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(Solved): Dimethylacetamide (DMA) is a common solvent: a) The 1H NMR spectrum of DMA exhibits three signal ...
Dimethylacetamide (DMA) is a common solvent: a) The NMR spectrum of DMA exhibits three signals. Upon treatment with excess followed by water. DMA is converted into a new compound that 'exhibits only three signal in its -NMR spectrum. Explain the number of signals observed in both H-NMR spectra. b) Based on your answer to part a, how many signals do you expect in the spectrum of DMA?
Expert Answer
Let us first see resonating forms of DMA - At Room temperature DMA majorly exist in form B . Form B has 2 CH3 attached to N that are diastereotopic because they are in different environment. Thus Form B of DMA shows 3 1H NMR signals ( two for -CH3 attached to nitrogen and one for -CH3 attached to carbonyl).