GB2258462A - Pesticidal semicarbazides - Google Patents

Abstract

Compounds of the general formula <IMAGE> in which each of R<1> and R<2> independently represents a hydrogen atom, a halogen atom or a methyl group; R<2> represents a hydrogen atom or a lower alkyl group; R<4> represents a halogen atom or an option ally substituted lower alkyl group; n represents 0,1, 2, 3 or 4; R<5> represents an optionally substituted lower alkyl or optionally substituted phenyl group, are effective in combating acarinae pests. Intermediates of the general formula <IMAGE> are novel compounds.

Description

PESTICIDAL COMPOUNDS hi invention relates to novel semicarbazide compounds, to their use as pesticidal, especially acaricidal agents, to pesticidal compositions containing such compounds, and to preparations of such compounds.

U.S. Patent No: 3 285 957 (Monsanto Company) discloses diphenyl semicarbazides of formula

wherein X and Y are halogen atoms. Such compounds are stated to have shown activity against the bacterial organism Staphyloccus aureus.

U.K. Patent No: 1 374 725 (N. V. Philips' Clocilampenfabricken) discloses benzylidenesemicarbazide compounds of formula

R and R represent substituents; A represents a hydrogen atom, a cyclopropyl group or an optionally substituted aikyl group; and B represents a hydrogen atom or methyl group. The compounds are stated to have a highly specific insecticidal activity, being effective against beetles and beetle larvae but substantially inactive against other specified insects.

European Patent Application No: 0 236 618 (Rohm and Haas Company) discloses compounds of general formula A-CX-NH-NR.CX-B wherein X, X = 0, S or NR; R = = optionally substituted alkyl; A, B B = optionally substituted naphthyl or phenyl.

The compounds are stated to be useful as insecticides.

The present invention is based upon the discovery of eertin novel compounds, and the subsequent discovery of their effectiveness in combating acarinae pests.

ing o a first aspect of the present invention, there is provided a compound of the general formula

in which each of R and R2 independently represents a hydrogen atom, a halogen atom or a methyl group; R represents a hydrogen atom or a lower alkyl group; R4 represents a haloaen atom or an optionally substituted lower alkyl group; n represents 0, 1, 2, 3 or 4; R5 its an optionally substituted lower alkyl or @ly substitued phenyl group.

Unless otherwise stated in this specification, a lower alkyl mciety may be linear or branched and suitably contains up , z , preferably up to 4, more preferably up to 2, carbon atoms. A preferred optionally substituted lower alkyl group is optionally substituted methyl.

Preferred halogen atoms are fluorine and chlorine atoms.

Unless otherwise stated in this specification, when any groups are designated as being optionally substituted, the substituent groups which are optionally present may be any of those customarily employed in the development of biocidal compounds, and/or the modification of such compounds to influence their structure/activity, persistence, penetration or other property. In relation to an alkyl moiety, specific examples of such substituents may include halogen, especially fluorine or chlorine atoms, a sty, hydroxy, cyano, amino or alkylamino groups.

In relation to a phenyl moiety, optional substituents may clude halogen atoms, especially fluorine and chlorine atoms, nitro, no, alkoxy, hydroxy, (alkyl)amino, alkyl and haloalkyl (especially CF3) groups.

Suitably, each of Rl and R2 independently represents a hydrogen atom, or a fluorine or chlorine atom.

Suitably, at least one of Rl and R2 may represent a nyctrngen tnni Both R and R2 may represent hydrogen atoms, Alternatively, both Rl and R2 may represent halogen atoms especially fluorine atoms. When R represents a hydrogen atom, 2 may represent a halogen atom, especially a chlorine atom. Preferred combinations of R and R are: fluorine/fluorine; and hydrogen/chlorine.

Suitably, R represents a hydrogen atom or an optionally substituted, preferably an unsubstituted, methyl group. Preferably, R3 represents a hydrogen atom.

Preferably, n represents 0 or 1. More preferably, n represents 1. When n represents 1, preferably the group R4 is ortho-located with reference to the connecting nitrogen atom. R4 preferably represents a fluorine or a chlorine atom. More preferably, R4 represents a fluorine atom.

When R5 represents an optionally substituted lower alkyl group, preferred substituents of said alkyl group include one or more halogen atoms, especially fluorine or chlorine atoms. Preferably, R5 represents an optionally substituted methyl group. Said methyl group is suitably mono- or poly-substituted preferably by halogen atom(s), especially by fluorine and/or chlorine atom(s). Said methyl group is preferably trisubstituted. R5 suitably represents a trifluoromethyl group.

More preferably, however, R5 represents an optionally substituted phenyl group. When R5 represents an optionally substituted phenyl group, it suitably represents a phenyl group optionally substituted by one or more halogen (especially chlorine or fluorine) atoms and/or by one or more optionally substituted alkyl groups.

Preferably, R5 as an optionally substituted phenyl group has a single halogen substituent, preferably a chlorine atom. Preferably, such a substituent is ortholocated. Preferably, R5 as an optionally substituted phenyl group has a single optionally substituted alkyl group, preferably a haloalkyl group, especially a trifluoromethyl group. Preferably, said single optionally substituted alkyl group is para-located. Preferably, R5 as an optionally substituted phenyl group has a single halogen substituent and a single optionally substituted alkyl group. Thus, in accordance with the preceeding passages, a preferred group R5 is 2 -chloro-4 - (trifluoromethyl) phenyl.

The compounds of general formula I appear to exhibit acaricidal activity during the developmental stages between ovum and adult.

Accordingly, the invention also provides an acaricidal composition comprising, as active ingredient, a compound of general formula I as defined in any of the preceding statements, together with a carrier.

Further in accordance with the invention, there is provided an acaricidal composition which comprises at least two carriers and, as active ingredient, a compound of general formula I, as defined in any of the preceding statements.

A carrier in a composition according to the invention is any material with which the active ingredient is formulated to facilitate application to a locus to be treated, or to facilitate storage, transport or handling.

A carrier may be a solid or a liquid, including a material which is normally gaseous but which has been compressed-to form a liquid, and any of the carriers normally used in formulating biocidal compositions may be used. Preferably compositions according to the invention contain 0.5 to 95% by weight of active ingredient.

Suitable solid carriers include natural and synthetic clays and silicates, for example natural silicas such as diatomaceous earths; magnesium silicates, for example talcs; magnesium aluminium silicates, for example attapulgites and vermiculites; aluminium silicates, for example kaolinites, montmorillonites and micas; calcium carbonate; calcium sulphate; ammonium sulphate; synthetic hydrated silicon oxides and synthetic calcium or aluminium silicates; elements, for example carbon and sulphur; natural and synthetic resins, for example coumarone resins, polyvinyl chloride, and styrene polymers and copolymers; solid polychlorophenols; bitumen; waxes; and solid fertilisers, for example superphosphates.

Suitable liquid carriers include water; alcohols, for example isopropanol and glycols; ketones, for example acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethers; aromatic or araliphatic hydrocarbons, for example benzene, toluene and xylene; petroleum fractions, for example kerosene and light mineral oils; chlorinated hydrocarbons, for example carbon tetrachloride, perchloroethylene and trichloroethane.

Mixtures of different liquids are often suitable.

Compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small amounts of a carrier which is a surface-active agent facilitates this process of dilution. Thus, preferably at least one carrier in a composition according to the invention is a surface-active agent. For example the composition may contain at least two carriers, at least one of which is a surface-active agent.

A surface-active agent may be an emulsifying agent, a dispersing-agent or a wetting agent; it may be nonionic or ionic. Examples of suitable surface-active agents include the sodium or calcium salts of polyacrylic acids and lignin sulphonic acids; the condensation of fatty acids or aliphatic amines or amides containing at least 12 carbon atoms in the molecule with ethylene oxide and/or propylene oxide; fatty acid esters of glycerol, sorbitol, sucrose or pentaerythritol; condensates of these with ethylene oxide and/or propylene oxide; condensation products of fatty alcohol or alkyl phenols, for example p-octylphenol or p-octylcresol, with ethylene oxide and/or propylene oxide; sulphates or sulphonates of these condensation products; alkali or alkaline earth metal salts, preferably sodium salts, of sulphuric or sulphonic acid esters containing at least 10 carbon atoms in the molecule, for example sodium lauryl sulphate, sodium secondary alkyl sulphates, sodium salts of sulphonated castor oil, and sodium alkylaryl sulphonates such as dodecylbenzene sulphonate; and polymers of ethylene oxide and copolymers of ethylene oxide and propylene oxide.

The compositions of the invention may for example be formulated as wettable powders, dusts, granules, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols. Wettable powders usually contain 25, 50 or 75% w of active ingredient and usually contain in addition to solid inert carrier, 3-10t w of a dispersing agent and, where necessary, 0-10t w of stabiliser(s) and/or other additives such as penetrants or stickers. Dusts are usually formulated as a dust concentrate having a similar composition to that of a wettable powder but without a dispersant, and are diluted in the field with further solid carrier to give a composition usually containing 0.5-10% w of active ingredient.Granules are usually prepared to have a size between 10 and 100 BS mesh (1.676 - 0.152 mm), and may be manufactured by agglomeration or impregnation techniques.

Generally, granules will contain 0.5-75t w active ingredient and 0-10% w of additives such as stabilisers, surfactants, slow release modifiers and binding agents.

The so-called "dry flowable powders" consist of relatively small granules having a relatively high concentration of active ingredient. Emulsifiable concentrates usually contain, in addition to a solvent and, when necessary, cosolvent, 10-50% w/v active ingredient, 2-20% w/v emulsifiers and 0-20% w/v of other additives such as stabilisers, penetrants and corrosion inhibitors.

Suspension concentrates are usually compounded so as to obtain a stable, non-sedimenting flowable product and usually contain 10-75% w active ingredient, 0.5-15% w of dispersing agents, 0.1-10% w of suspending agents such as protective colloids and thixotropic agents, 0-10t w of other additives such as defoamers, corrosion inhibitors, stabilisers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation or as anti-freeze agents for water.

Aqueous dispersions and emulsions, for example compositions obtained by diluting a wettable powder or a concentrate according to the invention with water, also lie within the scope of the invention. The said emulsions may be of the water-in-oil or of the oil-in-water type, and may have a thick "mayonnaise"-like consistency.

The composition of the invention may also contain other ingredients, for example other compounds possessing herbicidal, insecticidal or fungicidal properties.

The invention further provides a method of combating acarinae pests at a locus, which comprises applying to the locus a pesticidal compound or composition according to the invention.

In the method according to the invention the locus may be an agricultural or horticultural locus, for example, plants subject to attack, seeds of such plants or the medium in which plants are growing or are to be grown.

The method may comprise combating acarinae pests already present at a locus and/or prophylactic treatment at a locus.

The locus may conveniently be treated with a compound of formula I at an application in the rate 0.05-4 kg/ha, preferably 0.1-1 kg/ha.

The invention also provides the use of a compound of general formula I or of a composition as defined in any of the preceding statements, as an acaricide.

The invention extends to a process for the preparation of a compound of general formula I as defined in any of the preceding statements, the process comprising reacting a compound of general formula

with a compound of general formula

wherein Rl, R2, R3, R4, R5, and n are as defined in any of the preceding statements and L' is a leaving group.

Suitably Li represents a hydroxy group, or an alkoxy group, especially a methoxy group, or a halogen atom, especially a chlorine atom. Preferably, L1 represents a chlorine atom.

The reaction may be carried out under standard conditions which will be readily apparent to those skilled in the art. Thus, when L1 represents a chlorine atom, preferably, the reaction is carried out in an organic aprotic solvent, preferably in a chlorohydrocarbon solvent, for example, in dichloromethane. A base may suitably be provided in the reaction mixture. Suitably, .the base is an organic base, preferably an amine base, for example, triethylamine.

Preferably, a compound of general formula III in a solvent is added to a compound of general formula II in the same solvent.

Preferably, the reaction is carried out at a temperature in the range 0-50"C, more preferably, at ambient temperature.

The product may be isolated by standard techniques.

A compound of general formula II may be prepared by reacting a compound of general formula

wherein R4, R5 and n are as defined in any of the preceding statements and L2 is a leaving group, with a hydrazino compound of general formula R3NH-NH2 or a derivative thereof.

Suitably, L2 represents an alkoxy group, especially a methoxy or ethoxy group. Preferably L2 represents a methoxy group.

Preferably, said hydrazino compound of general formula R3NH-NH2 or derivative thereof is hydrazine hydrate.

Suitably, the reaction is carried out under reflux.

After ref fluxing for a period of the order of 24 hours the reaction mixture is suitably diluted with water. The product may then be isolated by standard techniques for subsequent process steps.

Compounds of general formula II, but not including the case wherein R5 represents an optionally substituted lower alkyl group, are believed to be novel and they and their preparation constitute further aspects of the present invention.

A compound of general formula IV may be prepared by reacting a compound of general formula

with phosgene (COCl2) followed by reacting the mixture with a compound of general formula L2-H wherein R4, R5, n and L2 are as defined in any of the preceding statements.

Preferably, therefore, the compound L2-H represents an alkanol, suitably methanol or ethanol, preferably methanol.

Suitably, the reaction is carried out in an organic solvent, preferably in an aprotic organic solvent, more preferably in an aromatic solvent, for example, in toluene. Preferably, the solvent is substantially anhydrous.

Preferably, a compound of general formula V, in said solvent, is added to a solution, preferably a saturated solution, of phosgene, preferably also in said solvent.

The reactants are suitably maintained at a temperature in the range -25 C to 250C, preferably in the range 100C 15"C. Phosgene gas may be passed into the reactant mixture. The mixture may be reflux, followed by cooling to a temperature in the range -25 C to 50CC, preferably to ambient temperature. Excess phosgene may be removed by purging with substantially anhydrous nitrogen gas.

The compound of general formula L2-H may then be added and the reaction suitably carried out under reflux. After refluxing, the desired product may be isolated by standard techniques for subsequent process steps.

Compounds of general formula III and VI are known or may be made by standard methods.

The invention will now be further described with reference to the following examples.

Example 1 Preparation of 4-[4-[2-chloro-4-(trifluoromethyl) phenoxy]-2-fluorophenyl]-1-(2,6-difluorobenzoyl) semicarbazide Rl=R2=fluorine; R3=H; n=l; R4=fluorine; R4 is ortho-located relative to the connecting nitrogen atom; R5=2-chloro-4- (trifluoromethyl) phenyl.

(i) Preparation of methyl N-f4-F2-chloro-4- (trifluoromethyl)phenoxy]-2-fluorophenyl] carbamate.

A solution of 4-[2-chloro-4 (trifluoromethyl)phenoxy]-2-fluoroaniline (30.6g) in toluene (lOOml) was added over 15 minutes to a stirred, saturated solution of phosgene in dry toluene (350ml) keeping the reaction temperature at 10-15 C. Phosgene gas was passed into the mixture for a further 10 minutes and the reaction was then warmed to reflux temperature which was sustained for 1.5 hours. The reaction mixture was cooled to 25 C, purging with anhydrous nitrogen to remove excess phosgene. Methanol (20 ml) was added over 5 minutes and the solution was heated under reflux for a further 1.5 hours. The solvent was finally removed under reduced pressure to leave the crude product as a solid residue.The pure carbamate (33.lg, 91%) was obtained as colourless crystals (melting point 76-78 C) by crystallisation from diethyl ether/petroleum ether (b.p. 40-60 C) (ii) P r e p a r at i o n o f 4 - [ 4 - [ 2 - c h l o r o - 4 - (trifluoromethyl) henoxv 1 -2-fluorohenyl 1 semicarbazide A mixture of methyl N-[4-[2-chloro-4- (trifluoromethyl) phenoxy] -2-fluorophenyl] carbamate (7. 3g) obtained in (i) and hydrazine hydrate (20 ml) was stirred under gentle reflux for 24 hours. The reaction mixture was then diluted with cold water (200ml) and the resulting emulsion was extracted with dichloromethane (3 x 100 ml).

After drying over anhydrous sodium sulphate, the extract was evaporated under reduced pressure to yield the crude product as a solid residue. Chromatography of this material on silica gel, using dichloromethane/10% v/v methanol as eluent afforded the pure hydrazide as colourless crystals (4.6g, 63%); melting point 127-128 C.

(iii) Preparation of 4 - F 4-F 2-chloro-4- (trifluoromethyl)phenoxy]-2-fluorophenyl]-1-(2,6difluorobenzoyl)semicarbazide.

A solution of 2,6-difluorobenzoyl chloride (1.0g) in anhydrous dichloromethane (15 ml) was added over 20 minutes to a stirred solution of 4-[4-[2-chloro-4- (trifluoromethyl)phenoxy]-2-fluorophenyl]semicarbazide (1.8g) obtained in (ii) in dichloromethane (60 ml) containing triethylamine (0.5g) at ambient temperature.

After 3 hours the reaction mixture was evaporated under reduced pressure. Chromatography of the residue on silica gel using dichloromethane/108 v/v methanol as eluent gave the pure semicarbazide as colourless crystals (2.3g, 91%); melting point 206-208 C.

C H N Analysis Calc: 50.1 2.4 8.3 % Found: 49.7 2.3 8.4 % Example 2 Preparation of 1-(2-chlorobenzoyl)-4-[4-[2-chloro-4 (trifluoromethyl)phenoxy]-2-fluorophenyl]semicarbazide Rl=chlorine; R2=H; R3=H; n=l; R4=fluorine; 4 is ortholocated relative to the connecting nitrogen atom; R5=2-chloro-4 (trifluoromethyl) phenyl.

A solution of 2-chlorobenzoyl chloride (l.Og) in anhydrous dichloromethane (10 ml) was added over 20 minutes to a stirred solution of 4-[4-[2-chloro-4 (trifluoromethyl)phenoxy]-2-fluorophenyl]semicarbazide (1.8g) obtained in Example 1 (ii) above in dichloromethane (70ml) containing triethylamine (0.65g), at ambient temperature. After stirring for 5 hours, the reaction mixture was evaporated under reduced pressure. The product was isolated from the resulting residue by chromatography on silica gel using dichloromethane/l0% v/v methanol as eluent.The pure semicarbazide was obtained as colourless crystals (1.6g, 64%); melting point 162-165 C C H N Analysis Calc: 50.2 2.6 8.4 % Found: 50.8 2.9 8.3 % Examples 3 to 8 By processes similar to those described above in relation to examples 1 and 2, further compounds according to the invention were prepared as noted in Table 1 below.

Elemental analysis data, melting point data and yield data for the compounds of examples 3 to 8 are given in Table 2 below.

Example 9 Acaricidal Activity (mite life cycle) The acaricidal activity of the compounds of Examples 1 to 8 was assessed against glasshouse red spider mites, Tetranychus urticae (T.u.), by the following procedure.

Solutions or suspensions of the test compound were made up over a range of concentrations in water (initially 0.1%w) containing lOtw acetone and 0.025%w "TRITON X-100" (trade mark) surface active agent (the condensation product of ethylene oxide with an alkyl phenol).

2cm diameter leaf discs cut from the leaves of French bean plants were placed, underside uppermost, on 5.5cm diameter filter papers, kept moist by a cotton wool wick dipped in water.

Each leaf disc was infested with 25 to 30 adult female mites which were removed after 6 hours, leaving about 50 eggs on each disc. Within 5 days the eggs hatched. The freshly emerged larvae on the leaf discs were sprayed with solutions of test compound made up as described above, at a rate equivalent to 340 litres per hectare (3.4 x 10-5 m3/m2).

The discs were thereafter kept under normal laboratory conditions (23 C + 2CC, fluctuating humidity and 16 hours day length). After 7 days assessment was made of the number of mites emerging as adults.

From the results the LC50 (the dosage of active material required to kill half of the test species) was calculated. The results are shown in Table 3 below. TABLE 1

Example R R R *(R4)n *R5 No.

1 F F H 2-F 2-chloro-4-(trifluormethyl)phenyl 2 Cl H H 2-F " 3 H H H 2-F " 4 F F Me 2-F " 5 F F H - " 6 Cl H H - " 7 F F H - trifluoromethyl 8 Cl H H - " * with respect to the conecting nitrogen atom.

TABLE 2

Example Mpt C Yield % Analysis No.

C H N Calc Found Calc Found Calc Found 1 206-208 91 50.1 49.7 2.4 2.3 8.3 8.4 2 162-165 64 50.2 50.8 2.6 2.9 8.4 8.3 3 178-180 43 53.9 54.6 3.0 3.2 9.0 9.0 4 164-165 58 51.0 50.5 2.7 2.7 8.1 7.9 5 215-216 48 51.9 51.7 2.7 3.0 8.7 9.0 6 183-184 41 52.1 51.9 2.9 2.8 8.7 9.3 7 194-197 72 48.0 48.1 2.7 2.6 11.2 10.9 8 210-212 88 48.2 48.8 2.9 3.5 11.2 12.0 TABLE 3

Example No. Mite Life-cycle LC50 1 0.00033 2 0.00030 3 0.0039 4 0.0053 5 0.0032 6 0.0015 7 0.032 8 0.023 Example 10 The compounds of Examples 1 to 8 were tested, using standard procedures, for activity against various pests and for ovicidal activity. These tests were short term tests in which, essentially, the pests remained at the same developmental stage. The compounds were tested against: Aedes aegypti (yellow fever mosquito) - early fourth instar larvae; Musca domestica (housefly) - 2 to 3 day old milk-fed adult females; Acyrthosiphon pisum (pea aphid) - young adults; Tetranychus urticae (red spider mites) - adult female.

In each case, the compounds showed no activity.

The compounds were then tested against Ssodoptera littoral is (Egyptian cotton leafworm), in tests in which leaf discs were sprayed with a standard test solution containing a compound of Examples 1 to 8, dried, then infested with ten 2nd instar larvae and, in other tests, with approximately fifty 24 hour old eggs. Mortality assessments were made after 24 hours and after 7 days following larvae tests; and after 6 days following the ova tests. Thus, the tests assessed activity against Spodoptera littoralis during developmental stages. The results are shown in Table 4. The letter "X" indicates no activity; the symbol "-" indicates that the test was not carried out.

TABLE 4

Example No. Instar Larvae Ova 24 hours 7 days 6 days 1 X X X 2 X X X 3 X X X 4 X X X 5 X X X 6 X X 7 X X 8 X X Example 11 The compounds referred to in Table 5 have been made and are believed to be novel. However, the compounds were subjected to the tests to which the compounds of Examples 1 to 8 were subjected, and were found, throughout, to have activity which was nil or very low.

TABLE 5

Q-CO.NH.NH.CONH-X Example Q X 11.1 tert-Butyl 2-fluoro-4-(2-chloro-4-(trifluoromethyl)phenoxy)phenyl 11.2 2,6-difluorophenyl 2-fluorophenyl 11.3 2-chlorophenyl " 11.4 2,6-difluorophenyl 4-chlorophenyl 11.5 2-chlorophenyl "

Claims (15)

1. CLAIMS 1. A compound of the general formula

   in which each of Rl and R2 independently represents a hydrogen atom, a halogen atom or a methyl group; R3 represents a hydrogen atom or a lower alkyl group; R4 represents a halogen atom or an optionally substituted lower alkyl group; n represents 0, 1, 2, 3 or 4; R5 represents an optionally substituted lower alkyl or optionally substituted phenyl group.
2. 2. A compound according to claim 1, wherein each of Rl and R2 independently represents a hydrogen atom, or a fluorine or chlorine atom.
3. 3. A compound according to claim 1 or claim 2, wherein R3 represents a hydrogen atom.
4. 4. A compound according to claim 1 or claim 2, wherein n represents 0 or 1.
5. 5. A compound according to any of the preceding claims, wherein R4 represents a fluorine atom.
6. 6. A compound according to any of the preceding claims, wherein R5 represents a trifluoromethyl group.
7. 7. A compound according to any of claims 1 to 5, wherein RS as an optionally substituted phenyl group is the group 2-chloro-4- (trifloromethyl) phenyl.
8. 8. An acaricidal composition comprising, as active ingredient, a compound of general formula I as defined in any of the preceding claims, together with a carrier.
9. 9. An acaricidal composition which comprises at least two carriers and, as active ingredient, a compound of general formula I, as defined in any of the claims 1 to 7.
10. 10. A method of combating acarinae pests at a locus, which comprises applying to the locus a pesticidal compound or composition according to any of the preceding claims.
11. 11. Use of a compound of general tormula I or of a composition as defined in any of the preceding claims, as an acaricide.
12. 12. A process for the preparation of a compound of general formula I as defined in any of claims 1 to 7, the process comprising reacting a compound of general formula

    with a compound of general formula

    wherein Rl, R2, R3, R4, R5, and n are as defined in any of the preceding statements and L1 is a leaving group.
13. 13. A compound of general formula II as defined in claim 12, but not including the case wherein RS represents an optionally substituted lower alkyl group.
14. 14. A process for the preparation of a compound of general formula II as defined in claim 13, the process comprising reacting a compound of general formula

    wherein R4, R5 and n are as defined in claim 13 and L2 is a leaving group, with a hydrazino compound of general formula R3NH-NH2 or a derivative thereof.
15. 15. A novel compound of general formula I, as named in any one of Examples 1 to 8 herein; or a process for the preparation of such a compound; or an acaricidal composition comprising such a compound; or an acaricidal method or use; or any novel intermediate or preparation thereof; any such aspect being substantially as herein described with reference to the Examples 1 to 8.