Quinoline and isoquinoline are two isomers of benzo pyridine, both present in coal tar. The quinoline and isoquinoline and their many substituted derivatives, all can get from cyclizing benzene derivatives by the ring system. The basic reaction of synthesizing quinoline ring compound is that get aniline, glycerol, sulfuric acid and oxidizing agent (nitrobenzene, etc.) heated together. Since glycerol is dehydrated to become acrolein and then react with aniline, various aniline derivatives and other α, β- unsaturated carbonyl compounds can be used to synthesize quinoline compounds which has a substituent on a ring. Such as 4-methyl-quinoline (Le Puy-pyridine) is obtained from aniline and methyl - vinyl ketone . The way to synthesize Other quinoline compounds synthesis including the condensation of anthranilic ketone formaldehyde condensation. Such as 2-methyl-quinoline (QUINALDINIC) is prepared by the condensation of o-benzaldehyde and acetone.

Quinoline compound refers quinoline and its homologue, a bicyclic aromatics with nitrogen(hetero). Quinoline compounds are known as the heavy pyridine which is called tar base together with pyridine bases, a basic product obtained from high-temperature coal tar processing, including quinoline,isoquinoline, quinoline methyl and dimethyl quinoline and so on. Quinoline compounds mainly exist in the coal tar naphthalene oil fraction and wash oil fraction.The content of quinoline compounds in coal tar is about 0.3% to 0.5%. Quinoline compounds have a special smell, when they are exposed to air or sunlight the color becomes deeper gradually.

Quinoline compounds can be used to produce medicine, dyes, photographic materials, rubber, solvents and chemical reagents. Quinoline medicine is primarily used in the manufacture of niacin-based, 8-hydroxy quinoline and quinine-based drugs. Niacin-based drugs including nicotinamide, tonic, stimulant and treatment of tapeworm medicine; 8-hydroxy quinoline can be used to make the treatment of amoebic coccidiosis medicine, trauma disinfectants, mildew and textile auxiliaries and the like. Primaquine Ning, quinine chloride and hydroxylamine quinine is a synthetic treatment of malaria medicine. Isoquinoline can be used in the manufacture of pesticides, antimalarials, rubber vulcanization accelerator and determination of rare metals by chemical agents. Methyl-quinoline can be used for the manufacture of color film sensitizing agent and dye, also used as a solvent, impregnating agents, corrosion inhibitors, quinine-based drugs and pesticides. The extraction of quinoline compounds is same as the heavy pyridine refined.