The McLafferty rearrangement is a fragmentation reaction observed in mass spectrometry of organic molecules in which the parent radical cation splits into daughter radical cation and neutral spin-paired molecule. It is sometimes found that a molecule containing a keto-group undergoes β-cleavage, with the gain of the γ-hydrogen atom, as first reported by Anthony Nicholson working in the Division of Chemical Physics at the CSIRO in Australia. This rearrangement is a retro-ene reaction, and a member of the sigmatropic family of reactions. The products of the McLafferty rearrangement are an alkene whose length depends on the size of the parent ketone's carbon chain, and a radical enol cation.
The reaction A description of the reaction was later published by the American chemist Fred McLafferty in 1959 leading to his name being associated with the process.
See also The Type II Norrish reaction is the equivalent photochemical process α-cleavage
References
Further reading IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006–) "McLafferty rearrangement". doi:10.1351/goldbook.M03772
External links Fred McLafferty Faculty Webpage at Cornell University