Quinoline vs. Isoquinoline — What's the Difference?

Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor. Aged samples, especially if exposed to light, become yellow and later brown.

Isoquinoline is a heterocyclic aromatic organic compound. It is a structural isomer of quinoline.

An aromatic organic base, C9H7N, having a pungent tarlike odor, synthesized or obtained from coal tar, and used as a food preservative and in making antiseptics, drugs, and dyes.

(organic compound) An isomer of quinoline, many of whose derivatives occur as alkaloids and are synthesized for use as dyes, pharmaceuticals etc.

(organic compound) Any of a class of aromatic heterocyclic compounds containing a benzene ring fused with a pyridine ring; especially the simplest such compound, C₉H₇N.

A nitrogenous base, C9H7N obtained as a pungent colorless liquid by the distillation of alkaloids, bones, coal tar, etc. It the nucleus of many organic bodies, especially of certain alkaloids and related substances; hence, by extension, any one of the series of alkaloidal bases of which quinoline proper is the type.