyl,

R ^{2 is} methyl, ethyl, n- or i-propyl, n-, i- or s-butyl, n-, i- or s-pentyl, n-, i- or s-hexyl (which are each optionally substituted by fluorine, Chlorine, cyano, methoxy or ethoxy are substituted), for

Propenyl, butenyl, pentenyl, propynyl, butynyl or pentynyl, for cyclopentyl or cyclohexyl (which are each optionally substituted by methyl and / or ethyl), for cyclohexenyl, for benzyl (which is optionally substituted by fluorine, chlorine and / or methyl) or for phenyl (which is optionally substituted in each case by fluorine, chlorine, bromine, cyano, nitro, methyl, ethyl, trifluoromethyl, methoxy or ethoxy), for methoxy, ethoxy, n- or i-propoxy, n-, i- or s- Butoxy, n-, i- or s-pentyloxy (which are each optionally substituted by methoxy or ethoxy), or

R ¹ and R ² together with the nitrogen atom to which they are attached, for piperidinyl optionally substituted one to three times by methyl and / or ethyl, for pyrrolidinyl optionally substituted once or twice by methyl and / or ethyl, for perhydroazepinyl or for 1,2,3,4-tetrahydro (iso) -quinolinyl,

Q stands for oxygen or sulfur and

Het for optionally substituted furyl, benzofuryl, tetrahydrofuryl, thienyl, pyrrolyl, benzopyrrolyl, tetrahydropyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl

Tetrahydropyranyl, the possible substituents being selected in particular from the following group:

Fluorine, chlorine, bromine, cyano, (each optionally substituted by fluorine and / or chlorine) methyl, ethyl, n- or i-propyl, n-, i-, s- or t-butyl, methoxy, ethoxy, n- or i-propoxy, methylthio,

Ethylthio, n- or i-propylthio, methylsulfinyl, ethylsulfinyl, n- or i-propylsulfinyl, methylsulfonyl, ethyl sulfonyl, n- or i-propylsulfonyl.

4. A process for the preparation of compounds of formula (I) according to

Claim 1, characterized in that alkylsulfonyl-1,2,4-oxa- or thiadiazoles of the general formula (II),

in which

Q and Het have the meaning given in claim 1 and

R represents alkyl or arylalkyl, with hydroxyacetamides of the general formula (III)

in which R ¹ and R ^{2 have} the meaning given in claim 1, if appropriate in the presence of a diluent, if appropriate in the presence of an acid binder and if appropriate in the presence of a catalyst.

5. Herbicidal agents, characterized by a content of at least one

A compound of formula (I) according to claim 1.

6. Use of compounds of the general formula (I) according to

Claim 1 to combat unwanted plant growth.

7. A method of combating weeds, characterized in that compounds of the general formula (I) according to Claim 1 are allowed to act on the weeds or their habitat.

8. A process for the preparation of herbicidal compositions, characterized in that compounds of the general formula (I) according to Claim 1 are mixed with extenders and / or surface-active agents.