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New and Improved Green Experiments for the Organic Chemistry Lab
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New and Improved Green Experiments for the Organic Chemistry Lab

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  1. New and Improved Green Experiments for the Organic Chemistry Lab Brian L. Groh Jason F. Pendleton, Duane M. Anderson, Mariya Nasiruddin, and Joel Heuton Department of Chemistry and Geology Minnesota State University, Mankato brian.groh@mnsu.edu July 30, 2006

  2. Presentation Outline • Lab Facilities and Constraints • Experiment Evaluation • Modified and New Experiments

  3. Lab Facilities • Students work on open bench tops • Have access to hood space as needed • Limited to 12-14 students simultaneously • New facility to be occupied in 2 years • Plan for similar lab without need for routine individual hood space

  4. Three Phase Transition to Greener Experiments • Evaluate current and proposed labs objectively • Modify existing labs with greener alternatives • Develop new, greener lab alternatives

  5. Lab Structure • Multiple sections of 24 students • 3h lab periods • Preparative, reduced and microscale experiments • “Cleaner” experiments done on larger scales • Minimizes waste • “Dirtier” or more “hazardous” labs done on smaller scales • Minimizes waste and cost • Increased safety • Students work independently and are taught to properly treat and dispose of their own waste

  6. Experiment Evaluation Examine all solvents and reagents and score current labs using objective criteria • Create scores based on – • NFPA codes • factor in hazard points (e.g. mutagens, carcinogens, etc. not included in NFPA rating) • factor in use of bio-based or renewable reagents and solvents • Consider total waste generated

  7. Modification Process • Find known modifications or propose reasonable substitutions • Better procedures, solvents or reagents • Consider experiments that produce considerable waste • Replace with catalytic reactions • Modifications vary from simple to complex • Solvent change (bromination experiment) • Redesign of experiment (Glaser reaction) • Experimentally verify modifications

  8. Glaser-Eglinton-Hayes Coupling • Original Glaser-Eglinton-Hayes procedure1 • Longer, involved an additional filtration and water wash, required 4h • Alternative procedures2,3 require heating • Modifications: • Simplify isolation procedure • Solvent change: Ethanol vs. methanol • Base change: TMEDA vs. pyridine 1. Kenneth Williamson, Macroscale and Microscale Organic Experiments, 4th ed., Houghton Mifflin Co, Boston, MA, 2003. Ch 24, pp. 335-337. 2. Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp 143-152. 3. Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, 1995. pp 349-352

  9. Experiment Evaluation • Score current labs using objective criteria

  10. Experiment Evaluation No Net Change • Comparison of NFPA ratings:

  11. Experiment Evaluation • Comparison of PELs and Specific Hazards: Net Change (-2)

  12. Experiment Evaluation • Experiment totals: • Methanol/pyridine = 11 • Ethanol/TMEDA = 8

  13. Improved Glaser-Eglinton-Hayes Coupling • Modifications • Ethanol (95%) with TMEDA • Simplified isolation procedure • Benefits: • Reduced amount of solvent for isolation • Reduced amount of aqueous waste • Homogenous reaction • Stunning color change (light green to midnight blue by completion) • Reaction time: 40-60 min at room temperature (heating noted w/other procedures)* • Generally cleaner product in comparable yields This reaction can also be run in 75% ethanol! Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp 143-152. Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, 1995. pp 349-352

  14. Improved Glaser-Eglinton-Hayes Coupling • Modifications • Ethanol (95%) with TMEDA • Simplified isolation procedure • Benefits: • Reduced amount of solvent for isolation • Reduced amount of aqueous waste • Homogenous reaction • Stunning color change (light green to midnight blue by completion) • Reaction time: 40-60 min at room temperature (heating noted w/other procedures)* • Generally cleaner product in comparable yields This reaction can also be run in 75% ethanol 50% ethanol Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp 143-152. Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, 1995. pp 349-352

  15. Improved Glaser-Eglinton-Hayes Coupling • Modifications • Ethanol (95%) with TMEDA • Simplified isolation procedure • Benefits: • Reduced amount of solvent for isolation • Reduced amount of aqueous waste • Homogenous reaction • Stunning color change (light green to midnight blue by completion) • Reaction time: 40-60 min at room temperature (heating noted w/other procedures)* • Generally cleaner product in comparable yields This reaction can also be run in 75% ethanol 50% ethanol 25% ethanol Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp 143-152. Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, 1995. pp 349-352

  16. Improved Glaser-Eglinton-Hayes Coupling • Modifications • Ethanol (95%) with TMEDA • Simplified isolation procedure • Benefits: • Reduced amount of solvent for isolation • Reduced amount of aqueous waste • Homogenous reaction • Stunning color change (light green to midnight blue by completion) • Reaction time: 40-60 min at room temperature (heating noted w/other procedures)* • Generally cleaner product in comparable yields This reaction can also be run even in water! Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp 143-152. Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, 1995. pp 349-352

  17. Experiment Evaluation • Experiment totals: • Methanol/pyridine = 11 • Water/TMEDA = 6

  18. New Experiment Candidate: Adipic Acid Synthesis • Current experiment sequence: • Drawbacks: • Requires excess KMnO4 (3g /g ketone!) • Large quantities of MnO2 (oxidizer) produced (1.8g /g ketone) • Contaminated product (isolate by NaCl precipitation) • Low yields (ave 33% est. on last step; ave 20% overall)

  19. New Experiment: Catalytic OxidationA Green Adipic Acid Synthesis • Propose1 – 1 g scale oxidation • Advantages • Catalytic oxidation • By-products: O2, H2O • Higher yields 1. Zhang, Shi-gang; Jiang, Heng; Gong, Hong; Sun, Zhao-lin Petroleum Science and Technology2003, 21 (1-2), 275-282.

  20. Experiment Evaluation • Scores: • KMnO4 method: 16 • Includes KMnO4, NaOH, NaHSO3, celite • H2O2 method: 9 • Includes H2O2, Na2WO4, sulfosalicylic acid

  21. New Experiment: Catalytic OxidationA Green Adipic Acid Synthesis • Reaction – 1 g scale oxidation • Heat: Steam bath, overnight • No residual peroxide • 75% average isolated yield of pure adipic acid from cyclohexanone

  22. Co-catalysts • Sulfosalicylic acid (23 mg) • Best yields – ave 75% • Cleanest product • Very water soluble • Sodium bisulfate (30 mg) • Reduced yields (by ~ 60%) • Discolored product • Narrowed reaction time • Ascorbic acid (40 mg) • Reduced yields (~ 30%) • Discolored product Ligand can be neutralized and sewered

  23. 7.5 mL 5 mL 15 mL

  24. New Experiment: Catalytic OxidationA Green Adipic Acid Synthesis • Reaction – 1 g scale oxidation • But, synthetic cyclohexanone sometimes gave poorer yields…

  25. Side reaction responsible for low yields • According to procedure: • Analysis by GC and GCMS indicates • Vigorous reaction gives 2-chlorocyclohexanone • High amounts correlate with poor yields of adipic acid

  26. Catalytic Oxidation:A Green Adipic Acid Synthesis • Proposed reaction pathway1 1. Based upon the work of Noyori and Fischer: Sato, K.; Aoki, M.; Noyori, R.; Science1998, 281, 1646. Fischer, J.; Holderich, W.F. Appl. Cat. A: General1999, 180, 435.

  27. Catalytic Oxidation:A Green Adipic Acid Synthesis • Waste reduction:

  28. Summary: Green Adipic Acid Synthesis

  29. SN2 Experiment Candidate • Synthesis of n-butyl bromide from n-butanol • Drawbacks: Low yields on a small scale Impure product Odor problems Use of concentrated sulfuric acid • Goals: Develop new experiment that still teaches the SN2 reaction High yields of pure product Simple experiment suitable for a beginning 3 h lab

  30. Proposed SN2 Experiment Use of PCl5 • Proposed reaction scheme • Potential Advantages Solventless reaction One step Short reaction time Clean, high yield reaction Introduce column chromatography for purification

  31. Experiment Evaluation • Scores: • NaBr/H2SO4 method: 18 • Includes NaBr, H2SO4, H2O, NaHCO3, 1-butanol, 1-chlorobutane • PCl5 method: 14 • Includes PCl5, pentane, H2O, NaHCO3, 1-tetradecanol, 1-chlorotetradecane (note: hexane score = 4)

  32. Synthesis of 1-chlorotetradecane from 1-tetradecanol Results: • high yield – up to 92% (ave 80%) • Highly pure >98% by GC analysis (crude) • Short reaction time (40 min) • No need to introduce column chromatography! • Product can easily be analyzed by IR, GC • By-products can easily be neutralized • Solventless reaction – visual reaction

  33. Reaction Mechanism is Relevant Gerrard, W.; Phillips, R. J. Chemistry & Industry1952, 540-1.

  34. Reaction Highlights • Analyze by GC for purity but… no need to introduce column chromatography! • IR, H & 13C NMR indicate high purity

  35. Reaction Highlights • Combine solid reagents

  36. Reaction Highlights Mix with cooling

  37. Reaction Highlights Heat in steam bath

  38. Reaction Highlights Isolate by extraction

  39. Experiment Summary

  40. Summary • Evaluated labs objectively with respect to safety and green character • Redesigned experiments while maintaining good yields • Designed new experiments that minimize waste, reagent or solvent use • Continue to look for greener alternatives and improvements – this is a continuing transition!

  41. Acknowledgements • Undergraduate Student researchers: Jason Pendleton Duane Anderson Mariya Nasiruddin Joel Heuton • Organic Chemistry students for their participation and feedback. • Minnesota State University, Mankato Center for Education, Teaching and Learning for partial funding of this work

  42. New and Improved Green Experiments for the Organic Chemistry Lab Brian L. Groh Jason F. Pendleton, Duane M. Anderson, Mariya Nasiruddin, and Joel Heuton Department of Chemistry and Geology Minnesota State University, Mankato brian.groh@mnsu.edu July 30, 2006 Website: http://www.intech.mnsu.edu/groh

  43. Experimental Procedures Procedures for the experiments outlined in this presentation may be requested from Brian Groh by email at brian.groh@mnsu.edu. The experiments will be available in a photo-essay type format on my website hopefully by fall semester 2006. Follow the “LabViews” link on the home page. Website: http://www.intech.mnsu.edu/groh