Abstract The main fragmentation pathway of ionized hydroxyallenes (1) consists of a methyl loss. Extensive deuterium-labelling experiments indicate that the terminal allenic carbon is implied in this fragmentation. Collisional activation spectra indicate a propenyl-acylium structure (a) for these [M–CH 3]+ ions which can originate from a 1, 4-hydroxyl migration followed by hydrogen rearrangements. Isomeric hydroxyacetylenes (2) behave similarly, ...
