question 1\n0.25 / 0.5 pts\nwhich of the following carbonyls have a stretching frequency around 1685 cm⁻¹…

question 1\n0.25 / 0.5 pts\nwhich of the following carbonyls have a stretching frequency around 1685 cm⁻¹? caution: more than one answer is possible.\nnone of these

question 1\n0.25 / 0.5 pts\nwhich of the following carbonyls have a stretching frequency around 1685 cm⁻¹? caution: more than one answer is possible.\nnone of these

Answer

Explanation:

Step1: Recall carbonyl IR - stretching trends

Conjugated carbonyls have lower - frequency stretching vibrations compared to non - conjugated carbonyls. A stretching frequency around 1685 cm⁻¹ is characteristic of a conjugated carbonyl.

Step2: Analyze each structure

The first structure is an $\alpha,\beta$ - unsaturated aldehyde (conjugated), the second structure is an $\alpha,\beta$ - unsaturated ketone attached to an aromatic ring (conjugated), and the third structure is an aromatic ketone (conjugated through resonance with the aromatic ring).

Answer:

All of the given carbonyl structures (the three structures shown, not "none of these")