A NUCLEAR MAGNETIC RESONANCE INVESTIGATION OF THE PROTONATION OF AMIDES IN FLUOROSULPHURIC ACID

The proton resonance spectra of solutions of acetamide, N,N-dimethylacetamide, formamide, and N,N-dimethylformamide in fluorosulphuric acid have been studied at temperatures between 25° and −98°. At low temperatures a new peak appears in the spectra of solutions of all four compounds which is not present at room temperatures and which, from peak areas and other consideration, may be assigned with certainty to the [Formula: see text] group. It is thereby unambiguously established that these amides protonate on the carbonyl oxygen and not on the nitrogen atom.