quinolina

Quinoline, also known as quinolina in some languages, is a heterocyclic aromatic organic compound with the formula C9H7N. It comprises a benzene ring fused to a pyridine ring, giving a bicyclic structure that contains a basic nitrogen atom.

Quinoline was first isolated from coal tar in the 19th century by Adolf von Baeyer. It occurs as a trace component in fossil fuels and is produced commercially by various condensation methods. A common laboratory and industrial route is the Skraup synthesis, which combines aniline, glycerol, and sulfuric acid under oxidative conditions; other routes include Doebner-type condensations and related reactions.

In industry, quinoline serves as a chemical building block for dyes, medicines, and agrochemicals. It is a core motif in many pharmaceuticals and in fluorescent dyes; derivatives such as 8-hydroxyquinoline function as chelating agents and are used in metal ion detection. The base compound is typically a colorless to pale yellow solid or liquid with limited water solubility and greater solubility in organic solvents.

Chemically related heterocycles include isoquinoline and quinazoline, which share the benzo-fused nitrogen-containing ring systems but differ in ring fusion and nitrogen position. Quinoline and its derivatives are widely used in chemical synthesis, coordination chemistry, and materials science.

Safety and handling: Quinoline and several of its derivatives can be toxic or irritant; appropriate safety precautions are advised. Environmental considerations apply, as some quinoline compounds are regulated pollutants and require careful management in industrial processes.