Chapter 13: Amines

Ans: The azo products have an extended conjugate system with both aromatic rings linked by the –N=N- bond. These compounds are frequently colored and used as dyes. Benzene diazonium chloride reacts with phenol to form p-hydroxy azobenzene by coupling the phenol molecule in its para position with the diazonium salt. This is referred to as a coupling reaction.

Ans: $\mathrm{CS}_{2}$ is a non-polar solvent which decreases the activating effect of $-\mathrm{NH}_{2}$. As a result, mono substitution occurs only at o- and p- positions giving a mixture of 2-bromoaniline (minor) and 4-bromoaniline (major) as products. 

Ans:  $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}<\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{NH}_{2}<\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$

As oxygen is more electronegative than nitrogen therefore, the O-H bond is more polar than the N-H bond. So ethanol has more dipole moments than ethylamine. Propane is non- polar in nature hence, had the least among all. 

Ans: Prop-2-en-1-amine

$\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2} \mathrm{NH}_{2}$

Ans: N, N-dimethylbenzenanmine 

Ans: $Z$ is an aliphatic amine that produces a solid that is insoluble in base. This means that the reaction with $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{SO}_{2} \mathrm{Cl}$ must produce a product with no replaceable hydrogen attached to nitrogen.

To put it another way, the amine must be a secondary amine.

Z stands for ethylmethylamine.

Ans: Carbylamine reaction is shown by primary amines only, primary amines react with chloroform in the presence of alcoholic KOH to form isocyanides which upon catalytic reduction gives secondary amines as the final product. 

$\underset{1^{\circ} \mathrm{Amine}}{R-\mathrm{NH}_{2}}+\mathrm{CHCl}_{3}+3 \mathrm{KOH} \rightarrow \underset{\text { Alkyl isocyanide }}{\longrightarrow} \frac{\mathrm{HC}_{2} / \mathrm{Pd}}{(\text { Reduction) })} \underset{2^{\circ} \text { Amine }}{\mathrm{N}}-\mathrm{NH}-\mathrm{CH}_{3}$

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Ans: On reaction with hydrochloric acid, aniline forms anilinium chloride ion which is water soluble. Therefore, the aniline solubility in aqueous HCl solution. 

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