What peaks would indicate a carboxylic acid in IR spectroscopy?

In IR spectroscopy, a carboxylic acid is indicated by strong peaks around 1700 cm-1 and broad peaks around 2500-3300 cm-1.

Infrared (IR) spectroscopy is a powerful tool in organic chemistry that allows us to identify different functional groups in a molecule. When it comes to carboxylic acids, there are two main peaks that we need to look out for. The first one is a strong, sharp peak around 1700 cm-1, which corresponds to the C=O (carbonyl) stretching vibration. This peak is a clear indication of a carbonyl group, which is a key component of carboxylic acids.

The second important peak is a broad one that appears around 2500-3300 cm-1. This peak is due to the O-H (hydroxyl) stretching vibration. It's worth noting that this peak is usually very broad and strong due to the hydrogen bonding that typically occurs in carboxylic acids. This broad peak can sometimes overlap with the C-H stretching vibrations that appear in the same region, but its intensity and breadth usually make it distinguishable.

It's also important to remember that while these peaks are characteristic of carboxylic acids, they can also appear in other types of compounds that contain carbonyl and hydroxyl groups. Therefore, it's always crucial to consider the whole IR spectrum and other pieces of information when identifying a compound.

In summary, if you see a strong peak around 1700 cm-1 and a broad peak around 2500-3300 cm-1 in an IR spectrum, it's a good indication that the compound you're dealing with might be a carboxylic acid. However, always remember to consider the entire spectrum and other available data before making a final decision.