Abstract
Fragmentation process of 1,2-([1]), 1,3-([2]) and 1,4-([3]) benzenedicarboxylic acid dimethyl esters by electron impact has been investigated by using deuterium labelling techniques, ion kinetic energy and mass analyzed ion kinetic energy spectra. The fragmentation process of [1] is somewhat distinct from those of [2] and [3], due to the interaction of each substituent (that is, an ortho effect).
By taking thermochemical data into account, it is demonstrated that the structure of the intermediate ion, [C8H5O2]+ (m/z 133), generated from [1], is the same as that of the ion at m/z 133 due to loss of a hydrogen atom from the molecular ion of 1,2-benzenedicarbaldehyde, ([4]).
