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Superelectrophiles
Author(s) -
Olah George A.
Publication year - 1993
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199307673
Subject(s) - dication , electrophile , chemistry , protonation , oxonium ion , carbonic acid , carbocation , sulfonium , photochemistry , medicinal chemistry , reactivity (psychology) , inorganic chemistry , organic chemistry , ion , catalysis , medicine , salt (chemistry) , alternative medicine , pathology
Electrophiles that are capable of further interaction (coordination, solvation) with strong Brønsted or Lewis acids can be activated in this way. The resulting enhancement of their reactivity is great compared to that of their parent compounds under conventional conditions and indicates superelectrophile formation (i.e., electrophiles with doubly electrodeficient (dipositive) nature whose reactivity substantially exceeds that of their parent electrophiles). As representative examples the protolytic or electrophilic activation of the following electrophiles in superacidic and related strongly electrophilic media is discussed: oxonium, carboxonium, sulfonium, selenonium, and telluronium ions; acyl cations; protonated CO, CO 2 , COS, and carbonic and thiocarbonic acids; heteroatom‐substituted carbocations (and some of their boron analogs); halonium ions; azonium (including nitronium) and carbazonium ions. Emphasis is placed on both experimental chemical investigations and theoretical treatment of the involved systems. As prototypes for protolytically activated onium ions, the protohydronium dication (diprotonated water) and its sulfur analogue, the protosulfonium dication, are of particular significance. The protoacetyl and protoformyl dication (diprotonated carbon monoxide), diprotonated carbonic acid and carbon dioxide, diprotonated hydrogen cyanide and nitriles, as well as the protonitronium dication among others—and their emerging chemistry are discussed as examples of superelectrophiles.