In organic chemistry, the Carbylamine Reaction (also widely known as the Isocyanide Test) is a highly famous and important qualitative test. It is used exclusively to detect the presence of primary amines (both aliphatic and aromatic).
Purpose: To test for the presence of primary (1°) amines.
Reagents Used: Chloroform (CHCl₃) and Alcoholic KOH.
Product Formed: An Isocyanide (Carbylamine).
Observation: Formation of a highly foul, disgusting-smelling gas.
Limitation: Secondary and tertiary amines do not show this reaction.
When a primary amine (R-NH₂) is heated with chloroform (CHCl₃) in the presence of an alcoholic base like Potassium Hydroxide (KOH), it undergoes a chemical transformation. The primary amine is converted into an isocyanide (also called a carbylamine).
The General Equation: R-NH₂ + CHCl₃ + 3KOH (alc) + Heat → R-NC + 3KCl + 3H₂O (Primary Amine + Chloroform + Potassium Hydroxide → Alkyl Isocyanide + Potassium Chloride + Water)
The defining feature of this reaction is the sensory output. The resulting product, the isocyanide (R-NC), produces an absolutely foul, highly offensive, and intolerable smell. If you perform this test in a lab and immediately smell a disgusting, pungent odor, it confirms that the unknown compound was indeed a primary amine.
The Carbylamine reaction is extremely useful because secondary (2°) and tertiary (3°) amines do NOT respond to this test. Only primary (1°) amines possess the two hydrogen atoms on the nitrogen required to react with the chloroform to form the isocyanide structure.
It is used as a chemical test to confirm the presence of primary aliphatic or aromatic amines.
The foul-smelling substance is an isocyanide (also called carbylamine), formed by the reaction of the primary amine with chloroform.
No. Secondary and tertiary amines lack the necessary hydrogen atoms on the nitrogen, so they do not react and do not produce the foul smell.
Why Is Potassium Nitrate Classified as an Electrolyte — Explained
Why is potassium nitrate classified as an electrolyte? KNO₃ dissociates completely into K⁺ and NO₃⁻ ions in water, conducting electricity. Strong electrolyte explained.
Why Is Sodium Hydrogen Carbonate (NaHCO₃) a Basic Salt?
Sodium hydrogen carbonate (NaHCO₃) is a basic salt because it gives an alkaline solution in water. HCO₃⁻ hydrolyses to form OH⁻. Learn the reason with FAQs.
Why is Sodium Kept Immersed in Kerosene Oil?
Learn why sodium metal is kept immersed in kerosene oil. Class 10 Chemistry guide on sodium's extreme reactivity with air and water, and how kerosene protects it.
Why is the Use of Iodised Salt Advisable?
Learn why iodised salt is advisable. Understand how iodine deficiency causes goitre, how iodised salt prevents it, and why the government mandates its use.
Why Is Water a Liquid at Room Temperature? Role of Hydrogen Bonding
Water is liquid at room temperature due to extensive hydrogen bonding between H₂O molecules. This raises its boiling point to 100°C, far above comparable molecules like H₂S (−60°C).
Turn this guide into revision flashcards, a practice exam, or an AI-generated podcast — free, no signup required.