Chapter 19, Problem 19.56P

Identify each compound from its spectral data.

$\begin{array}{c}\text{a}\text{. Molecular formula}:{\text{C}}_{\text{3}}{\text{H}}_{\text{5}}{\text{ClO}}_{\text{2}}\\ \text{IR}:3500-{\text{2500 cm}}^{-1}{\text{, 1714 cm}}^{-1}\\ {}^{\text{1}}\text{H NMR data}:\text{2}\text{.87}\left(\text{triplet, 2H}\right)\text{, 3}\text{.76}\left(\text{triplet, 2H}\right)\text{ and 11}\text{.8}\left(\text{singlet, 1H}\right)\text{ ppm}\\ \text{b}{\text{. Molecular formula: C}}_{\text{8}}{\text{H}}_{\text{8}}{\text{O}}_{\text{3}}\\ \text{IR}:3500-{\text{2500 cm}}^{-1}{\text{, 1688 cm}}^{-1}\\ {}^{\text{1}}\text{H NMR data}:\text{3}\text{.8}\left(\text{singlet, 3H}\right)\text{, 7}\text{.0}\left(\text{doublet, 2H}\right)\text{, 7}\text{.9}\left(\text{doublet, 2H}\right)\text{ and 12}\text{.7}\left(\text{singlet, 1H}\right)\text{ ppm}\\ \text{c}{\text{. Molecular formula: C}}_{\text{8}}{\text{H}}_{\text{8}}{\text{O}}_{\text{3}}\\ \text{IR}:3500-{\text{2500 cm}}^{-1}{\text{, 1710 cm}}^{-1}\\ {}^{\text{1}}\text{H NMR data}:\text{4}\text{.7}\left(\text{singlet, 2H}\right)\text{, 6}\text{.9-7}\text{.3}\left(\text{multiplet, 5H}\right)\text{ and 11}\text{.3}\left(\text{singlet, 1H}\right)\text{ ppm}\end{array}$

Interpretation Introduction

(a)

Interpretation: The given compound is to be identified from its spectral data.

Concept introduction: IR spectroscopy is used to identify the functional group present in a compound. Each and every bond vibrates at a characteristic frequency. Proton $\text{NMR}$ spectroscopy identifies the number of hydrogen atoms present in a molecule and the nature of the functional group. The value of chemical peaks depends upon the chemical environment around the hydrogen atom.

Answer to Problem 19.56P

The given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is,

Figure 1

Explanation of Solution

The spectral data for the given compound is as follows:

$\begin{array}{c}\text{Molecular formula}:{\text{C}}_{\text{3}}{\text{H}}_{\text{5}}{\text{ClO}}_{\text{2}}\\ \text{IR}:3500-{\text{2500 cm}}^{-1}{\text{, 1714 cm}}^{-1}\\ {}^{\text{1}}\text{H NMR data}:\text{2}\text{.87}\left(\text{triplet, 2H}\right)\text{, 3}\text{.76}\left(\text{triplet, 2H}\right)\text{ and 11}\text{.8}\left(\text{singlet, 1H}\right)\text{ ppm}\end{array}$ Information from IR spectrum data:

IR absorptions at $3600-2{\text{500 cm}}^{\text{-1}}$ suggests the presence of $\text{O}-\text{H}$ bond of carboxylic acid and absorption at ${\text{1714 cm}}^{-1}$ suggests the presence of $\text{C}=\text{O}$ bond of carboxylic acid.

Information from ${}^1\text{H}\text{NMR}$ spectrum data:

The observed chemical shift value at $3.76\left(\text{singlet,}2\text{H}\right)\text{ppm}$, suggests the presence of ${\text{CH}}_2$ group, bonded to the carbon that has $\text{2}\text{H's}$. The slightly downfield absorption shift indicates that ${\text{CH}}_2$ group is also bonded to some electron withdrawing group like chlorine.

The observed chemical shift value at $2.87\left(\text{triplet,}2\text{H}\right)\text{ppm}$, suggests the presence of ${\text{CH}}_2$ group, bonded to the adjacent carbon atom that has $2\text{H's}$ respectively.

The observed chemical shift values at $11.8\left(\text{singlet,}1\text{H}\right)\text{ppm}$, suggests the presence of carboxylic group.

Thus, the structure of a given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is,

Figure 1

Conclusion

The given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: The given compound is to be identified from its spectral data.

Concept introduction: IR spectroscopy is used to identify the functional group present in a compound. Each and every bond vibrates at a characteristic frequency. Proton $\text{NMR}$ spectroscopy identifies the number of hydrogen atoms present in a molecule and the nature of the functional group. The value of chemical peaks depends upon the chemical environment around the hydrogen atom.

Answer to Problem 19.56P

The structure of a given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is,

Figure 2

Explanation of Solution

The spectral data for the given compound is as follows:

$\begin{array}{c}{\text{Molecular formula : C}}_{\text{8}}{\text{H}}_{\text{8}}{\text{O}}_{\text{3}}\\ \text{IR}:3500-{\text{2500 cm}}^{-1}{\text{, 1688 cm}}^{-1}\\ {}^{\text{1}}\text{H NMR data}:\text{3}\text{.8}\left(\text{singlet, 3H}\right)\text{, 7}\text{.0}\left(\text{doublet, 2H}\right)\text{, 7}\text{.9}\left(\text{doublet, 2H}\right)\text{ and 12}\text{.7}\left(\text{singlet, 1H}\right)\text{ ppm}\end{array}$ Information from IR spectrum data:

IR absorptions at $3600-2{\text{500 cm}}^{\text{-1}}$ suggests the presence of $\text{O}-\text{H}$ bond of carboxylic acid and absorption at ${\text{1688 cm}}^{-1}$ suggests the presence of $\text{C}=\text{O}$ bond of carboxylic acid.

Information from ${}^1\text{H}\text{NMR}$ spectrum data:

The observed chemical shift values at $7.0\left(\text{doublet,}2\text{H}\right)\text{ppm}$ and $\text{7}\text{.93}\left(\text{doublet, 2H}\right)\text{ ppm}$ suggest the presence of para substitution on benzene ring. The slightly downfield absorption shift indicates that the adjacent carbon is also bonded to some electron withdrawing group like carboxylic.

The observed chemical shift value at $12.7\left(\text{singlet,}1\text{H}\right)\text{ppm}$, suggests the presence of carboxylic group.

The observed chemical shift value at $3.8\left(\text{singlet, 3H}\right)\text{ppm}$, suggests the presence of methyl group. The slightly downfield absorption shift indicates that ${\text{CH}}_3$ group is also bonded to some electron negative atom like oxygen. Thus, the chemical shift value indicates the presence of ester group.

Thus, the structure of a given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is,

Figure 2

Conclusion

The given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: The given compound is to be identified from its spectral data.

Concept introduction: IR spectroscopy is used to identify the functional group present in a compound. Each and every bond vibrates at a characteristic frequency. Proton $\text{NMR}$ spectroscopy identifies the number of hydrogen atoms present in a molecule and the nature of the functional group. The value of chemical peaks depends upon the chemical environment around the hydrogen atom

Answer to Problem 19.56P

The given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is as shown below.

Figure 3

Explanation of Solution

The spectral data for the given compound is as follows:

$\begin{array}{c}{\text{Molecular formula : C}}_{\text{8}}{\text{H}}_{\text{8}}{\text{O}}_{\text{3}}\\ \text{IR}:3500-{\text{2500 cm}}^{-1}{\text{, 1710 cm}}^{-1}\\ {}^{\text{1}}\text{H NMR data}:\text{4}\text{.7}\left(\text{singlet, 2H}\right)\text{, 6}\text{.9-7}\text{.3}\left(\text{multiplet, 5H}\right)\text{ and 11}\text{.3}\left(\text{singlet, 1H}\right)\text{ ppm}\end{array}$ Information from IR spectrum data:

IR absorptions at $3600-2{\text{500 cm}}^{\text{-1}}$ suggests the presence of $\text{O}-\text{H}$ bond of carboxylic acid and absorption at ${\text{1710 cm}}^{-1}$ suggests the presence of $\text{C}=\text{O}$ bond of carboxylic acid.

Information from ${}^1\text{H}\text{NMR}$ spectrum data:

The observed chemical shift values at $6.9-7.3\left(\text{multiplet,}5\text{H}\right)\text{ppm}$ suggest the presence of monosubstitution on benzene ring.

The observed chemical shift value at $11.3\left(\text{singlet,}1\text{H}\right)\text{ppm}$, suggests the presence of carboxylic group.

The observed chemical shift value at $4.7\left(\text{singlet, 2H}\right)\text{ppm}$, suggests the presence of methylene group. The slightly downfield absorption shift indicates that ${\text{CH}}_2$ group is also bonded to some electronegative atom like oxygen.

Thus, the structure of a given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is,

Figure 3

Conclusion

The given compound from its spectrum data of IR, and ${}^1\text{H}\text{NMR}$ is shown in Figure 3.