Mass and kinetic energy spectrometries of alkylketenes

Real‐time analysis of alkylketenes synthesized by flash vacuum thermolysis (FVT) of acid chlorides has been performed by mass spectrometric techniques using a triple sector (E/B/E) spectrometer. The major high energy reactions of the molecular ions consist of β‐cleavages relative to the CC bond of the ketene function, followed by decarbonylation. The unimolecular reactions of the metastable molecular ions are often different as shown by collisional activation of the fragment ions produced in a field‐free region of the spectrometer and also from estimated heats of formation.