Pesticidal heterocyclic compounds, processes for preparing them, compositions containing them, and their use

Claim 2

A compound of the formula: wherein R 1 represents phenyl substituted in at least the 2-position by fluorine, chlorine, bromine or iodine, R 2 represents a group R 3 , -OR 3 , -SR or -NR 3 R 4 where R represents hydrogen, alkyl of 1 to 6 carbon atoms, cycloalkyl of 3 to 7 carbon atoms, alkenyl of 2 to 6 carbon atoms, cycloalkenyl of 3 to 7 carbon atoms, alkynyl of 2 to 6 carbon atoms, phenyl, phenylalkyl of 7 to 10 carbon atoms or naphthyl, each of which may be unsubstituted or substituted by one or more halogen atoms, alkyl or alkoxy or alkylthio groups of 1 to 6 carbon atoms, nitro groups, cyano groups or mercapto groups, R 4 represents a group as defined for R 3 but not necessarily identical thereto, and A and B, together with the carbon atoms to which they are attached, form a 3,6-disubstituted pyridazine, 3,6-disubstituted dihydropyridazine, 2,5-disubstituted pyrimidine, 1,2,4-oxadiazole, 1,2,4-oxadiazoline or 1,2,4-triazole ring, each of which may be further substituted, and the quaternary salts thereof, with the exception of 3,5-bis(2-chlorophenyl)-1,2,4-oxadiazole.

Claim 3

A compound according to claim 1 wherein R 1 represents 2-chlorophenyl.

Claim 4

A compound according to claim 1 or claim 2 wherein R 2 represents a cycloalkyl group of 5 or 6 carbon atoms or a phenyl group mono-substituted by a halogen atom.

Claim 5

A compound according to claim 3 wherein R 2 represents cyclohexyl, 2-chlorophenyl, 2-fluorophenyl or 2-bromophenyl.

Claim 6

A compound according to any of claims 1 to 4 wherein A, B and the carbon atoms to which they are attached represent a 1,2,4-triazole ring substituted in the 1-position by an alkyl group of 1 to 4 carbon atoms or an alkenyl group of 2 to 6 carbon atoms.

Claim 7

A compound according to claim 5 wherein the ring is substituted in the 1-position by methyl, ethyl or allyl.

Claim 8

A compound according to claim 1 which is: 3,5-bis(2-chlorophenyl)-1-ethyl-1,2,4-triazole; 3,5-bis(2-chlorophenyl)-1-allyl-1,2,4-triazole; 3-(2-chlorophenyl)-5-(2-fluorophenyl)-1-methyl-1,2,4-triazole; 2,5-bis(2-chlorophenyl)pyrimidine; 3,6-bis(2-chlorophenyl)-4-phenylpyridazine; 3,6-bis(2-chlorophenyl)-4-isopropylpyridazine; or 3,6-bis(2-chlorophenyl)-4-methoxycarbonylpyridazine.

Claim 9

3,5-Bis(2-chlorophenyl)-1-methyl-1,2,4-triazole.

Claim 10

3,5-Bis(2-chlorophenyl)-1-methyl-1,2,4-triazole.

Claim 11

A pesticidal composition which comprises from 0.05 to 85% by weight of one or more compounds according to claim 1, in association with a suitable carrier and/or surface active agent.

Claim 12

A method of combating acarids, insects or aphids, or their eggs or larvae, which comprises applying to a site infested or liable to infestation therewith, an effective amount of one or more compounds according to claim 1.

Claim 13

A process for the preparation of a compound of formula I according to claim 1, which process comprises: (a) preparing a 3,6-disubstituted pyridazine of formula I by reacting a tetrazine of the formula: wherein R 1 and R 2 are as defined in claim 1 (i) with a substituted acetylene of the formula R 8 C≡CH wherein R 8 represents a group as defined in claim 1 for R 2 ; or (ii) with a ketone of the formula R 8 COCH 2 R 9 where R 8 and R 9 represent groups as defined in claim 1 for R 2 ; or (b) preparing a 3,6-disubstituted dihydropyridazine of formula I by reacting a compound of formula II with a substituted ethylene of the formula R 8 CH=CH 2 where R 8 is as defined hereinbefore; or (c) preparing a 1,2,4-triazole of formula I by reacting a substituted azine of the formula: where R 1 and R 2 are as defined in claim 1 and each X represents a leaving group, with ammonia or an amine of formula RNH 2 where R represents alkyl of 1 to 6 carbon atoms, alkenyl of 2 to 6 carbon atoms, phenyl, phenylalkyl of 7 to 10 carbon atoms, alkoxycarbonyl of 2 to 6 carbon atoms or alkanoyl of 2 to 6 carbon atoms, each of which may be unsubstituted or substituted by one or more halogen atoms, hydroxy groups, cyano groups or alkoxy groups of 1 to 4 carbon atoms; or (d) preparing a 1,2,4-triazole of formula I by reacting a 4-aminotriazole of the formula: wherein R 1 and R 2 are as defined in claim 1, or a quaternary derivative thereof, with nitrous acid to give the desired compound; or (e) preparing a 1,2,4-triazole of formula I by reacting a compound of the formula: where R 1 is as defined in claim 1 and R 2 represents a group R 3 , and Q and Q l , which may be the same or different, each represent O, S or NH, with a hydrazine of the formula R a NHNH 2 where R a represents hydrogen or a group R, where R is as defined hereinbefore; or (f) preparing a 1,2,4-triazole of formula I wherein R 2 represents -O R 3 or - N R 3 R 4 by reacting a 2-imino-1,3,4-oxadiazole of the formula: where R 1 and R a are as defined hereinbefore, with an alcohol R 2 OH or amine R 3 R 4 NH where R 2 , R 3 and R 4 are as defined hereinbefore, in the presence of a base; or (g) preparing a 1,2,4-triazole of formula I wherein R 2 represents -SR 3 by oxidatively cyclising a compound of the formula: where R 1 and R 3 are as defined hereinbefore, or an acid addition salt thereof in the presence of a base; or (h) preparing a 1-substituted 1,2,4-triazole of formula I by alkylating or aralkylating a corresponding 1,2,4-triazole which is unsubstituted at the 1-position; or (i) preparing a 1,2,4-oxadiazole of formula I by reacting an amidoxime of the formula: with an acid halide of the formula R B COHal wherein Hal represents halogen and R A and R B represent the pair of groups R 1 and R 2 as defined in claim 1; or (j) preparing a 1,2,4-oxadiazoline of formula I by reacting an amidoxime of formula IX with an aldehyde of formula R B C H O where R A an R B represent the pair of groups R 1 and R 2 as defined in claim 1; or (k) preparing a pyrimidine of formula I by reacting a compound of the formula where R 1 is as defined in claim 1, each T represents alkyl or aryl, and X represents an anion with a compound of the formula: where R 2 is as defined in claim 1.