Question

The following list of frequency ranges (in wavenumbers) are those that correspond to four most important regions of the IR spectrum. For each region indicate the most important structural information that it indicates.

Region 2: 3100-2500 cm⁻¹

Answer 1

The IR frequency range of 3100-2500 cm⁻¹ provides information on bond stretching vibrations of functional groups such as O-H in alcohols and acids, N-H in amines, and C-H in alkanes with sp³-hybridized carbons, which is useful for detecting hydrogen bonding.

Step-by-step explanation:

The frequency range of 3100-2500 cm⁻¹ in the infrared (IR) spectrum is indicative of certain types of chemical bonds found within molecules. In this particular region, the primary structural information that can be deduced involves the presence of of certain functional groups. For instance, this frequency range can correspond to the O-H stretching in alcohols and acids, N-H stretching in amines, and the C-H stretching vibrations in alkanes, particularly in molecules that contain sp³-hybridized carbon atoms. It is especially important for identifying the presence of hydrogen bonding, as the O-H and N-H stretching frequencies will shift based on the hydrogen bonding environment.