Novel Insecticides

The present invention relates to novel 2-cyclopropylamino-4-formamidino-6-amino-s-triazine derivatives, to a process for their manufacture and to their use in pest control.

The 2-cyclopropylamino-4-formamidino-6-amino-s-triazine derivatives have the formula ##STR2## wherein R.sub.1 represents hydrogen, C.sub.1 -C.sub.4 -alkyl which is unsubstituted or substituted by lower alkoxy, or represents C.sub.3 -C.sub.4 -alkenyl, C.sub.3 -C.sub.4 -alkynyl, cyclopropyl, hydroxyl, methoxy or ethoxy,

R.sub.2 represents hydrogen, methyl or ethyl, or

R.sub.1 and R.sub.2 together with the nitrogen atom to which they are attached present a 5- or 6-membered heterocyclic ring which can contain a further nitrogen atom or an oxygen atom,

R.sub.3 represents methyl or ethyl,

R.sub.4 represents methyl or ethyl, and

R.sub.5 represents hydrogen or methyl.

Possible alkyl groups represented by R.sub.1 can be straight-chain or branched, unsubstituted or substituted for example by lower alkoxy groups of 1 to 4 carbon atoms. Examples of such alkyl groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec. and tert.butyl and 2-methoxyethyl. Examples of possible C.sub.3 -C.sub.4 -alkenyl and C.sub.3 -C.sub.4 -alkynyl groups represented by R.sub.1 include allyl and propargyl respectively.

Preferred compounds on account of their action are compounds of the formula I in which R.sub.1 represents hydrogen, C.sub.1 -C.sub.4 -alkyl which is unsubstituted or substituted by lower alkoxy, or represents C.sub.3 -C.sub.4 -alkenyl, C.sub.3 -C.sub.4 -alkynyl, cyclopropyl, hydroxyl, methoxy or ethoxy, R.sub.2 represents hydrogen, methyl or ethyl, or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are attached represent 1-pyrrolidinyl, 1-piperidinyl, 4-morpholinyl, 1-piperazinyl, 1-(4-methyl)-piperazinyl or 1-imidazolyl, R.sub.3 represents methyl or ethyl, R.sub.4 represents methyl or ethyl and R.sub.5 represents hydrogen or methyl.

Particularly advantageous compounds are those in which R.sub.1 represents hydrogen, methyl, ethyl, isopropyl, 2-methoxyethyl, allyl, propargyl or cyclopropyl, R.sub.2 represents hydrogen or methyl or R.sub.1 and R.sub.2 together with the nitrogen atom to which they are attached represent 1-pyrrolidinyl, 4-morpholinyl or 1-imidazolyl, R.sub.3 represents methyl, R.sub.4 represents methyl and R.sub.5 represents hydrogen, and in which, if R.sub.1 represents propargyl, R.sub.2 preferably represents hydrogen.

Compounds to be particularly highlighted are those in which R.sub.1 represents hydrogen, methyl or ethyl, R.sub.2 represents hydrogen, R.sub.3 represents methyl, R.sub.4 represents methyl and R.sub.5 represents hydrogen.

Particularly preferred compounds are:

2-cyclopropylamino-4-dimethylformamidino-6-amino-s-triazine,

2-cyclopropylamino-4-dimethylformamidino-6-ethylamino-s-triazine,

2-cyclopropylamino-4-dimethylformamidino-6-methylamino-s-triazine, and

2-cyclopropylamino-4-dimethylformamidino-6-propargylamino-s-triazine.

The compounds of the formula I are obtained by methods which are known per se, for example by

(a) reacting a 2-cyclopropylamino-4,6-diamino-s-triazine of the formula II ##STR3## in which R.sub.1, R.sub.2 and R.sub.5 are as defined in formula I, with a carboxy amide acetal or ketal of the formula III ##STR4## in which R.sub.3 and R.sub.4 are as defined in formula I, or

(b) reacting a 2-cyclopropylamino-4-formamidino-6-chloro-s-triazine of the formula IV ##STR5## in which R.sub.3, R.sub.4 and R.sub.5 are as defined in formula I, with ammonia or with a primary or secondary amine of the formula V ##STR6## in which R.sub.1 and R.sub.2 are as defined in formula I.

The above reactions (a) and (b) are preferably carried out in solvents or diluents which are inert to the reactants, for example in aliphatic or aromatic hydrocarbons, halogenated hydrocarbons, ethers or ethereal compounds or ketones.

Catalysts, for example p-toluenesulphonic acid, can be added to the reaction mixture, but are not essential. The reaction temperatures are between 30.degree. and 130.degree. C.

The starting materials of the formulae II and IV can be prepared in accordance with known processes by replacing chlorine in chlorinated s-triazine derivatives by a corresponding amino group or by several corresponding amino groups.

The manufacture of 2-diallylamino-4-amino-6-(N,N-dimethylformamidine)-s-triazine is described in U.S. Pat. No. 3,073,851.

Diamino- and triamino-s-triazines are described as chemosterilants for adult houseflies (Musca domestica) in U.S. Pat. No. 3,189,521. The chemosterilising action on insects of 2,4,6-triamino-s-triazine derivatives (melamine derivatives) is also described by S. Nagasawa et al., Botyu-Kagaku 39 (4), 105 (1974). A. B. Borkovec and A. B. DeMilo [J.Med.Chem. 10 (5), 457 (1967)] and G. C. LaBrecque, R. L. Fye, A. B. DeMilo and A. B. Borkovec [J.Econ.Entomol. 61,(6), 1621 (1968) also describe the chemosterilising action of, inter alia, 2-cyclohexylamino-4,6-diamino-s-triazine, 2-cyclohexylamino-4,6-dihexylamino-s-triazine and 2,4,6-tris-cyclohexylamino-s-triazine, and the salts thereof, on adult houseflies (Musca domestica).

The above mentioned insecticidal chemosterilants are employed to adult insects, i.e. the stage of reproduction and dissemination for impairing or preventing capability of producing offspring of said insects. Combatting populations of harmful insects by introduction of sterile insects capable of copulating into a normal inset population taking final aim at self-destruction represents an indirect method for combatting insects.

In practice, degeneration of an insect population by introduction of sterile insects into said population extends to a sequence of some to numerous generations of insects and therefore, further dissemination of organisms harmful to men or animals may occur by vector insects. Furtheron, insects may gradually become resistent to applied chemosterilants.

Therefore, direct methods for combatting insects by killing them or preventing individual development are required.

Surprinsingly, it has now been found that treating insect larvae representing the stage of eating and growing with compounds of formula I results in killing the freshly hatched larvae or preventing adults from hatching the pupae. The mode of action of the compounds of formula I is not to be compared with that of classical insecticides, chemosterilants or juvenile hormone analogues.

The active compounds of the formula I can be used in particular for controlling hygiene pests and animal ectoparasites of the order Diptera and of the families: Culicidae, Simuliidae, Tipulidae, Muscidae and Calliphoridae.

The compounds of the formula I can be used as pure active substance or together with suitable carriers and/or additives. Suitable carriers and additives can be solid or liquid and correspond to the substances conventionally used in the art of formulation, for example natural or regenerated substances, solvents and/or dispersants.

The compositions according to the invention are manufactured in known manner by homogeneously mixing and/or grinding active substances (compounds) of the formula I with the suitable carriers, with or without the addition of dispersants or solvents which are inert to the active substances.

The active substances may be processed to the following formulations:

Solid formulations:

Dusts, tracking agents and granules (coated granules, impregnated granules and homogeneous granules), premix (feed additive).

Liquid formulations:

(a) active substance concentrates which are dispersible in water: wettable powders, pastes and emulsions;

(b) solutions: sprays (aerosols).

To manufacture solid forms, (dusts, tracking agents), the active substances are mixed with solid carriers. Suitable carriers are, for example: kaolin, talc, bolus, loess, chalk, limestome, ground limestone, attaclay, dolomite, diatomaceous earth, precipitated silica, alkaline earth silicates, sodium and potassium aluminium silicates (feldspar and mica), calcium and magnesium sulphates, magnesium oxide, ground synthetic materials, fertilisers, for example ammonium sulphate, ammonium phosphate, ammonium nitrate, urea, ground vegetable products, such as corn meal, bark dust, sawdust, nutshell meal, cellulose powder, residues of plant extractions, activated charcoal etc. These substances can either be used singly or in admixture with one another.

Granules can be very easily manufactured by dissolving an active substance of the formula I in an organic solvent and applying the solution thereby obtained to a granulated mineral, for example attapulgite, SiO.sub.2, granicalcium, bentonite etc. and then evaporating the solvent.

Polymer granules can also be manufactured by mixing the active substances of the formula I with polymerisable compounds (urea/formaldehyde; dicyandiamide/formaldehyde; melamine/formaldehyde or others), whereupon a mild polymerisation is carried out that does not affect the active substances and in the process of which the granulation is carried out during the gel formation. It is more advantageous to impregnate finished, porous polymer granules (urea/formaldehyde, polyacrylonitrile, polyester or others) which have a specific surface area and a favourable predeterminable adsorption/desorption ratio, with the active substances, for example in the form of their solutions (in a low boiling solvent) and to remove the solvent. Polymer granules of this kind in the form of microgranules having preferably a bulk density of 300 g/liter to 600 g/liter can also be manufactured with the aid of atomisers.

It is also possible to obtain granules by compacting the carrier with the active substance and additives and subsequently comminuting the product.

To these mixtures can also be added additives which stabilize the active substance and/or nonionics, anionics and cationics, which, for example, ensure a better wettability (wetting agents) and dispersibility (dispersants). Examples of suitable substances are: olein/chalk mixture, cellulose derivatives (methyl cellulose, carboxymethyl cellulose), hydroxyethyl glycol ethers of monoalkyl and dialkyl phenols having 5 to 15 ethylene oxide radicals per molecule and 8 to 9 carbon atoms in the alkyl moiety, ligninsulphonic acid, the alkali metal and alkaline earth metal salts thereof, polyethylene glycol ethers (carbowaxes), fatty alcohol polyethylene glycol ethers having 5 to 20 ethylene oxide radicals per molecule and 8 to 18 carbon atoms in the fatty alcohol moiety, condensation products of ethylene oxide, propylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, condensation products of urea and formaldehyde, and also latex products.

Water-dispersible concentrates, i.e. wettable powders, pastes and emulsifiable concentrates, are compositions which can be diluted with water to the desired concentration. They consist of active substance, carrier, optionally additives which stabilize the active substance, surface-active substances and anti-foams and, if appropriate, solvents.

Wettable powders and pastes are obtained by mixing and grinding the active substances with dispersants and pulverulent carriers in suitable devices until homogeneity is attained.

Suitable carriers are, for example, those already mentioned for the solid forms of application. In some cases it is advantageous to use mixtures of different carriers. Examples of dispersants are condensation products of sulphonated naphthalene and sulphonated naphthalene derivatives with formaldehyde, condensation products of naphthalene or naphthalene sulphonic acids with phenol and formaldehyde as well as alkali metal, ammonium and alkaline earth metal salts of ligninsulphonic acid, in addition, alkylaryl sulphonates, alkali metal and alkaline earth metal salts of dibutylnaphthalenesulphonic acid, fatty alcohol sulphates such as salts of sulphated hexa-decanols, heptadecanols, octadecanols, and salts of sulphated fatty alcohol glycol ethers, the sodium salt of oleyl methyl tauride, ditertiary ethylene glycols, dialkyl-dilaurylammonium chloride and fatty acid alkali metal and alkaline earth metal salts.

Suitable anti-foams are for example silicone oils.

The active substances are so mixed, ground, sieved and strained with the additives mentioned above that, in wettable powders, the solid particle size of 0.02 to 0.04 mm and in pastes, of 0.03 mm, is not exceeded. Emulsifiable concentrates and pastes are manufactured by using dispersants, such as those referred to above, organic solvents, and water. Examples of suitable solvents are: alcohols, dimethyl sulphoxide, and mineral oil fractions which boil between 120.degree. and 350.degree. C. The solvents must be virtually odourless and inert to the active substances.

Furthermore, the compositions according to the invention can be applied in the form of solutions. For this purpose the active substances or several active substances of the general formula I are dissolved in suitable organic solvents or mixtures of solvents. Aliphatic and aromatic hydrocarbons, chlorinated derivatives thereof, alkylnaphthalenes and mineral oils, singly or in admixture, can be used as organic solvents.

Formulations of the novel active compounds of the formula I are described hereinafter. The parts denote parts by weight.

Dusts:

The following substances are used to manufacture (a) a 0.5% and (b) a 2% dust:

0.5 part of active substance

99.5 parts of talc

2 parts of active substance

1 part of highly disperse silicic acid

97 parts of talc.

The active substances are mixed with the carriers and ground.

Tracking Agents:

5 parts of active substance are mixed with

95 parts of carbonate of lime and ground to an average particle size of 80.mu..

Granules:

5 parts of active substance are dissolved in a solvent, e.g. methylene chloride, and mixed with

2 parts of polyethylene glycol ("Carbowax").

91.5 parts of calcium carbonate are impregnated with the mixture and

1.5 parts of precipitated silicic acid are admixed.

The solvent is subsequently evaporated.

Wettable Powder:

50 parts of active substance are mixed with

5 parts of a dispersing agent, e.g. sodium ligninsulphonate,

5 parts of a wetting agent, e.g. dibutylnaphthalenesulphonic acid

10 parts of silicic acid and

30 parts of China clay and the mixture is finely ground.

Emulsifiable Concentrate:

20 parts of active substance are mixed with

20 parts of emulsifier, e.g. a mixture of alkylarylpolyglycol ether with alkylarylsulphonates, and

60 parts of solvent until the solution is completely homogeneous. By diluting this concentrate with water it is possible to obtain an emulsion of the desired concentration.

Premix (feed additive):

0.25 parts of active substance and

4.75 parts of secondary calcium phosphate, or China clay, aerosil or carbonate of lime are homogeneously mixed with

95 parts of an animal feed, e.g. poultry food.

Spray:

The following constituents are used to manufacture a 2% spray:

2 parts of active substance

98 parts of kerosene.

Other biocidal active substances or agents can be admixed with the compositions described hereinabove. Thus in addition to the cited compounds of the general formula I, the compositions of the present invention can obtain, for example, insecticides to broaden the activity spectrum. The compositions, or the active compounds contained therein, exert their inhibitory action therefore chiefly on the development of larvae or pupae of insects, preferably of the order Diptera.

20 g of 2-cyclopropylamino-4-amino-6-morpholino-s-triazine are suspended in 200 ml of benzene and the suspension is treated with 13 g of N,N-dimethylformamide-dimethyl acetal with the addition of 0.5 g of p-toluenesulphonic acid (as catalyst). The reaction mixture is refluxed for 10 hours. The solvent is then removed in vacuo and the residue is suspended in ether. The precipitated solid is recrystallised from isopropanol. Melting point: 160.degree.-162.degree. C.

The following compounds are prepared in accordance with the above procedure:

50 g of freshly prepared CSMA nutrient substrate for maggots are charged into beakers. 2.5 ml portions of a 1% acetonic solution of the respective active substance are pipetted onto the nutrient substrate present in the beakers. The substrate is then thoroughly mixed and the solvent subsequently allowed to evaporate.

Then 25 one-, two- and three- day-old maggots and approx. 50 eggs of Musca domestica are put into each of the beakers containing the treated nutrient substrate for testing with each active substance.

After the maggots have pupated, the pupae are separated from the substrate by flushing them out with water and counted.

The number of flies which have hatched out of the pupae is then counted after 10 days and any influence on the metamorphosis thereby determined.

The compounds of the formula I displayed good activity in this test.

1 ml of an aqueous solution containing 0.5% of active substance is added to 9 ml of a culture medium at 50.degree. C. Then approx. 30 freshly hatched larvae of Lucilia sericata are added to the culture medium and the insecticidal action is determined by evaluation of mortality after 48 and 96 hours respectively. In this test, the compounds of the formula I act well against Lucilia sericata.

Active substance concentrations of 10, 5 and 1 ppm respectively are obtained by pipetting a specific amount of a 0.1% solution of the active substance in acetone onto the surface of 150 ml of water in each of a number of beakers. After the actone has evaporated, 30 to 40 two-day-old larvae of Aedes aegypti are put into each of the beakers containing the active substance solution. Evaluation of mortality is made after 1, 2 and 5 days respectively.

In this test, the compounds of the formula I exhibit good action against Aedes aegypti.