Propanoyl ion formation from metastable [C3H6O]+˙ ions

Collisionally activated spectra demonstrate that CH₃CH₂C?O⁺ rather than documentclass{article}pagestyle{empty}begin{document}${rm CH}_{rm 2} = {rm CHCH = }mathop {rm O}limits^{rm + } {rm H}$end{document} is formed in the metastable losses of hydrogen from [C₃H₆O]^+˙ ions with the oxygen on the first carbon. This provides another example of formation of an acyl ion following ‘ketonization’ prior to metastable decomposition.