The 1H NMR spectrum of DMF exhibits three signals. Upon treatment with excess LAH followed by water, DMF is converted into a new compound that exhibits only one signal in its 1H NMR spectrum. Explain. DMF, like most , exhibits restricted rotation about the bond between the carbonyl group and the nitrogen atom. This restricted rotation causes the groups to be in different electronic environments. They are not chemically equivalent, and will therefore produce different signals (in addition to the signal from the other proton in the compound). Upon treatment with excess LAH followed by water, DMF is to an amine that exhibit restricted rotation. As such, the methyl groups chemically equivalent and will together produce .