Quinine is an alkaloid, or nitrogen-containing, molecule that is naturally produced by the bark of the cinchona tree, native to South America. It was the first pharmaceutical treatment for malaria, a mosquito-spread, life-threatening blood disease endemic to tropical and subtropical climates. While quinine has many interesting chemical properties, one of the most intriguing bits of information about the molecule is that it inspired Samuel Hahnemann to develop the theories of medicine that later came to be known as homeopathy.
Physical Properties
According to the "CRC Manual of Chemistry and Physics," quinine is a large organic molecule consisting of 20 carbon atoms, 24 hydrogen atoms, two nitrogen atoms and two oxygen atoms. It is quite heavy, at 324.4 g/mol, and melts at 351 degrees F. Because quinine is crystalline and melts at such a high temperature, it's nearly impossible to boil. As such, boiling points for quinine are rarely reported in literature.
Chemical Reactivity
Quinine is slightly basic, meaning that it reacts readily with acids. According to the material safety data sheet (MSDS), quinine is relatively stable and does not react with heat or light, nor is it particularly flammable, except at very high temperatures.
Chemical Symmetry
One of quinine's interesting chemical properties is that it's an asymmetric molecule and has a related mirror image molecule with a similar name and identical physical properties. Some molecules are symmetric, and the mirror image of such a molecule is an identical molecule of the same name. To understand this, it helps to picture a baseball---in the mirror, the image of a baseball is still a baseball. Other molecules, however, are asymmetric. A right hand, for instance, held up to the mirror, reflects the image of a left hand. While left and right hands are quite similar, they're not identical. In the same way, some molecules show mirror asymmetry. Their mirror images are very similar visually---like right and left hands---and are identical in terms of their weights, melting points and many other properties. In the body, however, the mirror image molecule of quinine behaves quite differently from quinine, which makes the distinction between the "right handed" and "left handed" versions of the molecule quite important.
Biochemical Reactivity
Quinine shows significant biochemical reactivity. In addition to relieving symptoms of malaria, it's also an antipyretic molecule, meaning that it reduces fever. Further, it's an analgesic, or pain reliever, and an anti-inflammatory. The MSDS warns that in high doses, quinine can cause skin irritation, blistering and burning. Inhalation leads to irritation and burning of the respiratory tract, and powdered quinine crystals can damage the eyes. Overdose of quinine is toxic to the liver and causes central nervous system activation, nervousness and generalized discomfort.
References
- Material Safety Data Sheet: Quinine (Rev. February 2005)
- "CRC Handbook of Chemistry and Physics"; David Lide; 1974
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