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. Cyclohexanone (first structure) and cyclopentanone (second structure) are ketones. Carboxylic acids (third structure) have carbon - carbonyl stretching frequencies around 1700 - 1725 cm⁻¹ but are also affected by hydrogen - bonding which can shift the frequency. However, in general, they are in the ball - park.

Answer:

All of the above (the three carbonyl - containing compounds shown)