Negative ion mass spectra of a series of fluorinated β-diketones

Electron capture by and the subsequent fragmentation of a series of eleven fluorinated β-diketones of general formula CF₃COCH₂COR has been studied in an MS-50 mass spectrometer. Consecutive loss of two HF molecules from molecular anions occurs with all compounds, as does elimination of CHF₃ from [M ? H]^? ions. Elimination of CO occurs from either documentclass{article}pagestyle{empty}begin{document}$ left[{{rm M - HF}} right]_{}^{_.^ - } $end{document} or documentclass{article}pagestyle{empty}begin{document}$ left[{{rm M - 2HF}} right]_{}^{_.^ - } $end{document} ions for five compounds where R ? CF₃ or a cyclic substituent. Kinetic energy release in metastable transitions associated with these HF and CO eliminations has been measured. Intensities of various fragment ions are in part influenced by the ion source temperature. Interaction of documentclass{article}pagestyle{empty}begin{document}$ left[{{rm O}} right]_{}^{_.^ - } $end{document} reagent ions with five of the β-diketones under chemical ionization conditions gave [M ? H]^? ions as the only significant ion-molecule reaction product.