Mass spectrometry of aralkyl compounds with a functional group-IX: Hydrogen scrambling in the molecular ion of hydrocinnamaldehyde

The molecular ion of hydrocinnamaldehyde (C6H5CH2CH2CHO) chiefly loses fragments C2H2O and C3H4O. Mass spectra of specifically deuterated analogues show that in the loss of C2H2O an α‐hydrogen atom (with respect to the aldehyde group) is transferred to the aromatic part. A shift of the aldehydic hydrogen to one of the ortho positions of the phenyl ring and loss of C2H2O by a McLafferty rearrangement is not observed. In the loss of C3H4O also an α‐hydrogen atom migrates to the aromatic part. Both reactions appear to occur with an extensive randomization of all hydrogen atoms in the molecular ion.