The metastable molecular ions of primary aliphatic amines branched at C2 can isomerize by cleavage–recombination, thereby facilitating fragmentation reactions that require less energy than simple cleavage of the initial molecular ion. This process complements the reactions described by Audier to account for the conspicuous absence of the conventional α-cleavage among the major fragmentation reactions of the metastable molecular ions of primary amines.
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