4,4′-Bipyridine (abbreviated to 4,4′-bipy or 4,4′-bpy) is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula . It is one of several isomers of bipyridine. It is a colorless solid that is soluble in organic solvents. is mainly used as a precursor to ''N'',''N''′-dimethyl-4,4′-bipyridinium C₅H₄NCH₃)₂sup>2+, known as

paraquat Paraquat ( trivial name; ), or ''N'',''N''′-dimethyl-4,4′-bipyridinium dichloride (systematic name), also known as methyl viologen, is a toxic organic compound with the chemical formula C6H7N)2l2. It is classified as a viologen, a family o ...

History

4,4′-Bipyridine was first obtained in 1868 by the Scottish chemist Thomas Anderson via heating

pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom . It is a highly flammable, weak ...

with sodium metal. However, Anderson's

empirical formula In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, is simply SO, as is the empir ...

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

, a widely-used herbicide. In this process,

is oxidized to 4,4'-bipyridine in a

coupling reaction In organic chemistry, a coupling reaction is a type of reaction in which two reactant molecules are bonded together. Such reactions often require the aid of a metal catalyst. In one important reaction type, a main group organometallic compound o ...

, followed by di

methylation Methylation, in the chemistry, chemical sciences, is the addition of a methyl group on a substrate (chemistry), substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replac ...

to form paraquat. : Paraquat synthesis

Reactions

The reducing agent is N,N'-bis(trimethylsilyl)-4,4'-bipyridinylidene is produced by reduction of 4,4'-bipyridine in the presence of

trimethylsilyl chloride Trimethylsilyl chloride, also known as chlorotrimethylsilane is an organosilicon compound ( silyl halide), with the formula , often abbreviated or TMSCl. It is a colourless volatile liquid that is stable in the absence of water. It is widely u ...

(Me = CH₃): : The silylated derivative, which is red, is used in salt-free reductions. 4,4′-bipyridine forms a variety of coordination polymers.

References

{{DEFAULTSORT:Bipyridine, 4,4'- Bipyridines 4-Pyridyl compounds Substances discovered in the 19th century