Chapter 15, Problem 59PP

Interpretation Introduction

Interpretation: The possible structures for the compounds should be determined by using the given IR and mass spectrum.

Concept Introduction:

IR spectral studies: It is a spectroscopic technique which is used to determine the functional groups present in the given compound sample by absorbing frequency in particular range with respect to the group present in the given sample.

Wavenumber: It is defined as the number of waves in one centimeter. The wavenumber indicates the location of each signal with respect to the functional group in the molecule and its unit is ${\text{cm}}^{\text{-1}}$.

Mass spectroscopy: It is a form of spectroscopic technique which is used for the elucidation of the molecular formula and molecular weight of the compound, depending upon the mass of the molecule.

Molecular formula: It represents the types of atoms with their total number present in a given molecule.

Molecular ion peak ${\text{(M)}}^{\text{+}·}$: It is defined as the heaviest peak in the IR spectrum of the molecule which represents the largest molecular ion in the given molecule with greater m/z value.

Base peak: It is the tallest peak in the spectrum.

The ${\text{(M+1)}}^{\text{+}•}$ peak: It denotes the peak that arises next to molecular ion peak in the mass spectrum. The peak arises due to the presence of the isotope of carbon $\left({}^{\text{13}}\text{C}\right).$

The ${\text{(M+1)}}^{\text{+}•}$ peak in mass spectroscopy is used to explain the number of carbon atoms present in a molecule depending on the abundance of ${\text{(M+1)}}^{\text{+}•}$ peak.

The Hydrogen Deficiency Index (HDI): It is used to measure the number of degrees of unsaturation (double and triple bonds) present in a given molecule. It is determined by using the formula

$\begin{array}{l}\text{HDI}\text{=}\frac{\text{1}}{\text{2}}\text{[(2}\times \text{No}\text{. of Carbon atoms)+2+(No}\text{. of Nitrogen atoms)}\\ \text{-(No}\text{. of Hydrogen atoms)-(No}\text{. of halogens)]}\end{array}$