Distinguishing Alcohols and Phenols

Three simple tests tell an aromatic phenol apart from a simple aliphatic alcohol such as ethanol. (1) Phenol couples with benzenediazonium chloride to give a red-orange azo dye; ethanol gives no such reaction. (2) Phenol gives a characteristic purple/violet colouration with neutral ferric chloride (FeCl3) solution (the phenoxide-iron complex); alcohols give no colouration with FeCl3. (3) Phenol reacts with aqueous NaOH to form sodium phenoxide (demons …