Question

When an aromatic amine A was treated with alcoholic potash and another compound Y, a foul-smelling gas was formed with formula $C_6{H}_{5}NC$. Y was formed by reacting a compound Z with $C{l}_2$ in presence of slaked lime. The compound Z is:

• A. $C_6{H}_{5}N{H}_2$
• B. $C{H}_{3}OH$
• C. $C{H}_{3}C{H}_{2}OH$
• D. $CHC{l}_3$

Answer 1

Answer: (C)

In Hoffmann's carbylamine test (also known as Isocyanide test), aliphatic or aromatic primary amine (A) is heated with chloroform (compound Y) in presence of alcoholic potassium hydroxide to give foul smelling alkyl/aryl isocyanide or carbylamine.
Compound $Y$ (chloroform) is obtained by reaction of compound $Z$ $({CH}_{3}C{H}_{2}OH)$ with chlorine in presence of slaked lime.
$\underset{A}{C_6{H}_5-N{H}_2}+CHC{l}_3+3KOH\stackrel{heat}{\to }{C}_6{H}_5-NC+3KCl+3H_{2}O$
$\underset{Z}{C{H}_{3}C{H}_{2}OH}+3C{l}_2\to CC{l}_{3}CHO+3HCl$
$2CC{l}_{3}CHO+Ca(OH{)}_2\to \underset{Y}{2CHC{l}_3}+(HCOO{)}_{2}Ca$