CA1050567A - Formamidines - Google Patents

Abstract

A B S T R A C T

Novel formamidines which can exist in the form of the free base or as a salt of an inorgnic or organic acid correspond to the formula

Description

66'7 This in~ention relakes to novel formamidines and their salts, the manufacture of such compounds and their use in pest controlO
The novel formam.idines which can exist in ~he form of ~he free base or as a salt of an inorganic or organic acid correspond to the formula I

~ R3 _ ~ ~ N = CH - N I tl) wherff~in Rl represents a methy or ethyl group, R2 represents an n-propyl, iso- - :
propyl, n-butyl, iso-butyl or sec~-butyl group, R3 represents a fluorine, : :
;

~- chlorine, bromine or iodine atom, and R4 represents a methyl or ethyl group and their acid addition salts. :
. The compounds of formula I can be manufactured by known methods, for example as follows:
. R4 a) SOC12 b) COC12 1. R3 ~ NH2 ~ = CH - N \ + c) POC13

2 e) PC15 f) tCH3)2S4 R4 g) Cl-SO

2. R3 ~ N = C = O + O = CH - N ~ 1 ~r ~r ~

'f R~ :

" Rl Temperature tI) . 3. R3~\ / ~ N = CH - O - Alkyl + ~ ~ . j -R2 -OH ~-Alkyl) . , '. ~F
..
- . . . ~ , ;,' ' '' . ~ ' ', ' :
'' ": , ., 5~7 These above processes form part of the invention.
In the abave formulae, Rl - R4 have the meaning given for formula I
and alkyl means Cl C4 alkyl, preferably methyl or ethyl.
Reactions 1 ~ 3 can be carried out suitably in the following inert solvents: aromatic hydrocarbons such as ~enzene, toluene, petrol, chloroben-zene, polychlorobenzene, bromobenzene; chlorinated alkanes having 1-3 carbon atoms; ethers such as dioxane, tetrahydrourane; esters such as ethyl acetate;
ketones such as methylethyl ketone, diethyl ketone; and nitriles such as acetonitrile.

; 10 The starting materials can be prepared according to known methods described in the literature.
The active agents of formula I are suitable for combatting the most varied types of plant and animal pests.
Above all they are effective against all development stages, for ' example, eggs, larvae and pupae, of insects and representatives of the order Acarina, for example mites and ticksO Thei:r activity against representatives o~ the order Acarina is substantially peculiar to the compounds of this invention. It is not shared by the closest prior art compounds of which applicants are aware iOe. those described in their Canadian Patent No.
713,556 or in United States Patent No. 3,502,720 to Schering.
The new active materials are most suited for combatting eating and sucking insects and plant and storage protec~ion and have as well as systemic insecticidal action and a repellant action against insects and representatives of the order Acarina. There should also be mentioned the satisfactory warm-blooded toxicity of the activr aeents of formula 1.

:

', 7''~
1~,,, The compounds of formula I can, for example, be used against the following insects or representatives of the order Acarina: Insects of the families: teltigonidae, gryllidae, gryllotalpidae, blattidae, peduviidae, phyrrhocoriae, cimicidae, delphacidae, aphididae, diaspididae, pseudococcidae, scarabaeidae, dermestidae, coccinellidae, tenebrionidae, chrysomelidae, bruchidae, tineidae, noctindae, lymatriidae, pyralidae, culicidae, tipulidae, stomoxydae, trypetidae, muscidae, calliphoridae and pulicidae together with Acarina of the families Ixodidae, argasidae, tetranychidae and dermanyssidae.
The insecticidal or acaricidal action can be substantially broaden-ed and matched to given circumstances by the addition of other insecticides ; and/or acaricides~
Apart from mixing with th~se acaricides and insecticides, in order to broaden the spectrum of activity, the active agents of formula I can also be mixed together with, for example, fungicides, bactericides, fungistatic ~` agents, bacteriostatic agents, nematocides and/or herbicidesO
The satisfactory warm-blooded toxicity of compounds of formula I as well as that of materials containing them is to be particularly noted~
The compounds of ormula I can be used alone or together with suit-able carriers and/or additivesO Suitable carriers and additi~es can be solid or liquid and correspond to the materials customary in formulation technique, for example natural or regenerated materials, solvents, dispersing agents, wetting agents, adhesives, thickening agents, binding and/or composting agents~
For application the compounds of formula I may be processed to form dusting agents, emulsion concentrates, granulates, dispersions, sprays, or solutions or slurries by customary formulation which is part of the general knowledge of the application technique art. Cattle dips and spray races should also be mentioned; aqueous preparations may be used in these~
The manufacture of pest control agents according to the invention takes place in known fashion by intimate mixing and/or milling together of active agent of formula I with suitable carrier materials, optionally with the addition of dispersing agents or solvents inert to the active material.
The active material can be present in the following useful forms for use:
_ 3 _ " ': , '' '. ' ' " . , . ' ' ' ,' . , .

~5~7 Solid use forms: Dusting agents, spreading agents, granulates, coated granulates, impregnated granulates and homogeneous granulates Liquid use forms: (a) Concentrates of active material which are dispersable in water: wettable powders, pastes, smulsions; (b) solutions.
For the manufacture of solid use forms ~dusting agents, spreading agents) the active substance is mixed with solid carrier materials. As car-riers materials there are for example, kaolin, talcum, bolus, loess, chalk, limestone, limestone gravel, ataclay, dolomite, diatomaeous earth, precipitated silica, alkaline earth metal silicates, sodium and potassium aluminium silicates(feldspars and mica) calcium and magnesium sulphate, magnesium oxide, ground plastics materials, fertilisers such as ammonium sulphate, ammonium phosphate, ; ammonium nitrate, urea, and ground vegetable products such as corn flour, bark flour, wood flour, nutshell flour, cellulose powder, residues from vegetable ; extractions, active carbon etc. These materials can all be used alone or as mixtures of two or more of them.
Granulates may be manufactured very simply by dissolving an active substance of formula I in an organic solvent and applying the so obtained solution to a granulated material such as attapulgite, silica, lime, bentonite, etc., and then evaporating the organic solvent again.
Polymeric granulates may also be manufactured by mixing the substance of formula I with polymerisable compounds (urea formaldehyde, dicyandiamide/
formaldehyde; melamine formaldehyde or others), and then by carrying out a careful polymerisation by which the active material remains unaffected, and wherein granulation is effected during the gel formation. It is more satis-factory however to take porous polymer granulate mateials (e.g. urea formalde-hyde, polyacrylonitrile, polyester and others) with a given surface area and satisfactory adsorption and desorption properties and to impregnate this with the ackive substance e.g. in the form of a solution (in a low boiling solvent) and then to remove the solvent. Such polymer granulates can be applied in the form of micro granulates with a bulk density of preferably 300-600 g per litre, with the aid of dust distributors. Dus~ng can be carried out over extensive areas of useful plant cultures with the aid of aircraft.
_ ~ _ ,! ~
' '' '' .

3.05~5~7 Granulates may also be obtained by compaction of the carrier mater-2i ial with the active substance and other additives and then breaking the com-pcac1; up, To these various mixtures, there can also be added stabilising additives for the active material and/or non-ionic, anionic or cationie mater-ials which, for example, improve the adherence of the active agent onto plaults and plant parts tadhesive and tackifying agents) and/or guarantee better wet-ting of the plants (wetting agents) or dispersability (dispersants).
For example, the following materials may be included: Olein-lime mixture, cellulose deri~atives (methyl cellulose, carboxy methyl cellulose), hydroxyethyleneglycol ethers or mono, and dialkylphenols with 5-15 e-thylene oxide groups per molecule and 8-9 carbon atoms in the alkyl group, lignOsul-fonie aeids, the aIkali and a~caline earth salts thereof, polyethyleneglycol e~hers (earbowax), fatty alcohol polyglycol ethers ~Yith 5-20 ethylene oxïde groups per moleeule and 8-18 carbon atoms in the fatty alcohol parts, conden-sation products of ethyJene oxide, propylene oxide, poly~inylpyrrolidone, polyvinyl alcohols, eondensation products of urea- and formaldehyde as well as latex products.
Coneentrates of active substances dispersable in water, i.e wettable po~ders, pastes and emulsion coneentrates are agents which can be diluted ~Yith water to any desired concentration. They consist of active substance, carrier, optionally stabilising additives for the aetive substance, surface active sub-stanees and anti-foc~ming agents and optionally solvents.
Wettable powders and pastes can be obtained by mixing or milling the active substance together with dispersing agents and powdery earriers in suitable devices until a homogeneous mix is obtained. As carrier materials, for example the materials noted above for solid application forms may be used.
T~ some eases it is advantageous to uso mixtures of various carrier materials.
As dispersallts there can be used, for example; condensation products of sul-phonated naphthalene and sulphonated naphthalene derivatives with formaldehyde,eondensation products of naphthalene or naphthalene sulphonic acids ~ith phenol ~ld formaldellyde to6ether with alkali, al~lonium and allcaline earth salts of urk 5_ lignin sulphonic ~cid, and furthcrmore alhyl aryl sulphonates, allsali and alkaline earth metal salts of ditcrbutylnaphtllalelle sulphonic acid~ fatty alcohol sulphates, such as salts of sulphated hcxadecanols, heptadccanols, octadecanols~ and salts of sulphated fatty alcohol glycol ethers, the sodium salt of oleylmethyltauride, ditertiary acetylene glycols, diall~yldilauryl-ammonium chloride, and alkali and alkaline earth salts of fatty acids. As anti-foaming agen~s, silicones may, for example~ be used.
The active substances are mixed with the additives noted above, ground, sieved ard checked so that in the spr'ayable powders the solid portion has a particle si~e of 0 02 0.04 mm and for pastes does not exceed 0.03 mm.
For the manufacture of emulsion concentrates and pastes, dispersing agents, as noted in the previous sections, organic solvents and water are used. As solvent there can be used, for example, alcohols~ benzene, xylenes, toluene, dimethylsulfoxide, and mineral oil fractions boiling in the range of 120~350O.
The solvent must be practically odourless, non-phytotoxic, and inert to the actiYe material Furthelmore the agents according to the invention can be used in the form of solution. For this one or more active agents according to general fo~nula I are dissolved in suitable organic solvents, mixtures of solvents or water. Aliphatic and aroma~ic hydrocarbolls can be used as organic solvents, ; also their chlorinated derivatives, alk3rl naphthalenes, mineral oils, alone or mixtures of any of these may be used.
The content of active substance in the above described agents lies between 0.1 and 95%. It is to be noted th~t in the case of application from aircraft or by means of other suitable application devices, concentrations of up to 99.5% or e~en pure substance may be used, The active substances of formula I can, for ex~mple, be formulated as follows:
Dusting agent: For the manufac~ure of a) a 5% and b) a 2% dusting agent, the ollowing matcrials wcre used:
a) 5 parts activc agent : 95 parts talcum ~ , -6-.. . . . .

5~
b)2 parts active agent 1 part highly dispersed silica 97 parts talcum The aetive substances were mixed with the carrier n~aterials and milled.
; Granulate: For the manufacture of a 5% granulate, the following materials were used:
5 parts active agent 0~25 parts epichlorohydrin 0c25 parts cetylpolyglycolether 3.50 parts polyethyleneglycol (t~Carbowax~t) 91 parts kaolin (particle size 0.3-0.8 mm).
l'he active substance was nuLxed with epichlorohydrin ~Id dissolved - . in 6 parts of acetone9 and to this the polyethylene glycol and cetylpolygly-eolether were then added. The solution so obtained was sprayed onto the kao'lin: ~ and khe acetone was finally evaporated ]n vacuo~
Sprayable po~der: For the manufacture of a) a 40% b) and c) a 25% and d) lOj,. sprayable powders, the following components were used: . ~' a)40 parts active agent ~ 5 parts sodium lignosulphonate 1 part dibutylnaphthalenesulfonic acid, sodium salt .
54 parts silica b)25 parts active agent

4.S parts ealcium lignosulphonate - ''::
1.9 parts ehampagne-challc-hydroxyethylcellulose mixture (1:1) 1.5 parts sodiumdibutylnaphthalene sulphonate ~ -19~5 parts si].ica ' - ~
19.5 parts ehampagne-challc .-.
28 1 parts kaolin ~ 30 e).25 parts ~cti.ve agent 2.5 parts isooctylphenox~polyoxyethylene ethanol, 1,7 ~arts ch~npagne-cha'J.lc-hydroxyethylcell.ulose m~cture (1:1) . ~ -7-. ~
. . . . : ,- . .
: . . .
. ', , , ' ,' .' " ' , . ,, ,: "

5~7 8.3 parts sodium aluminium silica~e 16.5 parts kieselguhr 46 parts kaolin d)10 parts active agent 3 parts of a mixture of sodi~ salts of saturated fatty alcohol sulphates 5 parts naphthalenesulfonicacidformaldehyde condensate 82 parts kaolin.
- The active agents were intimately mixed in suitable m~xers with the additive materials and milled together on suitable mills and rolls. A spray-able powder is obtained which can be diluted with water to a suspension of any desired concentration Emulsifiable concentrates: For the manufacture of a) 10% and b) 25% emul-sifiable concentrate, the following materials were used:
- a)10 parts active agent 3.4 parts epoxidised vegetable oil 13,4 parts of a combination emulsifier consisting of fatty alcohol ~-- polyglycol ethers and alkylarylsulfonate calcium salt 40 parts dimethylformamide ;~ 43,2 parts xylene -~ 20b)25 parts actiYe substance in aeid ester form 2,5 parts epoxidised vegetable oil 10 parts of an alkylarylsulfonate fatty alcohol polyglycolether mixture S parts dimethylform~mide 57.5 parts xylene From these concentrates, emulsions of any desired concentration can be made by dilution with water.
Spraying agent: For the manufacture of an a3 5% and b) Z% spraying agent, the following components were used:
a) S parts active agent 1 part epichlorohydrin 94 parts petrol (boiling range 160-190) ' .. . . .

~ L~S~S~7 b) 2 parts active agent 3 parts 4,~'-dichlorodiphenyl trichlorethane, 95 parts kerosene.
These solutions were sprayed with pressure sprays~
- The following examples will serve to illustrate the inventioll:

A I. The formyliminoester of the formula , .

Cl r ~ N = CH - OC2H5 1200 g of 2-amino-5-chloro-toluene were boiled under reflux with 2000 ml of ethylorthoformate, The ethyl alcohol formed was continuously distilled away via a colu~l, Towards the end, the reaction was accelerated by the addition of a few drops o~ concentrated sulphuric acid. The reaction solution was then distilled in vacuum.
Yield:1406 g Boiling point: 123-127 C/10 n~Mg .
II. CH
3 CH (compound No. l) C~Hg(n) ~
-~ .
1.35 kg of the above described formyliminoester were boiled under reflux in 2 litres of dry toluene with 630 g N-methyl-n-butylamine for 5 hours, The mix-tuxe was then fractionally distilled under vacuum.
Yield: 1.542`kg Boiling point: 140 C/0,14 n~Hg, j 20 By reaction wLth hydrochloric acid the hydrochloride of this base ; may be obtained. Melting point 148-~50, Cl ~ N = CH - N ~ / CU3 (compoind No. 2) : ' .

_9_ ,~.~ , .
,, , ', :, ''. ', : ' , ~5~
60 g N-methyl-n-isopropylfo~mamide ~boiling point 59-60C / lO mmHg) were heated with 67 g 4-chloro-2-methyl-phenylisocyanate to 160 C until no further carbon dioxide was given off. The reaction product was taken up in ben~ene, filtered and the filtrate distilled. 67 g of N-(2-methyl-4-chlorphenyl)-N~-methyl-N~-isopropyl formamidine of boiling point 114C / 0 009 mmHg were obtained.

/ ~ / (compound no. 3) Br ~ 4 9(n) In a stirring apparatus, with the exclusion of moisture the follow-ing series of steps was carried out: 40 g methyl-butyl-formamide, 300 ml absolute toluene and 24 ml thionyl chloride were mixed, this mixture was stirred for 2 hours at 40C and there was then added dropwise thereto a solu-tion of 56 g 4-bromo-2-methyl aniline in l50 ml absolute toluene at 40-50C.
After the end of the addition the mixture was heated to reflux for 4 hours.
After 2 hours reflux the mi~ture was cooled and made alkaline with 30% caustic soda. The organic phase was separated, washed and dried over sodium sulphate.
After evaporation of the solvent the residue was distilled under vacuum.
Boiling point 120C / 0.03 mmHg.
In similar fashion the following compounds could also be manufactured.
: ' ' _ PhysiCal data.Boiling point No. Melting point. Refractive index CH C

; 4 1 ~ ~ ~= CN-N \ 127 C/0.7 mnHg ~S 112~C/0.01 mmHg ,,~

= . . ~ . ..... .
~ompound . Physical d~taD Boiling pOillt No. . Melti ng point or refractiYe indcx . __ .

7 ~ C ~N=CH-N\ ~ 114 -117C/0,19 I lHg / I ~ 117 C/0.3 ImllHe :~ lC. ~ 1~N= CH-N~ 111 -11l C/0.01 mmH8 20, ¦ ~ ~o , 137 C/0, 7 n~nHg 21. 1 ~r 25 . I N=CH-N\ ND = 1.6171 22, ~ ~ ~<C H; ~ ND = 1.5845 ~ c~ 4 /0.02 '~ , ', , : ' !

Compound v . . ~hygiCal data. Doiling pOillt : No. Melting point or refractive index.
. _ . . . .

24. ~ ~U \ ~ N~= 1.6054 ~5~ 1 ~ ~ N CH~N ~ 125 C ~,56 m~Hg 26.

120 C/0,02 mmHg ~'~ ' ..
., .

~ -12-,. - .
.. . . .

. .

Exam~le 2 Three groups each of two oxen, which were strongly infcctcd with ,....... .
Boophilus microplus ~ere tested as follows: (1) One group was not treated and was used as control group, (2~ One group was treated with a 0.05% aqueous preparation of "chlorphenamidine" and (3) One group was treated with 0.05%
aqueous preparation of the compound No. I.
Treatment took place with a so-called hand spray in such a fashion ~- that the animals were sprayed until they were fully wetted. ~le aqueous pre-paration was made from an emulsion concentrate according to Example 2.
Evaluation started on the day after treatment, i.e. the enumeration of fully sucked females lasted from the first up to the twenty-first day after treatment. Egg laying was determined for six weeks on hatched larvae. The results are expressed in the following table.

, ~
Total of fully Total females Total of % of fertile sucked females which had laid fertile eggs eggs laid , ~ _ _ eggs _laid ; Contr~l 37 330 33 312 30 984 83 . 1, _ ..
, chlorphenamidine1630 924 ~ 542 33 : ~, : _ .
20~ ~ompound No. 1 740 409 22 3 Example 3 -l Two series of simulated "cattle dips~' were manufactured. As active agents A chlorphenamidine B compound No. 1 ' were used. The manufacture of dips took place by diluting an emulsion con-centra~e according to Example 2 with water, the active agent content of the dips , being adjusted to 1,000 ppm. The dips were tested for their effectiveness after 1, 2, 3, 4 and S weeks. As test animals, tick larvae were used which had been treated in each case with tests with a dilution row of 100, 10, 1 and 0.1 ppm active agent content. Rcsults are expressed in the following table in which:
- - equals less than 50% of the larvae werc dead , .

-: ,. ; . . , . : . .
: -, , .:
,, . , . ,, , ,. ,. , ., :,:
.. . .

~ equals 50-98% of the larvae were dead + all larvae dead.

CompoundConcentra~ion Action after number of weeks in ppm 1 2 3 4 -., 10 + + + + +
;~ 100 + + + + ~ . -., , ~ _ Example 4 ~- ~3 Rhipicephalus bursa In each case 5 adult ticks or 50 tick larvae were counted into a glass tube and dipped for 1-2 minutes in 2 ml of an aqueous emulsion from a , ~
dilution row with concentrations of 100, 10, 1 and 0.1 ppm test substance~ The tube was then closed with a standard cotton wool plug and turned on its head so that the emulsion of active substance could be taken up by the cotton wool.
Evaluation took place for adults after 2 weeks and for larvae after 2 days. ~ach test was repeated twice. 100% kill was determined at the follow-ing boundary concentrations (ppm):

., , :

:

"~.j~l I

.
. ,,, f , . , ;~, ~ ' : ; ` ;
~:

S~i7 . Compound Rhipicephalus bursa ; No. larvae adults ; _ - -0.5 _ _ 50 . 6 0.1 50 7 ~1 10 :~

'~,; 10 O.1 _ . .
B) Boophilus microplus ~larvae) With a similar dilution row as used in tes~ A, experiments were ~i carried out each time with 20 sensitive or op-resistant larvae (resistance was ~i related to compatability with diazinon). 100% kill was determined at the following boundary concentrations (ppm) after 2 weeks:
; .
I _ _ _ , Compound Boophilus microplus ~: No. Larvae i . resistant sensitive ' ._ _ _ _ .
.~ 1 0.1 0.1 , .
: ': 2 0.1 0.1 ..
~ 0.1 0.1

6 0.5 0.5 ~.
~ 7 0.1 0.1 ,, 8 0.1 0.1 .'~ 9 0.5 0.5 ~ :
,1 10 0. 1 0. 1 '. ~
, 25 10 10 27 10 10 , -,., ,, , . , - .

Acaricidal Action Phaseolus vulgaris (Dwarf bean) were infested 12 hours bcfore the test for acaricidal action with an infested leaf piece from a mass culture of Tetranychus urticae. The various stages which were over-running the plant were dusted with the emulsified test prcparation from a chromatography atomizer which ensured no running off of the spray layer. After 2-7 days, larvaeJ adults and eggs were evaluated under a binocular microscope for living and dead indivi&uals and the results expressed in percentages. During the holding time the treated plants were in a greenhouse at 25C, Compo~md No. 1 showed the following results (% kill) _ , Effect after Eggs Larvae Adults .
~' 2 days _ 100 100

7 days 90 100 100 .
Bxample 6 . .
a) Action against Chilo suppressalis (larvae) Substances No. 2 and 3 were tested' for their inJection effect on L-2-larvae. For this test the larvac ~ere put on the roots of rice seedlings which had previously been dipped in an emulsion of the active substance.
Bvaluation took place after 5 days and the results are expressed in the follow-ing table.
', - . :
: j . , _ _ .. _ Concentration of active Percentage kill for active substance in the emulsion substance . . .
(ppm) No.2 No. 3 . .

~00 80 BO

. _ .
b) Action against Orgya gonostigma The test witll Orgya ~onostigma in thc L-3-stage was carried out as .
,~

6~17 follows:
Young mallow plants (Malva silvestris) were dipped in an emulsion of the active agent preparation and then allowed to dry. The test animals (5 larvae per test) were provided in a cellophane bag which was ~hen inverted over the treated plan~ and closcd with a rubber band. After 5 days the effect-iveness of the treatment was carried out by counting the living and dead larvae and calculation of the percentage kill. For substances 1, 2 and 5 the following kills of the larvae (in %~ were determined.
. ~ .

~, Substance No. Concentration ppm j After 5 days I .

.1 S I lo~o I ~0 ., .

.
' ~ 17 -"

,

Claims (23)

The embodiments of the invention in which an exclusive property or privilege is claimed are devined as follows:

1. Formamidine derivatives of the formula I

(I) wherein R1 represents a methyl or ethyl group, R2 represents an n-propyl, isopropyl, n-butyl, iso-butyl or sec.-butyl group, R3 represents a fluorine, chlorine, bromine or iodine atom, and R4 represents a methyl or ethyl group and their acid addition salts.

2. A formamidine derivative according to claim 1, wherein R3 represents a chlorine atom.

3. The formamidine derivative of claim 1 of the formula

4. The formamidine derivative of claim 1 of the formula

5. The formamidine derivative of claim 1 of the formula

6. The formamidine derivative of claim 1 of the formula

7. The formamidine derivative of claim 1 of the formula

8. The formamidine derivative of claim 1 of the formula

9. The formamidine derivative of claim 1 of the formula

10. The formamidine derivative of claim 1 of the formula

11. The formamidine derivative of claim 1 of the formula

12. The formamidine derivative of claim 1 of the formula

13. The formamidine derivative of claim 1 of the formula

14. The formamidine derivative of claim 1 of the formula

15. The formamidine derivative of claim 1 of the formula

16. The formamidine derivative of claim 1 of the formula

17. The formamidine derivative of claim 1 of the formula

18. The formamidine derivative of claim 1 of the formula

19. Process for the production of a formamidine derivative of the formula I as defined in claim 1 or an acid addition salt thereof selected from :
a) reacting the corresponding compound of the formula II

(II) with a compound of the formula III

(III) wherein R1 and R2 have the meanings given in claim 1, in the presence of thionyl chloride, carbonyl chloride, phosphorous oxychloride, phosphorous trichloride, phosphorous pentachloride, dimethyl-sulphate or tosyl-chloride;
b) reacting the corresponding compound of the formula IV

(IV) wherein R5 represents an alkyl group having at most 4 carbon atoms with a compound of the formula V

(V) wherein R1 and R2 have the meanings given in claim 1, at a temperature of from 0°C to 200°C; and c) reacting the corresponding compound of the formula VI

(VI) with a compound of the formula III as defined above at a temperature of from 100°C to 200°C; and further when required converting a formamidine derivative of the formula I thus obtained into an acid addition salt thereof or converting an acid addition salt of a formamidine derivative of the formula I thus obtained into the free formamidine or into another acid addition salt thereof.

20. A method of combating pests at a locus, which method comprises applying to the locus a compound according to claim 1.

21. A method according to claim 20 wherein the pests are of the class Insecta or Acarina.

22. A method according to claim 21 wherein the compound is applied at a concentration of 10 to 800 ppm.

23. A method according to any one of claims 20 to 22 wherein the locus comprises agricultural or horticultural crops, plants or produce, the seeds or vegetation reproductive parts of such crops or plants, goods of organic material in storage or any area in which such goods are to be stored.