Phenol (C6H5OH) is a colorless needle-shaped crystal with a distinctive odor. It serves as an important raw material in the production of certain resins, bactericides, preservatives, and pharmaceuticals (such as aspirin). It can also be used for disinfecting surgical instruments, treating excreta, skin sterilization, relieving itching, and treating otitis media. Phenol has a melting point of 43°C and is slightly soluble in water at room temperature but easily soluble in organic solvents. When the temperature exceeds 65°C, it becomes miscible with water in any proportion. Phenol is corrosive and causes local protein denaturation upon contact. Solutions of phenol that come into contact with the skin can be washed off with alcohol. A small portion of phenol exposed to air oxidizes into quinone, turning pink. It turns purple when exposed to ferric ions, a property commonly used to test for phenol.
Discovery History
Phenol was discovered in coal tar in 1834 by the German chemist Friedlieb Ferdinand Runge, hence it is also known as carbolic acid. Phenol first gained widespread recognition thanks to the renowned British physician Joseph Lister. Lister observed that most postoperative deaths were due to wound infections and pus formation. By chance, he used a dilute phenol solution to spray surgical instruments and his hands, which significantly reduced patient infections. This discovery established phenol as a potent surgical antiseptic, earning Lister the title “Father of Antiseptic Surgery.”
Chemical Properties
Phenol can absorb moisture from the air and liquefy. It has a distinctive odor, and very dilute solutions taste sweet. It is highly corrosive and chemically reactive. It reacts with aldehydes and ketones to form phenolic resins and bisphenol A, and with acetic anhydride or salicylic acid to produce phenyl acetate and salicylate esters. It can also undergo halogenation, hydrogenation, oxidation, alkylation, carboxylation, esterification, and etherification reactions.
At normal temperatures, phenol is solid and does not readily react with sodium. If phenol is heated to melt before adding sodium for an experiment, it is easily reduced, and its color changes upon heating, affecting the experimental outcome. In teaching, an alternative method has been adopted to achieve satisfactory experimental results simply and effectively. In a test tube, 2–3 mL of anhydrous ether is added, followed by a pea-sized piece of sodium metal. After removing surface kerosene with filter paper, the sodium is placed in the ether, where it does not react. Adding a small amount of phenol and shaking the tube allows sodium to react rapidly, producing a large amount of gas. The principle behind this experiment is that phenol dissolves in ether, facilitating its reaction with sodium.
Post time: Jan-20-2026