How can you differentiate between aldehydes, ketones, and carboxylic acids using IR spectroscopy?
Understand the Problem
The question asks how to differentiate between aldehydes, ketones, and carboxylic acids using IR spectroscopy by analyzing spectral peaks.
Answer
The answer is D.
The answer is D: All compounds will show a sharp peak at 1700 cm⁻¹ due to the C=O stretch. Only aldehydes show medium strength bands around 2800 and 2700 cm⁻¹, while carboxylic acids show a broad band from 3100 to 2800 cm⁻¹ due to O-H stretching.
Answer for screen readers
The answer is D: All compounds will show a sharp peak at 1700 cm⁻¹ due to the C=O stretch. Only aldehydes show medium strength bands around 2800 and 2700 cm⁻¹, while carboxylic acids show a broad band from 3100 to 2800 cm⁻¹ due to O-H stretching.
More Information
Aldehydes are distinguished by C-H stretches near 2800 cm⁻¹, while carboxylic acids have broad O-H stretches, both lacking in ketones.
Tips
A common mistake is not recognizing the broad O-H stretch in carboxylic acids.
Sources
- Infrared Spectroscopy of Aldehydes, Ketones, Carboxylic Acids - utdallas.edu
- How can you tell the difference using IR spectroscopy? - socratic.org
