Synthesis of organic compounds

Once the properties endowed upon a substance by specific structural units called functional groups are known, it becomes possible to design novel molecules that may exhibit desired properties. The preparation, under controlled laboratory conditions, of specific compounds is known as synthetic chemistry. Some products are easier to synthesize than to collect and purify from their natural sources. For example, large amounts of vitamin C are synthesized annually. Many synthetic substances have novel properties that make them especially useful. Plastics are a prime example, as are many drugs and agricultural chemicals.

A continuing challenge for synthetic chemists is the structural complexity of most organic substances. To synthesize a desired compound, the atoms must be pieced together in the correct order and with the proper three-dimensional relationships. A fixed number of atoms can be connected in various ways to produce different molecules. However, only one structural arrangement out of the many possibilities will be identical with a naturally occurring molecule. For example, a molecule of the antibiotic erythromycin contains 37 carbon, 67 hydrogen, and 13 oxygen atoms along with 1 nitrogen atom. Even when joined together in the proper order, these 118 atoms can give rise to 262,144 different structures, only one of which has the characteristics of natural erythromycin.