Question

Which donot form carbylamine

• A. Ethanamines
• B. Benzamine
• C. Porp-2-amine
• D. Propan-1-amine
• E. N-methylethanamine

Hint:

The Carbylamine test is a reliable qualitative test for both aliphatic and aromatic primary amines.
If you see any prefix like "N-methyl" or "N,N-dimethyl", it indicates a secondary or tertiary amine, which will definitely fail this test.

Answer 1

Answer: (E)

Step 1: Understanding the Concept:
The carbylamine reaction, also known as the isocyanide test, is a chemical test exclusively used to detect the presence of primary (\( 1^\circ \)) amines.
Step 2: Key Formula or Approach:
The approach is to identify the degree of amine for each option; secondary (\( 2^\circ \)) and tertiary (\( 3^\circ \)) amines do not undergo this reaction.
Step 3: Detailed Explanation:
In the carbylamine test, a primary amine is heated with chloroform and alcoholic potassium hydroxide to form a foul-smelling isocyanide (carbylamine).
Let us analyze the given options to determine their amine class.
(A) Ethanamines (e.g., \( \text{CH}_3\text{CH}_2\text{NH}_2 \)) are aliphatic primary amines, so they give the test.
(B) Benzamine (aniline, \( \text{C}_6\text{H}_5\text{NH}_2 \)) is an aromatic primary amine, so it gives the test.
(C) Porp-2-amine (\( \text{CH}_3\text{CH(NH}_2\text{)CH}_3 \)) is an aliphatic primary amine, so it gives the test.
(D) Propan-1-amine (\( \text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2 \)) is an aliphatic primary amine, so it gives the test.
(E) N-methylethanamine (\( \text{CH}_3\text{CH}_2\text{NHCH}_3 \)) is a secondary amine.
Since it is a secondary amine, it does not form carbylamine.
Step 4: Final Answer:
N-methylethanamine does not form carbylamine.