Green Chemistry

Greening Across the Chemistry Curriculum English | Versión en Español Flag Spain| Versão em Português (Brasil) Flag Port

A Project with major funding from The Camille and Henry Dreyfus Foundation Special Grant Program in the Chemical Sciences. Additional funding was provided by the ACS/EPA Green Chemistry Educational Materials Development Project and the University of Scranton.

Notes to Instructors

Introduction to Green Chemistry

Michael C. CannChemistry DepartmentUniversity of Scranton

The late sixties and early seventies were times when the environment received a great deal of attention including the formation of the Environmental Protection Agency (EPA) and the celebration of the first Earth Day, both of which occurred in 1970. In the intervening years in excess of 100 environmental laws have been passed. These include the twelve major laws listed below.

  • 1970 Clean Air Act. Regulates air emissions.
  • 1972 National Environmental Policy Act. Requires in part that EPA review environmental impact statements of proposed major federal projects (e.g. highways, buildings, airports, parks and military complexes).
  • 1972 Clean Water Act. Establishes the sewage treatment construction grants program and a regulatory and enforcement program for discharges of pollutants into U.S. waters.
  • 1972 Federal Insecticide, Fungicide & Rodenticide Act. Governs distribution, sale and use of pesticide products. All pesticides must be registered (licensed) by EPA.
  • 1972 Ocean Dumping Act. Regulates the intentional disposal of materials into ocean waters.
  • 1974 Safe Drinking Water Act. Establishes primary drinking water standards.
  • 1976 Toxic Substances Control Act. Requires the testing, regulating, and screening of all chemical produced or imported in the U.S.
  • 1976 Resource Conservation & Recovery Act. Regulates solid and hazardous waste form “cradle to grave.”
  • 1976 Environmental Research & Development Demonstration Act. Authorizes all EPA research programs.
  • 1980 Comprehensive Environmental Response, Compensation & Liability Act, better known as Superfund. Provides for a federal “superfund” to clean up abandoned hazardous waste sites, accidental spills and other emergency releases of pollutants in the environment.
  • Emergency Planning & Community Right-to-Know Act. Requires that industries report toxic releases and encourages planning by local communities to respond to chemical emergencies.
  • 1990 Pollution Prevention Act. Seeks to prevent pollution by encouraging companies to reduce the generation of pollutants through cost-effective changes in production, operation, and raw material use.

All of these acts, with one exception, deal with pollution after it is formed. These laws are in general focused on the treatment or abatement of pollution and have become know as “command and control” laws. In many instances these laws, which were passed by the US congress, place limits on pollution and timetables for compliance, with little regard to whether the science/technology could attain these goals and with little regard to the economic costs of these laws. Risk associated with a toxic chemical is a function of Hazard and Exposure. The “end of the pipe” laws attempt to control Risk by dealing with the prevention of the Exposure to toxic hazardous chemicals. Of course all to often prevention of Exposure has failed.

Risk=f(Hazard, Exposure)

While these laws have accomplished a great deal in terms of improving our environment by controlling our exposure to hazardous substances, we still have a long way to go. For example under the Toxic Release Inventory (TRI), which is part of the Emergency Planning and Community Right to Know Act (EPCRA), companies are required to report the use and/or release of certain hazardous substances. In 1997 industries reported that 23.85 billion pounds of hazardous substances were treated, recycled, used for energy production, disposed of or released to the environment. This act covers only 650 of the 75,000 chemicals in use in US commerce today and only companies that manufacture or proce ss more that 25,000 pounds or use more than 10,000 pounds of a listed substance are required to report.

Companies traditionally have viewed environmental regulations with disdain and as an economic hardship. In order to comply with environmental regulations it is estimated to cost U.S. industries between $100 to 150 billion per year. Since the EPA is charged with the implementation and enforcement of these laws, the relationship between industry and the EPA has been adversarial and one of mistrust.

In the last decade a new paradigm has emerged at the EPA, ushered in, in part by the Pollution Prevention Act of 1990. This is the first and only act that is focused on pollution prevention rather than the typical treatment and remediation. The EPA is now attempting to partner with industry to find more flexible and cost effective ways of not only meeting exi sting regulations but also preventing pollution at the source. In 1991 green chemistry became a formal focus of EPA (green chemistry at EPA). Green Chemistry or environmentally benign chemistry is the design of chemical products and processes that reduce of eliminate the use and generation of hazardous substances .1 Thus instead of limiting Risk by control ling our Exposure to hazardous chemicals, green chemistry attempts to reduce and preferentially eliminate the Hazard thus negating the necessity to control Exposure. The bottom line is, if we don't use or produce hazardous substances then the Risk is zero, and we don't not have to worry about the treatment of hazardous substances or limiting our exposure to them.

Green chemistry has gained a strong foothold in the areas of research and development in both industry and academia. Several conferences and meetings (e.g. the Green Chemistry and Engineering Conference) are held each year with green chemistry/technology as their focus. The journal Green Chemistry made it debut in 1999, the Green Chemistry Institute was recently created and the Presidential Green Chemistry Challenge Awards were established in 1995.

THE PRESIDENTIAL GREEN CHEMISTRY CHALLENGE AWARDS

The Presidential Green Chemistry Challenge Awards were announced in 1995 by the Clinton administration and the first awards were presented in 1996. These awards are a means of recognizing outstanding achievements in applied green chemistry/technology and are the only awards in chemistry given out on the presidential level. Nominees for these awards must demonstrate how their work has met one or more of the following criteria:

  • Greener reaction conditions for an old synthesis (e.g., replacement of an organic solvent with water or the use of no solvent at all).
  • A greener synthesis for an old chemical (e.g., a synthesis which us es biomass rather than petrochemical feedstocks or the use of catalytic rather than stoichiometric reagents).
  • The synthesis of a new compound that is less toxic but has the same desirable properties as an existing compound (e.g., a new pesticide that is toxic only to target organisms and biodegrades to environmentally benign substances).

Examples of green chemistry/technology that have been developed encompass most all areas of chemistry including organic, biochemistry, inorganic, polymer, toxicology, environmental, physical, industrial etc. Some cases of green chemistry/technology that have won the Presidential Green Chemistry Challenge Award consist of (see links to abstracts for these awards at http://www.epa.gov/greenchemistry/pubs/pgcc/past.html

  • Barry Trost's concept of atom economy which looks at utilized and wasted atoms in a reaction.
  • A new synthesis of ibuprofen which has a much better record of atom economy and pollution prevention.
  • The use of waste carbon dioxide as a blowing agent (which is non ozone depleting unlike the traditional CFC blowing agents) for foam polystyrene.
  • Development of surfactants for carbon dioxide enabling CO2 to be used as a solvent (for example in dry cleaning).
  • Development of oxidant activators for hydrogen peroxide. This allows, for example, the replacement of chlorine containing (ozone depleting) bleaches with hydrogen peroxide in the manufacture of paper
  • The develop ment of new insecticides that are more specific to target organisms.

THE TWELVE PRINCIPLES OF GREEN CHEMISTRY 1

Anastas and Warner have developed the Twelve Principles of Green Chemistry to aid one in assessing how green a chemical, a reaction or a process is.

  1. It is better to prevent waste than to treat or clean up waste after it is formed.
  2. Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.
  3. Wherever practicable, synthetic methodologies should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
  4. Chemical products should be designed to preserve efficacy of function while reducing toxicity .
  5. The use of auxiliary substances (e.g. solvents, separation agents, etc.)should be made unnecessary whenever possible and, innocuous when used
  6. Energy requirements should be recognized for their environmental and economic impacts and should be minimized. Synthetic methods should be conducted at ambient temperature and pressure.
  7. A raw material feedstock should be renewable rather than depleting whenever technically and economically practical.
  8. Unnecessary derivatization (blocking group, protection/deprotection, temporary modification of physical/chemical processes) should be avoided whenever possible.
  9. Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
  10. Chemical products should be designed so that at the end of their function they do not persist in the environment and break down into innocuous degradation products.
  11. Analytical methodologies ne ed to be further developed to allow for real-time in-process monitoring and control prior to the formation of hazardous substances.
  12. Substances and the form of a substance used in a chemical process should chosen so as to minimize the potential for chemical accidents, including releases, explosions, and fires.

Exposing Students to Green Chemistry

In 2000, Daryle Busch, former president of the American Chemical Society said "Green chemistry represents the pillars that hold up our sustainable future. It is imperative to teach the value of green chemistry to tomorrow's chemists.”

It is clear that many industries and the research of many academics recognize the significance of green chemistry. However very little discussion of green chemistry has found its way into the chemistry curriculum. Although we and others2 have made some isolated attempts to bring green chemistry into the classroom, the EPA and ACS have recognized the need to make a concerted and sustained effort to green the curriculum so that future chemists are taught to “think green.” The EPA/ACS Green Chemistry Educational Materials Development Project was begun at a workshop in October 1998. The thrust of this project is to develop materials that will aid in the infusion of green chemistry into the curriculum. The major foci of this project are the development of an Annotated Bibliography of Green Chemistry, Green Chemistry Laboratory Experiments, Real-World Cases in Green Chemistry and short courses on green chemistry. John Warner of U. Mass. Boston is in charge of the first two projects and the third is a project accomplished by Michael Cann and Marc Connelly of the University of Scranton.

Real-World Cases in Green Chemistry was published in March of 2000. This work, which is published by ACS, is an attempt to compile and edit information on green chemistry so that chemistry instructors may use this information to green the chemistry curriculum at their institution. Each case focuses on a Presidential Green Chemistry Challenge award winner or nominee.

In order to take the greening of the chemistry curriculum to its next logical step we are developing green chemistry modules for insertion of green chemistry into specific chemistry courses. These modules are being developed by instructors who teach these courses. The introduction to green chemistry that you are now reading is part of this undertaking.

Questions

  1. What do the first eleven major environmental laws have in common? How does this contrast with the Pollution Prevention Act of 1990?
  2. What are the three criteria for the Presidential Green Chemistry Challenge Award?
  3. Define green chemistry.
  4. Which of the Twelve Principles of Green Chemistry deals with atom economy?
  5. In a chemical reaction what is meant by an auxiliary substance? Look up an example of an organic lab that you have done and list the auxiliary substances that you used.
  6. Why are catalytic reagents superior to stoichiometric reagents (in your answer make sure that you explain the terms catalytic and stoichiometric)?
  7. What is the Toxic Release Inventory?
  8. Consider a chemical product or process that you are aware of. With the Twelve Principles of Green Chemistry as your guide devise ways to make this product or process greener.

References

  1. Anastas, Paul T., and Warner, John C. Green Chemistry Theory and Practice, Oxford University Press, New York, 1998.
  2. a) http://jchemed.chem.wisc.edu/Journal/Issues/1995/Nov/abs965.html
    b) Teaching green chemistry, Albert Matlack, Green Chemistry, 1999, 1 (001), G19-G20

Please direct comments and suggestions to the author of the module or to:

Michael C. Cann
Chemistry Department
Univeristy of Scranton
800 Linden St. Scranton, PA 18510
570-941-7519
570-941-7510 (FAX)
michael.cann@scranton.edu