Imidacloprid

Abstract

In the 1960s the naturally occurring insecticide nicotine was simplified by Yamamoto (1965) to 3-pyridylmethylamines, but none of these were of practical value. At the IUPAC Conference in Zurich in 1978 Shell Chemical Co. (Soloway et al. 1978) introduced a new class of chemicals named nitromethylene insecticides represented by its most active member nithiazine which was never commercialized for broad agricultural use (Kollmeyer et al. 1999). In recent times a knock-down fly product against M. domestica containing nithiazine has been available. In 1985 finally the chemists of Nihon Tokushu Noyaku Seizo K.K. in Japan synthesized among other compounds the nitroguanidine NTN 33893, known today as imidacloprid (Fig. 13 and Fig. 14) (Elbert et al. 1998; Nauen et al. 2001). The addition of a heterocyclic substituent, the 6-chloro-3-pyridyl-methyl moiety, to the nitromethylene substituted heterocycles (NMHs) increased the insecticidal activity remarkably (Kagabu 1996; Yamamoto et al. 1998) and further optimization finally resulted in the invention of imidacloprid from Nihon Bayer Agrochem. K.K. (Shiokawa et al. 1986). Thus imidacloprid was the first commercialized member of a new class of insecticides, called chloronicotinyl or neonicotinoides (Nauen et al. 2001; Yamamoto et al. 1998).