هلجنة

In chemistry, halogenation is a chemical reaction which introduces one or more halogens into a chemical compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens (). Halides are also commonly introduced using halide salts and hydrogen halide acids. Many specialized reagents exist for introducing halogens into diverse substrates, e.g. thionyl chloride.