Question

Complete‌ ‌the‌ ‌following‌ ‌reactions:‌ ‌
${C_6}{H_5}N{H_2}‌ ‌+‌ ‌CHC{l_3}‌ ‌+‌ ‌alc.KOH‌ ‌\to‌ ‌$‌

Answer 1

Hint: Hoffman’s carbylamine test or isocyanide test is given by only aliphatic or aromatic primary amines and not given by tertiary and secondary amines.

Complete answer:
Hoffman’s carbylamine test or isocyanide test is given by only aliphatic or aromatic primary amines and not given by tertiary and secondary amines. In Hoffman’s carbylamine test the unknown compound to be tested is reacted with chloroform and alcoholic potassium hydroxide. if the unknown compound given is an aliphatic or aromatic primary amine then it gives foul smell which is due to aliphatic or aromatic primary isocyanide.
Here in the reaction, we are given aniline reacting with chloroform and alcoholic potassium hydroxide.
The reactants given are of Hoffman’s carbylamine test
Now let’s see if aniline is aromatic or aliphatic primary amine,
Yes, it is a primary aromatic amine
Now what happens in the reaction alcoholic potassium hydroxide gives a stable solution for the dehydrohalogenation of chloroform to give dichlorocarbene. This dichlorocarbene attacks the lone pair on the nitrogen of phenylamine, creating an intermediate compound first on reaction. a chlorine breaks out attacking hydrogen present at nitrogen of amine. The hydrogen chloride breaks and breaks nitrogen and carbon form two bonds and a third co-ordinate bond.
Therefore, on reaction of phenylamine with chloroform and alcoholic potassium hydroxide, phenyl cyanide is formed and potassium chloride and water are formed.
${C_6}{H_5}N{H_2} + CHC{l_3} + alc.3KOH \to {C_6}{H_5}NC + 3KCl + 3{H_2}O$

Note:
Tertiary and secondary aromatic and aliphatic compounds don’t give Hoffman’s carbylamine test or isocyanide test because they have very high hindrance at the lone pair of nitrogen so the dichlorocarbene can’t properly attack.