SENCER E-Newsletter, April 2005, Volume 4, Issue 8
Green Chemistry: Not an Oxymoron
Mary M. Kirchoff, Ph.D.
Assistant Director for Special Projects
Education Division, American Chemical Society
Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. It advocates the practice of chemistry in an environmentally responsible manner by focusing on pollution prevention at the atomic and molecular level. An attractive feature of green chemistry is its interdisciplinary nature, incorporating elements of economics, engineering, biology, ethics, and other disciplines.
Students frequently equate chemistry with pollution and view it as a discipline that creates environmental problems rather than solves them. By applying green chemistry technologies to some of our most challenging global problems, such as energy generation and resource depletion, students begin to appreciate that chemistry plays an important role in achieving sustainability. The implementation of green chemistry technologies minimizes the use of materials that are hazardous to human health and the environment, decreases energy and water usage, and maximizes efficiency. Green chemistry is not merely an academic exercise, but has real-world applications to global issues.
Because many students in chemistry courses are pursuing careers in the health professions, pharmaceutical examples are particularly appealing. The pharmaceutical industry generates more waste per kilogram of product than other chemistry-based industrial sectors due to a variety of factors, including the use of multistep syntheses, the presence of chiral centers, and the need for a highly pure product. A number of pharmaceutical companies are adopting green chemistry practices in order to cut down on the generation of waste. Pfizer, for example, has modified the synthesis of sertraline, the active ingredient in the antidepressant Zoloft, to eliminate hundreds of tons of waste. The redesigned synthesis nearly doubles the yield of product, thereby improving the economics of the process.
Given the high cost of gasoline, students are probably giving more thought to energy (and energy prices) than ever before. Green chemistry plays a critical role in developing alternatives to fossil fuels, such as photovoltaics, fuel cells, and biobased fuels. Energy efficiency can also be enhanced through the use of catalysts, which can minimize energy usage while maximizing selectivity. While alternative energy sources are being developed, technologies that sequester carbon dioxide in value-added products will help to lessen the global warming impact of fossil fuel combustion.
A key component of green chemistry is the design and use of substances that are less hazardous to human health and the environment. Chemists are discovering that a variety of reactions can be run in more benign solvents, such as water and carbon dioxide, rather than in traditional organic solvents, many of which are volatile organic compounds, flammable, and toxic.
Some polycarbonates, for example, can be synthesized in carbon dioxide, which serves as both co-monomer and solvent. More selective pesticides kill target insects without harming beneficial wildlife. CFCs have been replaced with substances that are less harmful to the ozone layer. Innovations in chemistry are providing consumers with the products they depend upon in a manner that is less damaging to the environment.
Despite the appeal that green chemistry holds for students, it is seldom introduced into the chemistry curriculum. The term "green chemistry" has only been around for the last 15 years, and many textbooks do not reflect this approach to chemistry. The American Chemical Society, through a cooperative agreement with the U.S. Environmental Protection Agency, has developed a number of resources suitable for students from high school through graduate school. Introduction to Green Chemistry presents six key green chemistry concepts to high school students through background readings and hands-on activities. Undergraduate students learn about academic and industrial applications of green chemistry by exploring Real-World Cases in Green Chemistry, while Greener Approaches to Undergraduate Chemistry Experiments presents a green chemistry approach to chemical concepts and laboratory techniques. Going Green: Integrating Green Chemistry into the Curriculum offers faculty members strategies for incorporating green chemistry concepts into their teaching, research, and outreach activities.
For more advanced students, the annual Summer School on Green Chemistry engages graduate and postdoctoral students in a program that introduces the basics of green chemistry and engineering, while providing in-depth coverage of green chemistry applications in such areas as pharmaceuticals, catalysis, and polymers. Workshops and conference symposia provide continuing education in green chemistry across a broad range of topics. Each summer, the Green Chemistry in Education Workshop at the University of Oregon engages faculty members in lectures, discussion, and hands-on activities that facilitate the incorporation of green chemistry concepts into the organic chemistry curriculum.
Green chemistry provides both students and faculty members with the tools to practice chemistry in an environmentally responsible manner. Students begin to appreciate that the choices they make, in terms of starting materials, reagents, and solvents, have consequences to human health and the environment. Educating students about green chemistry will expedite the implementation of cleaner technologies in industry and academia to the point where, one day, the term "green chemistry" will no longer be needed because all chemistry will be designed with the environment in mind.