Chapter 14, Problem 14.14P

Interpretation Introduction

(a)

Interpretation: The number of peaks for each indicated proton is to be predicted.

Concept introduction: The number of NMR signal in a compound is equal to the number of chemically non-equivalent protons present in that compound. Protons which are present in the same chemical environment that is between the same group of atoms are known as chemically equivalent protons and in ${}^1\text{H}-\text{NMR}$ all chemically equivalent proton generates one signal or one peak, whereas non-equivalent proton generates different signals.

Answer to Problem 14.14P

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. ${\text{H}}_{\text{a}}$ gives triplet and ${\text{H}}_{\text{b}}$ gives quartet peaks.

Explanation of Solution

The number of signals in each compound is equal to the number of hydrogen atoms present in a different chemical environment. The given compound is $\text{C}\underset{{\text{H}}_{\text{a}}}{{\text{H}}_{\text{3}}}\text{C}\underset{{\text{H}}_{\text{b}}}{{\text{H}}_{\text{2}}}\text{COCl}$.

It has two different types of non-equivalent protons shown in red color. Therefore, it gives two signals in ${}^1\text{H}-\text{NMR}$ spectrum. The signal ${\text{H}}_{\text{a}}$ gets split into a triplet by $2$ ${\text{H}}_{\text{b}}$ protons and the signal ${\text{H}}_{\text{b}}$ gets split into a quartet by $3$ ${\text{H}}_{\text{a}}$ protons.

Conclusion

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. ${\text{H}}_{\text{a}}$ gives triplet and ${\text{H}}_{\text{b}}$ gives quartet peaks.

Interpretation Introduction

(b)

Interpretation: The number of peaks for each indicated proton is to be predicted.

Concept introduction: The number of NMR signal in a compound is equal to the number of chemically non-equivalent protons present in that compound. Protons which are present in the same chemical environment that is between the same group of atoms are known as chemically equivalent protons and in ${}^1\text{H}-\text{NMR}$ all chemically equivalent proton generates one signal or one peak, whereas non-equivalent proton generates different signals.

Answer to Problem 14.14P

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. ${\text{H}}_{\text{a}}$ gives doublet and ${\text{H}}_{\text{b}}$ gives quartet peaks.

Explanation of Solution

The given compound is shown below.

Figure 1

It has two non-equivalent protons. Therefore, it gives two signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

The signal ${\text{H}}_{\text{a}}$ gets split into a doublet by $1$ ${\text{H}}_{\text{b}}$ proton and the signal ${\text{H}}_{\text{b}}$ gets split into a quartet by $3$ ${\text{H}}_{\text{a}}$ protons.

Conclusion

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. ${\text{H}}_{\text{a}}$ gives doublet and ${\text{H}}_{\text{b}}$ gives quartet peaks.

Interpretation Introduction

(c)

Interpretation: The number of peaks for each indicated proton is to be predicted.

Concept introduction: The number of NMR signal in a compound is equal to the number of chemically non-equivalent protons present in that compound. Protons which are present in the same chemical environment that is between the same group of atoms are known as chemically equivalent protons and in ${}^1\text{H}-\text{NMR}$ all chemically equivalent proton generates one signal or one peak, whereas non-equivalent proton generates different signals.

Answer to Problem 14.14P

The given compound shows three signals in ${}^{\text{1}}\text{H}$ NMR spectrum. ${\text{H}}_{\text{a}}$ gives singlet, ${\text{H}}_{\text{b}}$ and ${\text{H}}_{\text{c}}$ give triplet peaks.

Explanation of Solution

The given compound is shown below.

Figure 2

It has three non-equivalent protons. Therefore, it gives three signals in ${}^{\text{1}}\text{H}$ NMR spectrum. The signal ${\text{H}}_{\text{a}}$ has no adjacent non-equivalent protons, therefore; it gives only a single peak that is singlet.

The signal ${\text{H}}_{\text{b}}$ gets split into a triplet by $2$ ${\text{H}}_{\text{c}}$ protons and also, the signal ${\text{H}}_{\text{c}}$ gets split into a triplet by $2$ ${\text{H}}_{\text{b}}$ protons.

Conclusion

The given compound shows three signals in ${}^{\text{1}}\text{H}$ NMR spectrum. ${\text{H}}_{\text{a}}$ gives singlet, ${\text{H}}_{\text{b}}$ and ${\text{H}}_{\text{c}}$ give triplet peaks.

Interpretation Introduction

(d)

Interpretation: The number of peaks for each indicated proton is to be predicted.

Concept introduction: The number of NMR signal in a compound is equal to the number of chemically non-equivalent protons present in that compound. Protons which are present in the same chemical environment that is between the same group of atoms are known as chemically equivalent protons and in ${}^1\text{H}-\text{NMR}$ all chemically equivalent proton generates one signal or one peak, whereas non-equivalent proton generates different signals.

Answer to Problem 14.14P

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. Both ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$ give two peaks.

Explanation of Solution

The given compound is shown below.

Figure 3

It has two non-equivalent protons. Therefore, it gives two signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

The signal ${\text{H}}_{\text{a}}$ gets split into two peaks that is doublet by $1$ ${\text{H}}_{\text{b}}$ proton and also, the signal ${\text{H}}_{\text{b}}$ gets split into a doublet by $1$ ${\text{H}}_{\text{a}}$ proton.

Conclusion

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. Both ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$ give two peaks.

Interpretation Introduction

(e)

Interpretation: The number of peaks for each indicated proton is to be predicted.

Concept introduction: The number of NMR signal in a compound is equal to the number of chemically non-equivalent protons present in that compound. Protons which are present in the same chemical environment that is between the same group of atoms are known as chemically equivalent protons and in ${}^1\text{H}-\text{NMR}$ all chemically equivalent proton generates one signal or one peak, whereas non-equivalent proton generates different signals.

Answer to Problem 14.14P

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. Both ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$ give two peaks.

Explanation of Solution

The given compound is shown below.

Figure 4

It has two non-equivalent protons. Therefore, it gives two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. Both the protons are present on the same carbon atom.

The signal ${\text{H}}_{\text{a}}$ gets split into two peaks that is doublet by $1$ ${\text{H}}_{\text{b}}$ proton and also, the signal ${\text{H}}_{\text{b}}$ gets split into a doublet by $1$ ${\text{H}}_{\text{a}}$ proton.

Conclusion

The given compound shows two signals in ${}^{\text{1}}\text{H}$ NMR spectrum. Both ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$ give two peaks.

Interpretation Introduction

(f)

Interpretation: The number of peaks for each indicated proton is to be predicted.

Concept introduction: The number of NMR signal in a compound is equal to the number of chemically non-equivalent protons present in that compound. Protons which are present in the same chemical environment that is between the same group of atoms are known as chemically equivalent protons and in ${}^1\text{H}-\text{NMR}$ all chemically equivalent proton generates one signal or one peak, whereas non-equivalent proton generates different signals.

Answer to Problem 14.14P

The indicated protons ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$ shows doublet and triplet peaks.

Explanation of Solution

The given compound is shown below.

Figure 5

It has three non-equivalent protons. Therefore, it gives three signals in ${}^{\text{1}}\text{H}$ NMR spectrum.

The signal ${\text{H}}_{\text{a}}$ gets split into two peaks that is doublet by $1$ ${\text{H}}_{\text{b}}$ proton; the signal ${\text{H}}_{\text{b}}$ gets split into three peaks that is triplet by $2$ ${\text{H}}_{\text{a}}$ protons. The signal ${\text{H}}_{\text{c}}$ has no adjacent proton therefore; it gets split into a singlet.

Hence, the indicated protons which are shown in red color shows doublet and triplet peaks.

Conclusion

The indicated protons ${\text{H}}_{\text{a}}$ and ${\text{H}}_{\text{b}}$ shows doublet and triplet peaks.