How can you differentiate between aldehydes, ketones, and carboxylic acids using IR spectroscopy?

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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.

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