1. Organophosphorus: insecticides
Although a number of organic phosphorus (OP) compounds were synthesized in the 1800s, their development as insecticides only occurred in the late 1930s and early 1940s. The German chemist Gerhard Schrader is credited for the discovery of the general chemical structure of anticholinesterase OP compounds and for the synthesis of the first commercialized OP insecticide [Bladan, containing TEPP (tetraethyl pyrophosphate) as an active ingredient], and for one of the most known, parathion, in 1944 [1]. Since then, hundreds of OP compounds have been made and commercialized worldwide in a variety of formulations.
The chemistry of OPs, which leads to their classification in several subclasses, has been thoroughly investigated [2]. The general structure of OP insecticides can be represented by