Paraquat

Paraquat (trivial name; /ˈpærəkwɒt/) or N,N′-dimethyl-4,4′-bipyridinium dichloride (systematic name) is an organic compound with the chemical formula Cl2. It is classified as a viologen, a family of redox-active heterocycles of similar structure. Paraquat was manufactured by Chevron. This salt is one of the most widely used herbicides. It is quick-acting and non-selective, killing green plant tissue on contact. It is also toxic to human beings and animals due to its redox activity, which produces superoxide anions. It has been linked to the development of Parkinson's disease and is banned in several countries.In acute toxicity studies using laboratory animals, paraquat has been shown to be highly toxic by the inhalation route and has been placed in Toxicity Category I (the highest of four levels) for acute inhalation effects. However, the EPA has determined that particles used in agricultural practices (400–800 μm) are well beyond the respirable range and therefore inhalation toxicity is not a toxicological endpoint of concern. Paraquat is toxic (Category II) by the oral route and moderately toxic (Category III) by the dermal route. Paraquat will cause moderate to severe eye irritation and minimal dermal irritation, and has been placed in Toxicity Categories II and IV (slightly toxic) respectively for these effects. Paraquat (trivial name; /ˈpærəkwɒt/) or N,N′-dimethyl-4,4′-bipyridinium dichloride (systematic name) is an organic compound with the chemical formula Cl2. It is classified as a viologen, a family of redox-active heterocycles of similar structure. Paraquat was manufactured by Chevron. This salt is one of the most widely used herbicides. It is quick-acting and non-selective, killing green plant tissue on contact. It is also toxic to human beings and animals due to its redox activity, which produces superoxide anions. It has been linked to the development of Parkinson's disease and is banned in several countries. Paraquat may be in the form of salt with chloride or other anions; quantities of the substance are sometimes expressed by cation mass alone (paraquat cation, paraquat ion). The name is derived from the para positions of the quaternary nitrogens. Pyridine is coupled by treatment with sodium in ammonia followed by oxidation. The resulting 4,4′-bipyridine is then methylated with chloromethane to give the title compound: Although first synthesized in 1882, paraquat's herbicidal properties were not recognized until 1955. Paraquat was first manufactured and sold by ICI in early 1962, and is today among the most commonly used herbicides.