ceptors they influence. The emergence of directed enzyme evolution5 to modify natural microorganisms in order to carry out transformations with higher chemo and stereochemical selectivity has helped fuel this growth. Asymetric chiral catalysis is an alternate route.

As pointed out by Glenn Nedwin during the workshop,6 the production of textile derivatives synthesized by means of an enzymatic based process instead of a traditional multi-step chemical synthesis can lead to significant environmental benefits. It was found that utilizing enzymes can (1) reduce aquatic pollution by limiting the utilization of solvents, acids, chlorine derivates, oxidizing agents, sulphides, and other chemicals; (2) save energy by reducing process temperature; and (3) avoid having to resort to useful agricultural raw materials needed for other applications.

There are many other approaches to catalytic bond formation that still need to be explored, such as those being carried out at the Center for Environmentally Beneficial Catalysis (CEBC). CEBC is a multi-university NSF Engineering Research Center, headquartered at the University of Kansas with core partners at the University of Iowa, Washington University in St. Louis, and Prairie View A&M University. The center was created with a mandate to make “sustainable” manufacturing processes available to industry—that is, improved processes that minimize their “environmental footprint” while remaining profitable. CEBC’s approach to doing this is by reducing or eliminating the use of hazardous materials in manufacturing (including the catalysts themselves or hazardous solvents), minimizing the formation of wasteful byproducts, and by improving energy efficiency. In pursuit of its vision and research goals, CEBC is guided by the principles of “Green Engineering” and “Green Chemistry”.

Safer Solvent Selection

Another important green chemistry principle is to use safer solvents and reaction conditions by avoiding use of organic solvents, separation agents, or other auxiliary chemicals. When these chemicals are necessary, innocuous chemicals should then be used to the greatest extent possible.

Manufacturing chemicals can generate significant amounts of waste by-products and pollutants, such as halogenated or toxic organic solvents, volatile toxic or ozone-depleting organic compounds, hazardous air pollutants such as NOx, COx, SOx, and aqueous wastes. Roger Sheldon devel-

5  

For a review of this topic see: Farinas, E. T., T. Butler, and F. H. Arnold. 2001. Directed Enzyme Evolution. Current Opinion in Biotechnology 12:545–551.

6  

See comments by Glenn Nedwin, Workshop Summary in Appendix D, p. 143.



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