designing a green, inquiry- based organic chemistry...
TRANSCRIPT
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Designing a Green, Inquiry-Based Organic Chemistry Laboratory to Educate the Next Generation of Scientists
Loyd Bastin & Kaitlyn GerhartWidener University
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Teaching Green Chemistry“The era of procrastination, of half-measures, of soothing and baffling expedients, of delays is coming to its close. In its place we re entering a period of consequences.” – Winston Churchill
• We need to change the culture/mindset• We must educate students about GC in a way that encourages
application of their knowledge• Green Organic Chemistry Experience VS Green Organic Chemistry
Labs
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• Involve Students in the Process• Interviewed faculty about desired techniques for students
to learn
• Searched for experiments in the Journal of Chemical Education and GEMS database
http://greenchem.uoregon.edu/gems.html• Developed a 3-step synthesis as capstone experience• Designed course to introduce Green Principles and
techniques• Students APPLY this knowledge in the final experiment
How We Designed Our Lab
Extractions Chemical/Waste HandlingChromatography Hazard AwarenessIR GC
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• Introduction to Environmental Contamination & Chemical Exposure
• Introduction to Green Chemistry• Traditional vs Green Approaches• 12 Principles of Green Chemistry
• It’s important for students to apply Green Chemistry• Analyze greenness of current experiments
• Percent Yield, Atom Economy, Atom Efficiency, Effective Mass Yield, E-Factor
• Revise/design experiments
• Important to build-up as semester progresses
Creating a Green Chemistry Culture
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Techniques used:• Solubility• Recrystallization• Melting point• Mixed melting point
How it’s Green:• Not explicitly green
Recrystallization & Mixed MPs
Modified from a procedures acquired from Prof. Jim Patterson, Seattle Community College.
Techniques used:• Liquid-liquid extraction• Recrystallization• Mixed solvent
recrystallization
How it’s Green:• Benign extraction
solvents
Acid/Base Extraction
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Biosynthesis of EthanolIsolate/purify ethanol produced by yeast fermentation. This experiment is used to introduce Green Chemistry.
How it’s Green:
• Benign reagents
• Renewable feedstocks
• Ethanol used later
• Atom economy
Techniques used:
• Simple distillation
• Fractional distillation
• gas chromatography
Adapted from experiment by J. Thompson, Lane Community College, GEMS database, July 2006.
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Friedel-Crafts Acetylation
Adapted from: Mohrig et al. Modern Projects & Experiments in Organic Chemistry: Miniscale and Standard Taper Microscale, 2nd ed. W.H. Freeman: New York: 2003, 173-176.
Techniques used:• EAS• Column
chromatography• Thin layer
chromatography• Melting point• IR spectroscopy
How it’s Green:• Greener reagents
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Isolation of the Three Components of Spearmint Oil
Experiment adapted from Don R. Davies; Todd M. Johnson. J. Chem. Ed. 2007, 84, 318-320.
How it’s Green:• Greener reagents
Techniques used:• Column chromatography• Thin layer chromatography• IR spectroscopy
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• Capstone experiment• Students APPLY Green
Chemistry Knowledge• Focuses on choosing
greener methods• Emphasizes
Techniques from previous experiments
Synthesis of 1,2-dibromo-1-phenylpropane
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In the Classroom• Students research methods for each step • Required to bring at least one potential procedure for
each reaction to the lab lecture • Class explores different methods using Green Metrics
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Techniques used:• Liquid-liquid extraction• IR spectroscopy• BP determination
How it’s Green:• Atom economy• Atom efficiency
Experiment basics:• Ethanol from biosynthesis• CH2Cl2 used for extraction• Can experiment with
greener solvents• Product verified by BP & IR
Other Reagents• Baker’s Yeast• Carrot Reduction• LiAlH4
Experiment adapted from N. Pohl et al. J. Chem. Ed. 2002, 79, 727–728.
Reduction of Propiophenone
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Techniques used:• Distillation• IR spectroscopy• BP determination
How it’s Green:• Greener reagents• Atom economy• Atom efficiency
Experiment basics:• H3PO4 vs H2SO4
• Distillation purifies as well as drives rxn
• No work up necessary• Pdt verified by BP and IR
Experiment adapted from: Doxsee et al. Green Organic Chemistry. Thomson 2004. 129-134.
Elimination of 1-phenyl-1-propanol
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Experiment basics:• Opportunity to work with
strong acids
Other Reagents• Pyridinium tribromide• Br2 in CH2Cl2• Br2 in Me-THF
Techniques used:• Recrystallization• IR spectroscopy
How it’s Green:• Greener reagents• Atom economy
Experiment adapted from: McKenzie et Al. J. Chem. Ed. 2005, 82, 306-310.
Bromination of trans-β-methylstyrene
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Summary• Laboratory emphasizes applying green chemistry • Exposed to different chemical methods and challenged
to ‘think green’• Exposed to a wide variety of techniques• Final synthesis provides a venue for applying Green
Chemistry to a synthetic protocol• Analysis by NMR can easily be added if desired
What’s Next?• We are now having students “Green” the synthesis of
Aromatic Sulfa Drug Analogs in Organic II Lab
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AcknowledgementsKaitlyn GerhartOrganic Chemistry students:
Fall 2007, 2009Summer 2008, 2009
Krishna BhatIrina Knyazeva
UO GCEWA&S Summer Housing
FellowshipWidener Faculty Development
GrantChemistry, biochemistry, and
biology faculty
“There’s nothing that unusual about what I’m doing……. What is unusual is that I had the privilege to be shown it as a young man.” – Al Gore