What Is Green Chemistry?

1. Prevention
   It is better to prevent waste than to treat or clean up waste after it has been created.
2. Atom Economy
   Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product.
3. Less Hazardous Chemical Syntheses
   Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and the environment.
4. Designing Safer Chemicals
   Chemical products should be designed to effect their desired function while minimizing their toxicity.
5. Safer Solvents and Auxiliaries
   The use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessary wherever possible and innocuous when used.
6. Design for Energy Efficiency
   Energy requirements of chemical processes should be recognized for their environmental and economic impacts and should be minimized. If possible, synthetic methods should be conducted at ambient temperature and pressure.
7. Use of Renewable Feedstocks
   A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable.
8. Reduce Derivatives
   Unnecessary derivatization (use of blocking groups, protection / deprotection, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste.
9. Catalysis
   Catalytic reagents (as selective as possible) are superior to stoichiometric reagents.
10. Design for Degradation
    Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.
11. Real-time analysis for Pollution Prevention
    Analytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances.
12. Inherently Safer Chemistry for Accident Prevention
    Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical accidents, including releases, explosions, and fires.

Anastas, P. T. and Warner, J. C. Green Chemistry: Theory and Practice. Oxford University Press: New York, 1998, p. 30. By permission of Oxford University Press.

Green Engineering is the development and commercialization of industrial processes that are economically feasible and reduce the risk to human health and the environment.

1. Inherent Rather Than Circumstantial
   Designers need to strive to ensure that all materials and energy inputs and outputs are as inherently nonhazardous as possible.
2. Prevention Instead of Treatment
   It is better to prevent waste than to treat or clean up waste after it is formed.
3. Design for Separation
   Separation and purification operations should be designed to minimize energy consumption and materials use.
4. Maximize Efficiency
   Products, processes, and systems should be designed to maximize mass, energy, space, and time efficiency.
5. Output-Pulled Versus Input-Pushed
   Products, processes, and systems should be “output pulled” rather than “input pushed” through the use of energy and materials.
6. Conserve Complexity
   Embedded entropy and complexity must be viewed as an investment when making design choices on recycle, reuse, or beneficial disposition.
7. Durability Rather Than Immortality
   Targeted durability, not immortality, should be a design goal.
8. Meet Need, Minimize Excess
   Design for unnecessary capacity or capability (e.g., “one size fits all”) solutions should be considered a design flaw.
9. Minimize Material Diversity
   Material diversity in multicomponent products should be minimized to promote disassembly and value retention.
10. Integrate Material and Energy Flows
    Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows.
11. Design for Commercial “Afterlife”
    Products, processes, and systems should be designed for performance in a commercial “afterlife.”
12. Renewable Rather Than Depleting
    Material and energy inputs should be renewable rather than depleting.

*Anastas, P.T., and Zimmerman, J.B., “Design through the Twelve Principles of Green Engineering”, Env. Sci. Tech.2003, 37(5), 94A-101A.