Fragmentation of even electron ions: Protonated amines and esters

Abstract

Abstract The fragmentation of protonated amines and esters is examined by collision induced dissociation of mass selected ions generated by chemical ionization. Four fragmentation types are observed: (i) loss of an alkane moiety, explicable in terms of a four‐centered reaction, (ii) loss of alkene, also explicable as a four‐centered process, (iii) loss of an alkyl radical, requiring electron unpairing, (iv) losses of other neutral molecules, viz. acids and alcohols from protonated esters, or amines and ammonia from protonated amines. Proposed mechanisms were checked by characterizing selected product ions through their collision induced dissociation spectra. The usefulness of these generalizations is substantiated by the successful prediction of the fragmentation patterns and the order of relative abundances of daughter ions for eight unknowns including some containing functional groups not studied previously.