DDT and its related derivatives

The aim of Paul Muller s research work, begun in 1935 was to develop contact insecticide compounds to be used primarily against clothes-moth. In 1939 he established the insecticidal efficiency of those compounds in which two p-chloro-substituted benzene rings are linked together by a central bivalent radical (Muller, 1940 1955)  

Based on these earlier, promising results, Muller in the course of his later work extended his investigations to the study of dichlorodiphenyltrichloroethane (DDT, 1), with the trichloromethylmethylene group as the central bivalent radical in the general concept given above. 

The compound was already described by Zeidler in 1873 (Zeidler, 1873 Baeyer et al.. 1974). It was prepared by the reaction of chloral with chlorobenzene in the presence of sulfuric acid as condensing agent  

DDT exhibited a high insecticidal efficiency. It was marketed in 1942 under the name Gesarol in the crop protection field, and under the name Neocid in the field of human hygiene. The discovery was of immense importance in both fields, and marked the beginning of the application of modem synthetic products in plant protection. 

The industrial manufacture of DDT is based on the synthesis described by Zeidler. Chloral, chloral alcoholate or chloral hydrate is reacted with chlorobenzene in the presence of sulfuric acid, oleum or chlorosulfonic acid (Rueggeberg and Torrance, 1946). The t hnical product thus obtained contains several impurities, including the ortho-para (2) and ortho-ortho (3) isomers, 2,2-bis-(p-chlorophenyl)-1,1 -dichloroethane (p,p -DDD, 4), its ortho-para isomer (o,p -DDD, 

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