| Abstract: | Primary diazoketones, R? CO? CHN2, are O-protonated in HF? SbF5? SO2 or FSO3H? SbF5? SO2 at ?60°, as observed by NMR. The OH-proton resonates at 9.3–9.6 δ and is coupled with H? C 1 (J = 1–2.5 Hz). Secondary diazoketones, R? CO? C(N2)? R, when protonated, give an OH-singlet at 8.85 δ. The assignments are corroborated by use of deuterated diazoketones, R? CO? CDN2, or deuterated acid, FSO3D. Primary diazoketones react with FSO3H at ?60° to ?15°, giving products assigned the fluorosulfate structure, R? CO? CH2? OSO2F; they do not exchange H? C 1 with solvent before or during decomposition. Intermediate C-protonated diazonium ions and α-oxo-carbonium ions (vinyl carbonium ions) have not been identified. 3-Diazo-4-methyl-2-pentanone (VIII) reacts with FSO3H at ?15°, eliminating N2 and giving protonated mesityl oxide by a strictly intramolecular hydride shift. |
