IE910200A1 - Triazolopyridines herbicides - Google Patents

Abstract

Compounds usable as herbicides and having the formula (I) in which: * X, Y and Z represent a hydrogen atom or a halogen atom or an alkyl or haloalkyl or alkoxy group, one at least of the radicals X, Y or Z having a meaning other than the hydrogen atom, * Ar represents a phenyl group, optionally mono- or polysubstituted by a lower alkyl or lower alkoxy or lower alkylthio or phenyl or phenoxy group or a halogen atom, or a heterocycle Het, * Het represents a 5- or 6-membered heterocyclic ring containing one or more heteroatom(s) such as sulphur, nitrogen or oxygen, this heterocyclic ring being optionally mono- or polysubstituted by a lower alkyl or lower alkoxy or lower alkylthio group or a halogen atom. The herbicide compositions containing the products of formula (I) and the weeding processes using the compounds of formula (I) or the compositions containing them.

Description

The present invention thus concerns novel herbicidal compounds from the family of the 1,2,4triazolo[4,3-a]pyridines, as well as processes for their preparation, the compositions which contain them, and their use for combating weeds.

It is therefore an object of the present invention to propose compounds which can be used as herbicides both before emergence (in pre-emergence) and after emergence (in post-emergence).

It is another object of the present invention to propose compounds which can be used both against weeds of the monocotyledon type and those of the dicotyledon type.

It is another object of the present invention to propose compounds which can be used before and/or after emergence as selective herbicides in monocotyledon crops (in particular wheat, maize and rice) and dicotyledon crops (in particular soya, cotton or sunflower).

It has now been found that all, or some, of these aims can be achieved by means of the novel compounds according to the invention.

In the present exposition, the expression lower, qualifying a radical, is understood as meaning that this radical can have not more than 4 carbon atoms.

The compounds according to the invention are IE 91200 characterised by the fact that they have, as their formula, the formula (I) which is given at the end of the description, in which» * X, Y and 2 represent a hydrogen atom or a 5 halogen atom or an alkyl or haloalkyl or alkoxy group, at least one of the radicals X, Y or Z having a meaning other than the hydrogen atom, * Ar represents a phenyl group which is optionally mono- or polysubstituted (preferably monosubstituted) by a lower alkyl group or lower alkoxy group or lower alkylthio group or phenyl group or phenoxy group or a halogen atom, preferably chlorine or fluorine; or a heterocycle Het, * Het represents a heterocycle having 5 or 6 ring members and containing one or more hetero atom(s) such as sulphur, nitrogen or oxygen, this heterocycle being optionally mono- or polysubstituted (preferably monosubstituted) by a lower alkyl group or lower alkoxy group or lower alkylthio group or a halogen atom, preferably chlorine or fluorine with the exclusion of compounds wherein, ·· simultaneously Y represents a methyl group. X and Z represent a hydrogen atom, Ar represents a 3chloro phenyl or 4-chlorophenyl or 3-pyrJdyl or 3.4,5trimethoxy phenyl group; or ♦· simultaneously X represents a chlorine atom, Y and Z represent a hydrogen atom, Ar represents a 2pyrldyl or 4-pyridyl group.

* Preferred compounds amongst the compounds according to the invention are those having one or the other of the following characteristicst Only one or two of the three radicals X, Y or 25 S represent a radical other than the hydrogen atom, when X, Y or S are a halogen atom, the atom in question is chlorine or bromine, when X, Y or Z are a radical which is at IE 91200 least partially hydrocarbon in nature, this radical has preferably 1 to 4 carbon atoms, 1 carbon atom being even more preferred.

X is other than a chlorine atom, when Ar represents a substituted phenyl group, the substituent(s) is(are) in ortho or para position.

The following Het groups can be mcntlonned as especially useful in the invention: thienyl (preferably 2· or 3· thienyl), thiazolyl (preferably 2· or 4- thiazolyl), pyridyl (preferably 2-pyridyl). pyrrolyl (preferably 2-pyrrolyl), thiadiazolyl (preferably 5-thiadiazolyl).

The following compounds can be mentioned as 5 particular compounds which can be produced according to the invention (for the numbering of the atoms, see note at the end of the description): 8-chloro-3-(3'-methylthien-2'-yl)-s-triazolo[4,3-a]pyridine, 8-chloro-3-phenyl-s-triazolo[4,3-a]pyridine, 8-methyl-3-(3'-methylthien-2 *-yl)-s-triazolo[4,3-a]pyridine, 8-methyl-3-(thien-3'-yl)-s-triazolo[4,3-a]pyridine, 8-methyl-3-(pyrid-2'-yl)-s-triazolo(4,3-a]pyridine, 8-methyl-3- (4 · -methylphenyl) -β-triazolo [ 4,3-a Jpyridine, 8-methyl-3- (4 * -fluorophenyl) -s-triazolo (4,3-a] pyridine, 8-methyl-3-(2·-chlorophenyl)-s-triazolo[4,3-a]pyridine, 6- methyl-3-phenyl-s-triazolo[4,3-a]pyridine, 8-trifluoromethyl-3-phenyl-s-triazolo(4,3-a]pyridine, 6-chloro-3-phenyl-s-triazolo[4,3-a jpyridine, 8-methyl-3-(pyrid-3’-yl)-s-triazolo[4,3-a Jpyridine, 8-methyl-3-(pyrid-4'-yl)-s-triazolo(4,3-a Jpyridine, 8-methyl-3-(furan-2'-yl)-s-triazolo[4,3-aJpyridine, 8-methyl-3-(4·-methoxyphenyl)-s-triazolo[4,3-a]25 pyridine, 7- methyl-3-phenyl-s-triazolo[ 4,3-a Jpyridine, 8- methyl-3 - (3· -methylphenyl) -s-triazolo (4,3-a Jpyridine, 8-methyl-3-(2',4'-dichlorophenyl)-s-triazolo[4,3-a ] IE 91200 pyridine 8-methyl-3-(4'-chlorophenyl)-s-triazolo[4,3-a]pyridine, 8-methyl-3-(4'-phenylphenyl)-s-triazolo[4,3-a]pyridine, 8-methoxy-3-phenyl-s-triazolo[4,3-a]pyridine, 8-methyl-3-(thien-2'-yl)-s-triazolo[4,3-a]pyridine, 8-methyl-3-(4'-thiomethylphenyl)-s-triazolo[4,3-a]pyridine, 8-methyl-3-(2'-fluorophenyl)-s-triazolo[4,3-a]pyridine, 8-methyl-3- (2 ' -methylphenyl) -s-triazolo [ 4,3-a] pyridine, 8-methyl-3-(2', 4 '-dimethylphenyl)-s-triazolo[4,3-a]pyridine, 8-methyl-3-phenyl-s-triazolo[4,3-a]pyridine, 8-bromo-3-[3'-methylthien-2'-yl]-s-triazolo[4,3-a]pyridine, 8-trifluoromethyl-3-[3'-methylthien-2'-yl]-s-triazolo[4,3-a]pyridine, 8-methyl-3-[2' -methylthien-3·-yl]-s-triazolo[4,3-a]pyridine, 8-bromo-3-phenyl-s-triazolo[4,3-a]pyridine, 8-chloro-3-[2'-methylthien-3'-yl]-s-triazolo[4,3-a]pyridine, 8-chloro-3-[thien-3’-yl]-s-triazolo[4,3-a Jpyridine, 8-methyl-3-[1'-methylpyrrol-2'-yl]-s-triazolo[4,3-a]pyridine, 8-chloro-3-[3',5'-dimethylthien-2’-yl]-s-triazolo[4,3aJpyridine, 7,8-dimethyl-3-phenyl-s-triazolo[4,3-a]pyridine, 8-methyl-3-[3',5·-dimethylthien-2'-yl]-s-triazolo- I IE 91200 [4,3-a]pyridine, 8-ethyl-3-[3*-methylthien-2'-yl]-s-triazolo[4,3-a] pyridine, 8-ethyl-3-phenyl-s-triazolo[4,3-a]pyridine, 8-ethyl-3-[1'-methylpyrrol-2'-yl]-s-triazolo[4,3-a]pyridine, 8-ethyl-3-[thien-3'-yl]-s-triazolo[4,3-a]pyridine, 8-trifluoromethyl-3-[1'-methylpyrrol-2'-yl]-s-triazolo[4,3-a]pyridine, 8-trifluoromethyl-3-(pyrid-2'-yl]-s-triazolo[4,3-a ] pyridine, 8-chloro-3-[4·-methylthien-2'-yl]-s-triazolo[4,3-a]pyridine, 7,8-dimethyl-3-[3'-methylthien-2'-yl]-s-triazolo15 [4,3-a]pyridine, 8-methyl-3-[4'-methylthien-2·-yl]-s-triazolo[4,3-a ] pyridine, 8-trifluoromethyl-3-[thien-3'-yl]-s-triazolo[4,3-a ] pyridine, 8-methyl-3-[4'-isopropylphenyl]-s-triazolo[4,3-a]pyridine, 8-methyl-3-[4'-bromothien-2· -yl]-s-triazolo[4,3-a]pyridine, 8-chloro-3-[4'-bromothien-2'-yl]-s-triazolo[4,3-a]25 pyridine.

The compounds according to the invention can be prepared by means of various processes.

According to a first process for the IE 91200 e preparation of compounds of the formula (I), a compound of the arylidene-2-(pyrid-2'-yl) hydrazine type which has as its formula the formula (II), in which the various substituents have the meanings given above, is reacted with an oxidant according to a cyclising oxidation reaction. Substances which may be mentioned as oxidants are metal cations derived from metals which have various degrees of oxidation and which are in the state of a higher degree of oxidation, such as, for example, lead tetraacetate or ferric chloride; atmospheric oxygen can also be used as an oxidant. The reaction is advantageously carried out in a liguid organic solvent medium, the solvent preferably being selected in such a way as to dissolve the reactants and the final products as much as possible. Suitable solvents are hydrocarbons, halogenated hydrocarbons, acids and alcohols; solvents of the nitrated aromatic hydrocarbon type can also be used, specifically in those cases where the oxidant is atmospheric oxygen.

The molar ratio of the amount of oxidant used in relation to the compound of the formula (II) is generally between 1 and 5.

According to a first variant, the oxidation reaction for the compound of the formula (II) can also be effected by adding a halogen (preferably in approximately stoichiometric amount), such as bromine, followed by a dehalogenation reaction. These oxidation reactions (according to the general method or according IE 91200 to the variant) are generally effected between 10 and 210’C (preferably between 10 and 50’C in the case of the variant).

CycUsing oxidation is achieved by following 5 this oxidation by means of halogenation by a dehalogenation reaction which is generally effected in the presence of an alkaline agent, for example in the presence of an alkali metal salt of a carboxylic acid such as sodium acetate, in an acetic acid medium. The molar ratio of the amount of alkaline agent used in relation to the halogenated compound of the formula (II) is generally between 1 and 5.

According to a second variant, the oxidation reaction for the compound of the formula (II) can also be effected by adding an N-halo-N-metallosulphonamidate of the formula (IV): + RSO2NX M where R represents an alkyl group, or preferably phenyl which is optionally monosubstituted in the para position by an alkyl group (for example a p-tolyl group), X represents a halogen atom (preferably chlorine or bromine) and M a alkali metal atom (preferably sodium). A preferred example of an N-haloN-metallosulphonamidate is chloramine T, of the formula (IVa): CHj SOs NCI Na· IE 91200 —κ 8 The use of an N-halo-N-metallosulphonamidate of the preceding formula as an oxidant which cyclises arylidene-2-(pyrid-2'-yl) hydrazines, which have as their formula the general formula (II), is original and thus constitutes a novel preparation process for compounds of the formula (I).

This cyclising oxidation reaction is generally effected between 10 and 150*C (preferably between 20 and 50°C) and is advantageously effected in a liguid organic solvent medium, preferably alcohol.

The molar ratio of the amount of oxidant used in relation to the compound of the formula (II) is preferably approximately stoichiometric.

According to a second preparation method for 15 compounds of the formula (I), a compound of the 2-(aroylhydrazine) pyridine type, which has, as its formula, the formula (III) in which the various substituents have the same meaning as in formula (I), is dehydrated (cyclising dehydration).

The cyclising dehydration reaction of the compound of the formula (III) is usually carried out by heating at between 100 and 250*C, with elimination of the water formed as the reaction proceeds. The water formed can be eliminated by simple distillation or, alternatively, by azeotropic distillation, if the heating is effected in the presence of an aromatic solvent which is capable of dissolving the compound of the formula (III) and forming an azeotrope with water.

IE 91200 Azeotropic solvents which are suitable for this dehydration method and which may be mentioned are the halogenated or unhalogenated aromatic hydrocarbons, as well as the phenols, for example xylene, phenol and 1,2,4-trichlorobenzene.

According to a first variant of the cyclising dehydration of the compound of the formula (III), the process is carried out in the presence of a dehydrating agent, preferably in the presence of an inert solvent, for example an aromatic hydrocarbon such as benzene, toluene and xylene. The dehydrating agent is advantageously a water scavenger known per se, such as POC13 or concentrated acetic acid or polyphosphoric acid, the amount of dehydrating agent used being advantageously between 1 and 50 times the molar amount of the compound of the formula (III).

According to a second variant, the dehydrating cyclisation of the compounds of the formula (III) is effected via a transitory passage through an intermediate of the formula (XI) or (XII), in which the substituents have the same meanings as in formula (I).

The intermediates of the formula (XI) are formed by reaction of SOC12 with a compound of the formula (III) [in an amount of, for example, between 1 and 3 moles per mole of compound of the formula (III)], at a temperature between -5°C and 50°C, preferably at ambient temperature; the reaction is advantageously effected in the presence of a solvent and/or an acid IE 91200 scavenger, in particular pyridine or dimethylformamide (DMF) in the presence of triethylamine.

Thermolysis of the compounds of the formula (XI) to give compounds of the formula (I) is accompanied by a liberation of S02. It is preferred for this thermolysis to be carried out in the presence of a solvent such as nitriles or aromatic hydrocarbons, in particular acetonitrile, toluene, xylenes or naphthalenes, which are optionally alkylated 10 (preferably methylated).

The cyclising dehydration of compounds of the formula (III) to give compounds of the formula (I), via intermediates of the formula (XII), is advantageously effected by reacting compounds of the dichlorotriarylphosphorane type with a compound of the formula (III), in the presence of a tertiary base such as triethylamine, and of a solvent of the nitrile type.

According to a third preparation method for compounds of the formula (I), a cyclising deamination is carried out by heating a compound of the amidrazone type, which has, as its formula, (IV) in which the various substituents have the same meaning as in formula (I).

The reaction is advantageously effected In the presence of agents (liquids) which scavenge ammonia molecules, for example in the presence of acids, anhydrides or halides of acids, these acids preferably being carboxylic acids. The temperature is generally IE 91200 between 25 and 220’C, preferably between 50 and 180’C. The amount of agent which scavenges ammonia molecules is generally between 1 and 30 times the amount (in moles) of the product of the formula (IV).

The deamination can also be carried out by simple heating in a liguid medium (thermal deamination), preferably in an inert organic solvent medium, for example a halogenated or unhalogenated aromatic hydrocarbon.

According to a fourth preparation process for products of the formula (I), a compound of the hydrazine type of the formula (V) is reacted with a compound of the formula (VI): U1-C(=W1)-Ar according to the reaction: (V) + (VI) -> (I) + UiH + the various radicals of these formulae (V) and (VI) having the same meanings as in the formula (I) and, In addition: Wx represents an oxygen atom or an NH group, when Wx represents the oxygen atom, then υχ represents a hydroxyl group [(VI) is thus an acid] or alkoxy group [(VT) is thus an ester] or aroyloxy group [(VI) is thus an acid anhydride], or a halogen atom [(VI) is thus an acid halide], preferably chlorine, when represents an NH group, then Ux represents an alkoxy group or alkylthio group or IE 91200 arylalkylthio group.

The preceding reaction is effected at a temperature of generally between 20 and 200°C, preferably between 50 and 180’C, over a period of 1 to 24 hours. The reactants (V) and (VI) are used in respective molar proportions between 0.8 and 1.2, preferably equal to, or near, 1. The reaction can be effected in the presence or absence of a solvent. Solvents which can be used, as shown hereinafter in certain cases, are solvents which lead to the formation of azeotropic mixtures. Solvents of the alcohol type can also be used when the compound of the formula (VI) is an imidate, or an aromatic solvent such as a halogenated or unhalogenated hydrocarbon, or pyridine, when the compound of the formula (VI) is a thio imidate or an acid halide.

The light reaction products (UXH and ΝχΗ2) are advantageously eliminated as the reaction proceeds, generally by distillation when the product in question is water or alcohols (Ux thus represents a hydroxyl or alkoxy group), and also by scavenging with the aid of a tertiary base such as triethylamine, when Ux is a halogen atom, and also by scavenging of the ammonia molecule, when Wx is NH and Ut is alkoxy (the product of the formula (VI) is thus an imidate).

The abovementioned distillation of the light products can be an azeotropic distillation in the presence of aromatic halogenated or unhalogenated IE 91200 solvents such as pyridine, or the chlorobenzenes, in particular 1,2,4-trichlorobenzene.

The abovementioned scavenging of ammonia is advantageously effected in the presence of acids (preferably carboxylic acids) or of their derivatives such as acid anhydrides or acid halides. These acids or their derivatives are used in a molar amount of generally between 1 and 30 times the amount of product of the formula (VI) used. These propositions are in the same order of magnitude (mutatis mutandis) when a base is used when Ux is a halogen atom.

According to a fifth preparation process for compounds of the formula (I), a pyridine derivative of the formula (VIII) is reacted with a tetrazoie compound of the formula (IX), in which formulae X, Y, Z and Ar have the same meaning as in formula (I) and T represents a halogen atom, preferably chlorine. The reaction is advantageously effected between 20 and 150*C, preferably in an organic solvent, for example a halogenated or unhalogenated aromatic hydrocarbon such as xylenes, chlorobenzenes or tetralin, or a solvent of the heterocyclic type such as pyridine.

The invention also relates to novel products which can optionally be used as intermediates in the processes according to the invention, characterised in that they have, as their formula, one of the formulae (II), (IV), (VIII), (XI), or (XII) in which the symbols X, Y, Z and Ar have the meanings IE 91200 given in the case of the formula (I).

Another object of the invention is the use of the compounds of the formula (II) as herbicides. In what follows, but also in the preceding text, the reactions which are effected under hot conditions in a solvent, unless specifically indicated to the contrary, are advantageously carried out at the boiling point of the solvent in question.

The preparation of the tetrazoles of the 10 formula (IX) is conveniently effected by reacting an aromatic nitrile of the formula Ar-CN with an alkali metal azide, for example sodium azide or ammonium azide, at temperatures between 80 and 130°C. The molar amount of azide is advantageously between 1 and 3 times (preferably 1.5 and 2 times) the amount of nitrile.

This reaction is generally effected in a polar solvent such as DMF or acetic acid or the alcohols or their mixtures. Such a reaction is described in Advances in Heterocyclic Chemistry, vol. 21, pages 323-435, published in 1977 by Academic Press in an article by R.N. Butler with the title: Recent advances in tetrazole chemistry.

The preparation of the arylidene-2-(pyrid-2'yl)hydrazines of the formula (II) is conveniently effected by reacting 2-hydrazinopyridines of the formula (V) with aldehydes of the formula Ar-CHO in which the symbols X, Y, Z and Ar have the meanings given in the case of the formula (I). The reaction is IE 91200 generally effected at a temperature between 50 and 150°C, preferably in a solvent. A lower alcohol such as methanol or ethanol is advantageously used as the solvent. The reaction is promoted by the presence of catalytic amounts of a mineral inorganic or organic acid, for example hydrochloric acid, sulphuric acid, acetic acid, trichloroacetic acid or perchloric acid. Such a reaction is described in Quarterly review, Chemical Society, vol. 23, pages 37-56, 1969, in an article by J. Buckingham as well as in Houben-Weyl, Methoden der organischen Chemie, 4th edition, 1967, vol. X-2, pages 410-487.

The preparation of the 2-(aroylhydrazino)pyridines of the formula (III) is conveniently effected by reacting 2-hydrazinopyridines of the formula (V) with compounds of the formula Ar-C0-U2 in which the symbols X, Y, Z and Ar have the meanings given in the case of the formula (I), and U2 has one of the meanings given above in the case of Ux. The reaction proceeds in accordance with the equation: (V) + Ar-C0-U2 -> (III) + UjH The reaction is generally effected by mixing reactants at a temperature between 0 and 180*C, in the presence or absence of a solvent. A polar solvent is advantageously used as solvent.

The following can therefore be cited as IE 91200 solvents which can more particularly be used: alcohols when Ar-CO-U2 is not an acid halide; ethers or aliphatic chlorinated or unchlorinated hydrocarbons such as methylene chloride, chloroform; solvents which have acid-scavenging properties, such as pyridine, can likewise be used when Ar-C0-U2 represents an acid halide.

The proportion of the two reactants [that of the formula (V) and that of the formula Ar-C0-U2] can be varied within wide limits around stoichiometric. When Ar-C0-U2 is an acid (U2 is OH), an excess of the latter derivative is used in relation to the compound of the formula (V), for example from 2 to 8 moles per mole of (V). When Ar-CO-O2 is an ester (U2 is alkoxy), an approximately stoichiometric amount of the latter derivative Is used in relation to the compound of the formula (V), for example from 0.8 to 1.1 moles per mole of (V). When Ar-C0-U2 is an acid halide (U2 is a halogen atom), an excess of the compound of the formula (V) is used in relation to the compound of the formula Ar-C0-U2, for example from 1 to 5 moles per mole of Ar-C0-U2.

Processes which allow the compounds of the formula (III) to be obtained in accordance with what has just been described are described in the work by Patal, The chemistry of carboxylic acids and esters, vol. 5, chapter 9, pages 425-428, published in 1969 by Interscience/Wiley in an article by Satchell, and also IE 91200 in Houben-Weyl, Methoden der organischen Chemie, 1952, Vol. VIII, chapter 5, pages 676-680.

The 2-(aroylhydrazino)pyridines of the formula (III) can also be prepared conveniently by reacting a pyridine derivative of the formula (VIII) with an aryl hydrazide of the formula Ar-CO-NH-NH2 in which the symbols Τ, X, Y, Z and Ar have the meanings already given in the case of the formulae (I) and (VIII). The reaction proceeds in accordance with the equation: (VIII) + Ar-C0-NH-NH2 -> (III) This reaction is advantageously carried out at a temperature between 50 and 150°C, in solvents such as alcohols or aromatic solvents, for example pyridine or hydrocarbons such as toluene. The reactants are advantageously in an approximately stoichiometric proportion, for example in a molar ratio ranging from 0.8 to 1.2. The reaction can be promoted by the presence of a likewise approximately stoichiometric amount of a basic agent such as an alcoholate or an alkali metal bicarbonate.

The aryl hydrazides of the formula Ar—CO-NH-NH2 can be obtained by reacting hydrazine hydrate with an acid or one of its derivatives such as the esters, halides or anhydrides. The reaction is advantageously effected at a temperature between 0 and IE 91200 150’C, preferably in the presence of a solvent such as a lower alcohol, the molar proportion of hydrazine hydrate in relation to the other reactant generally being between 1.01 and 1.5.

Processes which allow the aryl hydrazides to be obtained in accordance with what has just been described are described in the work by Patal, The chemistry of amides, vol. 11, chapter 10, pages 515600, published in 1970 by Interscience/Wiley, in an article by Paulsen and Stoye, and also in Organic Reactions, the Curtius reaction, 1962, Vol. Ill, chapter 9, pages 366-369 published by Wiley.

The amidrazones of the formula (IV) can be prepared using 2-hydrazinopyridines of the formula (V) according to the following reaction equation: (V) + Ar-C(=NH)-U3 -> (IV) + U3H, the various radicals of these reactants and reaction products having the same meaning as in the preceding formulae, and U3 represents a preferably lower alkoxy or alkylthio radical.

The reaction is advantageously effected at a temperature between 0 and 30”C, preferably in an alcohol-type solvent.

Processes which allow the amidrazones of the formula (IV) to be obtained in accordance with what has just been described are described in the work by Patal, IE 91200 The chemistry of amidines and imidates, vol. 20, chapter 10, pages 491-545, published in 1975 by Interscience/Wiley in an article by Watson, as well as in an article by Neilson et al., Chemical Review, 1970, Vol. 70, pages 151-170.

The iminoethers of the formula Ar-C(=NH)-U3 in which U3 represents an alkoxy group can be prepared by reacting an aromatic nitrile Ar-CN with a lower alcohol, preferably an alkanol, between -20 and +30 °C, advantageously in an ether-type solvent, for example ethyl ether or 1,2-dimethoxyethane or dioxane, or a halogenated, preferably aliphatic, hydrocarbon such as chloroform. More precisely, the reaction is effected in an anhydrous medium in the presence of (gaseous) HCl.

Processes which allow these Iminoethers of the formula Ar-C(=NH)-U3 to be obtained are described in the work by Patai, The chemistry of amidines and imidates, vol. 20, chapter 9, pages 385-489, published in 1975 by Interscience/Wiley in an article by Neilson, as well as in an article by Roger and Neilson, Chemical Review, 1961, vol. 61, pages 179-211.

The thioimidates of the formula Ar-C(=NH)-U3 in which U3 represents an alkylthio group can be prepared by alkylation of arylthiobenzamidee by a process such as described by Doyle et al. in Synthesis, 583 (1974). These arylthiobenzamides themselves can be obtained for example as described In the work by Patax, The chemistry of amides, vol. 11, chapter 8, pages IE 91200 383-475, published in 1970 by Interscience/Wiley, in an article by Walta and Vos.

The 2-hydrazinopyridines of the formula (V) can be obtained by reacting hydrazine hydrate with a 25 halopyridine of the formula (VIII) at a temperature between 0 and 120°C, in the presence or absence of a solvent. Solvents which may be cited are, in particular, polar solvents such as alcohols, pyridine, or dimethyl sulphoxide. The molar amount of hydrazine hydrate is generally between 3 and 15 times the amount of product of the formula (VIII) used. Processes which allow the compounds of the formula (V) to be obtained in accordance with what has just been described are described by Enders in Houben-Weyl, Methoden der organischen Chemie, 4th edition, 1967, vol. X-2, chapter 5, pages 252-287.

In particular, the 2-halopyridines of the formula (VIII) can be prepared by a process similar to those described by Klinsberg in The Chemistry of Heterocyclic Compounds, Pyridine and its derivatives, parts I - IV, published in 1974-1975 by Interscience/Wiley, and by Abramovitch, in The chemistry of Heterocyclic compounds, Pyridine and its derivatives, supplements 1-5, published in 1960-1964 by Interscience/Wiley.

The following examples, which are given without implied limitation, illustrate the invention and show how it can be implemented. In these examples, IE 91200 the symbol Ac designates the radical CH3-CO-, the symbol DMF designates dimethylformamide. The word amidrazone designates compounds which have a group / -NH-N= C \ NHz Examples 1 to 14 illustrate the preparation 5 of herbicidal compounds according to the invention.

Examples I-l to 1-10 illustrate the preparation of intermediates of the preceding products.

♦Example 1: Lead tetraacetate (6.7 g; 0.015 mol) are 10 added to phenyl(3'-chloropyrid-2'-yl)hydrazone (3.5 g; 0.015 mol), prepared as in Example I-l, in glacial acetic acid (300 ml) at ambient temperature and with stirring. Stirring is continued for one hour at 60*C. The medium is concentrated to dryness under reduced pressure. The residue is triturated with water (100 ml), and the mixture is filtered, washed with water and dried. 8-Chloro-3-phenyl-s-triazolo[4,3alpyridine (3.1 g; 0.0135 mol), which melts at 153°C, is obtained (yield 90%).

*Example 2: A mixture of 3-formylthiophene (2.8 g; 0.025 mol) and 2-hydrazino-3-methylpyridine (3.1 g; 0.025 mol), prepared as in Example 1-8, in ethanol IE 91200 (30 ml) containing a few drops of concentrated HCl, is kept at boiling point for two hours. An ethanolic solution of FeCl3 · 6H2O (70 ml; 0.125 mol) is added gradually, and heating at boiling point is continued for two hours. The reaction medium is concentrated to dryness under reduced pressure, the residue is taken up in water (100 ml), the mixture is rendered neutral with the aid of gaseous NH3 (pH between 8 and 9), and extracted with CH2C12. After the organic phases have been concentrated and the residue has been dried and recrystallised using aqueous ethanol, 8-methyl-3(thien-3'-yl)-s-triazolo[4,3-a]pyridine (6.05 g; 0.02180 mol), which melts at 165°C, is obtained (yield 87%).

*Example 3: Bromine (1.25 ml) in glacial acetic acid (5 ml) is added at ambient temperature to a suspension of anhydrous sodium acetate (6.15 g; 0.075 mol) in glacial acetic acid (50 ml) containing phenyl (3'20 trifluoromethylpyrid-2'-yl)hydrazone (6.65 g; 0.025 mol) prepared as in Example 1-2. The reaction medium is stirred for one hour and poured into an aqueous solution of 2N NaOH (300 ml). The precipitate is filtered, washed with water and dried. 3-Phenyl-825 trifluoromethyl-s-triazolo[4,3-a]pyridine (4.75 g; 0.018 mol), which melts at 197°C, Is obtained (yield 72%).

IE 91200 ♦Example 4: 2-Formyl-3-methylthiophene (3.15 g; 0.025 mol), dissolved in ethanol (20 ml), is added at ambient temperature to a stirred solution of 3-chloro5 2-hydrazinopyridine (3.6 g; 0.025 mol), prepared as in Example 1-7, in ethanol (30 ml) which has been acidified with a little HCl. The mixture is heated at boiling point for 2 hours and concentrated to dryness. 3-Methylthien-2-yl(3 *-chloropyrid-2'-yl)hydrazone is obtained. This substance is dissolved in nitrobenzene (50 ml) and oxidised in air by heating at boiling point for 4 hours. The solution is concentrated under reduced pressure. The solid, which has been collected by cooling, is solubilised in N HCl (20 ml), and then reprecipitated by neutralisation with an ammoniacal solution. 3-(3'-Methylthien-2·-yl)-8-chloro-striazolo[4,3-a]pyridine (4.45 g; 0.0178 mol), which melts at 135°C, is obtained (yield 71%).

♦Example 5: A mixture of 3-methyl-2-(3'-methylthien-2'oylhydrazino)pyridine (1.25 g; 0.005 mol), prepared as in Example 1-5, and POC13 (7.65 g) in toluene (25 ml) is refluxed for two hours. The reaction medium is concentrated, the concentrate is taken up in iced water (50 ml), the mixture is rendered alkaline (pH between 8 and 9) with the aid of an agueous KHCO3 solution, and then extracted with CH2C12. The organic solution is dried over MgSO4 and then concentrated. The residue is IE 91200 washed with isopropanol and then dried. 8-Methyl-3-(3'methylthien-2'-yl)-s-triazolo[4,3-aJpyridine (0.8 g; 0.0035 mol), which melts at 94eC, is obtained (yield 70%).

*Example 6: SOC12 (4.2 g; 0.0425 mol) is added dropwise at O’C to a solution of 2-(2'-chlorobenzoylhydrazino)-3methylpyridine (13.1 g; 0.05 mol), prepared as in Example 1-3, in anhydrous pyridine (50 ml). The reaction mixture is stirred for one hour at O’C and then filtered. The insoluble portion is heated at boiling point for 3 hours in acetonitrile (50 ml). The solution is concentrated and the residue is recrystallised. 8-Methyl-3-(2'-chlorophenyl)-s15 triazolo[4,3-a]pyridine (5.75 g; 0.0235 mol), which melts at 72’C, is obtained (yield 47%).

♦Example 7: 2-(2',4'-Dimethylbenzoylhydrazino)-3methylpyridine (3.85 g; 0.015 mol), prepared as in Example 1-4, is dissolved at ambient temperature in 30 ml of glacial acetic acid.

The reaction mixture is kept at boiling point for 12 hours and then evaporated to dryness. The residue is washed with water and then with pentane and recrystallised from absolute ethanol. 8-Methyl-3(2',4'-dimethylphenyl)-s-triazolo[4,3-aJpyridine (1.65 gj 0.007 mol), which melts at 106’C, is obtained (yield 47%).

IE 91200 ♦Example 8: N1- (5' -methylpyrid-2' -yl) phenyl amidrazone (6.8 g; 0.03 mol), prepared as in Example 1-6, is dissolved in formic acid (25 ml). The batch is refluxed for one hour, cooled and poured into water (200 ml).

The precipitate is recovered by filtration, washed with water and dried. 3-Phenyl-6-methyl-s-triazolo[4,3-a]pyridine (4.7 g; 0.0225 mol), which melts at 160*C, is obtained (yield 75%).

*Example 9: A mixture of 2-hydrazino-3-methylpyridine (3.1 g; 0.025 mol), prepared as in Example 1-8, and 4fluorobenzoic acid (3.5 g; 0.025 mol) is heated at 180’C for 3 hours and then cooled and mixed with boiling chloroform (80 ml). The solution is filtered and the filtrate is concentrated to dryness. The residue is treated with an agueous solution of Na2CO3, filtered, washed with water, dried and recrystallised from methanol. 3-(4'-Fluorophenyl)-8-methyl-s-triazolo20 [4,3-a]pyridine (2.3 g; 0.01 mol), which melts at 166’C, is obtained (yield 40%).

♦Example 10: A mixture of 2-hydrazino-3-methylpyridine (3.1 g; 0.025 mol), prepared as in Example 1-8, and picolinic acid (3.1 g; 0.025 mol) is heated for 4 hours at 180’C, cooled, diluted with the aid of agueous ethanol (100 ml) and rendered alkaline (pH approximately 8-9) with a solution of dilute NaOH. The IE 91200 -------'--26 precipitate is recovered by filtration, washed with water, dried and recrystallised using agueous ethanol. 8-Methyl-3-(pyrid-2'-yl)-s-triazolo[4,3-a]pyridine (1.0 g; 0.00475 mol), which melts at 141’C, is obtained (yield 19%).

♦Example 11: Example 9 is repeated but 4-fluorobenzoic acid is replaced by 2-fluorobenzoic acid. 3-(2'Fluorophenyl)-8-methyl-s-triazolo[4,3-a]pyridine (4.1 g; 0.018 mol), which melts at 130C, is obtained (yield 72%).

♦Example 12: Triethylamine (5.05 g; 0.05 mol) and 2hydrazino-3-methylpyridine (3.1 g? 0.025 mol), prepared as in Example 1-8, are added successively at ambient temperature to a suspension of ethyl 4-methylbenzimidate chlorohydrate (5 g; 0.025 mol) in ethanol (50 ml). The reaction medium is kept at boiling point for one hour and then concentrated, cooled and poured into cold water (250 ml). The mixture is extracted with the aid of HCC13. The organic solution is dried and concentrated to dryness. 3-(4'-Ethylphenyl)-8-methyl-s-triazolo[4,3ajpyridine (3 g; 0.0135 mol), which melts at 145’C, is obtained (yield 54%).

*Example 13: Example 2 is repeated but the 3-f ormyl thiophene (2.8 g) is replaced by 4-phenylbenzaldehyde (4.6 g; 0.025 mol). 8-Methyl-3-( 4'-pheny lphenyl )-s-triazoloIE 91200 [4,3-a]pyridine (2.3 g; 0.008 mol), which melts at 156eC, is obtained (yield 32%).

♦Example 14: Example 12 is repeated, replacing the ethyl 5 4-methylbenzimidate chlorohydrate by methyl benzimidate chlorohydrate. 3-Phenyl-8-methyl-s-triazolo[4,3-a]pyridine (3.5 g? 0.0168 mol), which melts at 118*C, is obtained (yield 67%).

♦Example 15: Example 4 is repeated but replacing: 1) the 2-formyl-3-methylthiophene (3.15 g) by 4methylthiobenzaldehyde (4.00 g; 0.025 mol), and 2) 3-chloro-2-hydrazinopyridine (3.6 g) by 2-hydrazino3-me thy lpyridine (3.1 g; 0.025 mol). 4-Methyl thiophenyl (3'-methylpyrid-2'-yl)hydrazone is obtained and dissolved in nitrobenzene (50 ml), and then treated as in Example 4. 3'-(4'-Methylthiophenyl)-8-methyl-striazolo[4,3-a]pyridine (4.60 g; 0.018 mol), which melts at 137’C, is obtained (yield: 72%).

*Example 16: 2-Formylthiazole (2.0 g; 0.018 mol) dissolved in ethanol (20 ml) is added with stirring at ambient temperature to a solution of 3-chloro-2hydrazinopyridine (2.4 g? 0.018 mol), prepared as in 25 Example 1-7, in ethanol (30 ml) which contains ptoluenesulphonic acid (0.2 g). The mixture is heated at boiling point for 2 hours and evaporated to dryness.

Thiazol-2-yl(3'-chloropyrid-2'-yl)hydrazone is IE 91200 obtained. This substance is dissolved in ethanol (50 ml). Chloramine T (5.1 g; 0.018 mol) is added rapidly at ambient temperature to the preceding ethanolic solution. The reaction medium is stirred for minutes. After the solvent has been evaporated, the residue is chromatographed (eluent heptane/ethyl acetate 40/60). 3-(Thiazol-2'-yl)-8-chloro-striazolo [4, 3-a]pyridine (1.50 g; 0.0063 mol), which melts at 218“C, is obtained (yield 36%).

*Example 17: Example 16 is repeated but the 3-chloro-2hydrazinopyridine is replaced by 2-hydrazino-3methylpyridine (prepared as in Example 1-8). 3-(Thiazol-2·-yl)-8-methyl-s-triazolo[4,3-aJpyridine (1.26 g; 0.0058 mol), which melts at 140°C, is obtained (yield 32%).

♦Example 18: Example 17 is repeated but the 2formylthiazole is replaced by 4-phenoxybenzaldehyde. 3-(4 '-Phenoxyphenyl) -8-methyl-s-triazolo [4,3-a Jpyridine (4.7 g; 0.0156 mol), which melts at 132’C, is obtained (yield 87%).

♦Example 19: Example 16 is repeated but the 225 formyl thiazole is replaced by 4-phenoxybenzaldehyde. 3(4' -Phenoxyphenyl) -8-chloro-s-triazolo [ 4,3-a]pyridine (5.0 g; 0.0155 mol), which melts at 145’C, is obtained (yield 86%).

IE 91200 29 5 ♦Example 20: Example 5 is repeated but the 3-methyl-2-(3' methylthien-2'-oylhydrazinoJpyridine is replaced by 3- methyl-2-(4'-methyl-1',2',3'-thiadiazol-5'- oylhydrazino)pyridine. 3-(4'-Methyl-1',2',3'- thiadiazol-5-yl)-8-methyl-s-triazolo[4,3-a]pyridine (0.3 g; 0.0013 mol), which melts at 180°C, is obtained 10 (yield 26%). To obtain the compounds of the following examples, one of Examples 4 or 5 is repeated: ♦Example 21 8-Bromo-3-(3'-methylthien-2'-yl)-s- • 15 triazolo[4,3-aJpyridine, ♦Example 22 8-trifluoromethyl-3-(3'-methylthien-2'-yl)-s 20 triazolo[4,3-a]pyridine, ♦Example 23 8-methyl-3-(2'-methylthien-2'-yl)-s- triazolo[4,3-a]pyridine, ♦Example 23 8-methyl-3-(2-methylthien-2'-yl)s- triazolo[4,3,-a Jpyridine, 25 ♦Example 24 8-bromo-3-phenyl-s-triazolo[4,3-a Jpyridine, ♦Example 25 8-chloro-3-(2'-methylthien-3'-yl)-s- triazolo[4,3-aJpyridine, IE 91200 ♦Example 26 8-chloro-3-(thien-3'-yl)-s-triazolo[4,3-a] pyridine, ♦Example 27 8-methyl-3- (1' -methylpyrrol-2' -yl) -striazolo[4,3-a]pyridine, ♦Example 28 8-chloro-3-(3',5'-dimethylthien-2'-yl)-striazolo[4,3-a]pyridine, *Example 29 7,8-dimethyl-3-phenyl-s-triazolo[4,3-a]pyridine, ♦Example 30 8-methyl-3-(3’,5’-dimethylthien-2'-yl)-s15 triazolof4,3-aJpyridine, ♦Example 31 8-ethyl-3-(3'-methylthien-2'-yl)-striazolo[4,3-a]pyridine, ♦Example 32 8-ethyl-3-phenyl-s-triazolo[4,3-a Jpyridine, ♦Example 33 8-ethyl-3- (1' -methylpyrrol-2' -yl) -strIazolo[4,3-aJpyridine, ♦Example 34 8-ethyl-3-(thien-3'-yl)-s-triazolo[4,3-a]pyridine, ♦Example 35 8-trifluoromethyl-3-(1'-methylpyrrol-2'-yl) IE 91200 s-triazolo[4,3-a]pyridine, ♦Example 36 8-trifluoromethyl-3-(pyrrol-2'-yl)-striazolo[4,3-a]pyridine, ^Example 37 8-chloro-3-(4'-methylthien-2*-yl)-striazolo[4,3-a]pyridine, ♦Example 38 7,8-dimethyl-3-(3'-methylthien-2’-yl)-s 10 triazolo[4,3-a]pyridine, ♦Example 39 8-methyl-3-(4'-methylthien-2'-yl)-striazolo[4,3-a]pyridine, ♦Example 40 8-trifluoromethyl-3-(thien-3'-yl)-striazolo[4,3-a]pyridine, ♦Example 41 8-methyl-3-(4'-isopropylphenyl)-striazolo[4,3-a]pyridine, *Example 42 8-methyl-3-(4'-bromothien-2'-yl)-striazolo[4,3-a]pyridine, ♦Example 43 8-chloro-3-(4'-bromothien-2'-yl)-s25 triazolo[4,3-a]pyridine, ♦Example 44 8-methyl-3-(3'-chlorothien-2'-yl)-striazolo(4,3-a]pyridine, IE 91200 ♦Example 45 8-chloro-3-(3'-chlorothien-2' -yl) -striazolo[4,3-a]pyridine, ♦Example 46 8-methyl-3-(3'-bromothien-2'yl)-striazolo[4,3-a]pyridine, ♦Example 47 8-chloro-3-(3'-bromothien-2' -yl) -striazolo[4,3-a]pyridine, The above products are obtained in accordance with the methods described in Examples 4 and 5.

♦Example I-l: Benzaldehyde (5.35 g; 0.05 mol) in ethanol (20 ml) is added with stirring and at ambient temperature to a solution of 3-chloro-2hydrazinopyridine (7.2 g; 0.05 mol) in ethanol (30 ml) which contains a few drops of concentrated HCl. The batch is refluxed for two hours and then concentrated.

After the mixture has cooled, the solid residue is recovered by filtration, dried and recrystallised from ethanol. Phenyl (3'-chloropyrid-2'-yl)hydrazone (10.45 g; 0.045 mol), which melts at 151°C, is obtained (yield 91%).

♦Example 1-2: Benzaldehyde (5.35 g; 0.05 mol) in ethanol (20 ml) is added to a solution of 3-trifluoromethyl-2hydrazinopyridine (13.25 g; 0.05 mol), prepared as in Example 1-9, in ethanol (30 ml) which contains acetic IE 91200 acid (0.3 ml). The mixture is refluxed for 2 hours, concentrated, cooled and diluted with water (5 ml). The precipitate is recovered by filtration and dried.

Phenyl (3'-trifluoromethylpyrid-2'-yl)5 hydrazone (11.15 g; 0.042 mol), which metis at 119*C, is obtained (yield 84%).

♦Example 1-3¾ 2-Chlorobenzoyl chloride (8.75 g; 0.05 mol) are added slowly and at the temperature of the ice-bath to 3-methyl-2-hydrazinopyridine (6.15 g; 0.05 mol), prepared as in Example 1-8, in anhydrous pyridine (50 ml). The reaction mixture is stirred for 4 hours at ambient temperature and then poured into iced-water (100 ml). After the mixture has been allowed to stand for 12 hours at O’C, it is filtered and the precipitate is washed with water, dried and recrystallised using agueous ethanol. 2-(2'-Chlorobenzoylhydrazino)-3methylpyridine (10.45 g; 0.04 mol), which melts at 115*C, is obtained (yield 80%).

*Example 1-4t 2,4-Dimethylbenzoyl chloride (8.45 g; 0.05 mol) are added slowly at O’C to 3-methyl-2hydrazinopyridine (6.15 g; 0.05 mol), prepared as in Example 1-8, in CH2C12 (200 ml) containing triethylamine (5.5 g; 0.055 mol). The reaction mixture is refluxed for 3 hours, cooled, and filtered, and the filtrate is concentrated. The residue is washed with water, dried and recrystallised using agueous ethanol. 2-(2',4'IE 91200 and recrystallised using agueous ethanol. 2-(2',4'Dimethylbenzoylhydrazino)-3-methylpyridine (9.45 g; 0.037 mol), which melts at 120eC, is obtained (yield 74%).

*Example 1-5: A mixture of methyl 3-methylthien-2-yl carboxylate (3.9 g; 0.025 mol) and 2-hydrazino-3methylpyridine (3.1 g; 0.025 mol), prepared as in Example 1-8, is heated in n-butanol (30 ml) for 8 hours at boiling point. The mixture is concentrated to dryness and recrystallised from toluene. 3-Methyl-2(3'-methylthien-2'-oylhydrazino)pyridine (5.7 g; 0.023 mol), which melts at 196’C, is obtained (yield 92%).

*Example 1-6: Methyl benzimidate chlorohydrate (12 g; 0.07 mol) is added at ambient temperature to a solution of 2-hydrazino-5-methylpyridine (8.65 g; 0.07 mol), prepared as in Example 1-10, in a mixture of absolute ethanol (150 ml) and triethylamine (7.1 g; 0.07 mol). The batch is stirred for 24 hours at ambient temperature. The precipitate is recovered by filtration, washed with ethanol and then dried. ^-(5'methylpyrid-2'-yl)phenylamidrazone (9.95 g? 0.044 mol), which melts at a temperature around 166”C, is obtained (yield 63%).

♦Example 1-7: 85% hydrazine (125 ml) is added slowly and at IE 91200 ambient temperature to a solution of 2,3-dichloropyridine (74 g; 0.5 mol) in ethanol (400 ml). The reaction mixture is kept at boiling point for 24 hours and then cooled to O’C. The solid precipitate is recovered by filtration and recrystallised using ethanol. 2-Hydrazino-3-chloropyridine (66.05 g; 0.46 mol), which melts at 167’C, is obtained (yield 92%).

♦Example 1-8: A mixture of 2-bromo-3-methylpyridine 10 (51.6 g; 0.3 mol) and 85% hydrazine (110 ml) is kept at boiling point for 20 hours. After the mixture has returned to ambient temperature, the precipitate is recovered by filtration, washed with isopropyl ether and solubilised in CH2C12. The organic solution is filtered and evaporated to dryness. 2-Hydrazino-3methylpyridine (26.45 g; 0.215 mol), which melts at 122*C, is obtained (yield 71%).

♦Example 1-9: Example 1-8 is repeated, but the 2-bromo-320 methylpyridine (51.6 g) is replaced by 2-chloro-3trifluoromethylpyridine (54.45 g), and the mixture is heated for 24 hours. 2-Hydrazino-3-trifluoromethylpyridine (34.55 g; 0.195 mol), which melts at 63”C, is obtained (yield 65%).

*Example 1-10: Example 1-8 is repeated, but the 2-bromo-3methylpyridine is replaced by the same amount of 2bromo-5-methylpyridine. 2-Hydrazino-5-methylpyridine IE 91200 (yield 58%).

The examples hereinafter, which are given without implied limitation, illustrate the use of the products according to the invention and their application in weeding. In these examples, the following abbreviations are used: IE 91200 Abbrevia- tions English name of weeds i Latin name AVE Wild oat Avena fatua ECH Japanese millet Echinochloa crus-galli CHR Corn marigold Chrys anthemum segeturn POR Common purslane Portulaca oleracea DIG Hairy finger grass Digitaria sanguinalis SIN White mustard Sinapis alba ALO « Black grass Alopecurus myosuroides IPO China jute Ipomea purpurea ABU Black nightshade Abutilon theophrasti SOL Common chickweed Solanum nigrum STE Stitchwort Stellaria media CEN Cornflower Centaurea cyanus SES Hemp sesbania Sesbania exaltata SET Faber's foxtail Setaria faberii CHY Corn marigold Chrysanthemum segetum IE 91200 Abbrevia- English name of Latin name tions weeds RZ Wheat Triticum aestivum ZEA Maize Zea Mays ORY Rice Oryza sativa GLX Soya Glycine maximum GOS Cotton Gossypium hirsutum HEL Sunflower Helianthus annuus BRS Oilseed rape Brassica napus Example U,: Herbicidal application before emergence of the plant species.

A number of seeds selected as a function of the plant species and the size of the seed is sown in 7 x 7 x 8 cm pots filled with light agricultural soil.

The pots are treated by spraying them with a 20 mixture in an amount which corresponds to an application rate of 500 1/ha and which contains the active ingredient at the desired concentration.

The seeds which are not covered by soil are thus treated with the mixture (the term mixture is used to designate generally compositions which are diluted with water, such as are applied to the plants).

The mixture used for the treatment is a IE 91200 solution or suspension of the active ingredient in an acetone/water mixture in the ratio of 50/50, in the presence of 0.05% by weight of Cemulsol NP 10 (surfactant) which is composed of a polyethoxylated alkylphenol, in particular a polyethoxylated nonylphenol) and 0.04% by weight of Tween 20 (surfactant composed of an oleate of a derivative of a polycondensate of ethylene oxide with sorbitol).

In the case of a suspension, the latter is 10 obtained by mixing and grinding the ingredients in a microniser in such a way as to obtain an average particle size of less than 40 microns.

After the treatment, the seeds are covered by a layer of soil about 3 mm in thickness.

The pots are then placed in containers for receiving the watering water, by way of subirrigation, and maintained for 24 hours at ambient temperature and 60% relative humidity.

After 24 days, a destruction percentage (D) of the plants in the treated pot is determined in relation to the number of plants in the untreated pots (controls). On the remaining treated plants, the size reduction percentage (SR) is measured in relation to the control plants.

The percentage of foliar volume destroyed and reduced by the product is therefore given by the formula IE 91200 D + SR (100 ~ DI = A 100 This value A is transformed into a key from 0 to 5 according to the following gradation: 5 Key 0 < A < 10 0 no effect 10 < A < 30 1 30 < A < 50 2 50 < A < 70 3 10 70 < A < 90 4 < A < 100 5 complete destruction.

The results obtained are given hereinafter: IE 91200 Compound according to Ex.No. (applied at a dosage rate of 4 kg/ha) 6 8 1 9 7 4 2 10 3 5 1 Pre-emergence activity A AVE 0 0 2 0 5 5 1 4 3 5 ECH 3 0 2 1 5 4 3 5 5 5 ALO 2 1 4 3 5 5 4 5 5 5 DIG 5 5 5 3 5 5 5 5 5 5 IPO 4 3 4 5 5 3 1 5 2 5 SIN 5 5 5 3 5 5 2 5 5 5 ABU 4 5 5 5 5 4 3 5 5 5 SOL 5 5 0 5 5 5 55 t 1 5 5 IE 91200 PRE-EMERGENCE ACTIVITY EXAMPLES ECH ALO DIG SIN ABU SOL STE 16 5 5 5 5 5 5 5 17 4 5 5 2 5 5 20 4 5 5 5 5 5 5 22 ' 4 4 5 5 1 0 23 3 4 5 1 5 i 5 24 4 4 4 2 0 5 5 25 3 5 5 1 0 5 5 27 4 5 5 2 4 4 31 5 5 5 5 5 5 5 32 5 5 5 5 5 5 5 33 5 5 5 5 5 5 5 34 5 5 5. 5 5 35 5 5 5 5 5 5 5 37 5 5 5 5 0 5 38 5 4 5 0 3 5 5 39 3 5 5 1 0 5 5 40 5 5 4 0 3 5 5 41 4 4 5 2 1 5 4 42 3 5 5 5 0 5 5 43 5 5 5 5 5 5 IE 91200 PRE-EMERGENCE ACTIVITIES CROPS EXAM- PLES DOS- AGE RATE kg/ha BRS GOS GLX HEL TRZ ZEA ORY 10 17 2 0 0 1 0 0 0 0 27 2 5 0 0 1 0 0 31 1 0 0 0 0 0 00 36 2 5 0 0 4 1 0 1 38 1 5 0 0 0 0 0 0 IE 91200 PRE- -EMERGENCE WEEDS ACTIVITIES EXAM- PLES DOS- AGE RATE kg/ha STE CHY SOL DIG SET 17 2 5 5 5 5 5 27 2 5 5 1 5 5 31 1 2 5 4 4 36 2 5 5 5 5 5 38 1 5 5 5 5 5 IE 91200 PRE-EMERGENCE ACTIVITIES CROPS WEEDS EXAM- PLES DOS- AGE RATE kg/ha GLX TRZ ZEA STE ABU SOL DIG 32 2 0 0 0 0 5 4 4 39 1 0 0 0 5 5 5 5 35 1 0 2 0 4 5 5 5 33 2 0 0 0 4 1 4 5 16 2 0 2 0 5 4 5 5 43 4 1 0 1 5 5 5 ί 5 II—, IE 91200 Compound according to Ex.No. Applied at a dosage rate of (kg/ha) 5 2 1 1 12 4 Pre-emergence activity A DIG 5 5 4 ECH 5 4 1 SET 4 4 3 STE 3 4 4 SOL 4 5 5 CEN 5 4 3 GOS 0 HEL 0 3 2 GLX .1 0 1 TRZ 2 3 0 ZEA 0 2 1 ORY 1 0 0 Examples which follow: These examples show that, pre-emergence, the products according to the invention have a good general activity against the weeds and a good selectivity towards one or more crops such as wheat, maize, rice, cotton, sunflower, soya and oilseed rape.

IE 91200 Example U?: Herbicidal application after emergence of the plant species A number of seeds selected as a function of the 5 plant species and the size of the seed is sown in 7 x 7 x 8 cm pots filled with light agricultural soil.

The seeds are then covered by a layer of soil of about 3 mm in thickness and the seed Is allowed to germinate until it gives rise to a plantlet in a suitable stage. In the case of the Gramineae, the treatment stage is the formation of second leaf stage. In the case of the dicotyledons, the treatment stage is the cotyledons unfolded, first true leaf being developed stage.

The pots are then treated by spraying them with a mixture in an amount which corresponds to an application rate of 500 1/ha and which contains the active ingredient at the desired concentration.

The mixture used for the treatment is prepared as in Example Ux.

After the treatment, the seeds are covered by a soil layer of about 3 mm in thickness.

The pots are then placed in containers for receiving the watering water, by way of subirrigation, and maintained for 24 days at ambient temperature and 60% relative humidity.

A (percentage of destroyed foliage volume) is measured as in Example Ux.

The results obtained are given hereinafter: IE 91200 Compound in accordance with Ex.No. (applied at a dosage rate of 4 kg/ha) 6 4 2 10 3 5 1 ll! . 1 13 i 1 ι Post-emergence activity • AVE 2 3 1 2 5 5 4 2 5 2 3 2 ί ECH 3 4 5 4 5 5 4 3 5 5 5 5 , ALO 2 4 4 5 5 5 2 4 5 5 4 • DIG 2 3 3 3 5 4 4 3 5 4 4 5 IPO 2 4 4 5 5 5 4 3 5 5 5 5 SIN I 5 5 5 5 5 5 5 5 5 5 5 5 ABU 3 4 2 3 5 5 4 0 5 5 3 5 SOL 4 4 5 5 5 5 5 5 5 5 3 5 IE 91200 EXAMPLES POST-EMERGENCE ACTIVITIES ECH ALO DIG SIN ABU SOL STE 16 4 5 4 5 3 5 5 17 5 1 2 5 3 5 5 18 3 5 5 5 20 2 4 2 4 2 2 5 22 4 2 3 5 0 4 3 24 2 3 2 5 1 2 4 25 4 5 4 1 0 2 5 26 4 4 4 5 5 4 5 28 3 3 4 5 4 5 5 29 5 2 4 5 5 4 4 31 5 5 5 5 5 5 5 32 5 5 4 5 4 5 5 33 5 5 5 5 5 5 5 34 5 5 5 5 5 35 5 5 5 5 5 4 5 37 5 4 5 5 5 38 5 3 4 2 5 5 5 39 5 5 5 5 3 4 5 40 5 4 5 5 5 5 5 41 5 5 5 5 5 5 S 42 4 3 4 5 5 5 5 43 5 1 5 1 5 5 5 IE 91200 Compound accor- 1 i 2 7 10 1 1 12 9 ding to Ex.No. 5 Applied at a 1 I j i dosage rate of i ί 1 i (kg/ha) 0, 5 2 1 2 1 1 2 Post-emergence i 1 activity A weeds j Ϊ i: t IPO 3 4 3 4 3 4 3 SOL 5 5 5 5 5 5 5 SES 4 5 5 5 2 5 5 ECH 5 4 3 4 4 4 3 POR 5 5 5 4 2 3 4 STE 2 5 5 4 5 5 5 CHY 5 5 5 5 4 5 5 crops i i 1 TRZ 0 2 0 1 0 0 2 ZEA 0 1 1 0 0 0 0 ORY 1 1 1 1 1 0 1 IE 91200 I- I POSI V ^-emergence activities »iEEDS EXAM- PLES dosage; rate in Kg/h£ GOS TRZ ZEA ORY GLX 38 1 1 2 0 0 31 0,5 0 1 1 0 37 2 0 0 0 0 36 1 1 0 0 28 2 0 0 0 42 2 1 0 1 41 2 1 0 1 32 1 1 0 1 29 4 0 0 1 16 2 0 0 1 21 2 0 0 0 17 2 1 0 0 39 2 1 0 25 2 0 0 26 2 0 0 35 0,5 0 0 33 1 3 0 18 1 0 0 POST-EMERGENCE ACTIVITIES WEEDS EXAM- PLES DOSAGE RATE In Kg/ha STE CHY SES CEN SET 38 1 4 5 4 4 4 31 0,5 5 5 3 5 3 IE 91200 EXAM- ; POST-EMERGENCE ACTIVITIES PLES j Kg/hi WEEDS ABU — IPO — CHY ' 1 “ 1 SOL POL — STE 37 2 3 4 5 4 36 1 5 35 28 2 5 3 4 42 2 5 4 4 41 2 5 4 5 32 1 5 5 4 !POST-EMERGENCE ACTIVITIES ! WEEDS EXAMPLES 1 dosage RATZ-ln Zg/ha STE ABU SOL SET 29 4 4 5 4 4 16 2 5 3 5 4 21 2 5 3 4 4 17 2 5 5 3 5 IE 91200 POST-EMERGENCE ACTIVITIES j WEEDS dosage EXAM- .rate in PLES j Kg/ha 1 STE ABU IPO SOL ECH DIG 1 SET 39 2 5 5 4 5 55 5 . 25 2 5 4 5 5 5 5 5 1 26 2 4 5 4 4 5 4 4 35 0,5 5 5 4 5 5 3 5 33 1 5 5 5 5 5 3 5 28 1 5 5 5 5 1 5 4 Moreover, the compound of Example 14 has shown the following activities A at a dosage rate of 2 kg/ha: IPC SOL SES STE CHY GLX HEL TRZ ZEA ORY 4 5 3 4 5 0 1 0 0 0 These examples show that, post-emergence, the compounds according to the invention have a good general activity against weeds and a good selectivity in one or more crops, such as wheat, maize, rice, sunflower, cotton and soya.

The trials which have been carried out show therefore the advantageous properties of the compounds according to the invention as herbicides, in particular herbicides which have a broad spectrum of activity and IE 91200 which can be active pre-emergence and post-emergence. For their use in practice, the compounds according to the invention are rarely utilised by themselves. Most frequently, these compounds are part of compositions. These compositions, which can be used as herbicidal agents, contain, as the active ingredient, a compound according to the invention such as has been described above, in a mixture with at least one solid or liquid carrier which is agriculturally acceptable and, if appropriate, at least one agent with surface activity is likewise agriculturally acceptable. By agent with surface activity, there is to be understood, in the present statement, an agent known in the English language under the term surfactant, which embraces principally the surface-active agents, wetting agents or dispersants.

These compositions are likewise part of the invention. They can also contain a large range of other ingredients such as, for example, protective colloids, adhesives, thickeners, thixotropic agents, penetrants, stabilisers, sequestering agents, etc. More generally, the compounds used in the invention can be combined with all solid or liquid additives which correspond to techniques customary in the art of formulation.

Generally speaking, the compounds according to the invention customarily contain approximately from 0.05 to 95% (by weight) of a compound according to the invention, one or more solid or liquid carriers and, if IE 91200 desired, one or more surface-active agents.

The term carrier designates, in the present statement, an organic or inorganic natural or synthetic material, with which the compound is combined for facilitating its application to the plant, to the seeds or to the soil. This carrier is thus generally inert and it must be agriculturally acceptable, in particular to the treated plant.

The carrier can be of any customary type. In 10 particular, it can be solid (clays, natural or synthetic silicates, silica, resins, waxes, solid fertilizers, etc....) or liquid (water; alcohols, especially butanol etc...).

The agent with surface activity, or the 15 surface-active agent, can also be of any customary type. It can be an emulsifier, dispersant or wetting agent of the ionic or non-ionic type, or a mixture of such surface-active agents. Examples which may be mentioned are salts of polyacrylic acids, salts of lignosulfonic acids, salts of phenolsulfonic acids or naphthalenesulfonic acids, or polycondensates of ethylene oxide with fatty alcohols or with fatty acids or with fatty amines, or substituted phenols (especially alkylphenols or arylphenols), salts of esters of sulfosuccinic acids, derivatives of taurine (especially alkyltaurates), phosphoric esters of alcohols or of polycondensates of ethylene oxide with phenols, of fatty acid esters and of polyols, or IE 91200 derivatives of the preceding compounds which have sulfate, sulfonate and phosphate functions.

The presence of at least one surface-active agent is generally indispensable when the compound and/or inert carrier are not water-soluble and the vector agent for the application is water.

Thus, the compounds for agricultural use according to the invention can contain the active ingredients according to the invention within very wide limits, from 0.05% to 95% (by weight). Their content of surface-active agent is advantageously between 0.1% and 50% by weight.

As regards the compositions which are adapted to storage and transport, they contain more advantageously from 0.5 to 95% (by weight) of active substance, the compositions as they are applied to the plants being generally markedly more diluted than the compositions which are adapted to storage and transport, which are more concentrated.

The compositions according to the invention themselves come in a very wide range of forms, solid or liguid.

Solid composition forms which may be mentioned are the dusts for dusting (having a compound content which can reach 100%); the wettable powders; the granules, specially those obtained by extrusion, by compacting, by impregnating a granulated support, by granulation using a dust (the compound content in these IE 91200 granules being between 0.5 and 80% in the lastmentioned cases).

The wettable powders (or sprayable powder) are customarily prepared in such a way that they contain 20 to 95% of active compound, and they customarily contain, in addition to the solid carrier, from 0 to 30% of a wetting agent, from 3 to 20% of a dispersant and, if necessary, from 0 to 10% of one or more stabilisers and/or other additives, such as penetrants, adhesives, or anticaking agents, colourants, etc.

To obtain the sprayable powders, or wettable powders, the active substances are mixed intimately in suitable mixers with the additional substances, and the mixture is ground by means of mills or other suitable grinders. In this way, powders for spraying are obtained whose wettability and suspension properties are advantageous; they can be suspended in water at any desired concentration, and the suspensions can be used very advantageously, in particular for application to the leaves of the plants.

In place of the wettable powders, pastes can be realised. The conditions and details of production and utilisation of these pastes are similar to those in the case of the wettable powders or sprayable powders.

What follows now by way of example are various compositions of wettable powders (or sprayable powders): IE 91200 Example F 1: * Active compound (compound No.l) * Ethoxylated fatty alcohol (wetting agent) * Condensate of ethylene oxide with phenyl ethylphenol (dispersant) * Chalk (inert carrier) Example F 2: 50% 2.5% % 42.5% * Active compound (compound No.l) % * Synthetic oxo C13 alcohol of the branched type, ethoxylated with 8 to 10 ethylene oxide units (wetting agent) 0.75% * Neutral calcium lignosulfonate (dispersant) 12% * Calcium carbonate (inert filler) q.s. 100% Example F 3: this wettable powder contains the same ingredients as in the preceding example, in the following proportions: * Active compound 75% * Wetting agent 1.50% * Dispersant 8% * Calcium carbonate (inert filler) q.s. 100% Example F 4: * Active compound (compound No.l) 90% * Ethoxylated fatty alcohol (wetting agent) 4% * Ethoxylated phenylethylphenol (dispersant) 6% IE 91200 Example F5: * Active compound (compound No.l) 50% * Mixture of anionic and non-ionic surfactants (wetting agent) 2.5% * Sodium lignosulfonate (dispersant) 5% * Kaolin-type clay (inert carrier) 42.5% The compounds according to the invention which can be formulated in the form of water-dispersible granules are likewise comprised in the scope of the invention.

These dispersible granules, whose apparent density is generally between about 0.3 and 0.6, have a particle size of generally between about 0.15 and 2 mm and preferably between 0.3 and 1.5 mm.

The active substance content of these granules is generally between about 1% and 90%, and preferably between 25% and 90%.

The remainder of the granule is essentially composed of a solid filler and, if appropriate, of surface-active adjuvants which impart to the granule properties of water dispersibility. These granules can essentially be of two types which are distinguished according to whether the filler carried is watersoluble or not. When the filler is water-soluble, it can be inorganic or, preferably, organic. Excellent results have been obtained using urea. In the case of an insoluble filler, the latter is preferably inorganic, such as, for example, kaolin or bentonite.

IE 91200 It is therefore advantageously accompanied by surfaceactive agents (in a ratio of 2 to 20% by weight of the granule) of which more than half is, for example, composed by least one, essentially anionic, dispersant such as an alkali metal polynaphthalenesulfonate or alkaline earth metal polynaphthalenesulfonate or an alkali metal lignosulfonate or an alkaline earth metal lignosulfonate, the remainder being composed of nonionic or anionic wetting agents such as an alkali metal alkylnaphthalenesulfonate or alkaline earth metal alkylnaphthalenesulfonate.

Moreover, other adjuvants such as antifoam agents can be added, even though this is not indispensable.

The granules according to the invention can be prepared by mixing the necessary ingredients followed by granulation according to various techniques known per se (coating apparatus, fluidised bed, atomiser, extrusion, etc.). The process is generally finished by a crushing step followed by a sieving step at the particle dimension selected within the above limits mentioned.

It is preferably obtained by extrusion, proceeding as shown in the examples hereinafter.

Example F 6: Dispersible granules 90% by weight of active substance (compound No.l) and 10% of urea in bead form are mixed in a IE 91200 mixer. The mixture is subsequently ground in a pin mill. This gives a powder which is moistened with about 8% by weight of water. The moist powder is extruded in a perforated-roll extruder. This gives granules which are dried, then crushed and sieved, in such a way as to retain only the granules of a size between 0.15 and mm.

Example F 7: Dispersible granules The following components are mixed in a mixers 10 * Active substance (compound No.l) 75% * Wetting agent (sodium alkylnaphthalenesulfonate) 2% * Dispersant (sodium polynaphthalenesulfonate) 8% * Inert water-insoluble filler (kaolin) 15% This mixture is granulated in a fluidised bed in the presence of water, and then dried, crushed and sieved in such a way as to obtain granules of a size between 0.15 and 0.80 mm.

These granules can be used on their own, or in solution or dispersion in water in such a way as to obtain the desired dosage rate. They can also be used for preparing combinations with other active substances, especially herbicides, the latter being in the form of wettable powders or of granules or aqeuous suspensions.

The compounds of the formula (I) can also be used In the form of dusts for dusting; it is also possible to use a composition containing 50 g of active IE 91200 substance and 950 g of talc; it is also possible to use a composition containing 20 g of active substance, 10 g of finely-divided silica and 970 g of talc; the components are mixed and ground, and the mixture is applied by dusting.

Liguid forms of compositions, or forms of compositions intended for making up liguid compositions at the time of application, which may be mentioned are solutions, in particular water-soluble concentrates, emulsifiable concentrates, emulsions, flowables and aerosols; wettable powders (or sprayable powder) and pastes are solid compositions but intended for making up liquid compositions at the time of application.

The emulsifiable concentrates or soluble concentrates most frequently comprise 10 to 80% of active substance, while the ready-to-use emulsions or solutions, for their part, contain 0.001 to 20% of active substance.

Besides the solvent, the emulsifiable concentrates can contain, if necessary, 2 to 20% of suitable additives such as stabilisers, surface-active agents, penetrants, corrosion inhibitors, colourants or adhesives, as mentioned above.

Using these concentrates, dilution with water can give emulsions of any desired concentration, which is particularly convenient for application to crops.

What now follows by way of example is the composition of some emulsifiable concentrates: IE 91200 Example F 8s * Active substance 400 g/1 * Alkali metal dodecylbenzene sulfonate 24 g/1 * Nonylphenol with oxyethylated 10 molecules of ethylene oxide 16 g/1 * Cyclohexanone 200 g/1 * Aromatic solvent q.s. 1 litre According to another formula for an emulsifiable concentrate, the following are used: Example F 9: * Active substance 250 g * Epoxidised vegetable oil 25 g * Mixture of alkylarylsulfonate and an ether of polyglycol with fatty alcohols 100 g * Dimethylformamide 50 g * Xylene 575 g The flowables, which can likewise be applied by spraying, are prepared in such a way as to obtain a fluid stable product which does not settle out, and they customarily contain from 10 to 75% of active substance, from 0.5 to 15% of surface-active agents, from 0.1 to 10% of thixotropic agents, from 0 to 10% of suitable additives such as antifoams, corrosion inhibitors, stabilisers, penetrants and adhesives, and, as a carrier, water or an organic liguid in which the active substance is sparingly soluble, or insoluble: certain solid organic materials or mineral salts can be IE 91200 dissolved in the carrier for helping prevent sedimentation, or as antigels in the case of water.

What now follows by way of example is a composition of a flowable: Example F 10: * Compound 500 g * Polycondensate of ethylene oxide with tristyrylphenol phosphate 50 g * Polyethoxylated alkylphenol 50 g * Sodium polycarboxylate 20 g * Ethylene glycol 50 g * Organopolysiloxane-type oil (antifoam) 1 g * Polysaccharide 1.5 g * Water 327.5 g The agueous dispersions and emulsions, for example the compositions obtained by diluting a wettable powder or an emulsifiable concentrate according to the invention with the aid of water, are encompassed within the general scope of the present invention. The emulsions can be of the water-in-oil type or oil-in-water type, and they can have a thick consistency like that of a mayonnaise.

The present invention also relates to a weeding method (especially in areas of dicotyledon or monocotyledon crops), which consists of applying, to the area to be weeded, and/or on the plants to be destroyed, an effective amount of a compound according IE 91200 to the invention, especially a compound of the formula (I), it being possible for the plants (or weeds) which are to be destroyed, or whose growth it is desired to prevent, to be of the monocotyledon or dicotyledon type.

The products and compositions according to the invention are conveniently applied to the vegetation and especially to the weeds to be eliminated when they have a green foliage (post-emergence application).

It is also possible to use a weeding method which consists of applying an effective quantity of a compound of the formula (I) to the areas or terrains where it is desired to prevent the germination or the development of plants which have not yet germinated (pre-emergence application). In this case, it is possible for which the crop to be sown before or after the treatment.

The application rate of active substance is generally between 0.05 and 8 kg/ha, preferably between 0.4 and 4 kg/ha.

IE 91200 Ν— bi |i \N- ►» H Formula (IX) Formula (V) Formula (XII) IE 91200

Claims (28)

1. ------ gLAiM§ 1 A compound of the triazolopyridine type, which has the formula (1) Af in which: • X, Y and Z represent a hydrogen atom or a halogen atom or an alkyl group or haloalkyl group or alkoxy group, at least one of the radicals X, Y or Z having a meaning other than the hydrogen atom, • Ar represents a phenyl group which is optionally mono- or polyftuhfttitutezf by a lower alkyl group or lower alkoxy group or lower alkylthio group or phenyl group or phenoxy group or a halogen atom, preferably chlorine or fluorine: or a neterocycle Het, • Het represents a heterocycle having δ or 6 ring members and containing one or more hetero atom(s) such as sulphur, nitrogen or oxygen, this heterocycle being optionally mono- or polysubstitutea by a lower alkyl group or lower nlkovy group or lower alkylthio group or a halogen atom, preferably cnlorine or fluorine, • with the exclusion of compounds wherein, ·♦ simultaneously Y represents a methyl group, X and Z represent a hydrogen atom, Ar represents a 3chioro phenyl or 4-chlorophenyl or 3-pyridyl or 3,4,5trimethoxy phenyl group: or ·· simultaneously X represents a chlorine atom, Y and 2 represent a hydrogen atom, Ar represents a 2pyrldyl or 4-pyriayl group.

2. A compound according to claim 1, in which X is other than chlorine, and/or; when Ar represents a substituted phenyl group, its substituent(s) is(are) in the ortho or para position. S. Λ compound according to dalm 1 ora, m whtoh Het is selected in the group consisting of thienyl (preferably 2or 3- thienyl), thiazolyl (preferably 2- or 4- thiazolyl), pyridyl (preferably 2-pyridyl), pyrrolyl (preferably 2-pyrrofyl), tnladiazoiyl (preferably 5-thfadIazolyl) group. 4. A compound according to anyone of claims 1 to

3. , ln which Ar Is monosubstituted and Het represents a thienyl radical. 5. A compound according to anyone of claims 1 to

4. , ln which : only one. or two of the three radicals X, Y or Z represent a radical other than the hydrogen atom, and/or when X. Y or Z Are. a halogen atom, the atom In question Is chlorine or bromine, and/or when X. Y or Z are a radical which ts at least partially hydrocarbon in nature, this radical has preferably 1 to 4 carbon atoms, and 1 carbon atom being even more preferred

5. 6. A compound according to anyone of claims 1 to 5, in which Z Is other than the hydrogen atom. I IE 91200 6. 7 A compound according to anyone of claims 1 to 6, tn which X and Y are the hydrogen atom.

6. A compound according to anyone of claims 1 to 7. in which 2 is a chlorine atom or a methyl group.

7. 9. A herbicidal composition which contains 0.05 to 95% by weight of an active substance according to anyone of claims 1 to B in combination with one or more solid or liquid carriers which are agriculturally acceptable, and/or surfactants which are agriculturally acceptable.

8. 10. A weeding method which consists in applying, to the sone to be weeded and/or to the plants to be destroyed, an effective amount of a compound according to one of claims 1 to B or of a composition according to claim 9.

9. 11. A compound which can be used especially os an intermediate tor the prepat aUon of a compound according to claim 1, this compound naving one of the formulae (11), (IV), (Vlll), (Xl) or (XJI) Fonnu!e(Xli} Fomxite (Vlll) in which the various symbols have the meanings given in any of claims 1 to 8.

10. 12. The process for the preparation of a compound according to one of etalmo 1 to 8, in which a compound of the arylidenc-2-(pyrid-2’-yl)hydrazine type, which has, as Its formula, the formula (11) according to claim 11. is reacted with an oxidant in accordance with a cyclising oxidation reaction,

11. 13. The process according to claim 12, In which the oxidant ls selected from amongst the metal cations derived from metals which have various degrees of oxidation and arc at a higher degree of oxidation, or atmospheric oxygen.

12. 14. The process according to claim 12, in which the oxidation reaction of the compound of the formula (II, is effected by adding a halogen, followed by a dehalogenation.

13. 15. The process according to claim 12, in which the oxidation reaction of the compound of the formula (11, is effected by adding an N-halo-N-metallosulphonamidate (preferably chloramine T). IE 91200

14. 16. The process for the preparation of a compound according to one of claims 1 to 8, fn which a compound of the 2-(aroylhydrazlnojpyrldlne type which has. as Its formula, the formula (III), is dehydrated (cyclising dehydration) according to claim 11, tn which the various substituents have the same meaning as in any of claims 1 to 8.

15. 17. The process according to claim 16, which is carried out in the presence of a dehydrating agent.

16. 18. The process for the preparation of a compound according to one of claims 1 to 8, in which a cyclising deamination is effected by heating a compound of the amidrazone type which has, as its formula, (IV) according to claim 11, in which the various substituents have the same meaning as In any of claims 1 to 8.

17. 19. The process for the preparation of a compound according to one of claims 1 to 8, fn which a compound of the hydrazine type of the formula (V) according to claim 11 is reacted with a compound of the formula (VI): Uj-Ci-WJ-Ar according to the reaction; (V) + (VI).....>a) + U 1 H + W,H 2 the various radicals of these formulae (V) and (VI) having the same meanings as in any of claims 1 to 8. Wj represents an oxygen atom or an NH group, when Wi represents the oxygen atom, then Uj represents a hyaroxyl group or alkoxy group or aroyloxy group, or a halogen atom, when Wj represent® ftn NH group, then Uj icpiesentS an alkoxy group or alkylthio group or aiylalkyllhio group.

18. 20. Ihe process for the preparation of a compound according to one of claims 1 to 8, fn which a pyridinc-typc derivative of the formula (VIII) Formula (VIII) is reacted with a tetrazole-typc compound of the formula (IX) according to claim 11, X, Y, Z and Ar In these formulae having the same meaning as in any of claims 1 to 6. and T representing a halogen atom, preferably chlorine.

19. 21. The process for the preparation of arylidene2(pyrid-2 , -yl)hyarazlnes of the formula (II) according to claim 11, in which a 2-hydrazinopyridine of the formula (v) according to claim 11 is reacted with aldehydes of the formula Ar-CHO m which the symbols X. Y, Z and Ar have the meanings given in any of claims 1 to 8. IE 91200

20. 22. The process for the preparation of anildrazones of the formula (IVf according to claim 11, in which a 2hydrazinopyridtne derivative of the formula (V) according to claim 11 is reacted according to the equation: (V) + Ar-C(=NH)-U 3 ......> (IV) + UgH the various radicals of these reactants and reaction products having the same meaning as in any of claims 1 to 3, and Ug is an alkoxy or alkylthio radical.

21. 23. The use of compounds of the formula (Ii) as herbicides.

22. 24. A compound as claimed in claim 1, substantially as hereinbefore descirbed and exemplified.

23. 25. A herbicidal composition according to claim 9, substantially as hereinbefore described and exemplified.

24. 26. A method according to claim 10, substantially as hereinbefore described.

25. 27. A compound according to claim 11, substantially as hereinbefore described and exemplified.

26. 28. A process for the preparation of a compound as claimed in claim 1, substantially as hereinbefore described and exemplified.

27. 29. A compound as claimed in claim 1, whenever prepared by a process claimed in any one of claims 12-20 or 28.

28. 30. Use according to claim 23, substantially as hereinbefore described.