The strongest absorptions in the UV spectra of aldehydes and ketones are ones which result from ________ electronic transitions. A) σ to σ^* B) σ to π^* C) n to π^* D) π to π^* E) π to σ^*

Question

Quizplus · Accepted Answer

The strongest absorptions in the UV spectra of aldehydes and ketones are ones which result from π to π* electronic transitions, which is best represented by choice D. This is because the carbonyl group, which is present in both aldehydes and ketones, has a π bond between the carbon and oxygen atoms. When this π bond is excited by absorption of UV radiation, the electron is promoted from the π bonding orbital to the π* anti-bonding orbital, resulting in a characteristic absorption peak in the UV spectrum.

The Strongest Absorptions in the UV Spectra of Aldehydes and Ketones