Chemicals - Quinoline

Quinoline, also known as azanaphthalene or benzo[b]pyridine, is an organic compound from the heteroaromatic group and belongs to the binuclear heterocyclic parent systems. It consists of two fused aromatic six-membered rings – a benzene ring and a pyridine ring – resulting in the molecular formula C9H7N. Formally, it is thus a naphthalene molecule in which one carbon atom of the ring skeleton has been replaced by a nitrogen atom. Quinoline is a colorless, water-binding liquid with an unpleasant, pungent odor. As a heteroaromatic, quinoline exhibits lower reactivity than naphthalene with respect to electrophilic aromatic substitution, but enters into nucleophilic aromatic substitutions more readily in comparison. Quinoline is contained in coal tar and can be expelled from coal. Numerous natural derivatives of quinoline exist, which are often found as alkaloids in plants (see quinoline alkaloids). This group includes the China alkaloids with quinine as the best known representative. Quinoline was first isolated in pure form from coal tar by Friedlieb Ferdinand Runge in 1834. In 1842, it was obtained by Charles Frédéric Gerhardt through the degradation of the alkaloid cinchonine, from which the name quinoline is also derived. Quinoline is an important raw material in the chemical and pharmaceutical industries. It is used in the manufacture of pharmaceuticals, herbicides and fungicides, and as a basic solvent. Although several synthetic accesses to quinoline are known, for economic reasons a large part of the world’s quinoline requirements is still met today by isolation from coal tar.