Evaluation of two organic laboratory experiments according to the principles of green chemistry
Molly Carpenter, Margaret Anne Gray, Helen Dauer
Department of Chemistry
Atom Economy4
A new trend in chemical education incorporates green
chemistry practices into laboratory courses as evidenced by
the Green Organic Chemistry course taught by Kenneth
Doxee and James Hutchison at the University of Oregon. We
sought to compare an experiment from the Doxee and
Hutchison’s Green Organic Chemistry lab manual to an
experiment currently done in Sewanee’s Organic Chemistry
course. We performed the aldol reactions from each organic
laboratory manual and evaluated these reactions based on the
principles of green chemistry accepted by the US EPA and the
American Chemical Society.
Percent of atomic mass of all starting materials
that appear in the final product
Green Chemistry experiment
The Twelve Principles of Green Chemistry2
1) Prevent waste instead of treating waste
2) Design atom-efficient chemical syntheses
3) Use nontoxic compounds in synthesis
4) Create effective, nontoxic products
5) Minimize use of reagents and solvents
6) Minimize energy usage
7) Use renewable starting materials
8) Avoid unnecessary derivatization
9) Replace depleting reagents with reusable catalysts
10) Design biodegradable products
11) Analyze and monitor processes in real time
12) Design processes that minimize accidents
Reagents Used
Green Chemistry
Compound
1-indanone
3,4 dimethoxybenzaldehyde
Amount
0.200 g
0.252 g
NaOH
ethanol
HCl
0.05 g
20 mL
2 mL
Microscale Lab
Compound
benzaldehyde
acetone
NaOH
ethanol
Amount
0.084 g
0.023 g
0.06 g
2 mL
Yields
Green chemistry yield = 85.6%
Microscale yield = 53.0%
Reactions
Green Chemistry experiment1
O
O
O
NaOH
O
H
O
O
3,4-dimethoxybenzaldehyde
1-indanone
2-(3,4-dimethoxybenzylidene)indan-1-one
Microscale Organic experiment3
O
O
NaOH, H2O
O
C
H
benzaldehyde
H3C
CH3
acetone
C2H5OH
H
C
H
C
C
C
H
MW
166
132
298
Total
Used in product
C18H16O3
References
1. Doxee, K., Hutchison, J., Green Organic Chemistry: Strategies, Tools, and Laboratory
Experiments. Brooks/ Cole, 2004.
2. Anastas, P., Warner, J., Green Chemistry: Theory and Practice. New York: Oxford
University Press, 1998.
3. Mayo, D., Pike, R., Trumper, P., Microscale Organic Laboratory, New York: John Wiley
and Sons, 2000, 279-283.
4. Ibuprofen- A case study in green chemistry. 14, April 2009
MW
280
Unused in product
H2O
280
MW
18
18
Atom economy = 96.6%
Microscale Organic experiment
Reactant
2 C7H6O
C3H6O
Total
MW
106
58
270
Used in product
C17H14O
MW
234
Unused in product
2 H2O
234
MW
36
36
Atom economy = 86.7%
Economic Analysis
Following instructions from the Green Chemistry lab manual
we performed economic analysis for the major reagents used in
each experiment using prices found on Sigma-Aldrich.com.
Green Chemistry
Compound
Price
Cost for 15 students
1- indanone
$220 / 100 g
$ 8.32
3,4 dimethoxybenzaldehyde
$ 22.80 / 100 g
$0.68
Price
$90.70 / 500 mL
$90.40/ 4 L
Cost for 15 students
$0.22
$0.01
Microscale Lab
Compound
benzaldehyde
acetone
Green Chemistry Experiment
Benefits
- demonstrates a solventless reaction
- very high atom economy
- high percent yield
- low toxicity of reagents
Drawbacks
- high cost
- uses higher quantities of reagent
- extra product leads to waste
- heating and filtration use energy
Microscale Organic Experiment
Benefits
- uses very small quantities of reagents
- produces small amounts of waste
- low cost
Drawbacks
- lower atom economy
- lower yield
- stirring, heating, filtration use energy
C
H
dibenzalacetone
http://www.rsc.org/education/teachers/learnnet/green/ibuprofen/home.htm
Conclusions
Reactant
C9H10O3
C9H10O
Acknowledgements
Dr. John Shibata, Dr. Scott Borella
The microscale experiment
done currently in Sewanee’s lab
has fairly low environmental
impact. The main benefits of
the green chemistry aldol
reaction are that it
demonstrates a solventless
reaction and encourages
students to focus on the
economic and environmental
cost of the reaction in addition
to its chemical mechanism.
Green Chemistry Experiment
Benefits
Drawbacks
Demonstrates a solventless reaction
High cost
Very high atom economy
High percent yield
Low toxicity of regents
Can be done in groups
Uses higher quantities of reagent
Extra product leads to waste
Heating and filtration use energy
Microscale Organic Experiment
Benefits
Drawbacks
Uses very small quantities of reagents Lower atom economy
Produces small amounts of waste
Lower yield
Low cost
Stirring, heating, and filtration use energy