naphthalene, colorless, crystalline, solid aromatic hydrocarbon with a pungent odor. It melts at 80°C;, boils at 218°C;, and sublimes upon heating. It is insoluble in water, somewhat soluble in ethanol, soluble in benzene, and very soluble in ether, chloroform, or carbon disulfide. 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 molecular structure of naphthalene is that of two benzene rings fused together with two adjacent carbon atoms common to both rings.

Simplest of the fused (condensed) ring hydrocarbons, an aromatic compound composed of two benzene rings sharing two adjacent carbon atoms (C₁₀H₈). It is a white solid at room temperature, very volatile, with a characteristic odour. Naphthalene is an important raw material in the manufacture of dyes and synthetic resins and has been used as a moth repellent.

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