Question

which of the following carbonyls have a stretching frequency around 1715 cm^-1? caution: more than one answer is possible.

Explanation:

Step1: Recall carbonyl stretching frequencies

Ketones typically have carbon - carbonyl stretching frequencies around 1715 cm⁻¹. Esters have stretching frequencies around 1735 cm⁻¹.

Step2: Identify the functional groups

The first structure is a cyclic ester (lactone), the second is a cyclic ketone, and the third is an aromatic ester.

Step3: Determine the answer

The cyclic ketone will have a stretching frequency around 1715 cm⁻¹.

Answer:

The second structure (the cyclic ketone)