Why is the activation energy required to rotate the C-N bond in tertiary amides (i.e. N,N-dimethylacetamide) higher than for a primary amide (i.e. acetamide)?

1 Answer
Dr. Hayek
Sep 28, 2015

Because of the steric hindrance with the methyl connected to the carbonyl #C=O# group.

Explanation:

N,N-dimethylacetamide.

My best guess would be that the two methyl groups on the nitrogen atom restrict the rotation around the #C-N# bond because of the steric hindrance with the methyl connected to the carbonyl #C=O# group.
enter image source here

Acetamide.

However, we can see that there is more room around the nitrogen atom in the case of acetamide:
enter image source here

Related questions
Impact of this question
2483 views around the world
You can reuse this answer
Creative Commons License