346 18 · COMMON CLASSES OF ORGANIC COMPOUNDS
Benzoic acid
In benzoic acid, a carboxyl group is attached to the benzene ring:
The solid acid is slightly soluble in water and undergoes the typical reactions of
carboxylic acids described previously. It is used as a preservative in food and drinks
including iced lollies.Aniline
Aniline is an aromatic amine with the structure
BOX 18.5
Phenol
Phenol was originally called carbolic acid. In
the nineteenth century, Joseph Lister
(1827–1912) used it to prevent wounds going
septic and recommended that the compound
should be used as an antiseptic in hospitals.
Before this, amputees often had their fresh
wounds dipped in coal tar (which contains
phenol) and about half of patients operated
on died from infections gained during the
operations. The compound is a severe irritant
to the skin, however, so it had to be replaced
by alternatives. Many modern antisepticmolecules, however, still contain phenolic
groups:Joseph Lister proposed the use of phenol as an
antiseptic. He was a Scottish surgeon who rightly
suspected that germs might be responsible for
infection in wounds.