Chapter 21, Problem 21.30P

(a)

Interpretation Introduction

Interpretation:

The strucutral formula for each of the given compound has to be proposed using the given NMR data.

Concept Introduction:

The ${}^{1}HNMR$ 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 by the $\left(\text{N+1}\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  Withthis 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.

¹³C NMR Spectroscopy: This type of NMR splitting of signals tells us numbers of hydrogens atoms are attached to each carbon. The triangle rule (n+1) C. The chemical shift explains the different hybridization $\left(sp3,sp2,sp.,\right)$ of each carbon atoms. Moreover the chemical shift in carbon NMR spectra arises in the same way as in the ¹H NMR spectrum.

Explanation of Solution

Index of Hydrogen Deficiency (IHD) calculation,

Given molecular formula F is $C_9{H}_{9}BrO$

We calculate the $IHD$ as follows:

$\begin{array}{l}\text{HDI}\text{= }\frac{\left(\text{ 2C+2+N-H-X}\right)}{\text{2}}\\ =\frac{\text{2}\times 9\text{+2+0-9-1}}{2}\\ =\underset{\_}{5}\end{array}$

From the molecular formula $C_9{H}_{9}BrO$, there is an index of hydrogen deficiency of five, which is accounted for by the three double bonds and ring of the benzene ring plus the $\pi$ bond of the carbonyl group in corresponding molecular formula.

${}^1\text{H NMR}$ and ${}^{13}\text{C NMR}$ analysis for given molecular formula $C_9{H}_{9}BrO$:

The one signal in the ${}^{13}\text{C NMR}$ spectrum at $\text{δ}165.73$ it indicates the presence of carbonyl group. The signals around at $\text{δ}131.56$ indicates there is an aromatic ring. The one triplet in the ${}^1\text{H NMR}$ at $\text{δ}1.39$ that integrates to $\text{3H}$ indicates a one methyl group.

There are also one ${\text{-CH}}_2\text{-}$ groups one that is adjacent to other hydrogens the quartetobserved at $\text{δ}4.38$. Four aromatic hydrogens are found in the doublet of doublet at $\text{δ}7.57\text{and}7.90$.

Therefore, the based on above spectral details the structure that is consistent with the all of these facts is 4-Bromo-1- ethyl ester.

(b)

Interpretation Introduction

Interpretation:

The strucutral formula for each of the given compound has to be proposed using the given NMR data.

Concept Introduction:

The ${}^{1}HNMR$ 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 by the $\left(\text{N+1}\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  Withthis 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.

¹³C NMR Spectroscopy: This type of NMR splitting of signals tells us numbers of hydrogens atoms are attached to each carbon. The triangle rule (n+1) C. The chemical shift explains the different hybridization $\left(sp3,sp2,sp.,\right)$ of each carbon atoms. Moreover the chemical shift in carbon NMR spectra arises in the same way as in the ¹H NMR spectrum.

Explanation of Solution

Index of Hydrogen Deficiency (IHD) calculation,

Given molecular formula F is $C_8{H}_{9}NO$

We calculate the $IHD$ as follows:

$\begin{array}{l}\text{HDI}\text{= }\frac{\left(\text{ 2C+2+N-H-X}\right)}{\text{2}}\\ =\frac{\text{2}\times 8\text{+2+1-9-0}}{2}\\ =\underset{\_}{5}\end{array}$

From the molecular formula $C_8{H}_{9}NO$, there is an index of hydrogen deficiency of five, which is accounted for by the three double bonds and ring of the benzene ring plus the $\pi$ bond of the carbonyl group in corresponding molecular formula.

${}^1\text{H NMR}$ and ${}^{13}\text{C NMR}$ analysis for given molecular formula $C_8{H}_{9}NO$:

The one signal in the ${}^{13}\text{C NMR}$ spectrum at $\text{δ}168.14$ it indicates the presence of carbonyl group. The signals around at $\text{δ}139.24\text{and 128}\text{.51}$ indicates there is an aromatic ring. The one triplet in the ${}^1\text{H NMR}$ at $\text{δ}2.06$ that integrates to $\text{3H}$ indicates a one methyl group.

There are also one $\text{-NH-}$ groups one that is adjacent to other hydrogens the triplet observed at $\text{δ}9.90$. Four aromatic hydrogens are found in the doublet of doublet at $\text{δ}7.30\text{and}7.59$.

Therefore, the based on above spectral details the structure that is consistent with the all of these facts is 4-Bromo-1- methylacetamide.

(c)

Interpretation Introduction

Interpretation:

The strucutral formula for each of the given compound has to be proposed using the given NMR data.

Concept Introduction:

The ${}^{1}HNMR$ 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 by the $\left(\text{N+1}\right)$ rule predicts the number of hydrogens or protons attached to the adjacent carbon in a carbon chain of a compound.  Withthis 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.

¹³C NMR Spectroscopy: This type of NMR splitting of signals tells us numbers of hydrogens atoms are attached to each carbon. The triangle rule (n+1) C. The chemical shift explains the different hybridization $\left(sp3,sp2,sp.,\right)$ of each carbon atoms. Moreover the chemical shift in carbon NMR spectra arises in the same way as in the ¹H NMR spectrum.

Explanation of Solution

Index of Hydrogen Deficiency (IHD) calculation,

Given molecular formula F is $C_9{H}_{9}N{O}_3$

We calculate the $IHD$ as follows:

$\begin{array}{l}\text{HDI}\text{= }\frac{\left(\text{ 2C+2+N-H-X}\right)}{\text{2}}\\ =\frac{\text{2}\times 9\text{+2+1-9-0}}{2}\\ =\underset{\_}{5}\end{array}$

From the molecular formula $C_9{H}_{9}N{O}_3$, there is an index of hydrogen deficiency of five, which is accounted for by the three double bonds and ring of the benzene ring plus the $\pi$ bond of the carbonyl group in corresponding molecular formula.

${}^1\text{H NMR}$ and ${}^{13}\text{C NMR}$ analysis for given molecular formula $C_9{H}_{9}N{O}_3$:

The one signal in the ${}^{13}\text{C NMR}$ spectrum at $\text{δ}168.14\text{and}\text{166}\text{.85}$ it indicates the presence of carbonyl group and acid carbonyl group. The signals around at $\text{δ}143.23\text{and 130}\text{.28}$ indicates there is an aromatic ring. The one triplet in the ${}^1\text{H NMR}$ at $\text{δ}2.06$ that integrates to $\text{3H}$ indicates a one methyl group.

There are also one $\text{-NH-}$ groups and hydroxyl group one that is not adjacent to other hydrogens the singlet observed at $\text{δ}10.3\text{and}\text{12}\text{.7}$. Four aromatic hydrogens are found in the doublet of doublet at $\text{δ}7.91\text{and}7.72$.

Therefore, the based on above spectral details the structure that is consistent with the all of these facts is acid substituted phenylacetamide.