Patent GB-514678-A (GB)
Title: Improvement in insecticides
Filed: 1938-04-07
Abstract: 514,678. Insecticides. ROHM & HAAS CO. April 7, 1938, No. 10635. Convention date, May 11, 1937. [Class 81 (i)] [Also in Group IV] Insecticidal compositions are prepared by the admixture of a substantially neutral phenyl benzyl ether having as a nuclear substituent a nitro group, an acyl group, or a hydrocarbon group containing more than two carbon atoms, with a powdered carrier or with an emulsifying agent or both. The aromatic ring of either the benzyl or the phenyl group may be replaced by a polynuclear aromatic group such as a naphthyl radical, in which case the second ring produces the effect of a substituent group, which may be in ortho, meta, or para position, the latter being preferred owing to its greater activity. The substituents should have an atomic group weight of at least 30 in order that the ether may be of satisfactory toxic value. Inert powdered materials mentioned as carriers include talc, lime and magnesium carbonate. The method of use of the insecticides depends on the class of insects combated. Against chewing insects such as bean beetle a dust or a spray is used. The dust is prepared by adding the insecticide in an organic solvent such as acetone to the powdered inert carrier, and the spray is made by applying a larger amount of the insecticide to the powder, adding an emulsifying agent, and dispersing in water. Sprays to repel sucking insects such as red spiders are made as above, but omitting the solid material. The compounds used as the active ingredient according to this invention are prepared by condensing in an alkaline medium the substituted phenol with the particular benzyl chloride. An improved method of preparation which is described comprises the use of dimethylaniline in amounts substantially less than equimolecular with the benzyl chloride in conjunction with an alkali metal hydroxide as condensing agent. In examples of the proportion of the active materials (1) an aqueous suspension of a mixture of paranitro-sodium phenolate dihydrate, benzyl chloride, dimethylaniline and sodium hydroxide is heated on the water bath for 6 hours. The coke product is filtered, and the solid material worked with concentrated hydrochloric acid,.methanol and petroleum ether to give pure para nitro phenyl benzyl ether (2) an aqueous suspension of ortho-phenylphenol, benzyl chloride, sodium hydroxide and dimethylaniline is heated as in example (1) and from the product the top aqueous layer is removed. The bottom layer is extracted with ethylene dichloride and purified to give orthophenylphenyl benzyl ether. (3,) An aqueous suspension of paratertiarybutylphenol, dimethylaniline, sodium hydroxide and benzyl chloride is treated as in example (1) to give paratertiarybutylphenyl benzyl ether. (4) An aqueous suspension of paranitrobenzyl bromide, paratertiarybutylphenol and sodium hydroxide is treated as in example (1) to give paratertiarybutyl phenyl paranitrobenzyl ether. Examples are given of the efficacy of a large number of compounds which fall within the class of active materials and according to the present invention when used to combat various insect pests such as beetle larvae, diamond-back cabbage worm, red spiders, mealy bugs, and aphis. The Specification as open to inspection under Sect. 91 includes the use as insecticides of any phenyl benzyl ethers and thio ethers having a substantially neutral substituent of relative might of at least 30. This subject-matter does not appear in the Specification as accepted.