Chapter 14, Problem 18Q

Interpretation Introduction

Interpretation:

Functional groups that are likely to present in the sample have to be determined and also have to identify whether the concentrations of functional groups can be explained using their relative peak heights.

Concept Introduction:

• Electromagnetic spectrum is a range of all types of electromagnetic radiation.

• IR Spectroscopy: The bonds between atoms in the molecule stretch and bend, absorbing IR energy and creating the IR spectrum.
• IR spectroscopy is used to identify the functional groups in a compound. The frequencies in IR spectroscopy are reported using a unit called wavenumber and it is represented by $\overline{\nu }$ and their unit is $c{m}^{-1}$ . using wavenumber scale, IR absorptions occurs from $\text{4000}{\text{cm}}^{\text{-1}}\text{-}\text{400}{\text{cm}}^{\text{-1}}$

$\overline{\text{ν}}=\frac{\text{1}}{\text{λ}}\boxed{\text{λ}=wavelength}$

Carbonyl group: The functional group that contains carbon atom which is doubly bonded with the oxygen atom. The characteristic IR signal for $\text{CO}$ group in an amide is at $\sim 1660{\text{cm}}^{\text{-1}}$.

Primary and secondary amine:

Primary amine refers to the functional group that contains one nitrogen atom bonded to two hydrogen atoms and one carbon containing group and the secondary amine contains nitrogen bonded to one hydrogen atom and two carbon containing groups.

The characteristic IR signal for $\text{N-H}$ stretch is at range of $\sim 3500{\text{cm}}^{\text{-1}}-\sim 3200{\text{cm}}^{\text{-1}}$

Alcohol functional group: It refers to the functional group that contains one $\text{OH}$ group bonded with the carbon atom in a molecule. The characteristic IR signal for $\text{OH}$ group is broad signal at range of about $3550-3200{\text{cm}}^{\text{-1}}$.