CA1135703A - 4,5-dichloroimidazole derivatives, processes for their preparation and their use as herbicides - Google Patents

Abstract

Abstract of the Disclosure 4,?-Dichloroimidazole compound of the formula (I) wherein X1 is hydrogen, chlorine, bromine or iodine;
X2, X3 and X4 independently are hydrogen, chlorine or bromine; and X5 is hydrogen or chlorine; and x1 and X3 together can represent a C-C bond; and x2 and X4 together can represent a C-C bond; or x1 and x2 together can represent oxygen or the grouping -N - Y.
in which Y is hydroxyl or a radical -NH-E1 or wherein R is hydrogen or alkyl with up to 4 carbon atoms;
R1 is aryl or substituted aryl, the substituents being selected from halogen, alkyl, alkoxy, halo-alkyl and nitro;
Z is oxygen or sulfur; and R2, R3 and R4 independently are hydrogen or chlorine provided that X1, X2, X3, X4 and X5 do not simultaneously represent hydrogen, are oustandingly effecetive as herbicides.

Description

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The present invention relates to certain new 4,5- -dichloroimidazole derivatives, to a process for their preparation and to their use as herbicides.
It has already been disclosed that certain 4,5-dichloro-imidazole-2-carboxylic acid derivatives have herbicidal properties (see DE-OS (German Published Specification)

2,610,527). Thus, for example, 4,5-dichloroimidazole-2-carboxylic acid ethylamide can be employed for combating weeds, However, this substance is not always sufficiently active and its selectivity is not always completely satisfactory.
The present invention now provides, as new compounds, the 4,5-dichloroimidazole derivatives of the general formula Cl ~N ~ C - C ~ X5 (I) ' x2 X4 in which xl represents hydrogen, chlorine, bromine or iodine, X2, X3 and X4 independently represent hydrogen, chlorine or bromine and X5 represents hydrogen or chlorine, and Xl and X3 together can represent a C-C bond, and x2 and X4 together can represent a C-C bond, or xl and x2 together can represent oxygen or the grouping =N-Y, in which y represents hydroxyl or a radical -NH-C~NHR, z -NH-Rl or ~ ~ ~ f-~l ' Le A 19 ~92 ~ 3~ 3~5t~3 in which R represents hydrgen or alkyl with 1 to 4 carbon atoms, Rl represents aryl which optionally carries one or more substituents selected from halogen, alkyl, alkoxy, halogenoalkyl and nitro~
Z represents oxygen or sulphur and R2, R3 and R4 independently of one another repre-sent hydrogen or chlorine, provided that Xl, X2, X3, X4 and X5 do not simultaneously represent hydrogen.
It has been found that the 4,5-dichloroimidazole derivatives of the formula (I) have powerful herbicidal properties and, in p~rticular~ selective herbicidal properties Preferred compounds of the formula (I) are those in which xl represents hydrogen, chlorine, bromine or iodine, x2 represents hydrogen, chlorine or bromine, X3 represents hydrogen, chlorine or bromine, X4 represents hydrogen, chlorine or bromine, and X5 represents hydrogen or chlorine, provided that : -Xl, X2, X3, X4 and X5 never simultaneously all represent --hydrogen, xl and X3 together may alternatively represent a C-C
bond, x2 and X4 together may alternatively represent ~ C-C
bond, or xl and x2 together may represent oxygen or the grouping =N-Y, Y represents hydroxyl or a radical -NH-C-NH-R,-NHRl or ~Cl -N=C-~ Y~C1 Le A 19 392 ~L~3S7~3 R represents hydrogen or alkyl with 1 to 2 carbon atoms (especially hydrogen), Z represents sulphur, Rl represents phenyl or naphthyl, either of which may optionally carry one or more substituents selected from fluorine, chlorine, bromine, alkyl with 1 or 2 carbon atoms, alkoxy with 1 or 2 carbon akoms, trichloro-methyl, tri~luoromethyl and nitro, and R2, R3 and R4 each represent hydrogen.
The invention also provides a process for the preparation of a 4,5-dichloroimidazole derivative of the formula (I), in which (a) 2-ethylimidazole, of the formula N
~ N ~ 2H5 (II), or its hydrochloride i9 reacted with up to 7 moles of chlorine per mole of 2-ethylimidazole in a solvent which is inert under the reaction conditions, or (b) a 4,5-dichloroimidazole derivative of the general formula Cl 20 ~ ~ x6 X3 (III), H x7 x4 in which x6 represents chlorine or bromine, X7 represents chlorine or bromine and X3, X4 and X5 have the meanings indicated.above, provided that X , X and X do not simultaneously represent hydrogen, () is hydrolysed with water, or (e) is reacted with at least the stoichiometrically required A
Le A 19 392 ~3.~ 3 amount of a dehalogenating agent, if appropriate in the presence of a diluent, or (y) is reacted with at least the stoichiometrically required amount of a metal hydride customary for hydrogenation reactions, in the presence of a diluent, or (c) a 4,5-dichloroimidazole derivative of the general formula Cl- --N x6 ~ N ~ CH2-C-X5 (IV), cl ' X7 in which X5, x6 and X7 have the meanings indicated above, i8 reacted with an agent which splits off hydrogen chloride, in ~he presence of a diluent, or (d) 2,4,5-trichloro-2-(1,1-dichloroethyl)-2 H-imidazole~ of the formula Cl\~N~Cl Cl ~ N CC12-CH3 (V), (~) is reacted with a reducing agent, in the presence of a diluent, or (B) is reacted with an excess of at least 3 moles of an alkali metal iodide or with an excess of at least 1.5 moles of an alkaline earth metal iodide, in the presence of a lower aliphatic ketone as the diluent, or (y) is reacted with an at least equimolar amount of an alkali metal bromide or with an at least equivalent amount of an alkaline earth metal bromide, in the presence of a lower aliphatic nitrile or of a lower aliphatic ketone as the diluent, or (e) a 4,5-dichloroimidazole derivative of the general formula Le A 19 392 .: ~
, ' :

.
.

_ 5 _ Cl ~ C-CH2 (VI), in which Hal represents chlorine or iodine, (u) is reacted with an agent which splits off hydrogen halide, if appropriate in the presence of a diluent, or (~) is hydrolysed with water, in the presenoe of a base or of a basic salt, or (f) a 4,5-dichloroimidazole derivative of the general formula ~ ~ C- ~- X4 (VII), Cl H \ X5 in which X3, X4 and X5 have the meanings indicated above, is reacted with a compound of the general formula H2N-Y t (VIII), in which Y' represents amino, hydroxyl or a radical -NH-C-NHR or -NHRl ~t in which Z represents oxygen or sulphur, R represents hydrogen or alkyl with 1 to 4 carbon atoms and Rl represents aryl which optionally carries one or more substituents ~elected from halogen, alkyl, alkoxy, halogenoalkyl and nitro, in the presence of a diluent, or (g) 4,5-dichloro-2-ethynyl-imidazole, of the formula Cl ~ (IX), Cl N C-CH
H

v, ~ , Le A 19 392 ~3~ 3 is reacted with a chlorinatin~ or brominating agent, in the presence of a solvent which is inert under the reaction conditions, or (h) a 4,5-dichloroimidazole derivative of the general formula Cl~3`c-c\ (x) in which Xl, X3 and X4 have the meanin~s indicated above, is reacted with a chlorinating or brominating agent, in the presence of a solvent which is inert under the reaction conditions, or (i) a 4,5-dichloroimidazole derivative of the general formula Cl_ ~ ~ Hal Cl - , ~ C-CH2-X (XI), in which x6 and X7 have the meanin~ indicated above and Hal' represents chlorine, bromine or iodine, is dehydrohalogenated under the influence of heat, in the presence of a lower aliphatic nitrile.
Surprisingly, whilst having a very good herbicidal action, the 4,5-dichloroimidazole derivatives of the formula (I) according to the invention have, in particular, better possibilities for use as agents for selectively combating weeds in important crops than ~,5-dichloro-imidazole-2-carboxylic acid ethylamide, which is known from the state of the art and is an active compound of high activity and the same type o~ action The substances Le A 19 392 ~35~

according to the invention thus represent a valuable enrich-ment of herbicidal agents for selectively combating weeds.
If, in process variant (a),7 moles of chlorine are used per moleo~ 2-ethyl-imidazole, the course of the reaction can be represented by the following equation:

H C ~,~

If 4,5-dichloro-2-pentachloroethyl-imidazole is used as the starting material and water is used as the hydrolysing agent, the course of process variant (b)(~), 10 can be represented by the following equation:
Cl Cl Cl ~N ~ C2C15 + H20 ~ Cl ~ ~ C-CC13 + 2 HCl H H O
If 4~5-dichloro-2-pentachloroethyl-imidazole is used as the starting material and sodium iodide in acetone -is used as the dechlorinating agent, the course of process 15 variant (b)(~) can be represented by the following equation:

C ~ ~ 2 NaI Cl ~ N

H ~ .
If 4,5-dichloro-2-pentachloroethyI-imidazole is used as the starting material and sodium boranate is used as the hydrogenating agent, the course o~ process variant (b)(y) 20 can be represented by the following equation:

'-:,' Le A 19 392 ~3S~3 4 ' ~ ~ 2 HCl H H
If 4,5-dichloro-2-(2,2,2-trichloroethyl)-imidazole is used as the starting material and triethylamine is used as the agent which splits off hydrogen chloride, the course of process variant (c) can be represented by the following equation:

~ N 3 ~ ~ CH=CC12 + HCl Cl N H2-ccl3 - i Cl N
H H
If 2,4~5-trichloro-2-(1,1-dichloroethyl)-2H-imidazole is used as the starting material and catalytically activated hydrogen is used as the reducing agent, the course of process variant (d)(~) can be represented by the following equation:

Cl ~ 1 ~2 ~ N ~ C-CH2 + 2 HCl 2 3 toluene H
If 2,4,5-trichloro-2-(1,1-dichloroethyl)-2H-imidazole and sodium iodide are used as starting materials, the course of process variant (d)(~) can be represented by the following equation:
Cl ~ ~ Cl -CH3 + 3 NaI > Cl 1 2 Cl 2 - 3 NaCl H

Le A 19 392 ~ ~.3.5~
_ 9 _ If 2,4,5~trichloro-2-(1,1-dichloroethyl)-2H-imidazole and potassium bromide are used 2S starting substances, the course of process variant (d)(~) can be represented by the following equation:

Cl ~N ~ Cl2-CH3 ~ C ~ N l C-CH-Br - H Br If 4,5-dichloro-2-(l-iodo-ethenyl)-imidazole is used as the starting material and triethylamine is used as the agent which splits off hydrogen halide, the course of process variant (e)(a) can be represented by the following lO equation: ;.

Cl ~N 1 C=CH2 _ 3l ~ ~N l C--CN

If 4,5-dichloro-2-(l-iodo-vinyl)-imidazole is used as the starting material and water and sodium formate are used as the hydrolysing agent, the course of process variant (e)(~) can be represented by the following equation:
Cl~---N Cl N
NaOOCH ~
Cl/ N, C=CH2 + H20 ~ Cl/ N C-CH3 + ~I

If 4,5-dichloro-2-acetyl-imidazole and phenylhydra-zine are used as starting materialS the course of process variant (f) can be represented by following equation:

C ~, ~ C-C~33 + N2N-NN ~ ____ ~ C ~ C-N-N3 Le A 19 392 5~

If 4,5-dichloro-2-ethynyl-imidazolé is used as th0 starting material and sulphuryl chloride is used as the chlorinating agent, the course of process variant (g) can be represented by the following equation:

Cl ~ ;lC~:H ~ 3 C ~ ~ -CHCl If 4,5-dichloro-2-(1-chlorovinyl)-imidazole is used as the starting material and sulphuryl chloride is used as the chlorinating agent, the course of process variant (h) can be represented by the ~ollowing equation:
Cl ~ ~ Cl S02C12 ~ IN
H 2 CHC13 ~ Cl/~N CC12-CH2C

If 4,5-dichloro-2-(1,1,2-trichloro-ethyl)-imidazole is used as the starting substance, the course of process variant (i) can be represented by the following equation:

~ ~ CCl2-CH2Cl ~ Cl/ ~NJl--C--CHC1 Cl H ~0C H
-HCl The 2-ethylimidazole, or its hydrochloride, required as the starting material in process variant (a) is known.
Chlorine gas is used as the chlorinating agent in process variant (a).
Possible solvents in carrying out process variant (a) are any of the customary solvents which are inert under the reaction conditions. Preferred solvents include phosphorus oxychloride, 1,1,2,2-tetrachloroethane, tetrachlorethylene and thionyl chloride.

Le A 19 392 .
. . . ~

.

.

~ ~3S~

The reaction temperatures can be varied within a certain range in process variant (a)depending on the desired end product. If 4,5-dichloro-2-pentachloroethyl-imidazole is to be synthesised, the reaction is in general carried out at temperatures of from 90C to 150C, preferably from 100C to 130C. To prepare com-pounds chlorinated to a lesser extent, the reaction is in general carrled out at temperatures of from 60C to 100C, preferably from 70C to 90C.
In carrying out process variant (a), 2-ethylimidazole or its hydrochloride is reacted with various amounts of chlorine, depending on the desired end product. If 4,5-dichloro-2-pentachloroethyl-imidazole is to be prepared, 3 to 7 moles of chlorine are in general employed per mole of 2-ethylimidazole To moderate the strongly exothermic chlorination reaction, the formation of the hydrochloride from 2-ethylimidazole and hydrogen chloride, which is likewise exothermic, can be eliminated by using not 2-ethylimidazole itself but its hydrochloride as the starting material. The reaction product is isolated by customary methods. In general, a procedure is followed in which the solvent is distilled off and the residue is stirred with formic acid at room temperature. The re~
action product which is thereby obtained as crystals is filtered off. However, it is also possible to sublime the reaction product out of the residue, which has been freed from solvent, in vacuo, for example at 125C/0.01 mm Hg.
If a 4,5-dichloroimidazole derivative of the formula (I) in which the side chain contains fewer than 5 chlorine atoms is to be prepared in process variant (a), up to 6 moles of chlorine are employed per mole of 2-ethylimidazole or its hydrochloride, but in this case the reaction temperature is kept below that for the perchlorination of the ethyl group. In some cases, the reaction product is formed not in the pure form but as a mixture with varyin~ amounts of 4,5-dichloro-2-pentachloro-ethyl-Le A 19 392 ~3~V~

imidazole. However, the desired reaction product canthen be obtained in the pure form by customary methods of separation, such as (fractional) crystallisation, for example from chlorobenzene or from acetone, or by chromatography.
The formula (III) provides a definition of the 4,5-dichloroimidazole derivatives required as starting materials in carrying out process variant (b). In this formula, X3, X4 and X5 preferably have those meanings which have already been mentioned as preferred for X3, X4 and X5 in connection with the description of the compounds according to the invention. However, X3, X4 and X5 do not simultaneously represent hydrogen. x6 and X7 preferably represent chlorine or bromine.
The compounds of the formula (III) were hitherto unknown. However, they can be prepared by process variant (a) or by other process variants according to the ~-invention.
In carrying out process variant (b)(~), a 4,5-dichloroimidazole derivative of the formula (III) ishydrolysed with water. In this reaction, the water simultaneously functions as the reaction medium and is thus employed in a large excess.
The reaction temperature can be varied within a certain range in carrying out process variant (b) (a) . In general, the reaction is carried out at temperatures of ~rom 70C to 120C, preferably at the boiling point of the reaction mixture.
The reaction products are isolated by customary methods in the case of process variant (b)(a3. In general, the reaction products are obtained as crystals;
thus they can be filtered off.
Possible dehalogenating agents for carrying out process ~ariant (b)(~) are any of the reagents which can usually be employed for such purposes. The dehalogenating agents Le A 19 392 , ' -' ., ~ - ,, ' .

5~

which are preferably used in this variant are sodium iodide in acetone, copper(I~ chloride, zinc dust, iron powder, sulphur and phosphorus.
Possible diluents for process variant (b)(~) are any of the solvents customary for such dehalogenatlon reactions. Acetone, toluene, chlorobenzene, 1,2-dichlorobenzene and 1,2,4-trichlorobenzene are preferably used.
The particularly preferred dehalogenating agent is the sodium iodide/acetone system.
The reaction temperatures can be varied within a substantial range in process variant (b)(~). The re-action is in general carried out at temperatures of from 0 to 200C, preferably from 50C to 150C. If the sodium iodide/acetone system is used, the reaction is in general carried out at temperatures of from 0C to 50C, pre-ferably from 20C to 30C.
In carrying out process variant (b)(~), the 4,5-dichloroimidazole derivative of the formula (III) is reacted with at least the stoichiometric amount of de-halogenating agent. If sodium iodide is used~ this canbe employed in a several-fold excess without further de-chlorination taking place. The reaction products are isolated by customary methods. In general, if sodium iodide is used as the dechlorinating agent, a procedure is followed in which the reaction mixture is poured into water, the free iodine is removed by adding a reducing agent, for example aqueous sodium bisulphite solution, and the product, which is obtained as crystals, is then filtered of~.
Possible hydrogenating agents for carrying out process variant (b)(y) are any of the (complex) metal hydrides customary for such reactions. Sodium boranate may be mentioned in particularl Possible diluents for process variant (b)(y) according 5 ~3 to the invention are any of the solvents which can usually be used for such reactions. Water may be men-tioned in particular.
The sodium boranate/water system is particularly preferred.
The reaction temperatures can be varied within a substantial range in process variant (b) (r) . In general, the reaction is carried out at temperatures of from 0C
to 50C, preferably Erom 10C to 40C. If the sodium boranate/water system is used, the reaction is preferably carried out at room temperature or slightly below room temperature.
In carrying out process variant (b)(y), the 4,5-dichloroimidazole derivative of the formula (III) is~
in general, reacted with at least the stoichiometrically required amount of metal hydride. If sodium boranate is used, this can be employed in a several-fold, for example up to a ten-fold, excess without further undesired hydro-genation reactions taking place. The reaction products are isolated by customary methods. In general, if sodium boranate is used as the hydrogenating agent, a procedure is followed in which any excess sodium boranate present is first destroyed by carefully adding acid and any boric acid obtained is dissolved out of the reaction mixture with ~'ot water.
The formula (IV) provides a definition of the 4,5-dichloroimidazole derivatives required as starting materials in carrying out process variant (c). In this formula, X5 preferably represents hydrogen or chlorine. x6 and X7 preferably represent chlorine or bromine.
The compounds of the formula (IV) were hitherto unknown; however, they can be prepared by process variant (b)(y).
Possible agents which splik off hydrogen halide for carrying out process variant (c) are any of the reagents Le A 19 392 ,, , . , , ~
: , , ;
' , . ~ .
.: ~
.
..

. , ~ .
. .

5~ r~

customary for such reactions. These include inorganic and organic bases, such as alkali metal hydroxides, carbon-ates and bicarbonates, alkaline earth metal hydroxides, carbonates and bicarbonates, aluminium oxides and organic amines, especially tertiary amines, for example triethyl-amine.
Possible diluents for process variant (c) are any of the solvents customary for such dehydrohalogenation re-actions.
Water, an amine (which simultaneously serves as an agent which splits off hydrogen halide) or dioxan can preferably be used.
The reaction temperatures can be varied within a substantial range in process variant (c). The reaction is in general carried out at temperatures of from 0C
to 150C~ preferably from 20C to 120C.
In carrying out process variant (c), 1-1.2 moles of dehydrohalogenating agent are in general employed per mole of 4,5-dichloroimidazole derivative of the formula (IV). The reaction products are isolated by customary methods. In general, a procedure is followed in which the reaction mixture is acidified, water is added, if appropriate, and the reaction product, which is obtained as crystals, is then filtered off.
The 2,4,5-trichloro-2-(1,1-dichloroethyl)-2H-imidazole of the formula (V) required as the starting material in process variant (d) is known (see DE-OS (German Published Specification) 2,550,157).
Possible reducing agents for process variant (d)(a) are preferably hydrogen, activated by noble metals, for example platinum or palladium, or reducing agents such as hydrogen iodide or hydrogen bromide J if appropriate in the presence of sulphur dioxide.
Various solvents can be used as diluents in process variant (d)()~ depending on the reducing agent employed.

Le ~ 19 392 ' ~ ' . '~ ' ' ' Thus, in the case of catalytic hydrogenation, aromatic hydrocarbons, such as benzene, toluene and xylene, and cyclic ethers, such as dioxan and tetrahydrofuran, are generally employed as diluents. If the reaction is carried out with a chemical compound, such as hydrogen bromide or hydrogen iodide, preferred solvents are inert, water-immiscible organic solvents, such as methylene chloride, chloroform or toluene.
The reaction temperatures can be varied within a certain range in process variant (d)(a). The reaction is in general carried out at temperatures of from 0C to 50C, preferably from 10C to 30C.
In carrying out process variant (d)(), either an excess of catalytically activated hydrogen or at least 2 moles of a chemical reducing agent, such as hydrogen bromide or hydrogen iodide, are employed per mole of 2,4,5-trichloro-2-(1,1-dichloroethyl)-2H-imidazole of the formula (V). Hydrogen bromide and hydrogen iodide can preferably be employed in the form of their commercially available concentrated aqueous solutions (azeotropes).
In this case, saturation of the reaction mixtures with sulphur dioxide gas has a favourable effect on the yield of end product.
The end product is isolated by customary methods.
In general, a procedure is followed in which the solvent is first stripped o~f, the residue is suspended in water, the suspension is then neutralised and the solid is filtered off. The product can be purified by recry-stallisation, for example from acetonitrile, or by sublimation in vacuo.
Possible reactants in process variant (d)(~) are alkali metal iodides and alkaline earth metal iodides. These include) as preferences, sodium iodide, potassium iodide and calcium iodide.
Diluents which can be used in process variant (d)(~) Le A 19 392 '' ,:. . . ' " -

3-~

are any of the customary lower aliphatic ketones. Pcetone is particularly preferred.
The reaction temperatures can be varied within a substantial range in process variant (d)(~). The reaction is in general carried out at temperatures of from -20 to +100C, preferably from 0C to 60C.
In carrying out process variant (d)(~), at least 3 moles of alkall metal iodide or at least 1.5 moles of alkaline earth metal iodide are generally employed per 10 mole of 2,4,5-trichloro-2-(1,1-dichloroethyl)-2H-imidazole of the formula (V). The sodium iodide/acetone system is particularly preferred. In this case, sodium iodide can be employed in a large excess without troublesome side reactions proceeding. The reaction product is isolated by customary methods. In general, a procedure is followed in which the reaction mixture is poured into water, the free iodine present is removed by adding a reducing agent, such as aqueous sodium bisulphite solution, and the mixture is then filtered.
Possible reactants in process variant (d)(~) are alkali metal bromides and alkaline earth metal bromides.
These include, as preferences sodium bromide, potassium bromide and calcium bromide. Potassium bromide is particularly preferred.
Diluents which can be used for process variant (d)(y) are any of the customary lower aliphatic nitriles and lower aliphatic ketones. Acetonitrile and acetone are particularly preferred.
The reaction temperatures can be varied within a 3 substantial range in process variant (d)(y). The reaction is in general carried out at temperatures of from 50C to 150C, preferably from 70C to 120C.
In carrying out process variant (d) (r), at least 1 mole of alkali metal bromide or at least 0.5 mole of alkaline earth metal bromide is generally employed per mole of Le A 19 ~2 , .

3~

2,4,5-trichloro-2-(l,l-dichloroethyl)-2H-imidazole of the formula (V). The potassium bromide/acetonitrile and sodium bromide/acetone systems are particularly preferred. In these cases, the alkali metal bromide is preferably used in a 5-fold to lO-fold molar excess. The reaction products are isolated by customary methods. In general, a procedure is followed in which, after cooling, the mixture is poured into water (5 to 10 times the amount), the aqueous suspension is filtered and the residue is washed with water and dried.
The formula (VI) provides a definition of the 4,5-dichloroimidazole derivatives required as starting materials in process variant (e). In this formula, Hal preferably represents chlorine or iodine.
The compounds of ~he formula (VI) were hitherto unknown. However, they can be prepared by process variants (d)() and (d)(~).
Possible dehydrohalogenating agents for process variant (e)() are any of the reagents that are customary for such reactions. These include inorganic and organic bases, such as alkal metal hydroxides, carbonates and bicarbonates, alkaline earth metal hydroxides, carbonates and bicarbonates, and organic amines, such as tertiary aliphatic amines, for example triethylamine. Non-quaternisable aliphatic amines, such as ethyl diisopropylamine ("H~nig base") are particularly preferred.
Possible diluents for process variant (e)(~) are any of the inert organic solvents. Ethers, such as diethyl ether, dioxan or tetrahydrofuran, can preferably be used. It is furthermore possible for an amine used for splitting off a hydrogen halide to be simultaneously utilised as the solvent. In addition, water can also function as the diluent.
The reaction temperatures can be varied within a substantial range in process variant (e) (a) . The reaction ~ .
Le A 19 392 , ., r~

is in general carried out at temperatures of from 0C
to 100G, preferably from 10C and 50C.
In carrying out process variant (e)(~), 2 moles or a larger excess of almost any desired size of dehydrohalo-genating agent are in general employed per mole of a 4,5-dichloroimidazole derivative Or the formula (VI). The reaction product is isolated by customary methods. In general, a procedure is followed in which the reaction mixture is poured into water and acidified and the re-action product, which is obtained as crystals, isfiltered off.
In carrying out process variant (e)(~), a 4,5-dichloroimidazole derivative of the formula (VI) is hydro-lysed with water. In this variant, the water simultaneously functions as the reaction medium and is thus employed in a large excess.
Acid-binding agents which can be used f`or process variant (e)(~) are any of the customary bases or basic salts. Alkali metal salts of lower aliphatic carboxylic acids are preferred, sodium formate being mentioned in particular.
The reaction temperatures can be varied within a substantial range in process variant (e)(~). The reaction is in general carried out at temperatures of from 0C to 25 150C, preferably from 10C to 120C.
In carrying out process variant (e)(~)~ a large excess of water is employed per mole of 4,5-dichloroimidazole derivative of the formula (VI), it being necessary to remove the hydrogen halide acid, formed during the hydrolysis, continuously from the reaction mixture in order to achieve complete conversion. This can in principle be effected by bringing the pH value from the strongly acid range (pH 1-2) to the weakly acid to neutral range (pH 5-7) by controlled addition of a total of one mol of any desired customary base, with the proviso that pH 7 must Le A 19 392 ~3~5~S~

not be exceeded in any case, in order to avoid side reactions In a preferred embodiment of process variant (e)(~), the hydrolysis is carried out in the presence of at least one mol of an alkali metal salt of a lower ali-phatic carboxylic acid. Sodium formate, which can beemployed in any desired excess, can preferably be used in this embodiment. The reaction product is isolated by customary methods. In general, a procedure is followed in which the aqueous phase is separated off under the influence of heat and is allowed to cool and the reaction product, which thereby separates out as crystals~ is filtered off.
The formula (VII) provides a definition of the

4,5-dichloroimidazole derivatives required as starting materials in process variant (f). In this formula, X3, X4 and X5 preferably have those meanings which have already been mentioned as preferred in connection with the description of the compounds of the formula (I).
The compounds of the formula (VII) were hitherto unknown. However, they can be prepared by process variant (b)() or by process variant (e)(~). -The formula (VIII) provides a general definition of compounds also required as starting materials in process variant (f). In this formula~ Y' preferably has those ~ -meanings which have already been mentioned as preferred for Y in connection with the description of the compounds of the formula (I)~ but does not represent the radical of the formula N ~ Cl -N = C ~ ~ 1 R Y ~ R4 H
R

Y' furthermore preferably represents amino.

~:' Le A 19 392 7~r~3 The compounds of the formula (VIII) are known, or they can be prepared by processes which are known in prin-ciple.
Diluents which can be used in process variant (f) are any of the customary inert organic solvents, as well as water.
The reaction temperatures can be varied within a substantial range in process variant (f). The reaction is in general carried out at temperatures of from 20C to 120C, preferably from 80C to 110C.
In carrying out process variant (f), at least 1 mole of a compound of the formula (VIII) is in general employed per mole of 4,5-dichloroimidazole derivative of the formula (VII). The reaction products are isolated by customary methods. In general, a procedure is followed in which, if water is used as the diluent, the precipitate obtained, if necessary after prior acidification, is filtered off. If an organic solvent is used, when the reaction has ended, the mixture is concentrated, water is added to the residue, the mixture is heated and the pro cedure followed is then as described above.
The formula (IX) provides a definition of the 4,5-dichloro-2-ethynylimidazole required as the starting material in process variant (g). The substance was hitherto unknown; however3 it can be prepared by process variant (e).
Chlorinating and brominating agents which can be employed in process variant (g) are any of the customary reagents which can be used for such purposes. Chlorine, sulphuryl chloride and bromine are preferably used.
Diluents which can be employed in process variant (g) are any of the customary inert organic solvents. Chloro-form, methylene chloride and carbon tetrachloride are preferably used.
The reaction temperatures can be varied within a ~ . . , ..
Le A 19 392 57~

certain range in process variant (g). The reaction is in general carried out at temperatures of from 0C to 50C, preferably from 10C to 30C.
In carrying out process variant tg), 4,5-dichloro-2-ethynylimidazole of the formula (IX) is reacted withvarious amounts of chlorinating or brominating agent, depending on the desired end product. If an end product in which the side chain is saturated is to be prepared, at least 2 moles of chlorinating or brominating agent are employed per mole of 4~5-dichloro-2-ethynylimidazole of the formula (IX). If only 1 mole of chlorinating or brominating agent is used, compounds with an unsaturated side chain are formed. ~he reaction products are isolated by customary methods. In some cases~ the reaction product i3 obtained directly in the crystalline form, so that it can be filtered off.
The formula (X) provldes a definition of the 4,5-dichloroimidazole derivatives required as starting materials in process variant (h). In this formula, X1 preferably represents hydrogen, chlorine, bromine or iodine. X3 and X4 preferably have those meanings which have already been mentioned as preferred for X3 and X4 in connection with the description of the compounds of the formula (I).
The 4,5-dichloroimidazole derivatives of the formula (X) were hitherto unknown. However, they can be prepared by process variants according to the invention.
Chlorinating and brominatlng agents which can be employed in process variant (h) are any of the customary reagents which can be used for such purposes. Chlorine, sulphuryl chloride and bromine are preferably used.
Diluents which can be employed in process variant (h) are any of the customary inert organic solvents. Chloroform, methylene chloride and carbon tetrachloride can preferably be used.
The reaction temperatures can be varied within a ~
Le A 19 392 , rj~Q r,~

certain ran~e in process variant (h). The reaction is in general carried out at temperatures of from 0C to 50 C, preferably between 10C and 30C.
In carrying out process variant (h), 1 mole or even an excess Or chlorinating or brominating agent is employed per mole of 4,5-dichloroimidazole derivative of the formula (X). Working up is effected by customary methods. In general, a procedure is followed in which, if appropriate after prior concentration, the reaction product obtained in the crystalline form is filtered off.
The formula (XI) provides a definition of the 4,5-dichloroimidazole derivatives required as starting materials in process variant (i). In this formula, Hal' preferably represents chlorine, bromine and iodine. x6 and X7 preferably represent chlorine or bromine.
The compounds of the formula (XI) were hitherto --unknown. However, they can be prepared by process variants according to the invention.
Possible solvents in process variant (i) are any of the customary lower aliphatic nitriles. Acetonitrile is preferably used.
The reaction temperatures can be varied within a substantial range in process variant (i). The reaction is in general carried out at temperatures of from 50C to 150 C, preferably from 60C to 100C.
In carrying out process variant (i), a compound of the formula (XI) is heated in a lower aliphatic nitrile ~or some time. Thereafter, the mixture is worked up by customary methods. In general, a procedure is followed in which, after cooling, the reaction mixture is filtered, water is then added to the product phase and the product, which is obtained as crystals, is filtered off.
The active compounds according to the invention influence plant growth and can therefore be used as defoliants, desiccants, agents for destroying broad-Le A 19 392 ' ~
,:
. .
, ' ' ~' , .
, ~3~

leaved plants, germination inhibitors and, especially, as weed-killers. By ~'weeds" in the broadest sense there are meant plants growing in places where they are not desired.
Whether the compounds according to the invention act as total herbicides or selective herbicides depends essentially on the amount used.
The ac~ive compounds according to the present invention may be used, f~or example, to combat the following plants:
dicotyledon weeds of the genera Sinapis, Lepidium, Galium~ -Stellaria,' Matricaria,' Anthemi:, Ga'li'ns'o~_ , , IJrtica, Se'necio, Amaranthus, Portu'l'aca, Xanthium, Convolvulus, Ipomoea, ~ , Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Rorippa,-Rotala, Lindernia, Lamium, Veronica, Abut lon, Emex,' Datura, Viola, Galeo~sis, ~ , Centaurea and Solanum; and monocotyledon weeds of the genera Echinochloa, Setaria, Panicum, Digitaria, Phleum, Poa, Festuca, ' Eleusine, Brachiaria, Lolium, Bromus, Avena, Cyperus, Sorghum, Agropyron, Cynodon, MonochOria3 Fimbristylis, Sagittaria, Eleocharis, Scirpus, Paspalum,- Is-chae~um, Sphenoclea, Dactyloctenium, Agrostis, Alopecurus and -- . .
Apera.
-The active compounds according to the present invention may be used, for example, as selective herbicides in the following cultures:
dicotyledon cultures of the genera Gossypium, Glycine, Beta, Daucus, Phaseolus, Pisum, Solanum, Linum, 3o Ipomoea, Vicia, ~icotiana,' ~ , Arachis, ~as~sica, La'ctuca, Cucu~is and Cucurbita; and monocotyledon cultures of the genera 0ryza, Zea, Triticum, Hordeum, Avena, Se-cale, Sorghum, Panicum, Saccharum,'An'anas,' ~ and Allium.
However, the use of the active compounds according to the invention is in no way restricted to these genera , .
Le A 19 392 ` .

, ' but also embraces other plants, in the same way.
Depending on the concentrations, the compounds can be used for the total combating of weeds, for example on industrial terrain and railway tracks and on paths and squares with or without trees. Equally, the compounds can be employed for combating weeds in perennial cultures, for example afforestations, decorative tree plantings, orchards, vineyards, citrus groves, nut orchards, banana plantations, coffee plantations, tea plantations, rubber plantations, oil palm plantations, cacao plantations, soft fruit plantings and hopfields, and for the selective combating of weeds in annual cultures.
In addition to a powerful herbicidal action, the substances according to the invention also exhibit a very good selective herbicidal activity in various crops. The active compounds according to the invention are thus suitable, for example, for selectively combating weeds in maize, cotton and cereals.
The active compounds can be converted into the cus-tomary formulations, such as solutions, emulsions, suspen-sions, powders, dusting agents, pastes, soluble powders, granules, suspension-emulsion concentrates, natural and synthetic materials impregnated with active compound, and very fine capsules in polymeric substances.
These formulations may be produced in known manner, for example by mixing the active compounds with extenders~
that is to say liquid or solid diluents or carriers, option-ally with the use of surface-active agents,that is to say emulsifying agents and/or dispersing agents and/or foam-forming agents. In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents.
As liquid diluents or carriers, especially sulvents, there are suitable in the main, aromatic hydrocarbons, such as xylene, toluene or alkyl naphthalenes, chlorinated , Le A 19 392 ,:

, ~ ~ 3~Ul~

aromatic or chlorinated aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic or alicyclic hydrocarbons, such as cyclohexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, or strongly polar solvents, such as dimethylformamide and dimethyl-sulphoxide, as well as water.
As solid carriers there may be used ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth, and ground synthetic minerals, such as highly-dispersed silicic acid, alumina and silicates. As solid carriers for granules there may be used 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 shells, maize cobs and tobacco stalks.
As emulsifying and/or foam-forming agents there may be used non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylaryl polyglycol ethers, alkyl sulphonates, alkyl sulphates, aryl sul-phonates as well as albumin hydrolysis products. Dis-persing agents include, for example, lignin sulphite waste liquors and methylcellulose.
Adhesives such as carboxymethylcellulose and natural and synthetic polymers in the form of powders, granules or latices, such as gum arabic, polyvinyl alcohol and polyvinyl acetate, can be used in the formulations.
It is possible to use colorants such as inorganic pigments, for example iron oxide, titanium oxide and Prussian Blue, and organic dyestuffs, such as alizarin "~,' Le A 19 392 , 7~3 , - ~7 -dyestuffs, azo dyestuf~s or metal phthalocyanine dyestuffs, and trace nutrients, such as salts of iron, manganese, boron, copper, cobalt, molybdenum and zinc.
The formulations in general contain from 0.1 to 95 per cent by weight of active compound, preferably from 0.5 to 90 per cent by weight.
The active compounds according to the invention, as such or in the form of thelr formulations, can also be used for combating weeds as mixtures with othcr herbicides, finished formulations or tank mixing being possible. Mix-tures with other active compoundsJ such as fungicides, insecticides, acaricides, nematicides, bird repellants, growth factors 3 plant nutrients and agents which improve soil structure, are also possible.
The active compounds can be used as such, in the form of their formulations or in the use forms prepared therefrom by ~urther dilution, such as ready-to-use solu-tions, suspensions, emulsions~ powders, pastes and granules.
They may be used in the customary manner, for example by watering, spraying, atomising or scattering.
The active compounds according to the invention can be applied either before or after emergence of the plants.
They are preferably applied before emergence of the plants, that is to say by the pre-emergence method. They can also be incorporated into the soil before sowing.
The amount Or active compound used can vary within a substantial range. It depends essentially on the nature of the desired effect. In general~ the amounts used are from 0.1 to lO kg of active compound per hectare, preferably from 0.1 to 5 kg/ha.
The present invention also provides a herbicidal composition containing as active ingredient a compound of the present invention in admixture with a solid diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent.

Le A l9 392 ~3~

The present invention also provides a method of combating weeds which comprises applying to the weeds, or to a habitat thereof, a compound of the present in vention alone or in the form of a composition containing as active ingredient a compound of the present invention in admixture with a diluent or carrier.
The present invention further provides crops protected from damage by weeds by being grown in areas in which immediately prior to and/or during the time of the growing a compound of the present invention was applied alone or in admixture with a diluent or carrier.
It will be seen that the usual methods of providing a harvested crop may be improved by the present invention.
The herbicidal activity of the compounds of this invention is illustrated by the following biotest Examples.
In these Examples, the compounds according to the present invention are each identified by the number (given in brackets) of the corresponding preparative Example, which will be found later in this specification.
The known comparison compound is identified as follows:
C~N
(A)= ~ ~ 0 Cl N C-NH-C2H5 H

.

(4,5 Dichloroimidazole-2-carboxylic acid ethylamide) Pre-emergence test Solvent: 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a suitable preparation of active compound, 1 part by weight of active compound was mixed with the Le A 19 392 : ~ .
Q~

stated amount of solvent) the stated amount of emulsifier was added and the concentrate was diluted with water to the desired concentration.
Seeds of the test plants were sown in normal soil and, after 24 hours, watered with the preparation of the active compound. It was expedient to keep constant the amount of water per unit area. The concentration of the active compound in the preparation was of no importance, only the amount of active compound applied per unit area being decisive. After three weeks, the degree of damage to the plants was determined in % damage in comparison to the development of the untreated control.
The figures denoted:
0% - no action (like untreated control) 100% - total destruction In this test, active compounds (6), (9), (14), (18) and (19) exhibited a better activity than comparison substance (A).
Example B
Post-emergence Test Solvent: 5 parts by weight of acetone Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a suitable preparation of active compound 1 part by weight of active compound was mixed with the stated amount of solvent, the stated amount of emulsifier was added and the concentrate was then diluted with water to the desired concentration.
Test plants which had a height of 5-15 cm were sprayed with the preparation of the active compound in such a way as to apply the amounts of active compound per unit area which were prescribed. The concentration of the spray liquor was so chosen that the amounts of active compound prescribed were applied in 2,000 1 of water/ha. After three weeks, the degree of damage Le A 19 392 3j 3r3 ~ 30 ~
to the plants was rated in % damage in comparison to the development of the untreated control. The figures denoted: -0% - no action (like untreated control) 100% - total destruction.
In this test, compounds (6), (9), (14) and (19) exhibited a better activity than comparison substance (A).
Preparative Examples Example 1 C~NlC2Cl5 (1~ .

(a) 480 g (5 mol) of 2-ethylimidazole were introduced, whilst stirring and cooling, into 2 litres of phosphorus oxychloride, which had been pre-cooled to 5C, and HCl gas was then passed in between 20 and 40C until the exothermic reaction had ended. The mixture was then heated to the reflux temperature (about 107C) and 2,490 g (35 mol) of chlorine gas were then passed in at this temperature in the course of about 5 hours. After distilling off the phos-phorus oxychloride under a water pump vacuum up to a 20 bath temperature of 100C, 1.75 litres of formic acid were gradually stirred into the residue at room temperature.
The colourless, crystalline powder thereby formed was fil-tered off and rinsed first with formic acid and then thoroughly with water. After dryîng, 520 g (30.8% of theory) of 4,5-dichloro-2-pentachloroethyl-imidazole of melting point 232C (long thin needles when crystallised from wash benzine or a little anhydrous acetonitrile) were thus obtained.
IR (KBr): 1540, 1450, 1410, 1358, 1250, 1205, 1040, 780, 30 665 and 555 cm 1.

Le A 19 392 ~31.3S ;7~r3 ~ 31 -(b) 125 g (1.3 mol) of 2-ethylimidazole were introduced, whilst stirring and cooling, into 500 ml of POC13, which had been pre-cooled to about 5C. The mixture was then heated to the reflux temperature (about 107C) and 300 g (4.22 mol) of chlorine were passed in at this temperature in the course of 3 hours. The solvent was stripped off in vacuo and the residue was stirred with 400 ml Or formic acid at about 20C. The crystalline precipitate thereby formed was isolated as under (a) and was likewise 415-dichloro-2-pentachloroethyl-imidazole. Yield: 63 g, corresponding to 38% of theory, relative to the chlorine employed in less than the equivalent amount.
(c) 480 g (6.75 mol) of chlorine were passed into a solution of 96 g (1.0 mol) of 2-ethylimidazole in 400 ml of 1,1,2,2-tetrachloroethane between 110 and 115C in the course of 4.5 hours. The tetrachloroethane was then stripped off under a water pump vacuum up to a bath temperature of 100C. The cooled residue was stirred with 200 ml of pure formic acidg whereupon a colourless powder precipitated, which, after filtering off~ washing with formic acid and drying, gave 103 g (31.6% of theory) of 4,5-dichloro-2-pentachloroethyl-imidazole9 which was identical to the compound obtained under (a). In a repeat batch, the pure compound was also obtained by being sublimed out of the crude product at about 125C/O.Ol mm Hg.
Exam~e 2 Cl__~__ N
~ N ~ C12-CHC12 (2) (a) 34 g (0.25 mol) of sulphuryl chloride were added dropwise to a stirred mixture of 16.1 g (0.1 mol) of 4,5-dichloro-2-ethynyl-imidazole (for the preparation, see Example 13) and 100 ml of chloroform in the course of one Le A 19 392 ' . .

,t~r~

hour, whilst cooling at 15-20C. After subsequently stirring the mixture for two hours, the solid was filtered off and washed with a little chloroform. 4,5-Dichloro-2--(1,1,2,2-tetrachloroethyl)-imidazole of melting point 180C was thus obtained.
IR (K3r): 1547, 1465, 1427, 1360, 1260, 1248, 1208, 1055, 1015, 830, 770, 740, 682, 596 and 555 cm 1 (b) 120 g (1.25 mol) of 2-ethylimidazole were introduced into 500 ml of thionyl chloride, whilst stirring and cooling. The mixture was then heated to the reflux temperature (76C) and 530 g (7.5 mol) of chlorine were passed in at this temperature in the course of 5 hours.
After distilling off the thionyl chloride under a water pump vacuum up to a bath temperature of 100C, the residue was stirred with about 300 ml of formic acid at room temperature. The crystalline powder thereby formed was filtered off, washed with formic acid and dried. 72 g (19% of theory) of 4,5-dichloro-2-(1,1,2,2-tetrachloro-ethyl)-imidazole, which was identical to the compound obtained under (a), were thus obtained.
Example 3 Cl ~ ~
Cl/ N' ~C-CC13 (3) A suspension of 68 g (0.2 mol) of 4,5-dichloro-2-pentachloroethyl-imidazole in 1.2 litres of water was heated to the boil and about 700 ml of water were boiled off in the course of 2 hours. The solid was then fil-tered off and dried. Yield: 46 g (81~ of theory) of 4,5-dichloro-2-trichloroacetyl-imidazole of melting point lg9o~ ~
IR(K~r): 1700, 1525, 1410, 1270, 1200, 1090, 1050, 977, 845, 810, 754, 700, 660, 621, 609 and 527 cm 1.

Le A 19 392 ~xample 4 Cl N C-C~Cl (4) 4,5-Dichloro-2-dichloro-acetyl-imidazole of melting point 150C was obtained from 4,5-dichloro-2-(1,1,2,2-tetrachloroethyl)-imidazole in a manner analogous to that described in Example 3.
IR (KBr): 1692, 1535, 1423, 1412, 1190, 1075, 965, 808, 785, 758 and 608 cm 1.
Example 5 Cl N

Cl , ~ -C~2Cl (5) 4,5-Dichloro-2-chloroacetyl~imidazole of melting point 182C (when recrystallised from a little acetonitrile) was obtained ~rom 4,5-dlchloro-2-(1,1,2,2-tetrachloroethyl)-imidazole (for the preparation, seeExample 21) in a manner analogous to that described in Example 3.
IR(KBr): 1683, 1414, 1329, 1185, 1062, 1045, 945, 781 and 740 cm 1.
Example 6 C ~N ~C-C \ (6) 50 g (0.148 mol) of 4~5-dichloro-2-pentachloroethyl-imidazole were introduced into a solution of 150 g (1 mol) of sodium iodide in 900 ml of acetone at room temperature~
whilst stirring. After further stirring the mixture for Le A 19 392 ~. ' ., , , ' .
' r~

~ 34 ~
one hour, about 500 ml of acetone were stripped off, and 2 litres of ~ater and an amount of 40% strength aqueous NaHS03 solution such that the brown iodine colour disap-peared completely were added to the resi~ue. The solid was then filtered off, washed with water and dried.
Yield: 37 g (93.5% Or theory) of 4,5-dichloro-2-trichloro-vinyl-imidazole of melting point 168C.
IR (KBr): 1590, 1542, 1458, 1405, 1265, 1061, 1042, 965, 958, 869, 770, 700 and 556 cm 1.
Example 7 Cl N

Cl ~N ~ CH2-CC13 (7) 506 g (1.5 mol) of 4,5-dichloro-2-pentachloroethyl-imidazole were introduced into a solution of 285 g (7.5 mol) of sodium boranate in 1.3 litres of water in the course 15 f about 5 hours whilst stirring and cooling at 15-250C.
After subsequently stirring the mixture for three hours, it was acidified to a pH of about 1 with hydrochloric acid, whilst cooling. The precipitate was filtered off and then boiled up with about 4 litres of water, whilst stirring, filtered off at the boiling point and rinsed several times with hot water (removal of boric acid). After drying, 377 g (g3.5% of theory) of 4,5-dichloro-2 (2,2,2-trichloroethyl)-imidazole of melting point 224C (decomposition) were thus obtained.
25 I~ (KBr): 1557, 1425, 1370, 1248, 1222, 1194, 1045, 1035, 1011, 946, 840, 730, 709 and 558 cm 1.
Example 8 Cl FN, CH2-CHC12 (8) Le A 19 392 :, .
, , .
.

3~ -4,5-Dichloro-2-t2,2-dichloroethyl)-imidazole of melting point 143C, (when recrystallised from cyclo-hexane) was isolated from 4,5-dichloro-2-(1,1,2,2-tetra-chloroethyl)-imidazole in a manner analogous to that described in Example 7.
IR (KBr): 1577, 1560, 1435, 1410, 1215, 1038, 1015, 925, 810, 720, 688 and 648 cm 1.
Exam~le 9 Cl CH=CCl 2 ( 9 ) 10 (a) 4,5-Dichloro-2-(2,2,2-trichloroethyl)-imidazole was introduced into excess saturated, aqueous sodium bicarbonate solution and the mixture was heated to the boil, whereupon a clear solution was formed. After cooling the solution, it was acidified with dilute hydrochloric acid and the precipitate which had separated out was filtered ofr, washed with water and dried. 4,5-Dichloro-2-(2,2-dichlorovinyl)-imidazole of melting point 134C was thus obtained. The compound could be sublimed at 110C/0.01 mm Hg.
20 IR (KBr): 1625, 1550, 1465, 1414, 1235, 1035, 920, 835, 675 and 539 cm 1.
(b) A mixture of 67 g (0.25 mol) of 4,5-dichloro-2-(2,2,2-trichloroethyl)-imidazole, 200 ml of dioxan and 28 g (0.277 mol) of triethylamine was stirred under reflux for one hour. After cooling, it was poured into 1 litre of water, the mixture was acidified with hydrochloric acid and the precipitate was filtered off, washed with water and dried. Subsequent sublimation at 110C/0.01 mm Hg gave 47.5 g (82%) of 4,5-dichloro-2-(2,2-dichlorovinyl)-imida-zole, which was identical to the compound obtained under(a)-Le A 19 392 -- , . ~ , ..
- , : ' - : :

.. - ' , s~

Example 10 Cl`~r--N
~ Cl (10) C ~ N C=CH

(a) 5 g of catalyst (5% strength palladium-on-charcoal) were added to a solution of 50 g (0.186 mol) Or 2,4,5-tri-chloro-2-(1,1-dichloroethyl)-2H-imidazole in 450 ml of toluene in a glass autoclave and ~ydrogenation was carried out at about 20C in the course of 5 hours. The reaction mixture was concentrated to dryness on a rotary evaporator in vacuo, the residue was suspended in water and the suspen-sion was neutralised wi~h aqueous sodium bicarbonate solu-tion. The solid was then filtered off, washed with water and dried. Subsequent extraction with hot aceto-nitrile gave, after cooling and, as appropriate, concen-trating the filtered acetonitrile solution, 4J5-dichloro-2-(l-chlorovinyl)-imidazole as co~lpact, colourless crystals of melting point 210C (decomposition). The compound could be sublimed at 100C/0.1 mm Hg.
(b) A mixture of 67 g (0.25 mol) of 2,4,5-trichloro-2-(l,l-dichloroethyl)-2H-imidazole, 28.3 g (0.275 mol) of sodium bromide and 350 ml of acetone was stirred under reflux (58C) for 1 hour. After cooling, it was poured into 2 litres of water and the precipitate was filtered off, washed with water and dried. 41 g (83% of theory) of 4,5-dichloro-2-(1-chlorovinyl)-imidazole, which was identical to the compound obtained under (a), were obtained.
IR (KBr): 1622, 1550, 1477, 1430, 1355, 1265, 1120, 1050, 1009J 883J 795 and 734 cm 1 Example 11 r, ( 11 ) Cl - N C=CH2 H

Le A 19 392 A solution of 806 g (3 mol) of 2,4,5-trichloro-2-(l,l-dichloroethyl)-2H-imidazole (for the preparation, see DE-OS (German Published Specification) 2,550,157) in 1.5 litres of acetone was added dropwise to a stirred mix-ture of 1,600 g (10.6 mol) of sodium iodide in 2 litres of acetone at a maximum temperature of 50C in the course of 2 hours, whilst coolingn The mixture was then introduced into a mixture of 12 litres of water and 1,600 g of 40%
strength aqueous NaHS03 solution and the solid was filtered Off, washed with water and dried. Yield: 770 g (89% of theory) of 4,5-dichloro~-3-(1-iodovinyl)-imidazole.
Decomposition point: about 215C.
Example 12 Cl~ N
~ ~ Cl (12) Cl H

(a) A mixture of 400 g (3.36 mol) of potassium bromide, 135 g (0.5 mol) of 2,4,5-trichloro-2-(1,1-dichloroethyl)-2H-imidazole and 1.5 litres of acetonitrile was stirred under reflux (81C) for 10 hours. After cooling, it was added to 7.5 litres of water and the precipitate was filtered off, washed with water and dried. 121 g (87% of theory) of 4,5-dichloro-2-(1-chloro-2-bromovinyl)-imidazole were obtained. Melting point: 190C (from toluene).
IR (KBr): 1585, 1540, 1465, 1402, 1370, 1260, 1205, 1050, 895, 870, 775, 740, 690, 622 and 540 cm 1.
(b) 3.58 g (0.01 mol) of the compound of the formula Cl~ N

Cl ~ C-c~2Br (22) Br (for the preparation, see Example 22) were boiled in 30 ml of acetonitrile for 5~inutes. After cooling, the mixture Le A 19 392 , -.

- 3~ -was added to 200 ml of water and the precipitate was filtered off, washed with water and dried. 2.60 g (94%
of theory) of 4,5-dichloro-2-(1-chloro-2-bromovinyl)-imidazole, which was identical to the compound obtained

5 under (a), were obtained.
Example 13 Cl ~ N ~ (13) Cl/~`H C'C~

(a) 25 g (0.25 mol) of triethylamine were added to a suspension of 28.9 g (0~1 mol) of 4,5-dichloro-2-(1-iodo-vinyl)-imidazole in 50 ml of dioxan at room temperature, a solution being formed on warming. After subsequently stirring the solution for half an hour, it was poured into 1 litre of water, the mixture was rendered weakly acid with dilute hydrochloric acid and the solid was filtered off, washed with water and dried. Yield: 11.1 g (69% of theory) of 4,5-dichloro-2-ethynylimidazole. Decomposition point: about 185C. The compound could be sublimed at 100C/0.01 mm Hg.
(b) 32.3 g (0.25 mol) of ethyl-diisopropyl-amine ("H~ni~ base") were added to a solution of 28.9 g (0.1 mol) of 4,5-dichloro-2-(1-iodovinyl)-imidazole in 150 ml of dioxan at 20C. After subsequently stirring the mixture for one hour, it was poured into 750 ml of water and rendered weakly acid with dilute hydrochloric acid and the solid was filtered off, washed with water and dried. Yield: 11.7 g of 4,5-dichloro-2-ethynylimidazole. The filtrate was concentrated to about one third în vacuo, after which a further 4.3 g of 4,5-dichloro-2-ethynylimidazole could be isolated. Total yield: 16.0 g (99% of theory).
3 IR (KBr): 3295, 2125, 1563, 1545, 1470, 1390, 1050, 1020, 875, 702,688 and 610 cm 1 Le A 19 392 , , - ~ ~3~7~3 Example 14 ~ . .. _, ~
Cl N
N~ - C-CH (14) o (a) 289 g (1 mol) of 4,5-dichloro-2-(1-iodovinyl)-imidazole were added in portions to a stirred solution, boiling under re~lux, of 136 g (2 mol) of sodium formate in 4 litres of water and the mixture was further heated under reflux until the imidazole dissolved. The small amount of dark oil at the bottom of the reaction flask was then separated off whilst still at the boiling point and the clear aqueous solution was allowed to cool. Light yellow needles one centimetre in length separated out and were filtered off cold, washed with a little cold water and dried. Yield: 125 g (70% of theory) of 2-acetyl-4,5-dichloroimidazole of melting point 162C.
(b) A repeat batch in which the mother liquor of the batch described above was used instead of pure water gave an approximately 80% yield of 2-acetyl-4,5-dichloroimidazole.
(c) When the procedure was analogous to (a), with the -difference that instead of 4,5-dichloro-2-(1-iodovinyl)-imidazole the appropriate molar amount of 4,5-dichloro-2-(l-chlorovinyl)-imidazole was employed, 2-acetyl-4,5-dichloroimidazole was likewise obtained in comparable yields. -IR (KBr): 1666, 1432, 1408, 1212, 1050, 993, 950, 785, 693, 619, 580, 552, 512 and 592 cm 1.
Exam~le 15 C~
~ N (15) C ~ H ~ C~CH3 NOH

~i¢l Le A 19 392 - . . .

4.60 g (0.055 mol) of sodium bicaroonate were added in portions, initially at room temperature, to a mi%ture of 8.95 g (0.05 mol) of 2-acetyl-4,5-dichloroimidazole, 200 ml of water and 6.95 g (0.1 mol) of hydroxylamine hydrochloride and the mixture was then heated to the boil, whereupon a clear solution was formed. The precipitate which ~ystal-lised out on cooling was filtered off, washed with water and dried. Yield: 8.7 g (97% of theory) of the oxime with the above structural formula, of melting point 213 C
(decomposition).
Example 16 Cl\ Cl cl r~ ~ ==N - N = C ~

8.95 g (0.1 mol) of 2-acetyl-4,5-dichloroimidazole were dissolved in a mixture of 20 g of hydrazine hydrate and 200 ml of water and the solution was briefly heated to the boil. After cooling, it was acidified with hydrochloric acid~ whereupon a precipitate separated out. After filtering off, washing with water and drying, the azine with the above structural formula was obtained in virtually quantitative yield. The decomposition point was above Example 17 Cl Cl H C _ N-NH-c-NH2 (17) S

17.9 g (0.1 mol) of 2-acetyl-4,5-dichloroimidazole were dissolved in800 ml of water under the influence of heat and a hot solution of 15 g (0.165 mol) of thiosemicar- -bazide in 200 ml of water was added. After about half a Le A 19 392 3~3~

minute, a colourless precipitate formed, which, after cooling, was filtered off, washed with water and dried.
The thiosemicarbazine with the above structural formula and with a melting point above 290C was thus obtained.
Example 18 C ~N ~ C _ N-NH ~ (18) 17.9 g (0.1 mol) of 2-acetyl-4,5-dichloroimidazole were dissolved in 800 ml of water under the influence of heat, 14 g (0.13 mol) of phenylhydrazine were added and the mix-ture was briefly heated to the boil. After cooling;j thesolid was filtered off, washed with water and dried. The phenylhydrazone with the above structural formula, of melting point 175C, was obtained in virtually quantitative yield.
Example l9 4-Chlorophenylhydrazone with the structural formula Cl ~ ~ C -N-NN ~ Cl (19) was obtained in a manner analogous to that of Example 18.
Melting point: 240C (decomposition).
Example 20 ~ ~ C-CUCl (20) (a) 13.4 g (0.05 mol) of the compound of the formula Le A 19 392 ~ ~3~ 7.~

Cl ~

Cl ~ N ~ ,-CH2Cl (21) Cl (for the preparation, see Example 21) were boiled in 50 ml of acetonitrile for 10 minutes. The precipitate which crystallised out after cooling was filtered off, washed with some cold acetonitrile and dried. It was then stirred with water at about 20C, filtered off, washed with water and dried. 4,5-Dichloro-2-(1,2 dichlorovinyl)-imidazole of melting point 198C (when recrystallised from a little toluene) was thus obtained.
10 IR (KBr): 1591, 1545, 1468, 1407, 1375, 1257, 1055, 916, 694, 632 and 548 cm 1 (b) 26.8 g (0.0772 mol) of the compound of the formula C~
~ I Cl Br C ~ N ~ _ CH (23) Cl Cl (for the preparation see Example 23) were added to a solu- -15 tion of 50 g (0.33 mol) of sodium iodide in 150 ml of acetone and the mixture was then subsequently stirred at room temperature for 2 hours. Thereafter it was poured into about 1.5 litres of water and the free iodine was removed by adding 40% strength aqueous NaHS0~ solution 20 until decoloration took place. 17.1 g (95.5% of theory) of 435-dichloro-2-(1,2-dichlorovinyl)-imidazole, which was identical to the compound obtained under (a), were obtained by subsequent filtration3 washing with water and drying.
(c) A mixture of 6.75 g (0.05 mol) of sulphuryl chloride and 50 ml of chloroform was added dropwise to a solution of 8.05 g (0.05 mol) of the compound of the formula Le A 19 392 , ~ , ` ~ ~ 3 ~ (13) (for the preparation, see Example 13) in 50 ml of chloro-form at 10-15C in the course of one hour. The mixture was then subsequently stirrecl for 2 hours. Thereafter, the chloroform was stirpped off in vacuo and the residue was stirred with about 100 ml of water at 20C, ~iltered off, rinsed with water and dried. The crude product was then sublimed at 100C/0.01 mm Hg ~or the purpose of puri-fication. Colourless crystals of 4,5-dichloro-2-(1,2-dichlorovinyl)-imidazole~ which was identical to the compound obtained under ~a), were obtained.
Example 21 C
l~l Cl -CH2Cl (21) H
15.0 g (0.11 mol) of` sulphuryl chloride in about 40 ml of pure chloroform were added dropwise to a stirred mixture of` 19.75 g (0.1 mol) of 475-dichloro-2-(l-chloro-vinyl)-imidazole and 100 ml of pure chloroform in the course of 2 hours, whilst cooling at about 10C. The mixture was then subsequently stirred at room temperature for about 3 hours. Thereafter, the solid was filtered off, washed with chloroform and dried. 19.5 g (72.5% of theory) of colourless, crystalline 4,5-dichloro-2~ 1,2-trichloro-ethyl)-imidazole of melting point 140C (decomposition) were obtained. Further amounts of the product could be obtained by concentrating the mother liquor.
IR (KBr): 1545J 1465, 1420, 1360, 1254, 1215, 1185, 1075, 1040, 1010, 950, 812, 760, 7353 688 and 590 cm 1 Exam~le 22 C
~ ~ Cl Clf~N C-CH2Br ~r (22) ~, .
Le A 19 392 7~3 - 4~ -18.0 g (0.112 mol) of bromine in 50 ml of pure chloroform were added dropwise to a stirred mixture of 19.75 g (0.1 mol) of 4,5-dichloro-2-(1-chlorovinyl)-imidazole and 100 ml of pure chloroform in the course of one hour, whilst cooling at about 10C. After subsequently stirring the mixture at room temperature for four hours, it was filtered off, washed with chloroform and dried. 32.0 g (89.5% of theory) of crystalline 4,5-dichloro-2-(1-chloro-1,2-dibromoethyl)-imidazole of melting point 160C (decom-position) were obtained.IR (KBr): 1542, 1462, 1417, 13573 1253, 1219, 1168, 1072, 1040, 1004, 918, 795, 760, 6803 647, 618 and 575 cm 1.
Example 23 Cl ~ ~ Cl Br C~ N C -CH (23) ~1 Cl 4,5-Dichloro-2-(1,1,2-trichloro-2-bromoethyl)-imidazole of melting point 180C ~decomposition) (when recrystallised ~ -from toluene) were obtained from 4,5-dichloro-2-(1-chloro-2-bromovinyl)-imidazole in a manner similar to that of Example 21.
IR (KBr): 1545, 1462, 1425, 1357, 1257, 1208, 1170, 1050, 1011, 825, 809, 767, 680 and 655 cm 1 Example 24 Cjl ~ ~ C1 Br Cr~~H C - CH (24) Br sx 4,5-Dichloro-2-(1-chloro-1,2,2-tribromoethyl)-imidazole was obtained from 4,5-dichloro-2-(1-chloro-2-bromovinyl)-imidazole in 91.5% yield in a manner similar to that of Example 22.
IR (KBr)i 1540, 1455, 1415~ 1350, 1253, 1204, 1034 and 1005 cm Le A 19 392 ' . ' ' .

~3 .~ 3 3 .

Example 25 C~
~1¦ Cl Cl Cl ~ H ~ C - CH (25) sr Br 4,5-Dichloro-2-(1,2-dichloro-1,2-dibromoethyl)-imidazole of melting point 150C (decomposition) was obtained from 4,5-dichloro-2-(1,2-dichlorovinyl)-imidazole -in a manner similar to that of Example 22.
IR (KBr): 1540, 1454, 1415, 1350, 1252, 1230, 1203, 1165, 1135, 1043 and 1005 cm 1 Example 26 C ~ C'H-CCl3 (26)

6 g (0.044 mol) of sulphuryl chloride in 30 ml of chloroform were added dropwise to a stirred mixture of 5.9 g (0.0255 mol) of 4,5-dichloro-2-(2,2-dichlorovinyl)-lmidazole and 50 ml of pure chloroform in the course of half an hour, whilst cooling at about 10C. After subsequently stirring the mixture for two hours, the clear solution was concen-trated to dryness on a rotary evaporator in vacuo. The residue was recrystallised from acetonitrile. Colourless crystals of 495-dichloro-2~ 2,2,2-tetrachloroethyl)-imidazole of melting point 230C (decomposition) wereobtained.
IR (KBr): 1540, 1463, 1449~ 1420, 1391, 1305, 1260, 1237, 1037, 782, 759, 699, 684 and 625 cm 1 Example 27 C ~ ~ -CH2-Hr (27) Le A 19 392 , ~.~3~
.

1.79 g (0.005 mol) of 4,5-dichloro-2-(1-chloro-1,2-dlbromoethyl)-imidazole (for the preparation, see Example 22) were stirred in a solution of 3.4 g (0.05 mol) of sodium formate in 50 ml of water at room temperature for 10 minutes.
5 The solid was then filtered off, washed with water and dried. 1.20 g (93% of thery) of 4,5-dichloro-2-~romo-acetylimidazole were thus obtained. After recrystallising from cyclohexane, the compound melted at 177C.
IR (KBr): 1676, 1421, 1408, 1372, 1177, 1063, 1049, 949, 10 767 and 669 cm 1.
The following compounds were prepared according to processes, which are desc:ribed in the preceding Examples:

Le A 19 392 ,, : : ,. . . .
.
' ~

-' .

S70~

Starting Melting point(C) material Preparation Example (recrystallized disclosed according No. Conç~ d _from) in Example to Example 28 C ~ N ~ C-C~rCl (cyclohexane) 25 27 C ~ N ~ CBr2-CHBr (decomposition) 13 22 C ~ ~ -Ch3r2 (cyclohexene) 29 27 5 31 C ~ ~ Br-CHBr (cyclohexane) 29 6 H

C ~ 220 C ~ N ~ r-cBrcl~ (decomposition) 9~ 22 H (CC14) 33 C ~ N ~ -CHCl (tolu~ne) a 9 .,, i Le A 19 392

Claims (44)

Bayer 3842-PFF

WHAT IS CLAIMED IS:

1. 4,5-Dichloroimidazole compound of the formula (I) wherein x1 is hydrogen, chlorine, bromine or iodine;
X2, X3 and X4 independently are hydrogen, chlorine or bromine; and X5 is hydrogen or chlorine; and x1 and X3 together can represent a C-C bond; and x2 and X4 together can represent a C-C bond; or x1 and x2 together can represent oxygen or the grouping =N - Y, in which Y is hydroxyl or a radical , NH-R1 or wherein R is hydrogen or alkyl with up to 4 carbon atoms;
R1 is aryl or substituted aryl, the substituents being selected from halogen, alkyl, alkoxy, halo-alkyl and nitro;
Z is oxygen or sulfur; and R 2 , R3 and R4 independently are hydrogen or chlorine provided that X1, X2, X3, X4 and X5 do not simultaneously represent hydrogen.

2. A compound as claimed in claim 1 wherein X1 is hydrogen.

3. A compound as claimed in claim 1 wherein X1 is chlorine, bromine or iodine.

4. A compound as claimed in claim 1, 2 or 3 wherein X2, X3, X4 and X5 are hydrogen.

5. A compound as claimed in claim 1 wherein X2 is hydrogen.

6. A compound as claimed in claim 1 wherein X3 is hydrogen.

7. A compound as claimed in claim 1 wherein X4 is hydrogen.

8. A compound as claimed in claim 1 wherein X2 is chlorine or bromine.

9. A compound as claimed in claim 1 wherein X3 is chlorine or bromine.

10. A compound as claimed in claim 1 wherein X4 is chlorine or bromine.

11. A compound as claimed in claim 1 wherein X5 is hydrogen.

12. A compound as claimed in claim 1 wherein X5 is chlorine.

13. A compound as claimed in claim 1 wherein X1 and X3 represent a C-C
bond.

14. A compound as claimed in claim 1 wherein X2 and X4 together repre-sent a C-C bond.

15. A compound as claimed in claim 1 wherein X1 and X2 together re-present oxygen.

16. A compound as claimed in claim 1 wherein X1 and X2 together re-present the grouping =N - Y in which Y is hydroxyl.

17. A compound as claimed in claim 1 wherein X1 and x2 together represent the grouping =N - Y wherein Y is a radical .

18. A compound as claimed in claim 1 wherein X1 and x2 together repre-sent the grouping =N - Y wherein Y is NHR1.

19. A compound as claimed in claim 1 wherein X1 and x2 together repre-sent the grouping =N - Y wherein Y is

20. A compound as claimed in claim 17 wherein R is hydrogen.

21. A compound as claimed in claim 17 wherein R is alkyl of up to 4 car-bon atoms.

22. A compound as claimed in claim 17, 20 or 21 wherein Z is oxygen.

23. A compound as claimed in claim 17, 20 or 21 wherein Z is sulfur.

24. A compound as claimed in claim 18 wherein R1 is phenyl.

25. A compound as claimed in claim 18 wherein R1 is phenyl substituted by halogen, alkyl, alkoxy, haloalkyl or nitro.

26. A compound as claimed in claim 19 wherein R2, R3 and R4 are hydrogen.

27. A compound as claimed in claim 19 wherein R2 is chlorine.

28. A compound as claimed in claim 19 or 27 wherein R3 is chlorine.

29. A compound as claimed in claim 19 or 27 wherein R4 is chlorine.

30. A compound as claimed in claim 1 wherein X1 is hydrogen, chlorine or bromine;
x2 is hydrogen, chlorine or bromine;
X3 is hydrogen, chlorine or bromine;
X4 is hydrogen, chlorine or bromine; and X5 is hydrogen or chlorine, provided that X1, X2, X3, X4 and X5 do not simultaneously represent hydrogen;
X1 and X3 together may alternatively represent a C-C bond, X2 and X4 together may represent oxygen, or the grouping =N - Y
wherein Y is hydroxyl or the radical - , -NHR1, or wherein R is hydrogen or alkyl with up to 2 carbon atoms;
Z is sulfur;
R1 is phenyl, substituted phenyl, naphthyl, substituted naphthyl, the substituents being selected from the group consisting of fluorine, chlorine, bromine, alkyl with up to 2 carbon atoms alkoxy with up to 2 carbon atoms, trichloromethyl, trifluoromethyl and nitro; and R2, R3 and R4 each represent hydrogen.

31. 4,5-Dichloro-2-trichloro-vinyl-imidazole.

32. 4,5-Dichloro-2-(2,2-dichlorovinyl)-imidazole.

33. 4,5-Dichloro-2-(1-chlorovinyl)-imidazole.

34. 4,5-Dichloro-2-(1-chloro-2-bromovinyl)-imidazole.

35. 4,5-Dichloro-2-(1,2-dichlorovinyl)-imidazole.

36. A method of combating weeds which method comprises applying to the weeds, or to their habitat, a herbicidally effective amount of a 4,5-dichloro-imidazole compound as claimed in claim 1.

37. A method as claimed in claim 36 wherein said 4,5-dichloroimidazole com-pound is 4,5-dichloro-2-trichloro-vinyl imidazole.

38. A method as claimed in claim 36 wherein said 4,5-dichloroimidazole com-pound is 4,5-dichloro-2-(2,2-dichlorovinyl) imidazole.

39. A method as claimed in claim 36 wherein said 4,5-dichloroimidazole com-pound is 4,5-dichloro-2-(1-chlorovinyl)-imidazole.

40. A method as claimed in claim 36 wherein said 4,5-dichloroimidazole com-pound is 4,5-dichloro-2-(1-chloro-2-bromovinyl)-imidazole.

41. A method as claimed in claim 36 wherein said 4,5-dichloroimidazole cam-pound is 4,5-dichloro-2-(1,2-dichlorovinyl)-imidazole.

42. Method as claimed in claim 36 wherein said compound is applied at a dosage of 0.1 to 10 kg per hectare.

43. Method as claimed in claim 37, 38 or 39 wherein said compound is app-lied at a dosage of 0.1 to 5 kg per hectare.

44. Method as claimed in claim 40 or 41 wherein said compound is applied at a dosage of 0.1 to 5 kg per hectare.