THIOCYANATE INSECTICIDES: THE RELATION BETWEEN KNOCK-DOWN ACTIVITY AND CHEMICAL CONSTITUTION

The results of an investigation into the relation between chemical constitution and the knock-down activity and toxicity of thiocyanate insecticides are recorded. Linkage of the toxic thiocyano radical through a ketomethylene group to a lipoid soluble hydrocarbon residue gives rise to knock-down activity. The most active α-thiocyanoketones R. CO.CH₂.SCN and thiocyanoacetates R. O. CO. CH₂. SCN are too irritant to the eyes and nose for inclusion in domestic fly-sprays. Thiocyanoacetates derived from saturated 10-carbon alcohols, however, are non-irritant to the mucous membranes while possessing moderately high activity. The mode of action of these compounds is discussed.