Chapter 14, Problem 14.24P

(a)

Interpretation Introduction

Interpretation:

The appearance of an $M+2$ peak with approximately two thireds the intensity of the molecular ion peak has to accounded with the give mass spectrum of 1,2-dichloroethane.

Concept introduction:

Interpreting a mass spectrum:

1. 1. The each $m/z$ values is the $m/z$ value of one the fragments to the nearest whole number.
2. 2. The peak with the highest $m/z$ value in the molecular ions $\left({\text{M}}^{\text{+}}\right)$, the fragment that results when the molecules lose electrons as result of being bombarding by the electron beam.
3. 3. The $m/z$ value of the molecular ion gives the molecular mass of the compound.

Peaks with smaller m/z values, fragment ion peak represent positively charged fragments of the molecular ion.

Base peak of mass spectrum: The base peak is the one of highest (or) tallest peak, it has great abundance. It has the greatest relative abundance because it is generally the most stable positively charged fragment.

Percentage of base peak: The base peak is assigned a relative abundance (RA) of 100% and the relative abundance of each other peaks is respective mass spectrum percentage of base peak. For example the weak bonds break in preference to strong bonds and bonds that break to form more stable fragments break in performance to those that form less stable fragments.

(b)

Interpretation Introduction

Interpretation:

The intensity of the $M+4$ peak has to be predicted using the given mass spectrum.

Concept introduction:

Interpreting a mass spectrum:

1. 1. The each $m/z$ values is the $m/z$ value of one the fragments to the nearest whole number.
2. 2. The peak with the highest $m/z$ value in the molecular ions $\left({\text{M}}^{\text{+}}\right)$, the fragment that results when the molecules lose electrons as result of being bombarding by the electron beam.
3. 3. The $m/z$ value of the molecular ion gives the molecular mass of the compound.

Peaks with smaller m/z values, fragment ion peak represent positively charged fragments of the molecular ion.

(c)

Interpretation Introduction

Interpretation:

The 1,2-dichloroethane cationic stractural formula has to be proposed with the given $m/z$ values.

 Concept introduction:

Fundamental of Mass spectrometer: It is one of powerful tool in organic chemistry, used to quantity known materials, to identify unknown compounds within a sample and to elucidate the structure and chemical properties of different molecules.

Basic principle: It generates multiple ions from the sample under investigation, it than separates them according to their specific mass to charge ration $\left(m/z\right)$ and records the relative abundance (RA) of each ion types.

      $\begin{array}{l}\text{M}\stackrel{\begin{array}{l}\text{electron}\\ \text{beam}\end{array}}{\to }{\text{M}}^{\begin{array}{l}+\\ .\end{array}}+{\text{e}}^{\text{-}}\\ \text{[Molecule]}\text{Molecular ion}\text{electron}\\ [\text{Radical}\text{cation}]\end{array}$

Base peak of mass spectrum: The base peak is the one of highest (or) tallest peak, it has great abundance. It has the greatest relative abundance because it is generally the most stable positively charged fragment.

Percentage of base peak: The base peak is assigned a relative abundance (RA) of 100% and the relative abundance of each other peaks is respective mass spectrum percentage of base peak. For example the weak bonds break in preference to strong bonds and bonds that break to form more stable fragments break in performance to those that form less stable fragments.