naphtalene

"Colorless, crystalline, solid aromatic hydrocarbon with a pungent odor [...] Naphthalene is obtained from coal tar, a byproduct of the coking of coal. It is used in mothballs and gives them their characteristic odor. From it are prepared derivatives that are used in the preparation of dyes and as insecticides and organic solvents."

The Columbia Electronic Encyclopedia 2007, Columbia University Press

"A toxic carcinogenic hydrocarbon derived from coal tar or petroleum and used as a solvent."

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company