C10H7Cl

C10H7Cl is a chemical compound with the systematic name chlorobenzene, though it is more commonly referred to as chloronaphthalene when referring to its specific isomer structure. This formula represents a monochlorinated derivative of naphthalene, an aromatic hydrocarbon consisting of two fused benzene rings. The chlorine atom substitutes one hydrogen atom in the naphthalene structure, resulting in a variety of positional isomers depending on where the chlorine is attached.

Chloronaphthalene exists primarily as two distinct isomers: 1-chloronaphthalene (α-chloronaphthalene) and 2-chloronaphthalene (β-chloronaphthalene), with the chlorine atom bonded to either the first or second carbon in the naphthalene ring system. These isomers differ in their physical and chemical properties, including boiling points, solubility, and reactivity.

Chloronaphthalene is a colorless to pale yellow liquid with a mild aromatic odor, though it may darken upon exposure to light or air. It is insoluble in water but soluble in organic solvents such as ethanol, ether, and benzene. The compound is notable for its high boiling point, which makes it useful as a heat transfer medium in industrial applications, particularly in systems requiring stable performance at elevated temperatures.

Historically, chloronaphthalene has been employed as a flame retardant, a solvent for resins and waxes, and a component in electrical insulation materials. However, due to its potential toxicity and environmental persistence, its use has been restricted or phased out in many applications. Studies have indicated that prolonged exposure to chloronaphthalene may pose health risks, including skin and eye irritation, as well as potential carcinogenic effects.

Synthesis of chloronaphthalene typically involves the chlorination of naphthalene using reagents such as chlorine gas (Cl₂) in the presence of a catalyst like aluminum chloride (AlCl₃). The reaction proceeds via electrophilic aromatic substitution, where the chlorine atom replaces a hydrogen atom on the naphthalene ring. Proper handling and disposal of chloronaphthalene are essential due to its hazardous nature, requiring adherence to occupational safety guidelines and environmental regulations.