TAILIEUCHUNG - Learning Organic Chemistry Through Natural Products

The Convention also targets two industrial chemicals: hexachlorobenzene (HCB), which is also used as a pesticide and can be a byproduct of pesticide manufacture, and the class of industrial chemicals known as PCBs, or polychlorinated biphenyls. PCBs have received a great deal of publicity for polluting rivers and lakes in industrial regions, killing or poisoning fish, and causing several human health scandals, including contamination of rice oil in Japan in 1968 and Taiwan in 1979. In addition, the Convention covers two families of unintentional chemical by-products: polychlorinated dioxins and furans. These compounds have no commercial use. Dioxins and furans result from combustion and from industrial processes. | SERIES I ARTICLE Learning Organic Chemistry Through Natural Products 1. Natural Products - A Kaleidoscopic View N H Krishnaswamy N R Krishnaswamy was initiated into the world of natural products by T R Seshadri at University of Delhi and has carried on the glorious traditions of his mentor. He has taught at Bangalore University Calicut University and Sri Sathya Sai Institute of Higher Learning. Generations of students would vouch for the fact that he has the uncanny ability to present the chemistry of natural products logically and with feeling. 1 Empirical formula is determined from combustion analysis. 2 Thin layer chromatography TLC is an analytical tool to separate compounds based on their differential interactions with a stationary phase and a moving solvent. A species with a greater relative affinity for the solvent moves faster higher R value on a TLC plate. A naturally occurring organic compound has been chosen to illustrate a structure determination by chemical and spectroscopic methods and b synthesis and chemical transformations. Organic chemists isolate or synthesize new compounds all the time. How does one identify their structures Some may answer X-ray However X-ray diffraction can be used to determine structures only for compounds which form single crystals. For the vast majority of organic compounds structure elucidation is carried out by a combination of chemical transformations and spectroscopic analyses. In this article we discuss the general approach that is followed using a natural product as an example. In order to keep the focus on chemistry we defer giving its trivial name and plant source till the end of the discussion. An additional bonus of such an approach is that the student logically deduces the structure from the given set of data and does not merely recall the structure from memory. Further wherever possible we look at a problem from different angles thus covering a wider ground. As our first example we choose a molecule designated .

• Hoá dầu
• Guiding Force
• Energy Conversion
• Purple Bacteria
• Photosynthesis
• Carotenoids and Photosynthesis
• Carotenoid Biosyntesis