Introduction to Green Chemistry, Organic Synthesis and Pharmaceuticals

The well being of modern society is unimaginable without the myriad products of industrial organic synthesis. Our quality of life is strongly dependent on, inter alia , the products of the pharmaceutical industry, such as antibiotics for combating disease and analgesics or anti infl ammatory drugs for relieving pain. The origins of this industry date back to 1935, when Domagk discovered the antibacterial properties of the red dye, prontosil, the prototype of a range of sulfa drugs that quickly found their way into medical practice. The history of organic synthesis is generally traced back to W ö hler ’ s synthesis of the natural product urea from ammonium isocyanate in 1828. This laid to rest the vis vitalis (vital force) theory, which maintained that a substance produced by a living organism could not be produced synthetically. The discovery had monumental signifi cance, because it showed that, in principle, all organic compounds are amenable to synthesis in the laboratory. The next landmark in the development of organic synthesis was the preparation of the fi rst synthetic dye, mauveine (aniline purple) by Perkin in 1856, generally regarded as the fi rst industrial organic synthesis. It is also a remarkable example of serendipity. Perkin was trying to synthesize the anti malarial drug quinine by oxidation of N allyl toluidine with potassium dichromate. This noble but na ï ve attempt, bearing in mind that only the molecular formula of quinine (C 20 H 24 N 2 O 2 ) was known at the time, was doomed to fail. In subsequent experiments with aniline, fortuitously contaminated with toluidines, Perkin obtained a low yield of a purple colored product. Apparently, the young Perkin was not only a good chemist but also a good businessman, and he quickly recognized the commercial potential of his fi nding. The rapid development of the product, and the process to make it, culminated in the commercialization of mauveine, which replaced the natural dye, Tyrian purple. At the time of Perkin ’ s discovery Tyrian purple, which was extracted from a species of Mediterranean snail, cost more per kg than gold.