Arüülihalogeenid

Aryl halides are organic compounds in which an aryl group is bonded to a halogen atom. The aryl group is a phenyl ring or a related aromatic ring system. The halogen atom can be fluorine, chlorine, bromine, or iodine. The general formula for an aryl halide is Ar-X, where Ar represents the aryl group and X represents the halogen.

The properties of aryl halides are influenced by the nature of both the aryl group and the halogen. They are typically less reactive than alkyl halides due to the strong carbon-halogen bond in the aromatic ring. This increased stability is attributed to resonance effects, where the lone pairs on the halogen atom can delocalize into the pi system of the aromatic ring.

Aryl halides are important intermediates in organic synthesis. They can undergo various reactions, including nucleophilic aromatic substitution, electrophilic aromatic substitution, and coupling reactions like the Suzuki, Heck, and Sonogashira couplings. These reactions allow for the formation of new carbon-carbon and carbon-heteroatom bonds, making aryl halides valuable building blocks for the synthesis of pharmaceuticals, agrochemicals, and materials.

Industrially, aryl halides are produced through several methods, including direct halogenation of aromatic hydrocarbons or via diazotization of anilines followed by reaction with a halide salt (Sandmeyer reaction). Chlorobenzene and bromobenzene are common examples of aryl halides used in large-scale chemical production. Their applications range from solvents to precursors for more complex molecules.