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New and Improved Green Experiments for the Organic Chemistry Lab

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Presentation on theme: "New and Improved Green Experiments for the Organic Chemistry Lab"— Presentation transcript:

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 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 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, Ch 24, pp 2. Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp 3. Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, pp

9 Experiment Evaluation
Score current labs using objective criteria

10 Experiment Evaluation
Comparison of NFPA ratings: No Net Change

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: 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 Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, pp

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: 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 Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, pp

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: 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 Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, pp

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: min at room temperature (heating noted w/other procedures)* Generally cleaner product in comparable yields 1 H 50% EtOH = 57% isol 45 min 95% EtOH = 54% 45 min 75% EtOH = 42% 45 min 50% EtOH = 40% 45 min 25% EtOH = 43% 45 in in water = 28% This reaction can also be run even in water! Ken Doxsee, Jim Hutchinson, Green Organic Chemistry, Thompson Learning Custom Publ., Mason, OH, 2002, pp Charles Wilcox, Jr. and Mary Wilcox, Experimental Organic Chemistry, 2nd Ed., Prentice-Hall Publ. Englewood Cliffs, NJ, pp

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21 Experiment Evaluation
Experiment totals: Methanol/pyridine = 11 Water/TMEDA = 6

22 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)

23 New Experiment: Catalytic Oxidation A 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 Technology 2003, 21 (1-2),

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

25 New Experiment: Catalytic Oxidation A 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

26 Co-catalysts Sulfosalicylic acid (23 mg) Sodium bisulfate (30 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%) Ligand can be neutralized and sewered

27 5 mL 7.5 mL 15 mL

28 New Experiment: Catalytic Oxidation A Green Adipic Acid Synthesis
Reaction – 1 g scale oxidation But, synthetic cyclohexanone sometimes gave poorer yields…

29 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

30 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.; Science 1998, 281, Fischer, J.; Holderich, W.F. Appl. Cat. A: General 1999, 180, 435.

31 Catalytic Oxidation: A Green Adipic Acid Synthesis
Waste reduction:

32 Summary: Green Adipic Acid Synthesis
Advantages Disadvantages Improved Evaluation Score (9 vs. 16) Use of corrosive peroxide Yields are more than double Complex reaction mechanism Simple isolation Long heated reaction time Expt Atom Economy 60% vs 37% (theory) 45% vs 12% (observed) Waste reduction     % Experimental Atom Economy = (mass of reactants utilized in the desired product/total mass of all reactants) X 100                                                           = (theoretical yield/total mass of all reactants) X 100                                                           = (1.48 g/4.13 g) X 100 = 36% term Percentage Yield X Experimental Atom  Economy (%PE .EAE) to illustrate this.  This is calculated as follows: % Yield X Experimental Atom Economy = (actual yield/theoretical yield)  X (mass of reactants utilized in the desired                                                                                   product/total mass of all reactants) X 100                                                      %PE .EAE= (actual yield/theoretical yield)  X (theoretical yield/total mass of all reactants)                                                                                   X 100                                                                     = (actual yield/total mass of all the reactants) X 100                                                                     = (1.20 g/4.13 g) X 100                                                                     = 29% ATOM ECONOMY: A Measure of the Efficiency of a Reaction Michael C. Cann, Chemistry Department, University of Scranton

33 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

34 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

35 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)

36 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

37 Reaction Mechanism is Relevant
Gerrard, W.; Phillips, R. J. Chemistry & Industry 1952,

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

39 Combine solid reagents
Reaction Highlights Combine solid reagents

40 Reaction Highlights Mix with cooling

41 Reaction Highlights Heat in steam bath

42 Reaction Highlights Isolate by extraction

43 Experiment Summary Advantages Disadvantages Solventless reaction
% Atom Economy (55 vs 50 for n-butyl bromide) High yield, pure (% AE*yield = 44 vs 30) More complex mechanism Improved evaluation score (14 vs 18) Visual reaction Minimal waste

44 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!

45 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

46 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 July 30, 2006 Website:

47 Experimental Procedures
Procedures for the experiments outlined in this presentation may be requested from Brian Groh by at . The experiments will be available in a photo-essay type format on my website hopefully by fall semester Follow the “LabViews” link on the home page. Website:


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