Question

The compound that would produce a nauseating smell/odour with a hot mixture of chloroform and ethanolic potassium hydroxide is:
(A) $PhCON{H_2}$
(B) $PhNHC{H_3}$
(C) $PhN{H_2}$
(D) $PhOH$

Answer 1

To solve this question, we must first guess the type of reaction in which compound that would produce a nauseating smell/odour with a hot mixture of chloroform and ethanolic potassium hydroxide. Then we need to assess the compounds used or formed in the reaction and then only we can conclude the correct answer.

Complete step-by-step answer: Before we move forward with the solution of this given question, let us first understand some basic concepts about Carbylamine Reaction:
Carbylamine Reaction: (also known as the Hofmann isocyanide synthesis) is the synthesis of an isocyanide by the reaction of a primary amine, chloroform, and base. The conversion involves the intermediacy of dichlorocarbene.
Mechanism: First step is the dehydrohalogenation (removal of hydrogen halide from a given substrate) of chloroform to give dichlorocarbene intermediate. This dichlorocarbene intermediate is very reactive. The electrophilic dichlorocarbene attacks the nucleophilic nitrogen of the primary amine. The elimination of the hydrochloric acid leads to the formation of isonitrile. An illustration of the carbylamine reaction mechanism is provided below.
The carbylamine reaction can be used to synthesize isocyanides from primary amines with the help of chloroform and a base. The carbylamine reaction can also be employed to test the presence of a primary amine in a given substrate.
So, According to the above explanation:
${1^ \circ }$Aliphatic / Aromatic amine $\xrightarrow[{CHC{l_3}}]{{KOH(alc.)}}$ Isocyanide
And Isocyanide has a Nauseating smell or odour.
$\;Ph - N{H_2}\xrightarrow[{CHC{l_3}}]{{KOH(alc.)}}Ph - NC$

So, clearly we can conclude that the correct answer is Option (C).

Note: As this reaction is only effective for primary amines, the carbylamine reaction can be used as a chemical test for their presence. In this context, the reaction is also known as Saytzeff's isocyanide test.