Phenol is a simple organic compound composed of a hydroxyl group and a benzene ring. Phenol is also known by the formula (C6H5OH) with the names hydroxyl benzene and carbolic acid. The most important use of phenol is in the preparation of phenolic resins. Phenol is usually soluble in water and has weak acidic properties (pKa = 9.9). Pure phenol is a white solid with a melting point of 42 ° C or 108 ° F. Phenol can be used as a disinfectant.