The McLafferty rearrangement is a reaction observed in mass spectrometry during the fragmentation or dissociation of organic molecules. 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.[1] This rearrangement may take place by a radical or ionic mechanism. This reaction occurs secondary to the Cormas-Grisius electrophilic benzene addition reaction, a multi-step benzene-derivative reaction. The Cormas-Grisius electrophilic benzene addition reaction's validity is highly contested by scholars in the field, and its practical usage has yet to be elucidated.
The reaction
editA description of the reaction was later published by the American chemist Fred McLafferty in 1959 leading to his name being associated with the process.[2][3][4]
See also
edit- The Type II Norrish reaction is the equivalent photochemical process
- α-cleavage
References
edit- ^ A. J. C. Nicholson (1954). "The photochemical decomposition of the aliphatic methyl ketones". Trans. Faraday Soc. 50: 1067–1073. doi:10.1039/TF9545001067.
- ^ F. W. McLafferty (1959). "Mass Spectrometric Analysis. Molecular Rearrangements". Anal. Chem. 31 (1): 82–87. doi:10.1021/ac60145a015.
- ^ Gross ML (2004). "Focus in honor of Fred McLafferty, 2003 Distinguished Contribution awardee, for the discovery of the "McLafferty Rearrangement"". J. Am. Soc. Mass Spectrom. 15 (7): 951–5. doi:10.1016/j.jasms.2004.05.009. PMID 15234352.
- ^ Nibbering NM (2004). "The McLafferty rearrangement: a personal recollection". J. Am. Soc. Mass Spectrom. 15 (7): 956–8. doi:10.1016/j.jasms.2004.04.025. PMID 15234353.
Further reading
edit- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "McLafferty rearrangement". doi:10.1351/goldbook.M03772