GB2134513A - Herbicidal imidazo-triazinone and pyrimidino-triazinone derivatives - Google Patents

Abstract

Novel compounds of the general formula <IMAGE> in which R1 represents hydrogen; a (C1-C8)-alkyl radical optionally substituted by one or more halogen, cyano, hydroxy or (C1-C4)-alkoxy groups; a (C3-C8)-cycloalkyl radical optionally substituted by one or more alkyl, alkoxy, halogen or phenyl groups; a (C1-C4)-alkoxy-carbonylmethyl radical; an aromatic or aromatic-aliphatic hydrocarbon radical each unsubstituted or substituted by one or more (C1-C4)-alkyl, halogen, (C1-C4)-alkoxy nitro or trifluoromethyl groups; or an optionally halo-substituted heterocyclic radical; R2 represents hydrogen; a (C1-C8)-alkyl, (C3-C8)-alkenyl, (C3-C8)-alkynyl, (C3-C8-cycloalkyl or (C3-C8)-cycloalkenyl radical each unsubstituted or substituted by one or more halogen (C1-C4)-alkoxy, cyano, (C1-C4)-alkylthio or hydroxy groups; a (C2-C8)-alkyl radical which is interrupted by one or more oxygen, sulphur or nitrogen atoms; a (C1-C4)-alkoxy-carbonyl-(C1-C4)- alkyl radical; an optionally halo-substituted (C1-C6)-alkylsulphonyl group; an aromatic or aromatic-aliphatic hydrocarbon radical each unsubstituted or substituted by one or more (C1-C6)-alkyl, halogen, (C1-C4)-alkoxy, nitro or trifluoromethyl groups; or a cyano, acetyl or propionyl group; R3, R4 and R5, any two or more of which are the same or different, each represents hydrogen; an optionally halo-substituted (C1-C6)-alkyl radical; or an aryl radical which is unsubstituted or substituted by one or more (C1-C6)-alkyl, halogen, (C1-C4)-alkoxy, nitro or trifluoromethyl groups, and n represents 0 or 1, or a salt thereof with an inorganic or organic acid, possess herbicidal properties.

Description

SPECIFICATION Triazinones, processes for their preparation and compositions containing them having selective herbicidal action The invention relates to triazinones, processes for their preparation and compositions containing them having selective herbicidal action.

For economic reasons, the most important agricultural crops are increasingly being grown in close crop rotation systems. Consequently, more and more accompanying weed flora develop.

These almost always include weeds that are difficult to combat, and conditions may arise that lead to the dominance of such types.

Attempts have been made to combat this problem, for example by attempting to achieve control using the full amounts, or even excess amounts, of herbicide, but as a result the crops are often damaged. Since known herbicides can also act residually via the soil on the subsequent crop, this crop too is often damaged. It is therefore desirable to have an advanced herbicide with a good activity against problem weeds while, at the same time, a good compatability with respect to several principal agricultural crops that are used in a rotation system.

It is already known that 1,2,4-triazin-5-one derivatives, such as, for example, 4-amino-6-tert. butyl-4,5-dihydrn-3-methylthio-1 ,2,4-triazin-5-one (BE-PS 69 70 83), can be used as weed control agents. However, although these herbicides have a good herbicidal action against problem weeds, they have poor compatability with respect to several principal agricultural crops.

The present invention provides a triazinone of the general formula

in which R, represents a hydrogen atom; a (C1-C8)-alkyl radical which is unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms, cyano groups, hydroxy groups and (C,-C4)- alkoxy radicals; a (C3-C8)-cycloalkyl radical which is unsubstituted or substituted by one or more of the same or different substituents selected from alkyl and alkoxy radicals, halogen atoms and phenyl groups; a (C,-C4)-alkoxy-carbonylmethyl radical;; an aromatic or aromatic-aliphatic hydrocarbon radical each unsubstituted or substituted by one or more of the same or different substituents selected from (C,-C4)-alkyi radicals, halogen atoms, (C1-C4)-alkoxy radicals, and nitro and trifluoromethyl groups; or a heterocyclic radical which is unsubstituted or substituted by one or more of the same or different halogen atoms; R2 represents a hydrogen atom; a (C,-C8)-alkyl, (C3-C8)-alkenyl, (C3-C8)-alkynyl, (C3-C8)-cycloalkyl or (C3-C8)-cycloalkenyl radical each unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms, (C,-C4)-alkoxy radicals, cyano groups, (C,-C4)-alkylthio radicals and hydroxy groups;; a (C2-C8)-alkyl radical which is interrupted by one or more of the same or different heteroatoms selected from oxygen, sulphur and nitrogen; a (C,-C4)-alkoxy-carbonyl-(C,-C4)-alkyl radical; a (C,-C6-alkylsulphonyl group which is unsubstituted or substituted by one or more of the same or different halogen atoms; an aromatic or aromatic-aliphatic hydrocarbon radical each unsubstituted or substituted by one or more of the same or different substituents selected from (C,-C6)-alkyl radicals, halogen atoms, (C,-C4)-alkoxy radicals and nitro and trifluoromethyl groups; a cyano group; or an acetyl or propionyl group; R3, R4 and R5, any two or more of which are the same or different, each represents a hydrogen atom; a (C,-C6)-alkyl radical which is unsubstituted or substituted by one or more of the same or different halogen atoms; or an aryl radical which is unsubstituted or substituted by one or more of the same or different substituents selected from (C,-C6)-alkyl radicals, halogen atoms, (C,-C4)-alkoxy radicals and nitro and trifluoromethyl groups, and n represents 0 or 1, or a salt thereof with an inorganic or organic acid.

In some cases, the compounds of the invention occur as optical and/or geometrical isomers and the invention provides also these isomers, as well as mixtures thereof, and it should be understood that the written nomenclature and structural formulae shown in the specification should be taken to include these individual isomers as well as mixtures thereof.

Compounds of the invention may also occur as mixtures of structural isomers, for example as a mixture of compounds of the general formulae

where R3 and R5 are different.

A compound of the general formula I may be in admixture with an isomer in which the R2 substituent is in the 1-position of the ring system, that is, on the 2-position of the triazine ring.

Thus, the present invention also provides a mixture of a compound of the general formula I and a compound of the general formula

Triazinones of the present invention can be used in several principal agricultural crops against weeds that are difficult to control without the crops being damaged. They are very suitable for combating problem weeds while having a compatability, especially, for soya beans, potatoes, cotton, maize, wheat, barley and rice. In this respect they are superior to the known triazinones.

The herbicidal action extends to many types of weeds. Problem weeds that are readily controlled are, for example, Abutilon theophrastii, Ipomoea ssp., Solanum ssp., Viola ssp., Echinochloa crus galli, Setaria ssp., Digitaria ssp., Brassica kaber, Cassia, Sesbania and Datura.

The compounds may be used by being incorporated into the soil before the crop is sown or may be used in a pre- or post-emergence method.

The quantities applied for selective weed control are, for example, from 0.1 to 5 kg of active substance/ha. The compounds may also be used in higher quantities for total weed control.

Of the compounds according to the invention, those distinguished by an optimum action of the described type are especially those in which, in the general formula I, R, represents a phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2-chlorophenyl, 3-chlorophenyl, 4chlorophenyl, 2,4-dichlorophenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 2-thienyl, 2,5-dichloro-3-thienyl, isopropyl, sec.-butyl, tert.-butyl, chloro-tert.-butyl, 2-hydroxyl-l,l -dimethylethyl, methylcyclopropyl, 2, 2-d ich loro- 1 -methylcylopropyl, cyclopropyl, cyclopentyl or cyclohexyl group, R2 represents a methyl, ethyl, propyl, allyl or propargyl group, and R3, R4 and R5 each represents a hydrogen atom or a methyl group.

A heterocyclic radical represented by R, contains also carbon atoms in the ring and may be aromatic or non-aromatic, preferably aromatic.

An aromatic radical or an aromatic moiety in an aromatic-aliphatic hydrocarbon radical represented by R, or R2 and an aryl radical represented by R3/R4/R5 may comprise one or more rings. The aliphatic moiety in the aromatic-aliphatic hydrocarbon radicals may be saturated or unsaturated; an aromatic-aliphatic hydrocarbon radical may be unsubstituted or substituted, preferably in the aromatic moiety.

A (C,-C8)-alkyl radical and a (C3-C8)-cycloalkyl radical represented by R, and a (C,-C8)-alkyl, (C3-C8)-alkenyl, (C3-C8)-alkenyl, (C3-C8)-cycloalkyl and a (C2-C8)-cycloalkenyl radical represented by R2 may be unsubstituted or substituted as specified under formula I; it should be understood that the number of carbon atoms quoted is exclusive of substituents. It should be understood that in a (C,-C4)-alkoxy-carbonylmethyl radical represented by R, it is the alkoxy moiety that has 1 to 4 carbon atoms, and, similarly, in a (C,-C4)-alkoxy-carbonyl-(C,-C4)-alkyl radical represented by R2, there are 1 to 4 carbon atoms in the alkoxy moiety.A substituted cycloalkyl radical represented by R, may, for example, be substituted by one or more alkyl and/or alkoxy radicals having, for example, 1 to 4 carbon atoms each.

An alkyl radical represented by R2 may be uninterrupted or it may be interrupted by 0, S or NH or it may have two or more of these interruptions which may be the same or different, preferably the same.

Suitable inorganic and organic acids for the formation of the acid addition salts are, for example, hydrohalic acids, such as, for example, hydrochloric acid and hydrobromic acid, phosphoric acid, sulphuric acid, and, especially, nitric acid; and mono- and bifunctional carboxylic acids, including hydroxycarboxylic acids, such as, for example, acetic acid, maleic acid, succinic acid, fumaric acid, tartaric acid, citric acid, salicylic acid, sorbic acid and lactic acid; and sulphonic acids, such as, for example, ptoluene-sulphonic acid and 1,5-naphthalenedisulphonic acid.

Compounds of of the general formula I may be prepared, for example, as follows: (a) a compound of the general formula

in which R1, R3, R4, R5 and n have the meanings given above or a metal compound thereof is reacted with a compound of the general formula R2-X Ill in which R2 has the meanings given above and X represents a halogen atom, a sulphate group or a tosyl group, if desired in the presence of an acid-binding agent and/or in the presence of a catalyst, or (b) a compound of the general formula

in which R2, R3, R4, R8 and n have the meanings given above is reacted either with a compound of the general formula

in which R, has the meaning given above and R6 represents a hydrogen atom or a methyl or ethyl group, or, to form a compound in which R, represents a (C1-C4)-alkoxy-carbonylmethyl radical, with a compound of the general formula R7OOC-C=-C-COOR7 Vl in which R7 represents a (C,-C4)-alkyl radical and the two R7 moieties may be the same or different, if desired in the presence of a base, or (c) a compound of the general formula

in which R2, R3, R4, R5, R7 and n have the meanings given above and Y represents an oxygen or sulphur atom, is reacted with a compound of the general formula

in which R, and R6 have the meanings given above, or (d) a compound of the general formula

in which R, and R2 have the meanings given above, is reacted with a compound of the general formula

in which R3, R4, R5, n and X have the meanings given above, if desired, in the presence of a base, or (e) a compound of the general formula V shown above is reacted with a compound of the general formul

in which R2, R3, R4, R5 and n have the meanings given above and a compound of the formula

in the presence of a base.

Accordingly, the present invention provides a process for the preparation of a compound of the general formula I or a salt thereof by process (a), (b), (c), or (e) specified above, using where appropriate a reactant in the form of a salt and/or if desired, converting a resulting compound of the general formula I into a salt thereof.

The starting materials for the above processes are known per se or can be manufactured according to processes known per se.

The reaction of the reactants according to process variants (a) to (e) generally takes place at a temperature in the range of from 0 to 1 20 C, but usually from room temperature to the reflux temperature of the reaction mixture. The reaction period is generally from 1 to 72 hours.

the reactants are used, for example, in approximately equimolar quantities. The reactions may be carried out, for example, in solvents that are inert towards the reactants; the choice of solvent (or suspension agent) depends upon the particular starting material and the particular acid acceptor or base used. Suitable solvents and diluents are, for example, ethers, diisopropyl ether, tetrahydrofuran and dioxan, aromatic hydrocarbons, e.g. toluene and xylene, carboxylic acid nitriles, e.g. acetonitrile,carboxylic acid amides, e.g. dimethylformamide, and alcohols, e.g.

methanol, ethanol, propanol, isopropanol and tert.-butanol.

Suitable acid acceptors are, for example, organic bases, such as, for example, triethylamine, N,N-dimethylaniline and pyridine bases, and inorganic bases, such as, for example, oxides, hydroxides and carbonates of alkaline earth and alkali metals.

Liquid bases, such, for example, as pyridine, may be used simultaneously as solvents.

A metal compound which may be required for (a) may be prepared, for example, by reacting a compound of the general formula ll with a metal compounds of the general formula M-Z Xl where M represents a monovalent metal equivalent, preferably a sodium, potassium or lithium atom, and Z represents a hydrogen atom, a hydroxy group, a lower alkyl or alkoxy radical or an amino group, but preferably a hydrogen atom. If desired, the reaction may be carried out with the use of a solvent The reaction of a metal-free compound of the general formula II may, if desired, be effected in a two-phase system, comprising a triazinone of the general formula II dissolved in an inert solvent, an alkali metal hydroxide, solid or in the form of an aqueous solution, and a catalyst.

Suitable catalysts are, for example, onium compounds, such, for example, as quaternary ammonium, phosphonium and arsonium compounds, and sulphonium compounds. Polyglycol ethers, especially cyclic ethers, such as, for example, 1 8-Crown-6, and tertiary amines, such as, for example, tributylamine are also suitable. The ratio of the reactants employed may vary within wide limits. Preferably, the reactions are carried out with a 1 to 10 fold excess of the compound of the general formula R2-X and a 1 to 10 fold excess of hydroxide. 0.02 equivalents of the catalyst are sufficient. The reaction may be carried out at a temperature in the range of from 20 to 1 00 C, generally from 20 to 60"C. The reaction period may be, for example, from 1 to 72 hours. Thorough mixing is necessary during the entire reaction period.

The compounds of the invention may be isolated from the reaction mixture by customary methods, for example by distilling off the solvent used at normal or reduced pressure, or by precipitation with water.

If desired, isomeric mixtures, which are generally obtained in accordance with processes (a) and (d), may be separated by crystallisation or column chromatography.

Acid addition salts may be obtained, for example, by customary salt-forming processes, for example by dissolving a compound of the general formula I in a suitable solvent and adding the acid.

The compounds of the invention are generally colourless and odourless crystalline solids that have poor solubility in water and aliphatic hydrocarbons, and have moderate to good solubility in halogenated hydrocarbons, such, for example, as chloroform, in ketones, such, for example, as acetone, carboxylic acid am ides, such, for example, as dimethylformamide, sulphoxides, such, for example, as dimethyl sulphoxide, carboxylic acid nitriles, such, for example, as acetonitrile, and in lower alcohols, such, for example, as methanol and ethanol.

As solvents for recrystallisation there come into consideration especially ethanol, isopropanol, diisopropyl ether, toluene, acetonitrile and ethyl acetate.

The compounds of the invention may be used alone or in admixture with one another or with other active substances. If desired, defoliating agents, plan-protecting agents and/or pesticides may be added, depending on the desired purpose.

If a broadening of the spectrum of action is intended, one or more other biocides may be added. Examples of suitable herbicidally active mixing partners are the active substances listed in weed Abstracts, Vol. 31, No. 7, 1982, under the heading "List of common names and abbreviations employed for currently used herbicides and plant growth regulators in Weed Abstracts".

Advantageously, the active substances according to the invention or mixtures thereof are used in the form of preparations, for example powders, strewable agents, granulates, solutions, emulsions or suspensions, with the addition of liquid and/or solid carriers or diluents and, if desired, wetting agents, adhesion-promoting agents, emulsifiers and/or dispersion auxiliaries, but preferably in the form of emulsion concentrates.

Accordingly, the present invention provides a herbicidal preparation which comprises the compound of the general formula I or a salt thereof or two or more such compounds, and a suitable carrier.

The proportion of active substance(s) in the various prparations may vary within wide limits.

For example, the preparations may contain from 5 to 95 % by weight of active substances, from 95 to 5% by weight of liquid or solid carriers and, if desired, up to 20 % by weight of surfaceactive substances.

Suitable liquid carriers are, for example, water, aliphatic and aromatic hydrocarbons, such as, for example, toluene or xylene, ketones, such as, for example,cyclohexanone or isophorone, sulphoxides, such as, for example, dimethyl sulphoxide, carboxylic acid amides, such as, for example, dimethylformamide, and also mineral oil fractions.

Suitable solid carriers are, for example, mineral earths, for example bentonite, silica gel, talcum, kaolin, attapulgite, limestone, silicic acid and vegetable products, for example meals.

Suitable surface-active substances are, for example, calcium ligninsulphonate, polyoxyethylene alkyphenol ethers, naphthalenesulphonic acids and salts thereof, phenolsulphonic acids and salts thereof, formaldehyde condensates, fatty alcohol sulphates and substituted benzenesulphonic acids and salts thereof.

The present invention also provides a process for combating weeds, which comprises applying a compound of the general formula I or a salt thereof to the weed or weeds or to an area or soil infested with or liable to infestation by weeds.

The area or soil treated may be an area or soil in the vicinity of weeds. It may, for example, be a crop area or an area adjacent to a crop area.

The compounds or preparations may be applied in customary manner, for example using water as carrier in quantities of spraying liquor of from 1 00 to 1000 litres/ha. The agents may also be used in the so-called Low-Volume and Ultra-Low-Volume processes, and they may also be applied in the form of so-called microgranules.

The present invention also provides an area, crop, crop area or soil treated by a process of the present invention, and a crop or plant in or from a crop area or soil treated by a process of the present invention.

The following Examples illustrate the invention. Examples 1 to 113 illustrate compounds of the general formula I and salts thereof and their preparation. Examples A and B illustrate preparations containing these compounds and Examples I to III illustrate their use.

Example 1 3tert. -butyl-8-propargyl-4, 6, 7, 8-tetrahydroimidazo-[2, 1-cit 2, 4]triazin-4-one While stirring at room temperature, 1.5 g of 80 % sodium hydride (0.05 mol) were introduced into a solution of 9.7 9 (0.05 mol) of 3-tert.-butyl-4,6,7,8-tetrahydroimidazo(2,1- clil ,2,4]triazin-4-one in 1 50 ml of dimethylformamide. After 1 5 minutes, 5.95 g (0.05 mol) of propargyl bromide were added dropwise, the whole was stirred for one hour at from 25 to 30"Q= and the reaction mixture was poured into 1 litre of ice-water. The mixture was extracted twice using 1 50 ml of chloroform each time, dried over magnesium sulphate and concentrated to dryness. The residue was recrystallised from isopropyl ether.

Yield 7.71 g = 66.5 % of the theoretical yield M.p.: 89-90"C Analysis: C H N calculated 62.05 % 6.94 % 24.12 % found: 62.15 % 6.88 % 24.27 % Example 2 8-methyl-3-(3-methylphenyl)-4, 6, 7, 8-tetrahydroimidazo-[2, 1-cit 1,2, 4jtriazin-4-one While stirring at room temperature, 0.6 g of 80 % sodium hydride (0.02 moi) were introduced into a solution of 4.56 9 (0.02 mol) of 3-(3-methylphenyl)-4,6,7,8-tetrahydroimi dazoE2, 1 -c](1 ,2,4]triazin-4-one in 60 ml of dimethylformamide After 1 5 minutes, 2.84 g (0.02 mol) of methyl iodide were added dropwise and the whole was stirred for a further 10 hours at room temperature.The reaction mixture was then poured onto 1 litre of ice-water and extracted twice using 1 50 ml of chloroform each time, and the organic phase was dried over magnesium sulphate. After removal of the solvent, the residue was recrystallised from ethanol.

Yield: 1.24 9 = 25.6 % of the theoretical yield M.p.: 174-175 C Analysis: C H N calculated: 64.44 % 5.82 % 23.13 % found: 64.09 % 5.93 % 22.90 % Example 3 3-methoxycarbonylmethyl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 39.74 g(0.28 mol) of acetylenedicarboxylic acid dimethyl ester were stirred for 24 hours with 65.3 9 (0.286 mol) of 2-hydrazinoimidazoline hydriodide and 28.5 ml of triethylamine in 400 ml of methanol. The precipitate was filtered with suction, washed with isopropyl ether and dried in vacuo.

Yield: 26.45 9 = 45 % of the theoretical yield M.p.: 191-192 C (decomposition) Analysis: calculated: C 45.71 % H 4.80 % N 26.66 % found: C 45.53 % H 4.81 % N 26.53 % Example 4 8-ethyl-3-phenyl-4,6,7,8-tetrahydroimidazo[2,1-c]-[1,2,4]triazin-4-one 50 ml of a 2M sodium ethoxide solution were added dropwise to a solution of 24,46 g (0.096 mol) of 3-ethyl-2-hydrazinoimidazoline hydriodide and 17.8 g(0.1 mol) of phenylglyoxylic acid ethyl ester in 150 ml of ethanol and the whole was heated under reflux for 10 hours.

The alcohol was distilled off and 150 ml of H20 were added to the residue; the whole was extracted twice using 150 ml of CHCl3 each time and tho organic phase was dried over MgSO4.

After removal of the solvent, the product was recrystallised from isopropanol.

Yield: 3 9 = 13 % of the theoretical yield M.p. : 151-152 C Analysis: calculated: C 64.44 % H 5.82 % N 23.13 % found: C 64.10 % H 5.97 % N 23.11 % Example 5 3-phenyl-4, 6, 7, 8-tetrahydroimidazo[2, 1 -cjf 2, 4]triazin-4-one 1.78 9 (0.01 mol) of phenylglyoxylic acid ethyl ester were added to 1.22 g (0.01 mol) of dithiocarbazic acid methyl ester and then 5 ml of ethylene diamine were added. The whole was then heated at boiling for 15 minutes and after cooling, 50 ml of H2O were added and the whole was extracted with CHCl3,The organic phase was dried over MgSO4 and the resulting crude product was recrystallised from ethanol.

Yield: 0.47 9 = 22 % of the theoretical yield M.p.: 218-219 C Analysis: calculated: C 61.67 % H 4.71 % N 26.16 % found: C 61.60 % H 4.99 % N 26.41 % Using appropriate starting materials the compounds listed in tfhe following Table were obtained Table were obtained in analogous manner: Example Name of compound Physical constant 6 8-methyl-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c]- m.p. : 176 C [1,2,4]triazin-4-one 7 3-(3-methylphenyl)-4,6,7,8-tetrahydroimidazo [2,1-c]- m.p. : 198 C [1,2,4]triazin-4-one 8 3-(2-methylphenyl)-4,6,7,8-tetrahydroimidazo- m.p. : 223 C [2,1-c][1,2,4]triazin-4-one 9 3-phenyl-8-propargyl-4,6,7,8-tetrahydroimidazo- m.p. : 158 C [2,1-c][1,2,4]triazin-4-one 10 8-methylsulphonyl-3-phenyl-4,6,7,8-tetrahydro- m.p. : 259 C (dec.) imidazo[2,1-c][1,2,4]triazin-4-one 11 8-methyl-3-tert.-butyl-4,6,7,8-tetrahydroimidazo- m.p. : 129 C [2,1-c][1,2,4]triazin-4-one 12 3-tert.-butyl-8-methylsulphonyl-4,6,7,8-tetrahydro- m.p. : 215-216 C imidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 13 3-tert.-butyl-8-propargyl-4,6,7,8-tetrahydro- m.p. : 89-90 C imidazo[2,1-c][1,2,4]triazin-4-one 14 3-phenyl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]- m.p. : 220 C triazin-4-one 15 3-tert.-butyl-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 245 C [1,2,4]triazin-4-one 16 8-chloromethylsulphonyl-3-phenyl-4,6,7,8-tetrahydro- m.p. : 222 C (dec.) imidazo[2,1-c][1,2,4]triazin-4-one 17 8-allyl-3-phenyl-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 138 C [1,2,4]triazin-4-one 18 3-(4-fluorophenyl)-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 252 C [1,2,4]triazin-4-one 19 8-(2-butenyl)-3-phenyl-4,6,7,8-tetrahydroimidazo- m.p. : 85 C [2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 20 3-(2,5-dichloro-3-thienyl)-4,6,7,8-tetrahydroimidazo- m.p. : 236 C [2,1-c][1,2,4]triazin-4-one 21 8-methoxymethyl-3-phenyl-4,6,7,8-tetrahydroimidazo- m.p. : 151 C [2,1-c][1,2,4]triazin-4-one 22 3-phenyl-6,7,8,9-tetrahydro-4H-pyrimidino[2,1-c]- m.p. : 280 C [1,2,4]triazin-4-one 23 8-cyanomethyl-3-phenyl-4,6,7,8-tetrahydroimidazo- m.p. : 258 C [2,1-c][1,2,4]triazin-4-one 24 9-(2-butenyl)-3-phenyl-6,7,8,9-tetrahydro-4H- m.p. : 108 C pyrimidino[2,1-c][1,2,4]triazin-4-one 25 8-allyl-3-tert.-butyl-4,6,7,8-tetrahydroimidazo- oil [2,1-c][1,2,4]triazin-4-one 26 8-(2-methylallyl)-3-phenyl-4,6,7,8-tetrahydro- m.p. : 120 C imidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 27 3-phenyl-9-(2-propenyl)-6,7,8,9-tetrahydro-4H- m.p. : 106 C pyrimidino[2,1-c][1,2,4]triazin-4-one 28 3-(4-fluorophenyl)-8-methyl-4,6,7,8-tetrahydro- m.p. : 191-192 C imidazo[2,1-c][1,2,4]triazin-4-one 29 3-(4-fluorophenyl)-8-propargyl-4,6,7-8-tetrahydro- m.p. : 171 C imidazo[2,1-c][1,2,4]triazin-4-one 30 3-(3-methylphenyl)-8-propargyl-4,6,7,8-tetrahydro- m.p. :175 C imidazo[2,1-c][1,2,4]triazin-4-one 31 3-methoxycarbonylmethyl-4,6,7,8-tetrahydroimidazo- m.p. : 192 C [2,1-c][1,2,4]triazin-4-one 32 8-methyl-3-(3-methylphenyl)-4,6,7,8-tetrahydro- m.p. : 175 C imidazo[2,1-c][1,2,4]triazin-4-one 33 8-ethoxycarbonylmethyl-3-phenyl-4,6,7,8-tetrahydro- m.p. : 136 C imidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 34 3-tert.-butyl-9-methyl-6,7,8,9-tetrahydro-4H- m.p. : 138-140 C pyrimidino[2,1-c][1,2,4]triazin-4-one 36 3-phenyl-8(1)-(3,6,9-trioxadecyl)-(1),4,6,7,8- oil tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 36 3-tert.-butyl-8-trifluoromethylsulphonyl-4,6,7,8- m.p. : 174 C tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 37 3-phenyl-9-(2-propynyl)-6,7,8,9-tetrahydro-4H- m.p. : 140-141 C pyrimidino[2,1-c][1,2,4]triazin-4-one 38 3-tert. -butyl-9-(2-propynyl)-6,7,8,9-tetrahydro- m.p. : 134-135 C 4H-pyrimidino[2,1-c][1,2,4]triazin-4-one 39 3-isopropyl-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 227 C [1,2,4]triazin-4-one 40 3-cyclohexyl-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 239 C [1,2,4]triazin-4-one Example Name of compound Physical constant 41 3-isobutyl-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 187 C [1,2,4]triazin-4-one 42 3-(2-thienyl)-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 260-262 C [1,2,4]triazin-4-one 43 8-cyano-6(7)-methyl-3-phenyl-4,6,7,8-tetrahydro- m.p. : 235-237 C imidazo[2,1-c][1,2,4]triazin-4-one 44 3-isopropyl-8-methyl-4,6,7,8-tetrahydroimidazo- m.p. : 68 C [2,1-c][1,2,4]triazin-4-one 45 9-methyl-3-phenyl-6,7,8,9-tetrahydro-4H- m.p. : 183-185 C pyrimidino[2,1-c][1,2,4]triazin-4-one 46 3-cyclohexyl-9-methyl-6,7,8,9-tetrahydro-4H-pyrimidino- m.p. : 143-144 C [2,1-c][1,2,4]triazin-4-one 47 3-cyclohexyl-8-propargy1-4,6,7,8-tetrahydroimidazo- m.p. : 142 C [2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 48 3-cyclohexyl-8-methyl-4,6,7,8-tetrahydroimidazo- m.p.: 115 C [2,1-c][1,2,4]triazin-4-one 49 3-isopropyl-8-propargyl-4,6,7,8-tetrahydroimidazo- m.p. : 73 C [2,1-c][1,2,4]triazin-4-one 50 8-allyl-3-isobutyl-4,6,7,8-tetrahydroimidazo- m.p. : 85 [2,1-c][1,2,4]triazin-4-one 51 9-allyl-3-tert.-butyl-6,7,8,9-tetrahydro-4H-pyrimidino- m.p. : 116 C [2,1-c][1,2,4]triazin-4-one 52 3-tert.-butyl-6(7), 8-dimethyl-4,6,7,8-tetrahydroimidazo- m.p. : 127 C [2,1-c][1,2,4]triazin-4-one 53 8-cyclohexyl-3-phenyl-4,6,7,8-tetrahydroimidazo- m.p. : 154 C [2,1-c][1,2,4]triazin-4-one 54 3-(2,5-dichloro-3-thienyl)-8(1)-methyl-(1),4,6,7,8- m.p. : 163-165 C tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 55 3-(2,5-dichloro-3-thienyl)-8-propargyl-4,6,7,8-tetra- m.p. : 190-191 C hydroimidazo[2,1-c][1,2,4]triazin-4-one 56 3-isobutyl-8-propargyl-4,6,7,8-tetrahydroimidazo- m.p. : 107 C [2,1-c][1,2,4]triazin-4-one 57 3-methyl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]- m.p. : 250 C triazin-4-one 58 3-tert.-butyl-8-methyl-4,6,7,8-tetrahydroimidazo- m.p. : 186 C [2,1-c][1,2,4]triazin-4-one, hydrogen nitrate (decomposition) 59 3-tert.-butyl-8-chloromethylsulphonyl-4,6,7,8-tetrahydro- m.p. : 175 C imidazo[2,1-c][1,2,4]triazin-4-one 60 6(7),8-dimethyl-3-phenyl-4,6,7,8-tetrahydroimidazo- m.p. : 98 C [2,1-c][1,2,4]triazin-4-one 61 6(7)-methyl-3-phenyl-8-propargyl-4,6,7,8-tetrahydro- m.p. : 128 C imidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 62 3-tert.-butyl-8-methoxymethyl-4,6,7,8-tetrahydro- m.p. : 84 C imidazo[2,1-c][1,2,4]triazin-4-one 63 3-tert.-butyl-8-cyanomethyl-4,6,7,8-tetrahydroimidazo- m.p. : 100 C [2,1-c][1,2,4]triazin-4-one 64 8-methyl-3-(2-thienyl)-4,6,7,8-tetrahydroimidazo- m.p. : 201 C [2,1-c][1,2,4]triazin-4-one 65 3-isobutyl-8-methyl-4,6,7,8-tetrahydroimidazo- m.p. : 124 C [2,1-c][1,2,4]triazin-4-one 66 3-(2-chloro-1,1-dimethylethyl)-4,6,7,8-tetrahydro- m.p. : 204 C imidazo[2,1-c][1,2,4]triazin-4-one 67 8-allyl-3-isopropyl-4,6,7,8-tetrahydroimidazo- m.p. : oil [2,1-c][1,2,4]triazin-4-one 68 3-(2-hydroxy-1,1-dimethylethyl)-8-methyl-4,6,7,8- m.p. : 168 C tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 69 3-(2-hydroxy-1,1-dimethylethyl)-8-propargyl-4,6,7,8- m.p. : 103 C tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 70 3-methyl-8-propargyl-4,6,7,8-tetrahydroimidazo- m.p. : 135 C [2,1-c][1,2,4]triazin-4-one 71 3-cyclopentyl-4,6,7,8-tetrahydroimidazo[2,1-c] m.p. : 218 C [1,2,4]triazin-4-one 72 3-cyclopentyl-8-methyl-4,6,7,8-tetrahydroimidazo- m.p. : 121 C [2,1-c][1,2,4]triazin-4-one 73 3-cyclopentyl-8-propargyl-4,6,7,8-tetrahydroimidazo- m.p. : 111 C [2,1-c][1,2,4]triazin-4-one 74 8-ally-3-cyclopentyl-4,6,7,8-tetrahydroimidazo- m.p. : 55 C [2,1-c][1,2,4]triazin-4-one 75 3-tert.-butyl-8-ethyl-4,6,7,8-tetrahydroimidazo- m.p. : 131 C [2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 76 3-phenyl-8-ethyl-4,6,7,8-tetrahydroimidazo- m.p. : 152 C [2,1-c][1,2,4]triazin-4-one 77 3-(5-chloro-2-thienyl)-4,6,7,8-tetrahydroimidazo- m.p. : 270 C [2,1-c][1,2,4]triazin-4-one 78 3-(5-chloro-2-thienyl)-8-propargyl-4,6,7,8-tetra- m.p. : 190 C hydroimidazo[2,1-c][1,2,4]triazin-4-one 79 8-allyl-3-methyl-4,6,7,8-tetrahydroimidazo- m.p. : 67-68 C [2,1-c][1,2,4]triazin-4-one 80 3-tert.-butyl-6,7,8,9-tetrahydro-4H-pyrimidino- m.p. : 250 C [2,1-c][1,2,4]triazin-4-one (decomposition) 81 3-tert.-butyl-8-methyl-4,6,7,8-tetrahydroimidazo- m.p. : 250-251 C [2,1-c][1,2,4]triazin-4-one, hydrochloride 82 3-(3,4-dimethoxyphenyl)4,6,7,8-tetrahydroimidazo- m.p. : 250 C [2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 83 3-(3,4-dimethoxyphenyl)-8-methyl-4,6,7,8-tetra- m.p. : 233 C hydroimidazo[1,2-c][1,2,4]triazin-4-one 84 3-(3,4-dimethoxyphenyl)-8-propargyl-4,6,7,8-tetra- m.p. : 203 C hydroimidazo[1,2-c][1,2,4]triazin-4-one (decomposition) 85 8-allyl-3-(3,4-dimethoxyphenyl)-4,6,7,8-tetrahydro- m.p. : 163 C imidazo[1,2-c][1,2,4]triazin-4-one 86 3-tert.-butyl-4,6,7,8-tetrahydroimidazo[1,2-c] m.p. ; 161-163 C [1,2,4]triazin-4-one, dichloroacetate 87 3-(3-methoxyphenyl)-4,6,7,8-tetrahydroimidazo- m.p. : 180 C [1,2-c][1,2,4]triazin-4-one (decomposition) 88 3-(3-methoxyphenyl)-8-propargyl-4,6,7,8-tetra- m.p. : 175 C hydroimidazo[1,2-c][1,2,4]triazin-4-one (decomposition) 89 8-methyl-3-(3-methoxyphenyl)-4,6,7,8-tetrahydro- m.p. : 177 C imidazo[1,2-c][1,2,4]triazin-4-one Example Name of compound Physical constant 90 8(1)-methyl-3-(2-methylphenyl)-(1),4,6,7,8-tetra- m.p. : 110-112 C hydroimidazo[2,1-c][1,2,4]triazin-4-one 91 3-(2-methylphenyl)-8-propargyl-4,6,7,8-tetrahydro- m.p. : 203 C imidazo[2,1-c][1,2,4]triazin-4-one 92 8-allyl-3-(2-methylphenyl)-4,6,7,8-tetrahydro- m.p. : 173 C imidazo[2,1-c][1,2,4]triazin-4-one 93 3-(2-chlorophenyl)-8-propargyl-4,6,7,8-tetrahydro- m.p. : 224 C imidazo[2,1-c][1,2,4]triazin-4-one (decomposition) 94 8-allyl-3-(2-methylphenyl)-4,6,7,8-tetrahydroimidazo- m.p. : 147 C [2,1-c][1,2,4]triazin-4-one, hydronitrate (decomposition) 95 8-allyl-3-(3-methoxyphenyl)-4,6,7,8-tetrahydroimidazo- m.p. : 77 C [2,1-c][1,2,4]triazin-4-one 96 3-(4-chlorophenyl)-4,6,7,8-tetrahydroimidazo[2,1-c]- m.p. : 211 C [1,2,4]triazin-4-one Example Name of compound Physical constant 97 3-(4-chlorophenyl)-8-propargyl-4,6,7,8-tetrahydro- m.p. : 181-182 C imidazo[2,1-c][1,2,4]triazin-4-one (decomposition) 98 8-allyl-3-(4-chlorophenyl)-4,6,7,8-tetrahydroimidazo- m.p. : 153-155 C [2,1-c][1,2,4]triazin-4-one 99 3-(1-methylcyclohexyl)-4,6,7,8-tetrahydroimidazo- m.p. : 221 C [2,1-c][1,2,4]triazin-4-one 100 3-(1-methylcyclohexyl)-8-propargyl-4,6,7,8-tetra- m.p. : 114 C hydroimidazo[2,1-c][1,2,4]triazin-4-one 101 8-methyl-3-(1-methylcyclohexyl)-4,6,7,8-tetrahydro- m.p. : 102 C imidazo[2,1-c][1,2,4]triazin-4-one 102 6(7)-methyl-3-phenyl-4,6,7,8-tetrahydroimidazo- m.p. : 200-201 C [2,1-c][1,2,4]triazin-4-one 103 8-allyl-6(7)-methyl-3-phenyl1-4,6,7,8-tetrahydroimidazo- m.p. : 99 C [2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 104 3-(1-ethoxycyclohexyl)4,6,7,8-tetrahydroimidazo- m.p. : 170 C [2,1-c][1,2,4]triazin-4-one 105 3-(1-ethyoxycyclohexyl)-8-methyl-4,6,7,8-tetrahydro- m.p. : 102 C imidazo[2,1-c][1,2,4]triazin-4-one 106 6(7)-methyl-3-phenyl-8-propyl-4,6,7,8-tetrahydro- m.p. : 107 C imidazo[2,1-c][1,2,4]triazin-4-one 107 6(7)-methyl-3-phenyl-8-propyl-4,6,7,8-tetrahydro- m.p. : 168 C imidazo[2,1-c][1,2,4]triazin-4-one, hydrogen nitrate (decomposition) 108 3-(1-ethylcyclohexyl)-8-propargyl-4,6,7,8-tetrahydro- m.p. : 71-72 C imidazo[2,1-c][1,2,4]triazin-4-one 109 3-(1-methylcyclopentyl)-4,6,7,8-tetrahydroimidazo- m.p. : 239-240 C [2,1-c][1,2,4]triazin-4-one 110 3-(1-methylcyclopentyl)-8-methyl-4,6,7,8-tetrahydro- m.p. : 104-105 C imidazo[2,1-c][1,2,4]triazin-4-one Example Name of compound Physical constant 111 3-(1-methylcyclopentyl)-8-propargyl-4,6,7,8-tetra- m.p. : 105 C hydroimidazo[2,1-c][1,2,4]triazin-4-one 112 3-(1-methylcyclopentyl)-8-propargyl-4,6,7,8-tetra- m.p. : 148 C hydroimidazo[2,1-c][1,2,4]triazin-4-one, hydrogen nitrate (decomposition) 113 8-allyl-3-(2-chlorophenyl)-4,6,7,8-tetrahydroimidazo- m.p. : 211 C [2,1-c][1,2,4]triazin-4-one 114 8-allyl-3-(1-methylcyclopentyl)-4,7,7,8-tetrahydroimidazo- nD20:1.5560 [2,1-c][1,2,4]triazin-4-one 115 8-acetyl-3-(2,2-dichloro-1-methylcyclopropyl)-4,6,7,8- m.p. : 204 C tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one Examples of Preparations A. Wettable powder (a) 80 % by weight active substance 1 5 % by weight kaolin 5 % by weight surface-active substances based on the sodium salt of N-methyl-N oleyl taurine and the calcium salt of ligninsulphonic acid (b) 50 % by weight active substance 40 % by weight clay minerals 5 % by weight cellulose pitch 5 % by weight surface-active substances based on a mixture of the calcium salt of ligninsulphonic acid and alkylphenol polyglycol ethers (c) 20 % by weight active substance 70 % by weight clay minerals 5 % by weight cellulose pitch 5 % by weight surface-active substances based on a mixture of the calcium salt of ligninsulphonic acid and alkylphenol polyglycol ethers (d) 5 % by weight active substance 80 % by weight bentonite 10 % by weight cellulose pitch 5 % by weight surface-active substances based on a fatty acid condensation product B. Emulsion concentrate 20 % by weight active substance 40 e/O by weight xylene 35 % by weight dimethyl sulphoxide 5 % by weight mixture of nonylphenol poloxyethylenes or calcium dodecyl benzenesulphonate The following Examples illustrates the possible uses of compounds according to the invention which were used in the form of the above-mentioned preparations.

Example I A number of compounds of the invention, listed in the Table, were sprayed in amounts of 3 kg active substance/ha dissolved in 500 litres of water/ha onto Sinapsis lSi), Solanum (So) and Setaria (Se) as test plants in a greenhouse in a post-emergence method. Three weeks after the treatment, the results of the treatment were evaluated on a scale from 0 to 4 where 0 = no action 4 = plants destroyed The results are given in the Table below.

As will be seen, invariably the test plants were destroyed.

Compound of Compound according to the invention Post-emergence process Example No. Se Si So 6 8-methyl-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 7 3-(3-methylphenyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 10 8-methylsulphonyl-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 11 3-tert.-butyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 12 3-tert.-butyl-8-methylsulphonyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 13 3-tert.-butyl-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 16 8-chloromethylsulphonyl-3-phenyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 17 8-ally-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 18 3-(4-fluorophenyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 19 8-(2-butenyl)-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 21 8-methoxymethyl-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 22 3-phenyl-6,7,8,9-tetrahydro-4H-pyrimidino [2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 24 9-(2-butenyl)-3-phenyl-6,7,8,9-tetrahydro 4H-pyrimidino[2,1-c][1,2,4]triazin-4-one 4 4 4 25 8-allyl-3-tert.-butyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 26 8-(2-methylallyl)-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 27 3-phenyl-9-(2-propenyl)-6,7,8,9-tetrahydro-4H pyrimidino[2,1-c][1,2,4]triazin-4-one 4 4 4 28 3-(4-fluorophenyl)-8-methyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 29 3-(4-fluorophenyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 30 3-(3-methylphenyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 32 8-methyl-3-(3-methylphenyl)-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 34 3-tert.-butyl-9-methyl-6,7,8,9-tetrahydro-4H pyrimidino[2,1-c][1,2,4]triazin-4-one 4 4 4 37 3-phenyl-9-(2-propynyl)-6,7,8,9-tetrahydro-4H pyrimidino[2,1-c][1,2,4]triazin-4-one 4 4 4 38 3-tert.-butyl-9-(2-propynyl)-6,7,8,9-tetrahydro 4H-pyrimidino[2,1-c][1,2,4]triazin-4-one 4 4 4 40 3-cyclohexyl-4,6,7,8-tetrahydroimidazo[2,1-c] [1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 44 3-isopropyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 45 9-methyl-3-phenyl-6,7,8,9-tetrahydro-4H pyrimidino[2,1-c][1,2,4]triazin-4-one 4 4 4 46 3-cyclohexyl-9-methyl-6,7,8,9-tetrahydro-4H-pyrimidino [2,1-c][1,2,4]triazin-4-one 4 4 4 47 3-cyclohexyl-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 48 3-cyclohexyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 49 3-isopropyl-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 50 8-allyl-3-isobutyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 51 9-allyl-3-tert.-butyl-6,7,8,9-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 52 3-tert.-butyl-6(7),8-dimethyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 53 8-cyclohexyl-3-phenyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 54 3-(2,5-dichloro-3-thienyl)-8(1)-methyl-(1),4,6,7,8 tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 (isomeric mixture) 55 3-(2,5-dichloro-3-thienyl)-8-propargyl-4,6,7,8 tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 56 3-isobutyl-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 58 3-tert.-butyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 hydrogen nitrate 59 3-tert.-butyl-8-chloromethylsulphonyl-4,6,7,8 tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 60 6(7),8-dimethyl-3-phenyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 61 6(7)-methyl-3-phenyl-8-propargyl-4,6,7,8-tetra hydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 62 3-tert.-butyl-8-methyoxymethyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]54iazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 64 8-methyl-3-(2-thienyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 65 3-isobutyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 67 8-allyl-3-isopropyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 68 3-(2-hydroxy-1,1,-dimethylethyl)-8-methyl-4,6,7,8 tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 69 3-(2-hydroxy-1,1-dimethylethyl)-8-propargyl 4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 70 3-methyl-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 71 3-cyclopentyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 72 3-cyclopentyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 73 3-cyclopentyl-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 74 8-allyl-3-cyclopentyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 75 3-tert.-butyl-8-ethyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No. Se Si So 80 3-tert.-butyl-6,7,8,9-tetrahydro-4H-pyrimidino [2,1-c][1,2,4]triazin-4-one 4 4 4 81 3-tetr.-butyl-8-methyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one, hydrochloride 4 4 4 83 3-(3,4-dimethoxyphenyl-8-methyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 88 3-(3-methoxyphenyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 89 8-methyl-3-(3-methoxyphenyl)-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 90 8(1)-methyl-3-(2-methylphenyl)-(1),4,6,7,8 tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 92 8-allyl-3-(2-methylphenyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 93 3-(2-chlorophenyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 95 8-allyl-3-(3-methoxyphenyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 97 3-(4-chlorophenyl)-8-propargyl-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 100 3-(1-methylcyclohexyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 101 8-methyl-3-(1-methylcyclohexyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 Compound of Compound according to the invention Post-emergence process Example No.Se Si So 105 3-(1-ethoxycyclohexyl)-8-methyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 108 3-(1-ethylcyclohexyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 109 3-(1-methylcyclopentyl)-4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 110 3-(1-methylcyclopentyl)-8-methyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 111 3-(1-methylcyclopentyl)-8-propargyl-4,6,7,8-tetrahydro imidazo [2,1-c][1,2,4]triazin-4-one 4 4 4 112 3-(1-methylcyclopentyl)-8-propargyl-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one hydrogen nitrate 4 4 4 Compound of Compound according to the invention Post-emergence proces Example No.Se Si So 114 8-allyl-3-(1-methylcyclopentyl)-4,6,7,8-tetrahydro imidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 115 8-acetyl-3-(2,2-dichloro-1-methylcyclopropyl)-4,6,7,8 tetrahydroimidazo[2,1-c][1,2,4]triazin-4-one 4 4 4 Example II The plants listed in the following Table were treated before emergence with test compounds in a greenhouse in an amount of 0.4 kg active substance/ha; the test compounds, which consisted of compounds of the invention and a comparison agent, were applied uniformly to the soil in the form of aqueous solutions or suspensions with 500 litres of water/ha.

Three weeks after the treatment, the results of the treatment were evaluated on a scale from 0 to 10 where 0 = plants totally destroyed 10 = no action The results are given below These show that the compounds of the invention exhibited better compatability and action than the comparison agent.

Compound of Compound according to the Example No. invention 11 3-tert.-butyl-8-methyl-4,6,7,8- 10 10 10 10 0 0 0 0 0 0 0 0 0 0 0 tetrahydroimidazo[2,1-c][1,2,4] triazin-4-one 34 3-tert.-butyl-9-methyl-6,7,8,9- 10 10 10 10 0 0 0 0 0 0 0 0 0 0 0 tetrahydro-4H-pyrimidino[2,1-c] [1,2,4]triazin-4-one 52 3-tert.-butyl-6(7),8-dimethyl- 10 10 10 10 0 0 0 0 0 0 0 0 0 0 0 4,6,7,8-tetrahydroimidazo [2,1-c][1,2,4]triazin-4-one Comparison agent (according to BE-PS 69 70 83) 4-amino-6-tert.-butyl-4,5- 10 10 5 5 0 0 0 0 3 0 0 1 0 0 2 dihydro-3-methylthio-1,2,4 triazin-5-one untreated 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10

Example Ill After emergence, the plants listed below were treated in a greenhouse with the compounds listed below in an amount of 0.4 kg active substance/ha. For this purpose the compounds were sprayed uniformly over the plants in the form of an aqueous solution or suspension with 500 litres of water/ha. Three weeks after the treatment, the results of the treatment were evaluated on a scale from 1 to 10: 0 = plants totally destroyed 10 = no action The results are shown below.

In this test too, three weeks after the treatment the compounds according to the invention exhibited a high selectivity and an excellent action against the weeds. The comparison agent did not exhibit this selectivity.

Compound of Compound according to the Example No. invention 11 3-tert.-butyl-8-methyl-4,6,7,8- 10 10 0 0 0 0 0 0 tetrahydroimidazo[2,1-c][1,2,4] triazin-4-one 13 3-tert. -butyl-8-propargyl-4,6,7,8- 10 10 0 0 0 0 0 0 terrahydroimidazo[2,1-c][1,2,4] triazin-4-one 34 3-tert.-butyl-9-methyl-6,7,8,9- 10 10 0 0 0 0 0 0 tetrahydro-4H-pyrimidino[2,1-c] [1,2,4]triazin-4-one 48 3-cyclohexyl-8-methyl-4,6,7,8- 10 10 0 0 0 0 0 0 tetrahydroimidazo[2,1-c][1,2,4] triazin-4-one Comparison agent (according to BE-PS 69 70 83) 4-amino-6-tert.-butyl-4,5- 0 0 0 0 0 0 0 0 dihydro-3-methylthio-1,2,4 triazin-5-one untreated 10 10 10 10 10 10 10 10

Claims (31)

1. A compound of the general formula

in which R1 represents a hydrogen atom; a (C1-Ca)-alkyl radical which is unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms, cyano groups, hydroxy groups and (C1-C4)- alkoxy radicals; a (C3-C8)-cycloalkyl radical which is unsubstituted or substituted by one or more of the same or different substituents selected from alkyl and alkoxy radicals, halogen atoms and phenyl groups; a (C1-C4)-alkoxy-carbonylmethyl radical; an aromatic or aromatic-aliphatic hydrocarbon radical each unsubstituted or substituted by one or more of the same or different substituents selected from (C1-C4)-alkyl radicals, halogen atoms, (C1-C4)-alkoxy radicals, and nitro and trifluoromethyl groups; or a heterocyclic radical which is unsubstituted or substituted by one or more of the same or different halogen atoms; R2 represents a hydrogen atom; a (C,-C8)-alkyl, (C3-C8)-alkenyl, (C3-C8)-alkynyl, (C3-C8)-cycloalkyl or (C3-C8)-cycloalkenyl radical each unsubstituted or substituted by one or more of the same or different substituents selected from halogen atoms, (C,-C4)-alkoxy radicals, cyano groups, (C,-C4)-alkylthio radicals and hydroxy groups; a (C2-C8)-alkyl radical which is interrupted by one or more of the same or different heteroatoms selected from oxygen, sulphur and nitrogen; a (C1 -C4)-alkoxy-carbonyl-C1 -C4)-alkyl radical; a (C,-C6)-alkylsulphonyl group which is unsubstituted or substituted by one or more of the same or different halogen atoms;; an aromatic or aromatic-aliphatic hydrocarbon radical each unsubstituted or substituted by one or more of the same or different substituents selected from (C,-C6)-alkyl radicals, halogen atoms, (C,-C4)-alkoxy radicals and nitro and trifluoromethyl groups; a cyano group; or an acetyl or propionyl group; R3, R4 and R5, any two or more of which are the same or different, each represents a hydrogen atom; a (C,-C6)-alkyl radical which is unsubstituted or substituted by one or more of the same or different halogen atoms; or an aryl radical which is unsubstitufted or substituted by one or more of the same or different substituents selected from (C,-C6)-alkyl radicals, halogen atoms, (C,-C4)-alkoxy radicals and nitro and trifluoromethyl groups, and n represents 0 or 1, or a salt thereof with an inorganic or organic acid.

2. A compound as claimed in claim 1, wherein R, represents a phenyl, 2-methylphenyl, 3methylphenyl, 4-methylphenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 4-fluorophenyl, 4-trifluoromethylphenyl, 2-th ienyl, 2, 5-dichloro-3-thienyl, isopropyl, sec.-butyl, tert.-butyl, chloro-tert.-butyl, 2-hydroxy-1 , 1-dimethylethyl, methycyclopropyl, 2,2 dichloro-1-methylcyclopropyl, cyclopropyl, cyclopentyl or cyclohexyl group.

3. A compound as claimed in claim 1 or claim 2, wherein R2 represents a methyl, ethyl, propyl, allyl or propargyl group.

4. A compound as claimed in any one of claims 1 to 3, wherein R3 represents a hydrogen atom or a methyl group.

5. A compound as claimed in any one of claims 1 to 4, wherein R4 represents a hydrogen atom or a methyl group.

6. A compound as claimed in any one of claims 1 to 5, wherein R5 represents a hydrogen atom or a- methyl group.

7. A mixture of a compound as claimed in any one of claims 1 to 6 in which R3 and R5 are different, and its isomer in which the group represented by R3 is in the position of the group represented by R5 and vice-versa.

8. A mixture of a compound as claimed in any one of claims 1 to 6 and its isomer of the general formula

or a salt thereof

9. 3-tert.-butyl-8-propargyl-4, 6, 7,8-tetrahydroimidazo[2, 1 -cJ[1 ,2,4]triazin-4-one.

10. 3-tert.-butyl-9-methyl-6, 7,8, 9-tetrahydro-4H-pyrimidino[2, 1 -c][1 ,2,4]triazin-4-one.

11. 3-cyclohexyl-8-methyl-4, 6, 7,8-tetrahydroimidazo-[2, 1 -c][1 ,2,4,]triazin-4-one,

1 2. 3-tert.-butyl-6(7), 8-dimethyl-4,6,7,8-tetrahydroimidazo[2, 1 -c][1 ,2,4]triazin-4-one.

13. 3-tert.-butyl-8-methyl-4,6,7,8-tetrahydroimidazo-[2,1-c][1,2,4]triazin-4-one

14. A compound as claimed in claim 1 or a mixture as claimed in claim 7 or claim 8, which is described in any one of the Examples herein.

15. A process for preparing a compound as claimed in claim 1 or a mixture as claimed in claim 6 or claim 7, which comprises (a) reacting a compound of the general formula

@@ @@@@@ @ @ @ @ @@@ @ @@@@ @@@ @@@@@@@@ @@@@@ @@ @@@@@ @ @@@ @@@@@ @@@@@@@@ @@@@@@@ with a compound of the general formula R2-X Ill in which R2 has the meaning given in claim 1 and X represents a halogen atom, a sulphate group or a tosyl group, if desired in the presence of an acid-binding agent and/or in the presence of a catalyst, or (b) reacting a compound of the general formula

in which R2, R3, R4, R5 and n have the meanings given above either with a compound of the general formula

in which R, has the meaning given above and R6 represents a hydrogen atom or a methyl or ethyl group, or, to form a compound in which R, represents a (C,-CJ-alkoxy-carbonylmethyl radical, with a compound of the general formula R700C-CC-COOR7 Vl in which R7 represents a (C,-C4)-alkyl radical and the two R7 moieties may be the same or different, if desired in the presence of a base, or (c) reacting a compound of the general formula

in which R2, R3, R4, R5, R7 and n have the meanings given above and Y represents an oxygen or sulphur atom, with a compound of the general formula

in which R1 and R6 have the meanings given above, or (d) reacting a compound of the general formula

in which R, and R2 have the meanings given above, with a compound of the general formula

in which R3, R4, R5, n and X have the meanings given above, if desired, in the presence of a base, or (e) reacting a compound of the general formula V shown above with a compound of the general formula

in which R2, R3, R4, R5 and n have the meanings given above and with a compound of the formula

in the presence of a base, wherein, in any of the processes (a) to (e) where appropriate a reactant is used in the form of a salt, and, if desired a resulting compound of the general formula I is converted into a salt thereof.

1 6. A process as claimed in claim 15, carried out substantially as described in any one of the Examples 1 to 11 5 herein.

1 7. A compound as claimed in claim 1 or a mixture as claimed in claim 6 or claim 7, whenever prepared by a process as claimed in claim 1 5 or claim 1 6.

1 8. A herbicidal preparation which comprises a compound or mixture as claimed in any one of claims 1 to 1 4 and 17, and a suitable carrier.

1 9. A preparation as claimed in claim 18, containing from 5 to 95 % by weight of active substance(s), from 95 to 5 % by weight of carrier(s) and, if desired, up to 20 % by weight of surface active substance(s).

20. A preparation as claimed in claim 1 8 or claim 19, which is in the form of a powder, strewable agent, granulate, solution, emulsion or suspension.

21. A preparation as claimed in claim 20, having substantially any one of the compositions described in Examples A and B herein.

22. A process for combating weeds, which comprises applying a compound or mixture as claimed in any one of claims 1 to 1 4 and 1 7 or two or more such compounds or mixtures to a weed or weeds or to an area or soil infested with or liable to infestation by weeds.

23. A process as claimed in claim 22, wherein the active substance(s) are applied in a total amount of from 0.1 to 5 kg/ha

24. A process as claimed in claim 22 or claim 23, wherein there is used a preparation as claimed in any one of claims 18 to 21.

25. A process as claimed in any one of claims 22 to 24, wherein the active substance(s) are applied to a crop area or an area adjacent to a crop area.

26. A process as claimed in any one of claims 22 to 25, wherein the crop area treated is soya, rice, maize, cotton, wheat, barley or potatoes.

27. A process as claimed in any one of claims 22 to 26, wherein the weeds comprise Abutilon theophrastii, Ipomoea ssp., Solanum ssp., Viola ssp., Echinochloa crus galli, Setaria ssp., Digitaria ssp., Brassica kaber, Cassis, Sesbania or Datura or two or more such weeds.

28. A process as claimed in claim 22, carried out substantially as described in Example I, II or Example Ill herein.

29. An area, crop, crop area or soil treated by a process as claimed in any one of claims 22 to 27.

30. A crop or other plant in or from a crop area or soil treated by a process as claimed in any one of claims 22 to 27.

31. A compound of the general formula

in which R1, R2, R3, R4, R5 and n have the meanings given in claim 1, or a salt thereof with an inorganic or organic acid.