Experiment 31

Objective

To identify primary amines through the carbylamine test.

Introduction

The carbylamine test is specific to primary amines, both aliphatic and aromatic, and is sometimes referred to as the primary amine test. In this reaction, a primary amine reacts with chloroform and potassium hydroxide (KOH) at 60–70°C to produce an isocyanide (or carbylamine), which has a distinctive, pungent odor.

Reaction:

RNH2 ​+ CHCl3 ​+ 3KOH → RNC + 3KCl + 3H2​O

Materials

Chemicals

●      Chloroform

●      Primary amine (e.g., aniline or methylamine)

●      Potassium hydroxide (KOH)

Apparatus

●      Test tube

●      Test tube holder

●      Bunsen burner

Reagents

●      3-4 ml of methylamine

●      8-9 ml of KOH solution

●      Chloroform, added dropwise

Procedure

1.    In a test tube, combine methylamine and KOH.

2.    Add chloroform dropwise to the test tube.

3.    Heat the mixture at 60–70°C for 5–6 minutes.

4.    Once the pungent odor of the reaction product is detected, stop heating.

Observation

The formation of a strong, unpleasant odor (isocyanide or carbylamine) indicates the presence of a primary amine.

Questions

1.    What are carbylamines?

2.    Why is the carbylamine test performed?

3.    What occurs during the carbylamine test?