the importance of green chemistry sarah gunderson april 26, 2005
TRANSCRIPT
The Importance of Green Chemistry
Sarah Gunderson
April 26, 2005
What is Green Chemistry?
What is Green Chemistry?
• Use of chemistry for pollution prevention– Reduce or eliminate use and generation of
hazardous substances– Alternative pathways or reaction conditions– Design of safer chemicals (less toxic, inherently
safer)– Benign processes and products pose no risk
• Launched in 1991 by EPA
What is Green Chemistry?
• EPA– Presidential Green Chemistry Challenge– Partner with NSF to sponsor research– Small Business Innovation Research Program
• Green Chemistry Institute (1997)– Focuses on research, education, conferences,
public awareness– Allied with ACS in 2000
12 Principles of Green Chemistry
1. Prevent waste2. Design safer chemicals and products3. Design less hazardous chemical syntheses4. Use renewable feedstocks5. Use catalysts, not stoichiometric reagents6. Avoid chemical derivatives7. Maximize atom economy8. Use safer solvents and reaction conditions9. Increase energy efficiency10. Design chemicals and products to degrade after use11. Analyze in real time to prevent pollution12. Minimize the potential for accidents
12 Principles of Green Chemistry
1. Prevent waste• Easier than cleaning up later
2. Design safer chemicals and products• Give desired function with lower toxicity
3. Design less hazardous chemical syntheses• Use and generate non-toxic substances whenever
possible
12 Principles of Green Chemistry
4. Use renewable feedstocks• Non petrochemically dervied
5. Use catalysts, not stoichiometric reagents• Increased selectivity
6. Avoid chemical derivatives• Blocking groups
• Protection/deprotection
• Using additional steps and reagents
12 Principles of Green Chemistry
7. Maximize atom economy• Incorporate all materials into final product if possible
8. Use safer solvents and reaction conditions• Minimize risk of serious accidents and injuries
9. Increase energy efficiency• Operate at ambient conditions whenever feasible
12 Principles of Green Chemistry
10. Design chemicals and products to degrade after use
• Break down into biocompatible products
11. Analyze in real time to prevent pollution• Recognize problems before they turn into tragedies
12. Minimize the potential for accidents• Releases, explosions and fires
• Check operability and sizing of safety equipment
Atom Economy vs. Yield
• Different way of measuring reaction efficiency, using formula weight
• Yield definition is flawed– Does not account for co-product production
• Example: CH4 + 1.5 O2 CO2 + 2 H2O
– If desire H2O• yield ~100%
• Atom economy=
Successful Applications
• Supercritical CO2 processing– Caffeine extraction, dry cleaning– Semiconductor processing
• Ionic liquid solvents– Emit no VOCs, quicker reactions, tunable
• Catalysts• Biobased / Renewable feedstocks
– Agricultural wastes -> alcohols, ketones, carboxylic acids
Successful Applications
• Microreactors– Higher purity, faster– More efficient heat transfer
From [4]
Successful Applications
www.pyrocool.org
Green Chemistry Problems
• Development can be expensive
• Determining toxicity of new compounds is difficult
• Difficult to transition from a reactive to a proactive methodology
Pharmaceuticals
• One of the leading industries to adapt
• Allowed to use toxic chemicals restricted in other industries
• Want to minimize environmental impacts
Industry Annual Product Tons
Kg waste / Kg product
Oil refining 106-108 0.1
Bulk Chemicals 104-106 <1-5
Fine Chemicals 102-104 5-50
Pharmaceuticals 10-103 25-100
Ibuprofen Synthesis
• Originally developed and patented in 1960’s by Boots Company
• Green process patented in 1991 by BHC
www.chemistry.org
www.chemistry.org
Other Green Pharma Processes
• Viagra (Pfizer)
From [7]
Other Green Pharma Processes
• Pfizer has a team at each R&D site– Zoloft
• Bristol Myers Squibb– Taxol process
• Abbott Laboratories educates at main R&D site
Education in Green Chemistry
• Few colleges offer this option
• Industry has taken the initiative for training
• Should colleges focus more on training?
Changes in Education
• Need to train new scientists in these techniques
• Replacement of “yield” with “atom economy”
• Modification of organic chemistry laboratory
• Basic concepts of chemical toxicology and the molecular basis of hazards [2]
Personal Responsibility
• Ability to challenge current process operation
• Educate co-workers
• Green process development
Conclusions
• Green chemistry is a new way of thinking
• Concepts apply in all industries
Questions?
References
1. http://www.epa.gov/greenchemistry/
2. Anastas, P.T., Kirchhoff, M.M., Origins, Current Status and Future Challenges of Green Chemistry, Acc. Chem. Res. 2002, 35, 686-694
3. http://www.chemistry.org/portal/resources/ACS/ACSContent/education/greenchem/case.pdf
4. Haswell, S.J., Watts, P., Green Chemistry: Synthesis in micro reactors, Green Chemistry, 2003, 5, 240-249.
5. Hjeresen, D.L., Schutt, D.L., Boese, J.M., Green Chemistry and Education, J Chem Ed, 2000 (77), 12, 1543-1547.
6. http://www.pyrocool.org
7. Dunn, P.J., Galvin, S., Hettenbach, K., The development of an environmentally benign synthesis of sildenafil citrate (Viagra) and its assessment by Green Chemistry Metrics, Green Chemistry, 2004, 6, 43-48.