Chapter 26, Problem 26.33AP

Interpretation Introduction

(a)

Interpretation:

The structure of quinine in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of quinine in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

When quinine reacts with $\text{1}M\text{HCl}$, a conjugate acid of quinine is formed as protonation of aliphatic nitrogen of tertiary amine occurs since it is more basic than the aromatic amine. The corresponding reaction is shown below.

Figure 1

Conclusion

The structure of quinine in $\text{1}M\text{HCl}$ is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation:

The structure of nicotine in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of nicotine in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

When nicotine reacts with $\text{1}M\text{HCl}$, the aliphatine anime gets protonated to form a conjugate acid of nicotine since it is more basic than the aromatic amine as shown below.

Figure 2

Conclusion

The structure of nicotine in $\text{1}M\text{HCl}$ is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation:

The structure of tryptamine in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of tryptamine in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

The aliphatic amine present on the side chain of tryptamine gets protonated in $\text{1}M\text{HCl}$ to give its conjugated acid as shown below.

Figure 3

Conclusion

The structure of tryptamine in $\text{1}M\text{HCl}$ is shown in Figure 3.

Interpretation Introduction

(d)

Interpretation:

The structure of $\text{3, 4-diaminopyridine}$ in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of $\text{3, 4-diaminopyridine}$ in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

In the structure of $\text{3, 4-diaminopyridine}$, the amine present at the carbon $\text{-4}$ is in conjugation with pyridine, therefore, it will not get protonated as it is electron deficient. The amine present at carbon $\text{-3}$ will get protonated in $\text{1}M\text{HCl}$ to give its conjugate acid as it is not involved in conjugation as shown below.

Figure 4

Conclusion

The structure of $\text{3, 4-diaminopyridine}$ in $\text{1}M\text{HCl}$ is shown in Figure 4.

Interpretation Introduction

(e)

Interpretation:

The structure of $\text{1, 4-diazaindene}$ in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of $\text{1, 4-diazaindene}$ in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

In $\text{1, 4-diazaindene}$, the lone pair of electrons on nitrogen atom in pyridine nucleus are not involved in conjugation while the lone pair of electrons on nitrogen atom in pyrrole are involved in conjugation. Therefore, nitrogen atom in pyridine nucleus is electron rich, so it gets protonated in $\text{1}M\text{HCl}$ as shown below.

Figure 5

Conclusion

The structure of $\text{1, 4-diazaindene}$ in $\text{1}M\text{HCl}$ is shown in Figure 5.

Interpretation Introduction

(f)

Interpretation:

The structure of $\text{1-methyl-1, 2, 3-benzotriazole}$ in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of $\text{1-methyl-1, 2, 3-benzotriazole}$ in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

In $\text{1-methyl-1, 2, 3-benzotriazole}$, the nitrogen atom adjacent to the methyl group will get protonated as its lone pair of electrons are not involved in conjugation and the electron density also increases due to $\text{+I}$ effect of the methyl group. The nitrogen atom present at the third position has its lone pair of electrons involved in conjugation.

The formation of conjugated acid of $\text{1-methyl-1, 2, 3-benzotriazole}$ in $\text{1}M\text{HCl}$ is shown below.

Figure 6

Conclusion

The structure of $\text{1-methyl-1, 2, 3-benzotriazole}$ in $\text{1}M\text{HCl}$ is shown in Figure 6.

Interpretation Introduction

(g)

Interpretation:

The structure of imitanib in $\text{1}M\text{HCl}$ is to be drawn.

Concept introduction:

Aliphatic amines are more basic than aromatic amines. In aliphatic amines, the nitrogen atom is attached to a methyl group which is electron donating group; therefore, it increases the electron density on nitrogen by $\text{+I}$ effect. So, basicity of aliphatic amines increases. Aromatic amines are less basic because the lone pair of electrons on nitrogen atom is involved in delocalization with the phenyl ring.

Answer to Problem 26.33AP

The structure of imitanib in $\text{1}M\text{HCl}$ is shown below.

Explanation of Solution

In imitanib, the aliphatic amine will be protonated than aromatic amine since the basicity of aliphatic amines is more. The aliphatic amine present adjacent to the methyl group will be protonated as it is electron rich due to the $\text{+I}$ effect of the methyl group as shown below.

Figure 7

Conclusion

The structure of imitanib in $\text{1}M\text{HCl}$ is shown in Figure 7.