Term: α-cleavage (alpha-cleavage)
https://doi.org/10.1351/goldbook.A00004

Definition:
The fission of a bond originating at an atom which is adjacent to one assumed to bear the charge; the definition of β-, γ-cleavage then follows automatically. The process: A00004.png would thus be described as α-fission of a ketone with expulsion of a radical R1·. The carbon atoms of the radical R1· are called the α-, β-, γ-carbons, starting with the atom nearest the functional group.

Related Terms:
1) functional group (http://doi.org/10.1351/goldbook.F02555).

Image: Generalized α-cleavage reaction (https://goldbook.iupac.org/img/inline/A00004.png) 

Source: PAC, 1991, 63, 1541. 'Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)' on page 1558 (https://doi.org/10.1351/pac199163101541)

Citation: 'α-cleavage (alpha-cleavage)' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.A00004

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