organic phosphorus insecticide with low toxicity and their method of preparation

摘要

The invention comprises O,O-dimethyl-O-(4-cyanophenyl) thionophosphate. It may be obtained by reacting O,O-dimethyl chlorothionophosphate with 4-cyanophenyl or an alkali metal salt thereof. The reaction is preferably carried out in an inert organic solvent and substantially equimolecular proportions of the reactants are general employed. When the free 4-cyanophenyl is used the reaction is preferably carried out in the presence of an acid binding agent, e.g. an organic base such as pyridine or diethylamine, or an alkali metal carbonate or bicarbonate. Suitable solvents are hydrocarbons, halogenated hydrocarbons, alcohols, ketones and ethers. A dehydrohalogenation catalyst, e.g. copper powder or a cuprous salt may also be present. The product has insecticidal properties (see Division A5).ALSO:An insecticidal composition comprises an inert carrier and as active ingredient O,O-dimethyl O - (4 - cyanophenyl) thionophosphate (see Division C2). The invention also includes a method of eradicating injurious insects, especially borers of rice, from a crop area containing a growing crop which comprises applying to the crop area an insecticide comprising O,O-dimethyl O-(4-cyanophenyl) thionophosphate. The insecticidal compositions may be in the form of an emulsion, suspension, dust or oil preparation. In preparing the emulsion the active ingredient, which is stated to have low toxicity to warm blooded animals, may be mixed with an organic solvent, e.g. benzene or xylene, and a non-ionic surface active agent to form an emulsifiable concentrate suitable for dilution with water before use. Wettable powders may be obtained by mixing the active ingredient with a non-ionic surface active agent and a powdered carrier and are then added to water to form a suspension. Dusts may be formed by mixing the active ingredient with a powdered carrier with or without the use of a volatile solvent, e.g. acetone. Oil preparations may be obtained by dissolving the active ingredient in a solvent such as deodorized kerosene if desired with the use of a co-solvent, e.g. an aromatic hydrocarbon such as benzene, xylene or methylnaphthalene. A fungicide, herbicide or other insecticide may also be present.