Chapter 25, Problem 25.58P

Interpretation Introduction

(a)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}\text{Br}$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. The reaction of alkyl halide with ammonia results in the formation of primary amine. Such reactions are commonly known as alkylation of ammonia.

Answer to Problem 25.58P

The reaction for the preparation of benzylamine from benzyl bromide is,

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}\text{Br}+{\text{NH}}_{\text{3}}\to {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}+{\text{NH}}_{\text{4}}^{\text{+}}{\text{Br}}^{-}\\ \text{ excess}\end{array}$

Explanation of Solution

The given compound is benzyl bromide. The conversion of this to benzylamine occurs by using excess of ammonia through ${\text{S}}_{\text{N}}\text{2}$ mechanism. The reaction for the preparation of benzylamine from benzyl bromide is shown below.

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}\text{Br}+{\text{NH}}_{\text{3}}\to {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}+{\text{NH}}_{\text{4}}^{\text{+}}{\text{Br}}^{-}\\ \text{ excess}\end{array}$

Conclusion

Benzylamine is prepared from benzyl bromide by using excess of ammonia.

Interpretation Introduction

(b)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. Lithium aluminium hydride is a strong reducing agent. It is an inorganic compound which is used as a reducing agent in organic synthesis.

Answer to Problem 25.58P

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}$ is,

${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$

Explanation of Solution

The given compound is benzonitrile. The conversion of this to benzylamine occurs by using reagents like Lithium aluminium hydride. The reaction for the preparation of benzylamine from benzonitrile is shown below.

${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$

In this reaction, benzonitrile undergoes reduction with Lithium aluminium hydride in the presence of ${\text{H}}_{\text{2}}\text{O}$ to form the final product benzylamine.

Conclusion

Benzylamine is prepared from benzonitrile by using reagent Lithium aluminium hydride.

Interpretation Introduction

(c)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. Lithium aluminium hydride is a strong reducing agent. It is an inorganic compound which is used as a reducing agent in organic synthesis.

Answer to Problem 25.58P

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2$ is,

${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$

Explanation of Solution

The given compound is benzamide. The conversion of this to benzylamine occurs by using reagents like Lithium aluminium hydride. The reaction for the preparation of benzylamine from benzamide is shown below.

${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$

In this reaction, benzamide undergoes reduction with Lithium aluminium hydride in the presence of ${\text{H}}_{\text{2}}\text{O}$ to form the final product benzylamine.

Conclusion

Benzylamine is prepared from benzamide by using reagent Lithium aluminium hydride.

Interpretation Introduction

(d)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CHO}$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. When an aldehyde or a ketone is converted to an amine, the process is known as reductive amination. The conversion takes place through the formation of an intermediate known as imine. The excess ammonia is used when a primary amine is synthesized by reductive amination.

Answer to Problem 25.58P

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CHO}$ is,

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CHO}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CH=NH}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CH=NH}\stackrel{{\text{NaBH}}_{\text{3}}\text{CN}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

Explanation of Solution

The given compound is benzaldehyde. The conversion of this to benzylamine occurs by reductive animation with ammonia. The reaction for the preparation of benzylamine from benzaldehyde is shown below.

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CHO}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CH=NH}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CH=NH}\stackrel{{\text{NaBH}}_{\text{3}}\text{CN}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

Conclusion

Benzylamine is prepared from benzaldehyde on reductive animation with ammonia.

Interpretation Introduction

(e)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. Lithium aluminium hydride is a strong reducing agent. It is an inorganic compound which is used as a reducing agent in organic synthesis.

Answer to Problem 25.58P

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3$ is,

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3\stackrel{{\text{KMnO}}_{\text{4}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\stackrel{{\text{SOCl}}_{\text{2}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

Explanation of Solution

The given compound is toluene. The conversion of this to benzylamine occurs by using reagents like potassium permanganate, thionyl chloride, ammonia, and Lithium aluminium hydride. The reactions for the preparation of benzylamine from toluene are shown below.

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3\stackrel{{\text{KMnO}}_{\text{4}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\stackrel{{\text{SOCl}}_{\text{2}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

In the first step of reaction, toluene undergoes oxidation to form benzoic acid. In the second step, benzoic acid reacts with thionyl chloride to gives benzoyl chloride which further reacts with ammonia to form benzamide. In the final step, benzamide undergoes reduction with Lithium aluminium hydride in the presence of ${\text{H}}_{\text{2}}\text{O}$ to form the final product benzylamine.

Conclusion

Benzylamine is prepared from toluene by using reagents like potassium permanganate, thionyl chloride, ammonia, and Lithium aluminium hydride.

Interpretation Introduction

(f)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. Lithium aluminium hydride is a strong reducing agent. It is an inorganic compound which is used as a reducing agent in organic synthesis.

Answer to Problem 25.58P

Explanation of Solution

The given compound is benzoic acid. The conversion of this to benzylamine occurs by using reagents like, thionyl chloride, ammonia, and Lithium aluminium hydride. The reactions for the preparation of benzylamine from benzoic acid are shown below.

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\stackrel{{\text{SOCl}}_{\text{2}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

In the first step of reaction, benzoic acid reacts with thionyl chloride to gives benzoyl chloride which further reacts with ammonia to form benzamide. In the final step, benzamide undergoes reduction with Lithium aluminium hydride in the presence of ${\text{H}}_{\text{2}}\text{O}$ to form the final product benzylamine.

Conclusion

Benzylamine is prepared from benzoic acid by using reagents like thionyl chloride, ammonia, and Lithium aluminium hydride.

Interpretation Introduction

(g)

Interpretation:

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}_{\text{2}}$ is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. Diazonium salts are prepared by the treatment of aromatic amines with nitrous acid and additional acid.

Answer to Problem 25.58P

The preparation of benzylamine from ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}_{\text{2}}$ is,

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}_{\text{2}}\underset{\text{HCl}}{\overset{{\text{NaNO}}_{\text{2}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{N}}_2^{+}{\text{Cl}}^{-}\left(\text{diazonium salt}\right)\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{N}}_2^{+}{\text{Cl}}^{-}\stackrel{\text{CuCl}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

Explanation of Solution

The given compound is aniline. The conversion of this to benzylamine occurs by using reagents like nitrous acid, copper cyanide, and Lithium aluminium hydride. The reactions for the preparation of benzylamine from aniline are shown below.

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{NH}}_{\text{2}}\underset{\text{HCl}}{\overset{{\text{NaNO}}_{\text{2}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{N}}_2^{+}{\text{Cl}}^{-}\left(\text{diazonium salt}\right)\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{N}}_2^{+}{\text{Cl}}^{-}\stackrel{\text{CuCl}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{CN}\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}\end{array}$

In the first step of reaction, aniline reacts with nitrous acid to form diazonium salt which further reacts with copper cyanide to form benzonitrile. In the final step, benzonitrile undergoes reduction with Lithium aluminium hydride in the presence of ${\text{H}}_{\text{2}}\text{O}$ to form the final product benzylamine.

Conclusion

Benzylamine is prepared from aniline by using reagents like nitrous acid, copper cyanide, and Lithium aluminium hydride.

Interpretation Introduction

(h)

Interpretation:

The preparation of benzylamine from benzene is to be stated.

Concept introduction:

Synthesis is one of the major areas in the field of organic chemistry. It can be a simple one-step reaction or it may involve many steps. Friedel-craft alkylation is an electrophilic aromatic substitution. In this type of reaction, an alkyl cation acts as an electrophile. Electrophilic attack takes place to form a sigma complex.

Answer to Problem 25.58P

The preparation of benzylamine from benzene is,

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{6}}\underset{{\text{AlCl}}_{\text{3}}}{\overset{{\text{CH}}_{\text{3}}\text{Cl}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3\stackrel{{\text{KMnO}}_{\text{4}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\stackrel{{\text{SOCl}}_{\text{2}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\end{array}$

${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$

Explanation of Solution

The given compound is benzene. The conversion of this to benzylamine occurs by using reagents like methyl chloride in the presence of aluminium chloride, potassium permanganate, thionyl chloride, ammonia, and Lithium aluminium hydride. The reactions for the preparation of benzylamine from benzene are shown below.

$\begin{array}{l}{\text{C}}_{\text{6}}{\text{H}}_{\text{6}}\underset{{\text{AlCl}}_{\text{3}}}{\overset{{\text{CH}}_{\text{3}}\text{Cl}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_3\stackrel{{\text{KMnO}}_{\text{4}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COOH}\stackrel{{\text{SOCl}}_{\text{2}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\\ {\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{COCl}\stackrel{{\text{NH}}_{\text{3}}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\end{array}$

${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CONH}}_2\underset{\left(2\right){\text{H}}_{\text{2}}\text{O}}{\overset{\left(1\right){\text{LiAlH}}_{\text{4}}}{\to }}{\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$

In the first step of reaction, benzene undergoes Friedel-craft alkylation reaction with methyl chloride to form toluene. In the second step, toluene undergoes oxidation to form benzoic acid. In the third step, benzoic acid reacts with thionyl chloride to gives benzoyl chloride which further reacts with ammonia to form benzamide. In the final step, benzamide undergoes reduction with Lithium aluminium hydride in the presence of ${\text{H}}_{\text{2}}\text{O}$ to form the final product benzylamine.

Conclusion

Benzylamine is prepared from benzene by using reagents like methyl chloride in the presence of aluminium chloride, potassium permanganate, thionyl chloride, ammonia, and Lithium aluminium hydride.