ISSN:
0951-4198
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Physics
Notes:
During the unimolecular decomposition of an ion IN→I(ion) + N(neutral), the fragments may mutually reorient before decomposition, when the energy has reached the reorientation critical energy. After I-N reorientation, I and N have only a very low probability of recombining into the original IN structure, but can only decompose (or occasionally follow a different reaction pathway, if thermochemically allowed). As a consequence, decompositions of metastable ions are irreversibly decided as soon as their corresponding I-N reorientation threshold has been reached. It is shown, from the mass-analysed ion kinetic energy of several series of homologous primary amines, that the competition between α-cleavages (and the occasionally accompanying losses of alkanes) is governed by the relative I-N reorientation-(rather than decomposition)-critical energies.When the neutral has no permanent dipole, the I-N reorientation critical energy depends on the sizes of the fragments, especially that of the fragment ion. An interpretation is proposed related to the McAdoo and Hudson hypothesis.27
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/rcm.1290091221
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