Question

In the following boxes, list the types of bonds and the approximate wavenumber at which each type of bond is expected to show an IR absorption:

Short answer

Type of bonds showing the given IR spectra

Step-by-step solution

IR spectroscopy

It stands for Infrared spectroscopy which is used to determine the functional group of the atom by measuring the vibrational energy of the bonds of the atom each functional group shows a specific range of wavenumber so, that we can differentiate the two atoms on the basis of the functional group.

IR region 3600-3000

The alcoholic group containing OH shows absorptions at the 3300-3000 region of the IR spectra.

The amine group NHR shows the absorption in the range of 3600-3200 as nitrogen is high electronegative in nature so more range of IR spectra.

The C-C bond also shows absorption in the range of 3300 and the unsaturated bond like alkene shows the range under 3050 due to its short bond length.

IR region 1800-3000

The carbonyl group aldehyde shows the absorption at 2700 due to the carbonyl bond.

Alkyne shows the absorption at 2100 due to a short wavelength than alkene by the presence of a triple bond

Nitrile also has to have a triple bond but shows absorption at 2250 due to the presence of the electronegative nitrogen atom.

IR region 1800-1400

The aromatic benzene ring shows absorption at 1500 due to the presence of three double bonds.

Double bond shows absorption at 1600 and the carbonyls show absorption at 1700

IR region 1000-1400

Here, the C-N bond shows absorption between 1230-1020 the weak absorption due to one electropositive atom and one electronegative atom without an unsaturation bond.