Unexpected Structural Integrity of Gas Phase Isoquinoline Cations that Eliminate HCN

Article abstract of DOI:10.1002/oms.1210180308

13C labellining has been used to study isoquinoline molecular ions undergoing breakdown by HCN elimination in a mass spectrometer.For otherwise stable ions caused to fragment by collisional activation, there is no skeletal rearrangement prior to HCN loss.Of the ions formed by 70 eV electron impact, 69percent of those which fragment in the ion source by HCN loss retain their structural integrity, as do 44percent of the metastable ions.Of the ions that eliminate HCN without prior arrangement, approximately two-thirds eliminate C-1 and one-third eliminate C-3.Critical energies are reported for the elimination of HCN from pyridine and isoquinoline molecular ions.