On heating an aliphatic primary amine with chloroform and ethanolic potassium hydroxide, the organic compound formed is :
Isocyanide test for primary amine
This reaction is known as the Carbylamine test or Isocyanide test. It is a specific and reliable test used to distinguish primary amines from secondary and tertiary amines.
Step 1: Understanding the Reagents
The reaction involves an aliphatic primary amine (R-NH2), chloroform (CHCl3), and ethanolic potassium hydroxide (KOH in ethanol).
Step 2: The Reaction Mechanism
Ethanolic KOH acts as a strong base. It first deprotonates chloroform to form the trichloromethane anion (dichlorocarbene precursor).
This anion then undergoes alpha-elimination to form the highly reactive intermediate called dichlorocarbene (:CCl2).
Step 3: Reaction with the Primary Amine
The primary amine (R-NH2) attacks the electrophilic dichlorocarbene. This is followed by a series of eliminations, ultimately resulting in the formation of an alkyl isocyanide (R-NC).
The overall reaction is:
Step 4: Identifying the Product
The product, an alkyl isocyanide (R-NC), has a very characteristic and extremely unpleasant, foul odor. This offensive smell is a positive indicator for the presence of a primary amine.
Final Answer: The organic compound formed is an alkyl isocyanide.
Carbylamine Reaction: A test specific for primary amines (both aliphatic and aromatic) where they react with chloroform and a base to produce isocyanides.
Isocyanide: Functional group with the formula R-NC. It is an isomer of the nitrile group (R-CN). Isocyanides are notoriously known for their repulsive smell.
Distinction Test: Secondary and tertiary amines do not give this test, which makes it a crucial method for qualitative analysis in organic chemistry.
The correct functional group X and the reagent/reaction conditions Y in the following scheme are :
