Question

When chloroform reacts with ethylamine in presence of alc. $KOH$, the compound formed is:

• A. ethyl cyanide
• B. ethyl isocyanide
• C. formic acid
• D. phosgene

Answer 1

The correct option is B ethyl isocyanide

Carbylamine reaction mechanism includes the addition of amine to the intermediate created from the dehydrohalogenation of chloroform. This intermediate is called dichlorocarbene. The carbylamine reaction is also known as Hoffmann isocyanide synthesis. It is the reaction of a primary amine, chloroform and a base to synthesize isocyanides. The dichlorocarbene intermediate is very important for this conversion. The carbylamine reaction cannot be used to synthesize isocyanides from secondary or tertiary amines.

The carbylamine reaction is:
$C{H}_{3}N{H}_2+CHC{l}_3+KOH\to C{H}_{3}NC+3KCl++3H_{2}O$

This test is done to detect primary amines because isocyanide has a specific odour (unpleasant) and presence of primary amines form this foul smelling isocyanides. Secondary or tertiary amines do not give this reaction.

Hence, the correct answer is option (b).