4,4'-Bipyridine


4,4′-Bipyridine is a bipyridine which is mainly used as a precursor to N,N′-dimethyl-4,4′-bipyridinium 2+, known as paraquat. This species is electroactive, and its toxicity arises from the ability of this dication to interrupt biological electron transfer. Because of its structure, 4,4′-bipyridine can bridge between metal centres to give coordination polymers. 4,4′-Bipyridine can also mediate electronic effects between two paramagnetic metal centers.

History

4,4′-Bipyridine was first obtained in 1868 by the Scottish chemist Thomas Anderson via heating pyridine with sodium metal. However, Anderson's empirical formula for 4,4′-bipyridine was incorrect. The correct empirical formula, and the correct molecular structure, for 4,4′-bipyridine was provided in 1882 by the Austrian chemist Hugo Weidel and his student M. Russo.

Uses

4,4'-Bipyridine is an intermediate in the production of paraquat, a widely-used herbicide. In this process, pyridine is oxidized to 4,4'-bipyridine in a coupling reaction, followed by dimethylation to form paraquat.