Daily answer writing · Fri, 6 Nov, 2026
Mass spectrometry: telling 2-hexanone from 3-hexanone by α-cleavage and McLafferty rearrangement
2-Hexanone and 3-hexanone both show a molecular ion at m/z 100. Explain how their electron-impact mass spectra distinguish them. Write the α-cleavage fragments and the McLafferty rearrangement ion expected from each, with m/z values, and state the structural condition needed for a McLafferty rearrangement.
Syllabus: Common to CSE Paper II, IFoS Paper II and Geo-Scientist Mains Paper III (organic/analytical): mass spectrometry – molecular ion, base peak, fragmentation, McLafferty rearrangement.
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