→ The simplest hydroxyl derivative of benzene is phenol. It is its common name and also an accepted IUPAC name. As structure of phenol involves a benzene ring, in its substituted compounds the term ortho (1,2- disubstituted), meta (1,3- disubstituted) and para (1,4- disubstituted) are often used in the common names.
Example:

→ Dihydroxy derivatives of benzene are known as 1, 2, 1, 3- and 1, 4-benzenediol.
