A hygroscopic unpleasant-smelling colourless oily liquid, C9H7N; b.p. 240°C. Its molecules consist of a benzene ring fused to a pyridine ring. It occurs in coal tar and bone oil, and is made from phenylamine and nitrobenzene. Quinoline is a basic compound, forming salts with mineral acids and forming quaternary ammonium compounds with haloalkanes. It is used for making medicines and dyes. In quinoline, the nitrogen atom is one atom away from the position at which the rings are fused. In an isomer, isoquinoline, the nitrogen atom is positioned two atoms away from the fused ring.