Question

Match the reactions with the reagents to be used for the corresponding conversions.

• A. $\mathrm{KCN}/\mathrm{EtOH},H_2/\mathrm{Pd}$
• B. ${\mathrm{Br}}_2,\mathrm{NaOH}$
• C. $\mathrm{Sn}/\mathrm{HCl}$
• D. ${\mathrm{LiAlH}}_4,H_{2}O$

Answer 1

Hoffmann bromamide degradation reaction of an amide gives a primary amine having one carbon atom less than that of the amide taken.

${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CONH}}_2+{\mathrm{Br}}_2+4\mathrm{NaOH}\to {\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{NH}}_2+{\mathrm{Na}}_2{\mathrm{CO}}_3+2\mathrm{NaBr}+2H_{2}O$

Reduction of amides using lithium aluminium hydride yields corresponding amines with same number of carbon atoms.
${\mathrm{CH}}_3{\mathrm{CONH}}_2\underset{H_{2}O}{\overset{{\mathrm{LiAlH}}_4}{\to }}{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{NH}}_2$

For preparation of amines having one carbon atom more than the starting alkyl halide, conversion to nitrile followed by reduction is carried out.
${\mathrm{CH}}_3\mathrm{Cl}\underset{\mathrm{EtOH}}{\overset{\mathrm{KCN}}{\to }}{\mathrm{CH}}_3\mathrm{CN}\stackrel{H_2/\mathrm{Pd}}{\to }{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{NH}}_2$

Reduction of niroalkanes/arenes using Sn or Fe in acid medium will give corresponding amine.