Any of a class of nitrogen -containing organic compounds derived, either in principle or in practice, from ammonia (NH 3 ).
Almost all their chemical names end in -ine . Replacement of one, two, or all three of the hydrogen atoms in ammonia with organic groups yields primary, secondary, or tertiary amines, respectively. Addition of a fourth hydrogen with an accompanying positive charge on the nitrogen atom results in a quaternary amine. Naturally occurring amines include alkaloid s, present in certain plants; some neurotransmitter s, including dopamine and epinephrine ; and histamine . Industrially important amines include aniline , ethanolamine, and others, used in making rubber, dyes, pharmaceuticals, and synthetic resins and fibres and in a host of other applications. A nitrogen atom with one or two hydrogens is often referred to as an amino group.