Nucleophilic substitution at the halogen atom (halogenophilic reactions)

The key features of halogenophilic reactions defining their role in organic chemistry are considered. The results of studies of mechanisms involving a nucleophilic attack at the halogen atom (S_N2Hal) are summarized. The main mechanistic evidence comes from the studies of halogen–metal exchange reactions. Primary attention is paid to the role of halogenophilic reaction as a competing process or a concealed mechanism in ordinary nucleophilic substitution reaction at carbon atoms. The bibliography includes 249 references.