It is difficult to imagine organic chemistry without organo-halogen compounds and the molecular halogens needed for their
preparation. In fact, It is implied that halogenation of organic compounds is a key industrial process; for example, the halogenated products
are used in the synthesis of many pesticides and pharmaceuticals. Conventional halogenation methods typically use pollutant, toxic
and corrosive elemental halogens (X2), which also generate hydrohalic acid as byproduct and effectively reduce the atom efficiency.
Hence, to avoid their use, various modified reagents (N-halo reagents such as trichloisocyanuric acid, haloglycolurils, N-halosuccinimid
and …), methods such as oxidative halogenation in the presence of alkali halogen salts, biohalogenations, solid phase and ionic liquid
have been developed. In this review article, we will focus on strategies that are much greener and more sustainable than those using elemental