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Basic Concepts from Organic Chemistry 5.1 | INTRODUCTION The fundamental information that environmental engineers and scientists need concerning organic chemistry differs considerably from that which the organic chemist requires. This difference is due to the fact that chemists are concerned principally with the synthesis of compounds, whereas environmental engineers and scientists are concerned, in the main, with how the organic compounds in liquid, solid, and gaseous wastes can be destroyed and how they react in the environment. Another major difference lies in the fact that the organic chemist is usually concerned with the product of the reaction: the by-products of a reaction are of little interest to him or her. Since few organic reactions give better than 85 percent yields, the amount of by-products and unreacted raw materials that represent processing wastes is of considerable magnitude. In addition, many raw materials contain impurities that do not enter the desired reaction and, of course, add to the organic load in waste streams. A classical example is formaldehyde, which normally contains about 5 percent of methanol unless special precautions are taken in its manufacture. Unfortunately, organic chemists have presented very little information on the nature of the by-products of reactions to aid environmental engineers and scientists in solving industrial and hazardous waste problems. Fortunately, this is changing because of the large liabilities that companies now face from discharge of environmental pollutants. Awards are now being given for “green chemistry,� that is, for changing the ways chemicals are produced in order to reduce the environmental harm they or their production cause. The environmental engineer and scientist, like the biochemist, must have a fundamental knowledge of organic chemistry. It is not important for either to know a multiplicity of ways of preparing a given organic compound and the yields to be expected from each. Rather, the important consideration is how the compounds react in the atmosphere, in the soil, in water, and in treatment reactors, especially when serving as a source of energy for living organisms. It is from this viewpoint that organic chemistry will be treated in this chapter, and considerations will be from the viewpoint of classes rather than individual compounds. 212