Which compound gives this infrared spectrum? A B C D (Reference image provided) - AQA - A-Level Chemistry - Question 12 - 2017 - Paper 3

To identify which compound corresponds to the given infrared spectrum, we need to analyze the characteristic absorption peaks. Each compound has unique functional groups that can be identified through their distinctive peaks in the infrared region.

In this case, the spectrum shows significant absorption around key wavenumber regions. For example:

• A sharp peak around 1700 cm⁻¹ typically indicates the presence of a carbonyl group (C=O), which is common in aldehydes such as butanal.
• Absorption near 3300 cm⁻¹ suggests the presence of an -OH group potentially from an alcohol, which could indicate butan-1-ol or butanoic acid.

After analyzing the options provided:

• 1-bromobutane does not show characteristic peaks of the aforementioned functional groups.
• Butan-1-ol would show an -OH peak but also needs a carbonyl peak to be valid.
• Butanal presents the expected peak around 1700 cm⁻¹, supporting its identification.
• Butanoic acid would exhibit both an -OH peak and a carbonyl peak, but the absence of a strong broad -OH peak in this spectrum indicates it's less likely.

Thus, based on the analysis of the spectrum, the compound that gives this infrared spectrum is likely C: butanal.