1. 18.3 Heterocyclic Amines
A heterocyclic amine is a cyclic organic compound that consists of a ring of five or six atoms, of which one or two are nitrogen atoms.
The aroma of pepper is due to piperidine, a heterocyclic amine.
Learning Goal Identify heterocyclic amines; distinguish between the types of heterocyclic amines.

2. Heterocyclic Amines, Five-atom Rings
Of the five-atom rings,
the simplest one is pyrrolidine, which is a ring of four carbon atoms and one nitrogen atom, all with single bonds.
pyrrole is a five-atom ring with one nitrogen atom and two double bonds.
imidazole is a five-atom ring that contains two nitrogen atoms.

3. Heterocyclic Amines, Six-atom Rings
Of the six-atom rings,
piperidine, responsible for the pungent aroma and taste of black pepper, is a six-atom heterocyclic ring with a nitrogen atom.
purine and pyrimidine rings are found in DNA and RNA.
In purine, the structures of six-atom pyrimidine and five-atom imidazole are combined.

4. Chemistry Link to Health: Alkaloids: Amines in Plants
Alkaloids are
physiologically active compounds produced by plants that contain heterocyclic amines.
used in anesthetics, in antidepressants, and as stimulants, and many are habit forming.
Nicotine, an alkaloid, is a stimulant that
increases the level of adrenaline in the
blood, increases the heart rate, and increases blood pressure.
Nicotine is addictive because it activates
pleasure centers in the brain.

5. Chemistry Link to Health: Alkaloids: Amines in Plants
Caffeine
is an alkaloid found in coffee beans, tea, chocolate, and soft drinks.
is a stimulant of the central nervous system.
increases alertness but may cause insomnia.

6. Chemistry Link to Health: Alkaloids: Amines in Plants
Morphine and codeine are
alkaloids obtained from the oriental poppy plant.
used as painkillers and in cough syrups.

7. Chemistry Link to Health: Alkaloids: Amines in Plants
Heroin, obtained by a chemical modification of morphine, is strongly addictive and is not used medically.
The prescription drug OxyContin (oxycodone) is used to relieve severe pain. Its structure is similar to that of heroin.

8. Study Check
Identify the heterocyclic amines in the following: A. B. C. D.

9. Study Check
Identify the heterocyclic amines in the following: A. B. C. D. A, B, and C are heterocyclic amines; D is not.