Infrared IR spectroscopy is a powerful analytical technique used to identify functional groups in a given compound by measuring the absorption of infrared radiation by the compound's molecules. The principle of IR spectroscopy is based on the fact that molecules absorb specific frequencies of infrared radiation that correspond to the energy required to excite the vibrational modes of their chemical bonds. Different functional groups have characteristic absorption bands, which can be used to identify them in a compound.Here's a step-by-step procedure for interpreting an IR spectrum to identify the functional groups present in a compound:1. Obtain the IR spectrum of the compound: The first step is to obtain the IR spectrum of the compound by exposing it to a range of infrared frequencies. The resulting spectrum will show the absorbance or transmittance of the compound as a function of the frequency or wavenumber of the incident radiation.2. Identify the characteristic absorption bands: Examine the IR spectrum and look for the characteristic absorption bands associated with different functional groups. These bands are typically reported in wavenumbers cm . Some common functional groups and their characteristic absorption bands include: - O-H alcohol or phenol : broad band around 3200-3600 cm - N-H amine or amide : sharp band around 3300-3500 cm - C=O carbonyl : strong band around 1650-1750 cm - C=C alkene : weak to medium band around 1600-1680 cm - CC alkyne : medium to strong band around 2100-2260 cm - C-H alkane : medium to strong bands around 2850-2960 cm3. Analyze the fingerprint region: The fingerprint region below 1500 cm contains many overlapping absorption bands that are unique to each compound. Comparing the fingerprint region of the unknown compound with those of known compounds can help confirm the presence of specific functional groups.4. Combine the information: Use the identified absorption bands and the fingerprint region analysis to determine the functional groups present in the compound.Example:Let's say we have an IR spectrum of an unknown compound with the following absorption bands:- A broad band around 3300 cm- A strong band around 1700 cm- Medium to strong bands around 2900 cmBased on the characteristic absorption bands, we can infer the following functional groups:- The broad band around 3300 cm suggests the presence of an O-H group alcohol or phenol .- The strong band around 1700 cm indicates the presence of a C=O group carbonyl .- The medium to strong bands around 2900 cm are indicative of C-H bonds alkane .By combining this information, we can conclude that the compound likely contains an alcohol or phenol group, a carbonyl group, and an alkane group. Further analysis of the fingerprint region and other spectroscopic techniques e.g., NMR may be needed to confirm the exact structure of the compound.