Abstract The mutual interconversion of the molecular ions [C 5 H 6 O]+ of 2-methylfuran (1), 3-methylfuran (2) and 4H-pyran (3) before fragmentation to [C 5 H 5 O]+ ions has been studied by collisional activation spectrometry, by deuterium labelling, by the kinetic energy release during the fragmentation, by appearance energles and by a MNDO calculation of the minimum energy reaction path. The electron impact and collisional activation mass ...
