Designing a Green, Inquiry- Based Organic Chemistry Laboratory to Educate the Next Generation of Scientists

Transcription

1 Designing a Green, Inquiry- Based Organic Chemistry Laboratory to Educate the Next Generation of Scientists Loyd Bastin & Kaitlyn Gerhart Widener University

2 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

3 How We Designed Our Lab Involve Students in the Process Interviewed faculty about desired techniques for students to learn Extractions Chromatography IR Chemical/Waste Handling Hazard Awareness GC Searched for experiments in the Journal of Chemical Education and GEMS database Developed a 3-step synthesis as capstone experience Designed course to introduce Green Principles and techniques Students APPLY this knowledge in the final experiment

4 Creating a Green Chemistry Culture 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

5 Recrystallization & Mixed MPs Solubility Recrystallization Melting point Mixed melting point Not explicitly green Acid/Base Extraction Liquid-liquid extraction Recrystallization Mixed solvent recrystallization Benign extraction solvents Modified from a procedures acquired from Prof. Jim Patterson, Seattle Community College.

6 Biosynthesis of Ethanol Isolate/purify ethanol produced by yeast fermentation. This experiment is used to introduce Green Chemistry. Simple distillation Fractional distillation gas chromatography Benign reagents Renewable feedstocks Ethanol used later Atom economy Adapted from experiment by J. Thompson, Lane Community College, GEMS database, July 2006.

7 Friedel-Crafts Acetylation EAS Column chromatography Thin layer chromatography Melting point IR spectroscopy Greener reagents Adapted from: Mohrig et al. Modern Projects & Experiments in Organic Chemistry: Miniscale and Standard Taper Microscale, 2 nd ed. W.H. Freeman: New York: 2003,

8 Isolation of the Three Components of Spearmint Oil Column chromatography Thin layer chromatography IR spectroscopy Greener reagents Experiment adapted from Don R. Davies; Todd M. Johnson. J. Chem. Ed. 2007, 84,

9 Synthesis of 1,2-dibromo-1-phenylpropane Capstone experiment Students APPLY Green Chemistry Knowledge Focuses on choosing greener methods Emphasizes Techniques from previous experiments

10 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

11 Reduction of Propiophenone Experiment basics: Ethanol from biosynthesis CH 2 Cl 2 used for extraction Can experiment with greener solvents Product verified by BP & IR Other Reagents Baker s Yeast Carrot Reduction LiAlH 4 Liquid-liquid extraction IR spectroscopy BP determination Atom economy Atom efficiency Experiment adapted from N. Pohl et al. J. Chem. Ed. 2002, 79,

12 Elimination of 1-phenyl-1-propanol Experiment basics: H 3 PO 4 vs H 2 SO 4 Distillation purifies as well as drives rxn No work up necessary Pdt verified by BP and IR Distillation IR spectroscopy BP determination Greener reagents Atom economy Atom efficiency Experiment adapted from: Doxsee et al. Green Organic Chemistry. Thomson

13 Bromination of trans-β-methylstyrene Experiment basics: Opportunity to work with strong acids Recrystallization IR spectroscopy Other Reagents Pyridinium tribromide Br 2 in CH 2 Cl 2 Br 2 in Me-THF Greener reagents Atom economy Experiment adapted from: McKenzie et Al. J. Chem. Ed. 2005, 82,

14 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

15 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 Acknowledgements Kaitlyn Gerhart Organic Chemistry students: Fall 2007, 2009 Summer 2008, 2009 Krishna Bhat Irina Knyazeva UO GCEW A&S Summer Housing Fellowship Widener Faculty Development Grant Chemistry, biochemistry, and biology faculty