Question

Which one of the following five compounds produced the IR spectrum shown below?

Short answer

The given IR spectra best fit with the structure of phenol.

Step-by-step solution

Infrared (IR) spectroscopy

The Infrared spectroscopy is the study of the interaction of the sample with IR radiation brings about change in vibrational-rotational level. Therefore it is also called rotational-vibrational spectroscopy.

• It is a technique based on the vibrations of the atoms of a molecule.
• The waves are electromagnetic in nature and interact with polarity of the chemical bonds of the molecule.
• If there is no polarity in the molecule then the infrared interaction is inactive and the molecule does not produce any IR spectrum.

Idenification of compound having given IR spectra

In the given, IR spectrum the absorption at 3000 cm^-1region indicate that the compound has hydrogen attached to sp²carbons but not to sp³ carbons.

There is no peak at 1700 cm^-1 which indicates that the absence of carbonyl (C=O) functional group. So, the compounds containing carbonyl functional group is not fit in the given spectrum.

The absorption peak at 1470-1500 cm^-1 and at 1600 cm^-1 indicates that the compound containing aromatic benzene ring.

Hence, all the above observations from the given IR spectra predicts that the structure of compound is phenol which best fits with the given spectra.