Ferric Chloride Test for Phenols and Enols

Preparation Sign in at www.cengage.com/login to read the MSDSs for the chemicals used or produced in this procedure. 

Dissolve 30-50 mg of the unknown compound in 1-2 mL of water, or a mixture of water and 95% ethanol if the compound is not water-soluble, and add several drops of a 0.2 A4 aqueous solution of ferric chloride. Most phenols produce red. blue, purple. or green coloration enols give red. violet, or tan coloration. 

Two useful solid derivatives of phenols are a-naphthylurethanes and bromo compounds. 

The preparation of urethanes is discussed in Section 25.11D. Although either a phenyl- or naphthyl-substituted urethane could be prepared, the majority of the derivatives reported are the a-naphthylurethanes, and they are generally the urethanes of choice. 

The high reactivity of phenols toward electrophilic aromatic bromination is discussed in Section 25.12A. This reaction can be used to prepare bromophenols, which may serve as solid derivatives. 

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