NO122652B - - Google Patents

Description

Pyrimidine derivative with insecticidal and fungicidal action.

This invention relates to a pyrimidine derivative with insecticidal and fungicidal action.

In our British Patent No. 1,019,227 we have described pyrimidine derivatives of the formula:

where R 1, R 2 and R<5>, which may be the same or different, mean alkyl or alkenyl radicals with no more than 6 carbon atoms, or R<1> and R<2 >together with the adjacent nitrogen atom form a heterocyclic radical , R and R are hydrogen or an alkyl or alkenyl radical of not more than 6 carbon atoms, and X is an oxygen or sulfur atom. These

pyrimidine derivatives have insecticidal and fungicidal properties.

According to the present invention, a new pyrimidine derivative is provided, namely 0-(2-diethylamino-4-methyl-6-pyrimidinyl)-0,0-dimethylphosphorothioate. This compound has the formula:

in

The above connection is new. It differs from other compounds of the general formula set out in British Patent No.

1,019,227, in that it has a remarkably low oral toxicity to mammals. It has an acute oral LD^Q for female rats of 2,250 mg per kg and it is thus an order of magnitude less toxic than other closely related pyrimidine derivatives. As an example, the toxicities of two known insecticides with similar chemical structure are given below:

Said pyrimidine derivative according to the invention can be prepared by reacting a compound with the formula: where R is hydrogen or an alkali metal atom with a halogen derivative with the formula:

where Y is a halogen atom.

When R means an alkali metal atom, it can e.g. be a sodium or potassium atom. Appropriately, Y is e.g. a chlorine or bromine atom.

In the case where R is hydrogen, . the starting compound - the ice is first converted into a corresponding alkali metal derivative, e.g. by reaction with a solution of sodium in ethanol, or the reaction is carried out in the presence of an acid-binding agent, e.g. an alkali metal salt of a weak acid, such as an alkali metal carbonate, e.g. potassium carbonate, or a tertiary organic base, such as a trialkylamine of not more than 12 carbon atoms, e.g. an N,N-dialkylarylamine of not more than 12 carbon atoms, such as N,N-dimethylaniline.

The reaction can conveniently be carried out in an inert diluent or solvent, e.g. ethyl acetate or benzene, and it may be accelerated or brought to completion by the application of heat.

The pyrimidine derivative according to the invention can optionally be used in the form of its acid addition salts. These can be made by reacting the pyrimidine derivative with an equivalent amount of an acid, e.g. a mineral acid. Examples of suitable acids are hydrogen halides, nitric acid and phosphoric acid. Diluted acids are preferably used.

The pyrimidine derivative according to the invention particularly possesses good insecticidal properties. It also has fungicidal properties. <

The pyrimidine derivative according to the invention can thus be used in biologically active derivatives together with a diluent or carrier.

The preparations can be used for agricultural, horticultural or veterinary purposes, and the type of preparation used in each individual case will depend on the particular purpose.

The preparations can be in the form of loose powders where the active ingredient is mixed with a solid diluent or carrier. Suitable solid diluents or carriers can e.g. be kaolin, benonite, diatomaceous earth, dolomite, calcium carbonate, talc, powdered magnesium oxide, valke earth, gypsum, Hewitt's earth and diatomaceous earth.

The preparations can also be in the form of liquid preparations used as dipping or spraying agents, which are generally aqueous dispersions or emulsions containing the active ingredient in the presence of one or more wetting agents, dispersing agents, emulsifying agents or suspending agents.

Humectants, dispersants and emulsifiers can be of cationic, anionic or non-ionic type. Suitable agents of the cationic type include e.g. quaternary ammonium compounds, such as cetyltrimethylammonium chromide. Suitable agents of the anionic type include e.g. soaps, salts of aliphatic monoesters^ of sulfuric acid, such as sodium lauryl sulfate, salts of sulfonated aromatic compounds, such as sodium dodecylbenzene sulfonate, sodium, calcium or ammonium lignosulfonate, butyl naphthalene sulfonate and a mixture of the sodium salts of diisopropyl and triisopropyl naphthalenesulfonic acids. Suitable agents of the non-ioric type include e.g. the condensation products of ethylene oxide with fatty alcohols such as oleyl alcohol, or with alkylphenols such as octylphenol, nonylphenol and octylcresol. Other non-ionic agents are the partial esters derived from long-chain fatty acids and hexitol anhydrides, the condensation products of said partial esters with ethylene oxide, and lecithins. Suitable suspending agents are e.g. hydrophilic colloids, e.g. polyvinylpyrrolidone and sodium carboxymethylcellulose, and vegetable gums such as acacia gum and tragacanth gum.

The aqueous dispersions or emulsions can be prepared by

to dissolve the active ingredient or the active ingredients in an organic dispersing agent which may contain one or more wetting agents, dispersing agents or emulsifying agents, and then the thus obtained mixture is added to water which likewise contains one or more wetting agents, dispersing agents or emulsifying agents. Suitable organic solvents are isopropyl alcohol, propylene glycol, diacetone alcohol, toluene, kerosene, methylnaphthalene, xylenes and trichloroethylene.

The preparations to be used as spray preparations can also be in the form of aerosols, where the preparation is held in a container under pressure in the presence of a propellant such as fluorotrichloromethane or dichlorodifluoromethane.

By introducing suitable additives, e.g. in order to improve the distribution, adhesiveness and resistance to rain on treated surfaces, the different preparations can be made better suited to the different forms of application for which they are to be used.

The preparations to be used in the form of aqueous dispersions or emulsions are generally sold in the form of a concentrate containing a high proportion of the active ingredient or active ingredients, and this concentrate is diluted with water before use. The concentrates often have to withstand dilution with water in order to form aqueous preparations which remain homogeneous for a sufficient time so that they can be sprayed with ordinary spraying equipment. The concentrates can contain from 10 to 85% by weight of the active ingredient or active ingredients. When diluted to form aqueous preparations, the preparations may contain varying amounts of the active ingredient or active ingredients depending on the intended use.

For agricultural or horticultural purposes, an aqueous preparation containing between 0.001 and 0.1% by weight of the active ingredient or active ingredients can be used.

The preparations can be stabilized by introducing stabilizers, e.g. epoxides, such as epichlorohydrin. They can possibly be mixed with other crop protection products.

Pests can be combated by applying an insecticidal amount of the pyrimidine derivative according to the invention to the pests as such or at their place of residence.

The compound of the invention exhibits considerable toxicity to a variety of pests including, in addition to those illustrated in the examples, Lucilia sericata (spit fly) and Pieris brassicae and also soil pests including flies, beetles and Meloidogyne incognia (nematodes) .

They are also effective against various plant fungal diseases, e.g. rice blight (Piricularia oryzae).

The invention is illustrated by the following examples:

EXAMPLE 1

The compound O-(2-diethylamino-4-methyl-6-pyrimidinyl)-0,0-dimethylphosphorothioate was prepared as follows: 2-diethylamino-4-methyl-6-hydroxypyrimidine (0.06 mol) was mixed with 0.7 g (0.07 mol) anhydrous potassium carbonate in ethyl acetate

(130 mL), and dimethyl chlorothiophosphate (0.06 mol) was slowly added. The solution was refluxed overnight, cooled and evaporated to dryness under reduced pressure. The residue was then taken up in toluene, washed free of unreacted hydroxypyrimidine with cold 3% aqueous sodium hydroxide followed by water, until the washes were neutral. After drying over anhydrous magnesium sulfate and removal of the solvent, the crude product was obtained. This was heated to 75°C under a pressure of 0.2 mm Hg for 2 h to remove unreacted chlorothiophosphate, giving a final wt yield of pure O-(2-diethylamino-4-methyl-6-pyrimidi-

nyl)-0,0-dimethyl phosphorothioate, which was 80% of the theoretical yield, 24

n£ = 1.5291.

in

EXAMPLE 2

The activity of the compound prepared according to Example 1 was tested against a number of different insects. The compound was in each case used in the form of liquid preparations containing 1000, 500 or 125 parts by weight of the compound per million. The preparations were prepared by dissolving the compound with a mixture of solvents consisting of 4 parts by volume of acetone and 1 part by volume of diacetone alcohol. The solutions were then diluted with water containing 0.01% by weight of a wetting agent, sold under the name "LISSAPOL NX"

(condensate of one mole of nonylphenol with 8 moles of ethylene oxide), until the liquid preparations contained the desired concentration of the compound.

The test method used for each test insect was generally the same and included that a number of the insects were placed on a medium that was a host plant or a food item that the insect eats, and either the insect or the medium or both were treated with the preparations.: The mortality of the insects was then determined at certain times which usually varied from 1 to 3 days after the treatment.

The results of the test are reproduced in the following table I.

In this table, the first column means the concentration of the compound in the used test solution. Each of the following columns indicates the name of the test insect, the host plant or the medium on which the insect was placed, and the number of days after treatment before the number of insects killed was noted. The measurements are expressed as whole numbers in the range from 0-4.

EXAMPLE 3

The compound prepared by the method according to example 1 was tested against mosquito larvae in comparison with diazinon. The test insect was placed in dilute solutions of the compounds, and the mortality was measured after 24 hours. The results are shown in the following table 2.

In the log 2 tables, a line indicates that no test was carried out.

EXAMPLE 4

The hydrochloride of O-(2-diethylamino-4-methyl-6-pyrimidinyl)-0,O-dimethyl phosphorothioate was prepared as follows: 3.05 g of the product from Example 1 was added to 10 ml of 1 N hydrochloric acid in a 250 ml conical flask. This was heated in a steam bath

for 10 minutes with the addition of ethanol to homogenize the mixture. The solution was then evaporated on a rotary evaporator, taken up in absolute ethanol and evaporated again, and this procedure was

repeated four times to remove water. The remaining oil was heated on a steam bath at approx. 100°C for 4 hours under a pressure of 0.05 mm Hg to remove all traces of solvent. The pure salt was available as a very viscous, straw-yellow oil.

EXAMPLE 5

The hydrogen oxalate salt of O-(2-diethylamino-4-methyl-6-pyrimidinyl)-O,O-dimethyl phosphorothioate was prepared as follows: 3.05 g of the pyrimidine derivative, 1.26 g of oxalic acid dihydrate and 25 ml of ethanol was placed in a 250 ml conical flask and heated on a steam bath until all the ethanol had evaporated. The residue was taken up in ethanol and subjected to the same drying process as that used in Example 4. The salt was returned as a pale straw-yellow oil which solidified to a

in

in

glass upon cooling.

The fluoroborate and p-toluene sulfonate salts were made by similar methods. They were obtained as viscous liquids which solidified into glass upon cooling.

Claims (1)

Pyrimidine derivative and acid addition salts thereof with insecticidal and fungicidal action, characterized in that it is 0-(2-diethylamino-4-methyl-6-pyrimidinyl)-0,O-dimethylphosphorothioate which has the formula: