O638: Identification of Phenols – Ferric Chloride Test

Introduction

Compounds with a phenol group will form a blue, violet, purple, green, or red-brown color upon addition of aqueous ferric chloride.  This reaction can be used as a test for phenol groups.

Equations 

3ArOH + FeCl3 → Fe(OAr)3 + 3HCl

To Conduct Demonstration:  

  1. Mix several drops or a few crystals of compound to be tested in a beaker or in a 200mm test tube.
  2. Add a few drops of 1% FeCl3.
  3. As a control, add a few drops of 1% FeCl3 to water in a second beaker.  Also, mix aspirin in water to use as a control
  4. Observe color change, if any.

Safety   

Gloves are recommended.

Reference:

D.J. Pasto and C.R. Johnson, Laboratory Text for Organic Chemistry, p 410, 1979.

Acknowledgment:

Margaret Asirvatham, Spring 1992.