INSECTICIDE Research Develops a Promising Substitute for Nicotine

The insecticides of value in common use are made from poisonous plants, from suitable extracts of these, and from combinations of common mineral poisons. Pyrethrum, Derris, tobacco, sulphur, arsenic, fluorides, and a few other less commonly used insecticides fall into these classes.

Considerable effort has been put forth in testing a large number of substances used in the dye and pharmaceutical industries and in other industries in which chemistry elaborates new compounds. It was found in this way that paradichlorobenzene, naphthalene, carbon tetrachloride, and other products have insecticidal properties, but the haphazard experimentation has given meager results and must give way to a more scientific study of insect poisons.

Nature has indeed given us effective poisons in pyrethrum, tobacco, and Derris, and in other members of the plant kingdom which, as we might expect, are harmless to plant hosts although occasionally harmful to animals. The principal disadvantage of these poisons is their cost, for an insecticide must be cheap to permit its general use. Can the chemist synthesize these active poisons in the laboratory?  Even in this age of synthetic rubber, camphor, dyes, and plastics the economic synthesis of these naturally occurring insect poisons presents great difficulties. Nicotine, it is true, has been synthesized at great cost in effort and material, but its economic synthesis is a problem for future accomplishment.

If the chemist can not duplicate nature’s organic insecticides, he may still have the chance of imitating them. With this idea in mind, neonicotine, a substance almost identical in chemical structure with nicotine, has been prepared. Laboratory tests have shown it to be equivalent to nicotine for many purposes in its toxicity to certain insects. The full estimate of its usefulness naturally awaits the production of sufficient material for tests in the field.

Neonicotine can be changed to other forms, such as methyl, ethyl, and other derivatives not possible with nicotine, with physical properties better adapted to some purposes but with no loss in toxicity. The series of neonicotine insecticides offers interesting possibilities.

Can neonicotine be produced cheaply?  The answer to this can not be given at this time.  Its synthesis from benzol is now being studied, with a view to preparing it more economically. The unsolved problems do not appear to be unduly formidable.