Unit 13 Amines (Intext Questions-1)
Intext Questions
13.1 Classify the following amines as primary, secondary or tertiary:
(iii) $\left(\mathrm{C_2} \mathrm{H_5}\right)_{2} \mathrm{CHNH_2} \quad$
(iv) $\left(\mathrm{C_2} \mathrm{H_5}\right)_2 \mathrm{NH}$
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Answer
Primary: (i) and (iii)
Secondary: (iv)
Tertiary: (ii)
13.2 (i) Write structures of different isomeric amines corresponding to the molecular formula, $\mathrm{C_4} \mathrm{H_{11}} \mathrm{~N}$.
(ii) Write IUPAC names of all the isomers.
(iii) What type of isomerism is exhibited by different pairs of amines?
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Answer
(i), (ii) The structures and their IUPAC names of different isomeric amines corresponding to the molecular formula, $\mathrm{C_4} \mathrm{H_11} \mathrm{~N}$ are given below:
(a) $\mathrm{CH_3}-\mathrm{CH_2}-\mathrm{CH_2}-\mathrm{CH_2}-\mathrm{NH_2}$
Butanamine $(1^\circ)$
(b)
Butan-2-amine $(1^\circ)$
(c)
2-Methylpropanamine $(1^\circ)$
(d)
2-Methylpropan-2-amine $(1^\circ)$
(e) $\mathrm{CH_3}-\mathrm{CH_2}-\mathrm{CH_2}-\mathrm{NH}-\mathrm{CH_3}$
$\mathrm{N}$-Methylpropanamine $(2^\circ)$
(f) $\mathrm{CH_3}-\mathrm{CH_2}-\mathrm{NH}-\mathrm{CH_2}-\mathrm{CH_3}$
$\mathrm{N}$-Ethylethanamine $(2^\circ)$
(g)
N-Methylpropan-2-amine $(2^\circ)$
$\mathrm{N}, \mathrm{N}$-Dimethylethanamine $\left(3^{\circ}\right)$
(iii) The pairs (a) and (b) and (e) and (g) exhibit position isomerism.
The pairs (a) and (c); (a) and (d); (b) and (c); (b) and (d) exhibit chain isomerism.
The pairs (e) and (f) and (f) and (g) exhibit metamerism.
All primary amines exhibit functional isomerism with secondary and tertiary amines and viceversa.
