Analyze the IR diagram shown below.
The given IR spectrum is that of phenol. Look at some of the important peaks that are present in this IR spectrum of phenol.
1) The peak 1 around 3400 cm-1 represents the peak caused by the -OH group.
2) The peak 2 at 3050 cm-1 represents the aromatic -CH.
3) The peak 3 denotes the benzene ring stretch.
In the IR spectrum shown above, identify the most likely peak which represents the carbonyl group.
The carbonyl peak is roughly around 1700 cm-1. So Peak 2 indicated in the IR diagram is the correct answer.
Infrared (IR) spectroscopyInfrared spectroscopy is a widely used tool to identify and analyze compounds. As you know, the infrared radiation is part of the electromagnetic spectrum. The IR has wavelengths between those of the visible light and the microwaves. From the analytical point of view, only a portion of the entire infrared range is actually useful for the spectroscopic analysis.
In order to analyze organic compounds, certain properties at the molecular level are put to use in the infrared spectroscopy. In this technique, the infrared light is passed through organic compound samples. By doing this, some of the frequencies are absorbed by the sample and the other frequencies simply pass through. The percentage absorbance or transmittance is plotted against the frequency or, to be more precise, the wave number. The wave number (cm-1) is the reciprocal of wavelength expressed in centimeters. The plot can be used to analyze the structure of a compound by identifying the peaks that are characteristic to the groups present in the compound.
Other very complex IR diagrams can only be interpreted by skilled and experienced professionals.