Chapter 13, Problem 13.24P

Write structural formulas for the following compounds.

1. (a) C₂H₄Br₂:    δ 2.5 (d, 3H) and 5.9 (q, 1H)
2. (b) C₄H_gCl₂:    δ 1.60 (d, 3H), 2.15 (m, 2H), 3.72 (t, 2H), and 4.27 (m, 1H)
3. (c) C₅H₈Br₄:    δ 3.6 (s, 8H)
4. (d) C₄H₈O:    δ 1.0 (t, 3H), 2.1 (s, 3H), and 2.4 (quartet, 2H)
5. (e) C₄H₈O₂:    δ 1.2 (t, 3H), 2.1 (s, 3H), and 4.1 (quartet, 2H); contains an ester
6. (f) C₄H₈O₂:    δ 1.2 (t, 3H), 2.3 (quartet, 2H), and 3.6 (s, 3H); contains an ester
7. (g) C₄H₉Br:    δ 1.1 (d, 6H), 1.9 (m, 1H), and 3.4 (d, 2H)
8. (h) C₆H₁₂O₂:    δ 1.5 (s, 9H) and 2.0 (s, 3H)
9. (i) C₇H₁₄O:    δ 0.9 (t, 6H), 1.6 (sextet, 4H), and 2.4 (t, 4H)
10. (j) C₅H₁₀O₂:    δ 1.2 (d, 6H), 2.0 (s, 3H), and 5.0 (septet, 1H)
11. (k) C₅H₁₁Br:    δ 1.1 (s, 9H) and 3.2 (s, 2H)
12. (l) C₇H₁₅Cl    δ 1.1 (s, 9H) and 1.6 (s, 6H)

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (a) is ${\text{C}}_2{\text{H}}_4{\text{Br}}_2$.

There are 2 peaks observed in the given ${}^1\text{H NMR}$ data’s thus 2 sets of non-equivalent protons are present in the molecule.

A doublet is observed for 3 hydrogens at around $\text{δ}2.5\text{ ppm}$ that indicate the presence of methyl $\left({\text{-CH}}_3\right)$ group.

Another quartet peak for 1 hydrogen at around $\text{5}\text{.9 ppm}$ is observed that corresponds to the $\left(\text{-CH}\right)$ group it is attached with halogen group.

Based on the above ${}^1\text{H NMR}$ spectral details, the structural formula for compound (a) is:

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (b) is ${\text{C}}_4{\text{H}}_8{\text{Cl}}_2$.

A doublet is observed for 3 hydrogens at around $\text{δ}1.60\text{ ppm}$ that indicate the presence of methyl $\left({\text{-CH}}_3\right)$ group.

A multiplet is observed for 2 hydrogens at around $\text{2}\text{.15 ppm}$ that indicates that has the adjacent groups $\left({\text{CH}}_{\text{2}}\right)$ containing a total of two hydrogens.

One triplet peak is observed for 2 hydrogens at around $\text{3}\text{.72 ppm}$ that indicates the presence $\left({\text{CH}}_{\text{2}}\right)$ group adjacent to it as per the $\left(N+1\right)$ rule.

Another multiplet is observed for 1 hydrogen at around $\text{4}\text{.27 ppm}$ that indicates that has the adjacent groups $\left(\text{CH}\right)$ containing a total of one hydrogen.

Thus, the structure of the compound (b) is 1,3-dichlorobutane:

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (c) is ${\text{C}}_4{\text{H}}_8{\text{Br}}_2$.

This molecule only one singlet is observed for 8 hydrogens at around $\text{δ}3.6\text{ ppm}$ that indicate the presence of $\left({\text{CH}}_{\text{2}}-\text{Br}\right)$ groups it is containing a total of eight hydrogens.

Therefore, the structure of the compound (c) is given below and this molecule symmetrical.

  

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (d) is ${\text{C}}_4{\text{H}}_8\text{O}$.

A triplet is observed for 3 hydrogens at around $\text{δ}1.0\text{ ppm}$ that indicate the presence of methyl $\left({\text{-CH}}_3\right)$ group.

One singlet is observed for 3 hydrogens at around $\text{δ}2.1\text{ ppm}$ that indicate the presence of another one methyl $\left({\text{-CH}}_3\right)$ group.

Another quartet is observed for 2 hydrogens at around $\text{2}\text{.40}\text{ppm}$ that indicates that has the adjacent groups $\left({\text{CH}}_2\right)$ containing a total of two hydrogens.

Thus, the structure of the compound (d) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (e) is ${\text{C}}_4{\text{H}}_8{\text{O}}_{\text{2}}$.

A triplet is observed for 3 hydrogens at around $\text{δ}1.2\text{ ppm}$ that indicate the presence of methyl $\left({\text{-CH}}_3\right)$ group.

One singlet is observed for 3 hydrogens at around $\text{δ}2.1\text{ ppm}$ that indicate the presence of another one ester methyl $\left({\text{-CH}}_3\right)$ group.

Another quartet is observed for 2 hydrogens at around $\text{2}\text{.40}\text{ppm}$ that indicates that has the ester $\left({\text{CH}}_2\right)$ groups it is containing a total of two hydrogens.

Thus, the structure of the compound (e) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (f) is ${\text{C}}_4{\text{H}}_8{\text{O}}_{\text{2}}$.

A triplet is observed for 3 hydrogens at around $\text{δ}1.2\text{ ppm}$ that indicate the presence of methyl $\left({\text{-CH}}_3\right)$ group.

One singlet is observed for 3 hydrogens at around $\text{δ}4.1\text{ ppm}$ that indicate the presence of ester methyl $\left({\text{-O-CH}}_3\right)$ group.

Another quartet is observed for 2 hydrogens at around $\text{2}\text{.3}\text{ppm}$ that indicates that has the $\left({\text{CH}}_2\right)$ groups it is containing a total of two hydrogens.

Thus, the structure of the compound (f) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (g) is ${\text{C}}_4{\text{H}}_9\text{Br}$.

A doublet is observed for 6 hydrogens at around $\text{δ}1.1\text{ ppm}$ that indicate the presence of two methyl $\left({\text{-CH}}_3\right)$ groups.

One multiplet is observed for 1 hydrogen at around $\text{δ}1.9\text{ ppm}$ that indicate the presence of $\left(\text{-CH-}\right)$ group.

Another multiplet is observed for 2 hydrogens at around $3.4\text{ppm}$ that indicates that has the $\left({\text{CH}}_2\right)$ groups it is containing a total of two hydrogens.

Thus, the structure of the compound (g) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (h) is ${\text{C}}_6{\text{H}}_{12}{\text{O}}_{\text{2}}$.

A singlet is observed for 9 hydrogens at around $\text{δ}1.5\text{ ppm}$ that indicate the presence of tertiary $\left({\text{-CH}}_3\right)$ groups.

Another one singlet is observed for 3 hydrogens at around $\text{δ}2.0\text{ ppm}$ that indicate the presence of $\left({\text{-CH}}_3\right)$ group.

Thus, the structure of the compound (h) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (i) is ${\text{C}}_7{\text{H}}_{14}\text{O}$.

A singlet is observed for 6 hydrogens at around $\text{δ}0.9\text{ ppm}$ that indicate the presence of two $\left({\text{-CH}}_3\right)$ groups.

One sextet is observed for 4 hydrogens at around $\text{δ}1.6\text{ ppm}$ that indicate the presence of $\left({\text{-CH}}_2\right)$ group.

Another triplet peak for 4 hydrogens at around $\text{2}\text{.4 ppm}$ is observed that corresponds to the $\left({\text{CH}}_2\right)$ group.  A triplet is observed because the group $\left({\text{CH}}_{\text{2}}\right)$ must have been adjacent to the methyl group.

Thus, the structure of the compound (i) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (J) is ${\text{C}}_5{\text{H}}_{10}{\text{O}}_{\text{2}}$.

A doublet is observed for 6 hydrogens at around $\text{δ}1.2\text{ ppm}$ that indicate the presence of two $\left({\text{-CH}}_3\right)$ groups.

One septet is observed for 1 hydrogen at around $\text{δ}2.0\text{ ppm}$ that indicate the presence of $\left(\text{-CH}\right)$ group.

Another singlet peak for 3 hydrogens at around $\text{2}\text{.0 ppm}$ is observed that corresponds to the $\left({\text{CH}}_3\right)$ group.  A triplet is observed because the group $\left(\text{-C=O}\right)$ must have been adjacent to the methyl group.

Thus, the structure of the compound (J) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (K) is ${\text{C}}_5{\text{H}}_{10}\text{Br}$.

A singlet is observed for 9 hydrogens at around $\text{δ}1.1\text{ ppm}$ that indicate the presence of three $\left({\text{-CH}}_3\right)$ groups.

One singlet is observed for 2 hydrogens at around $\text{δ}3.2\text{ ppm}$ that indicate the presence of $\left({\text{-CH}}_2\right)$ group.

Thus, the structure of the compound (K) is,

Interpretation Introduction

Interpretation:

The structural formula of the given compound has to be proposed with the help of given molecular formula and  its ${}^{\text{1}}\text{H NMR}$ spectral data.

Concept introduction:

The ${}^1\text{H NMR}$ spectrum of a compound provides some vital information that is required to predict the structure of the compound.  The chemical shift values can predict the groups that are present in the molecule.  The splitting of signals as per the $\left(N+1\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  With this information, the structure of the compound can be predicted.

Chemical shift: The NMR spectrum of any compound is taken with reference to a standard compound called reference compound.  Generally, tetramethylsilane (TMS) is taken as the reference compound.  The methyl protons of TMS are equivalent and produces only one sharp peak at the rightmost end of the scale.

The distance between the TMS signal and the signals produced by the compound is called the chemical shift.  Chemical shift basically measures the shift in the signal position of the compound with respect to the reference signal.

Chemical shift in delta scale is given as,

$\text{chemical shift,}\delta \left(\text{ppm}\right)=\frac{\text{distance from the TMS signal}\left(\text{Hz}\right)}{\text{operating frequency of the spectrometer (MHz)}}$

Explanation of Solution

The given molecular formula (L) is ${\text{C}}_5{\text{H}}_{10}\text{Cl}$.

A singlet is observed for 9 hydrogens at around $\text{δ}1.1\text{ ppm}$ that indicate the presence of three $\left({\text{-CH}}_3\right)$ groups.

One singlet is observed for 6 hydrogens at around $\text{δ}1.6\text{ ppm}$ that indicate the presence of $\left({\text{-CH}}_3\right)$ group.

Thus, the structure of the compound (L) is,