Question

How does the formation of $2^{\circ }$ and $3^{\circ }$ amines can be avoided during the preparation of $1^{\circ }$ amines by alkylation?

Answer 1

The use of very large excess of $N{H}_3$ may partially avoid the formation of $2^o$ and $3^o$ amines during preparation of $P$ amines. But $\left(a\right)$ by treatment of with $Na{N}_3$ followed by reduction or $\left(b\right)$ Gabriel phthalimide synthesis or $\left(c\right)$ reduction of amide can give $P$ amines only.

(a) $R-X\stackrel{Na{N}_3}{\to }R-N_3\stackrel{H_2/Pd}{\to }\underset{1^{o}amine}{R-N{H}_2+N_2}$

(b) (Refer to Image)

(c) $O$

$R-\stackrel{||}{C}-N{H}_2\stackrel{LiAl{H}_4}{\to }R-C{H}_{2}N{H}_2$