fragmentation

https://doi.org/10.1351/goldbook.F02506
  1. The heterolytic cleavage of a molecule according to the general reaction:
    F02506-1.png
    where a-b is an electrofuge and X is a nucleofuge (which may emerge from the reaction in combined form), and the middle group affords the unsaturated fragment c=d. For example,
    F02506-2.png
  2. The breakdown of a radical into a diamagnetic molecule or ion and a smaller radical, e.g.
    F02506-3.png
    F02506-4.png
  3. The breakdown of a radical ion in a mass spectrometer or in solution, forming an ion of lower molar mass and a radical, e.g.
    F02506-5.png
See also: fragmentation reaction (in mass spectrometry)
Source:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1116 (https://doi.org/10.1351/pac199466051077)