The ferric chloride test is a test to determine if an organic compound contains a phenolic alcohol group. Phenols are usually weakly acidic. Phenols can react with ferric chloride solution to form a colored complex.

The reaction is as follows:

Materials

• Test tubes

• Test tube rack

• Ferric chloride solution

• Sodium hydroxide solution

• Blue litmus paper

• Compound to be tested

Safety

Ferric chloride solution is corrosive and an irritant. Sodium hydroxide solution is corrosive. Phenol is toxic and corrosive so should be handled with care.

Procedure

1. Put 2 mL of the organic compound in solution into a test tube.

2. Prepare a neutral ferric chloride solution. This solution should always be freshly prepared and very dilute.

   • Add dilute sodium hydroxide solution to ferric chloride solution drop by drop till a small but permanent brown precipitate appears.

   • Filter the solution. The clear filtrate is used for the test.

   • You can test if the filtrate is neutral with blue litmus paper.

3. Add neutral ferric chloride solution drop-wise.

4. Note the color change.

5. A blue, green, violet, or red color indicates the presence of a phenolic alcohol group.

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References:

• NCERT Lab Manual for Functional Group tests