Worked example 1
An organic compound shows strong, very broad infrared absorption in the region 3200–3500 cm−1 and strong absorption at 1715 cm−1. What functional group is consistent with both of these absorptions?
Carboxylic acids have 2 strong absorptions: a broad peak between 2400 and 3400 cm−1, due to the hydroxyl group attached to the carbonyl carbon, and a strong peak around 1715 cm−1, due to the carbonyl stretching vibration.