chloro

Chloro is a chemical prefix derived from chlorine, the element with symbol Cl and atomic number 17. The term originates from the Greek chloros, meaning greenish-yellow, which also influenced the name of chlorine itself. In chemistry, chloro- denotes the substitution of one or more hydrogen atoms in a molecule with chlorine, or the addition of chlorine-containing groups during a reaction. It is commonly seen in the names of chlorinated organic compounds such as chloromethane (CH3Cl), chloroform (CHCl3), and dichloromethane (CH2Cl2).

Chlorine is a highly reactive halogen gas at standard conditions. In chemistry, it forms a wide range of compounds, from simple chlorides to complex organochlorines. The chloride ion (Cl−) is an essential electrolyte in biological systems, supporting fluid balance, nerve function, and digestion through hydrochloric acid in the stomach. Industrially, chlorine is produced mainly by the electrolysis of saltwater (the chlor-alkali process), yielding chlorine gas along with sodium hydroxide and hydrogen.

Chlorinated compounds have numerous applications and environmental considerations. Chlorine is crucial in water disinfection, paper and textile bleaching, and the production of many polymers, including polyvinyl chloride (PVC). However, many organochlorine compounds can be toxic or persistent in the environment, necessitating careful handling and regulation. The use of chloro- in nomenclature helps chemists describe the presence and position of chlorine substituents in organic molecules, aiding communication and standardization within chemical literature.