C6HCl5O

C6HCl5O is the chemical formula for pentachlorophenol (PCP), an organochlorine phenol. Its IUPAC name is pentachlorophenol, and it is sometimes referred to simply as PCP. The molecule consists of a benzene ring bearing a hydroxyl group and five chlorine substituents, giving it the formula C6HCl5O and a relatively high molecular weight.

Pentachlorophenol is a solid at room temperature. It is sparingly soluble in water but dissolves readily in many organic solvents. The compound is described as persistent in the environment, with limited natural degradation under ordinary conditions, and it can bioaccumulate in aquatic and terrestrial organisms.

Historically, PCP was produced and used as a wood preservative, pesticide, disinfectant, and fungicide. Its use was widespread in the mid-20th century, but concerns about health and environmental risks led to regulatory restrictions and bans in many countries. Old treated wood, contaminated soils, and waste streams can still be sources of PCP exposure.

Health and environmental effects are a major consideration with PCP. It is toxic to humans and wildlife, capable of causing skin and eye irritation and, with greater exposure, systemic effects affecting the liver and nervous system. Because PCP is persistent and lipophilic, it can remain in soils and sediments for extended periods and may contribute to environmental contamination if released or improperly disposed of. Combustion or high-temperature processes involving PCP can produce toxic byproducts such as dioxins and furans, underscoring the importance of careful handling and disposal.

Synthesis typically involves chlorination of phenol to substitute hydrogen atoms with chlorine, yielding pentachlorophenol under controlled industrial conditions.