Transforming the organic chemistry laboratory
experience with greener laboratory experiments
Green chemistry offers many practical and
fundamental advantages for chemistry education
Table 1 Starting Material Employed in Classic Organic Laboratory Syntheses
1902-1980
Date
The challenge of greening the chemistry curriculum
UO green organic chemistry curriculum: Keys to our success
Recent developments - experiments and momentum
1902
1915
1933
1941
1963
1980
Author
Levy, 4th ed.
Cohen, 3rd ed.
Adkins
Fieser, 2nd ed.
Adams
Drust
Acetanilide
4-Bromoacetanilide
Benzoin
Starting Materials Required (grams)
Aniline
Acetanilide
Benzaldehyde
46.2
50.0
25.0
5.0
25.0
28.0
13.5
10.0
18.2
13.5
25.0
20.0
13.5
16.0
10.0
5.2
10.0
Adapted from: From Microscale Organic Laboratory by D.W. Mayo, R.M. Pike and S.S.
Butcher, 1985
Department of Chemistry and Materials
Science Institute
University of Oregon
http://greenchem.uoregon.edu
Green chemistry challenges for the academic
community
•
Alternative processing methods. Rapid, high yield transformations
at room temperature - catalysis
•
Better understanding of how molecular structure dictates desirable
and undesirable properties - Structure-Activity Relationships (SARs)
Hazardless, completely recyclable products
•
“Waste” or renewable resources as raw materials
•
Integrating green chemistry into the curriculum
Green chemistry is a multidisciplinary field, involving
fundamental sciences, business, law and engineering
How can we bring green chemistry into an already
crowded chemistry curriculum?
Challenges
• Overcoming the misconception that
green chemistry is less rigorous
• Finding experiments that illustrate
green chemistry concepts and are
effective in the teaching labs
• Involving students in the process of
greening the curriculum
• Building a community to support the
development and use of the curriculum
Strategies
• Replace rather than add course material
• Modernize the curriculum using the
latest green chemistry developments
• Ensure quality through thorough testing
• Provide a wide range of choices
• Help others learn from our experience
Process used to develop and teach greener
laboratory procedures
A safer bromination of an olefin
TRADITIONAL
H
+
H
Assess existing
procedure
H Br
GREENER
Find/develop
alternative methods
1. HBr
2. 30% H2O2
H
Identify hazards
or inefficiencies
Test efficacy
of new procedure
Greener
alternative
Reed, S.M.; Hutchison, J.E. J. Chem. Ed. 2000, 77, 1627-1629.
Analysis using green metrics
• Appropriate metrics for teaching laboratories:
– Enhance student safety
– Reduce the volume and hazard of the wastestream
– Ease reliance on environmental controls
– Improve reaction efficiency
• Atom economy, percent experimental atom
economy, E factor, effective mass yield
McKenzie, L. C.; Huffman, L. M.; Hutchison, J. E. "The evolution of a green
chemistry laboratory experiment greener brominations of stilbene," Journal of
Chemical Education 2005, 82, 306-310.
H
ethanol, reflux
H
We teach this simple process to
our students as we implement it.
Br H
CCl4 or CH2Cl2
Br2
H
BrH
ethanol
GREEN
ethanol
N H
Br
N H Br
Br3
+
H
Br2
Laboratory Skills:
Green Lessons Taught:
Reaction set-up
Less toxic solvents can be selected
Vacuum filtration
Hazardous reagents can be generated in situ
Melting point determination
Djerassi, C; Scholz, C.R. J. Am. Chem. Soc. 1948, 70, 417.
McKenzie, L. C.; Huffman, L. M.; Hutchison, J. E. J. Chem. Ed. 2005, 82, 306-310.
Solventless Aldol Condensation
mp 40-42 oCmp 42-45 oCmp 178 - 181 ° C
O
O
O
1. NaOH
2. H3O+ workup
+
OCH3
OCH3
H3CO
Chemical Concepts:
Melting point determination
and depression
Aldol condensation reaction
Recrystallization skills
OCH3
Green Lessons:
Solventless reactions
Atom economical reactions
Rothenberg, G.; Downie, A. P.; Raston, C. L.; Scott, J. L.
J. Am. Chem. Soc. 2001, 123, 8701-8708.
Raston, C. L.; Scott, J. L. Green Chemistry 2000, 2, 49-52.
Liquid CO2 as a green extraction solvent
Liquid CO2 extraction in the teaching laboratory
Traditional Method
Orange Peel
Steam distill
and/or
Organic solvent
D-limonene
Green Method
Orange Peel
CO2(liquid)
No organic solvent
Chemical Concepts:
Solid/liquid extraction
Natural products (terpenes)
Spectroscopy
Phase transitions
Green Lessons:
Use of safer solvents
Prevention of waste
Green materials processing
McKenzie, L. C.; Thompson, J. E.; Sullivan, R.; Hutchison, J. E. "Green
chemical processing in the teaching laboratory: A convenient liquid CO2
extraction of natural products," Green Chem. 2004, 355-358.
Laboratory curriculum project implementation
Green Organic Chemistry Laboratory Manual
250
200
Target audience: Sophomore-level organic
chemistry laboratory
•
•
•
•
•
•
•
•
•
Introduction
Identification of Chemical Hazards
Chemical Exposure and
Environmental Contamination
Evaluation of Chemical Hazards
Introduction to Green Chemistry
Alternative Solvents
Alternative Reagents
Reaction Design and Efficiency
Alternative Feedstocks and Products
Plus 19 Green Organic Chemistry Experiments
150
Number of
Students
100
50
0
97- 98- 99- 00- 01- 0498 99 00 01 02 05
Fall term 2003
Synthesis, separations, spectroscopy
1. Solventless Aldol condensation
2. Bromination of an alkene
3. Preparation/distillation of
cyclohexene
4. Synthesis of adipic acid
5. Oxidative coupling of alkynes
6. Gas phase porphyrin synthesis
7. Solvent effects on kinetics
8. Molecular mechanics modeling
Winter term 2004
Synthesis, spectroscopy, applications
1. Electrophilic iodination with KI/NaOCl
2. Palladium-catalyzed aryl halide/alkyne
coupling
3. Polymer-supported oxidation chemistry
4. Friedel-Crafts acylation of ferrocene
5. Thiamine-mediated benzoin condensation
6. Self-assembled monolayers/patterning
7. Combinatorial synthesis of antibiotics
The approach changes the way students think about
chemical hazards and chemistry
"After taking this course I have a much better opinion of chemistry .... I feel like
I am learning something that has an actual important application to the real
world."
"I have decided to get a minor in chemistry so I can make more conscious
decisions regarding chemistry and avoid destructive practices for my health or
the environment."
•
•
•
Teaches students a rational procedure for analyzing/minimizing
hazards
Empowers students to use chemistry to solve environmental
problems - "Ambassadors of Green Chemistry"
Changes the way students and society view chemicals, chemistry
and chemists - "Know the hazards, not all chemicals are hazardous"
The new green chemistry lab
Our experience introducing green chemistry - there
are many incentives
We are generating less waste and a less hazardous waste stream.
Winter term disposal numbers (14.2L of aqueous, 1L of flammable
organic and 1kg of solid waste for 180 students)
The project has been great for University public relations
More than 20 articles have now been published around the world
Enhances student recruiting
We have seen strong interest from undergrads and grads who want to
be part of green chemistry
Opportunity to upgrade curriculum and facilities
University invested in a showcase lab facility to highlight the program
Improved educational atmosphere
The new lab setting is an excellent learning environment
Green chemistry offers many practical and
fundamental advantages for chemistry education
Table 1 Starting Material Employed in Classic Organic Laboratory Syntheses
1902-1980
Date
1902
1915
1933
1941
1963
1980
Author
Levy, 4th ed.
Cohen, 3rd ed.
Adkins
Fieser, 2nd ed.
Adams
Drust
Acetanilide
4-Bromoacetanilide
Benzoin
Starting Materials Required (grams)
Aniline
Acetanilide
Benzaldehyde
46.2
50.0
25.0
5.0
25.0
28.0
13.5
10.0
18.2
13.5
25.0
20.0
13.5
16.0
10.0
5.2
10.0
Adapted from: From Microscale Organic Laboratory by D.W. Mayo, R.M. Pike and S.S.
Butcher, 1985
Next steps
More labs!
Disseminate our and other’s labs via the GEMs
database
Promote the community through workshops,
symposia and collaborations
Build the “business case” for green chemistry
Workshop participants 2001-present
Addressing the case for green chemistry
“Green chemistry will be more expensive”
Must carefully consider costs of reagents, solvents, disposal, engineering
controls, new labs, etc.
“There are no lab exercises available and I don’t have time to develop my own”
A wide range of experiments are now in development around the
country. There should be a lot of choice soon.
“There is no room in the curriculum for new material”
Don’t add, replace.
“The curriculum will not train students to work with hazardous materials”
Most students will not work with hazardous substances after organic.
Don’t have to work with hazardous substances to learn proper technique.
“Green is political, not scientific…green chemistry is not rigorous”
Designing better products and better processes is what synthetic chemists
do. Green chemistry provides a new challenge.
Acknowledgments
Prof. Ken Doxsee
Dr. Scott Reed
Ms. Lallie McKenzie
Mr. Marvin Warner
Ms. Lauren Huffman
Dr. Julie Haack
Dr. Rob Gilbertson
Mr. Gary Succaw
Dr. John Thompson
Ms. Kathryn Parent
Ms. Anna Shope
The Alice C.
Dr. Leif Brown
The
Mr. Gerd Woehrle
and the Students of CH337G and CH338G
Tyler Perpetual Trust
University of Oregon