Chapter 16, Problem 16.39P

Interpretation Introduction

(a)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate two signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has two distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

The given compound has a plane of symmetry and thus has two chemically distinct protons indicated as ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$, so there must be two signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has two signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(b)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate five signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has five distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

The protons cis to chlorine atoms and those trans to chlorine atoms are diastereotropic. Thus, the compound has five chemically distinct protons indicated as ${\text{H}}_{\text{a}}{\text{, H}}_{\text{b}}{\text{, H}}_{\text{c}}{\text{, H}}_{\text{d}}$, and ${\text{H}}_{\text{e}}$, so there must be five signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has five signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(c)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate eight signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has eight distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

As the ring has two different substituents, all the protons are chemically non-equivalent. Thus, the compound has eight chemically distinct protons indicated as ${\text{H}}_{\text{a}}{\text{, H}}_{\text{b}}{\text{, H}}_{\text{c}}{\text{, H}}_{\text{d}}{\text{, H}}_{\text{e}}{\text{, H}}_{\text{f}}$, and ${\text{H}}_{\text{h}}$, so there must be eight signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has eight signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(d)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate four signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has four distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

In the given compounds, both ethyl groups are in different chemical environment. One is attached to oxygen and another to carbonyl carbon. Thus the compound has four chemically distinct protons indicated as ${\text{H}}_{\text{a}}{\text{, H}}_{\text{b}}{\text{, H}}_{\text{c}}$, and ${\text{H}}_{\text{d}}$, so there must be four signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has four signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(e)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate two signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has two distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

In the given compounds, both ethyl groups are in the same chemical environment. Thus, the compound has two chemically distinct protons indicated as ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$, so there must be two signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has two signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(f)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate three signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has three distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

As the molecule is para disubstituted, it has a plane of symmetry passing through $\text{Br-C-C-OH}$, which divides the aromatic protons in two types. Thus, the compound has three chemically distinct protons indicated as ${\text{H}}_{\text{a}},{\text{H}}_{\text{b}}$, and ${\text{H}}_{\text{c}}$, so there must be three signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has three signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(g)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate five signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has five distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

The molecule is meta disubstituted with different substituents and has no plane of symmetry; thus, all protons are chemically non-equivalent. Hence the compound has five chemically distinct protons indicated as ${\text{H}}_{\text{a}}{\text{, H}}_{\text{c}}{\text{, H}}_{\text{d}}{\text{, H}}_{\text{e}}$, and ${\text{H}}_{\text{f}}$, so there must be five signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has five signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(h)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate five signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has five distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

The molecule is ortho disubstituted with different substituents and has no plane of symmetry; thus, all protons are chemically non-equivalent. Hence the compound has five chemically distinct protons indicated as ${\text{H}}_{\text{a}}{\text{, H}}_{\text{c}}{\text{, H}}_{\text{d}}{\text{, H}}_{\text{e}}$, and ${\text{H}}_{\text{f}}$, so there must be five signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has five signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.

Interpretation Introduction

(i)

Interpretation:

The number of signals that would be generated in the ${}^{\text{1}}\text{H}$ NMR spectrum for the given molecule is to be determined.

Concept introduction:

In ${}^{\text{1}}\text{H}$ NMR, the number of signals is equal to the number of types of protons in the molecule. The chemically equivalent protons absorb at the same magnetic field and produce one signal whereas the chemically non-equivalent or distinct protons absorb at different magnetic fields, producing different signals.

Answer to Problem 16.39P

The given molecule could generate six signals in ${}^{\text{1}}\text{H}$ NMR spectrum because it has six distinct protons, as shown below:

Explanation of Solution

The structure of the given compound is

The molecule is monosubstituted benzene; thus, there are three types of aromatic protons. The three methyl protons are in same chemical environment; thus they are identical. Hence the compound has six chemically distinct protons indicated as ${\text{H}}_{\text{a}}{\text{, H}}_{\text{c}}{\text{, H}}_{\text{d}}{\text{, H}}_{\text{e}}$, and ${\text{H}}_{\text{f}}$, so there must be six signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

Conclusion

It is determined that the given molecule has six signals in ${}^{\text{1}}\text{H}$ NMR spectrum by determining the number of distinct protons in it.