16.7: Amines in Plants- Alkaloids
- Page ID
- 86284
- Objective 1
- Objective 2
Addictive Alkaloids
Since ancient times, plants have been used for medicinal purposes. One class of substances, called alkaloids, found in many of these plants has been isolated and found to contain cyclic molecules with an amine functional group. These amines are bases. They can react with H3O+ in a dilute acid to form an ammonium salt, and this property is used to extract them from the plant:
\[\ce{R3N + H3O+ + Cl- ⟶[R3NH+]Cl- + H2O} \nonumber \]
The name alkaloid means “like an alkali.” Thus, an alkaloid reacts with acid. The free compound can be recovered after extraction by reaction with a base:
\[\ce{[R3NH+]Cl- + OH- ⟶R3N + H2O + Cl-} \nonumber \]
The structures of many naturally occurring alkaloids have profound physiological and psychotropic effects in humans. Examples of these drugs include nicotine, morphine, codeine, and heroin. The plant produces these substances, collectively called secondary plant compounds, as chemical defenses against the numerous pests that attempt to feed on the plant: