Power Point Presentation (PDF) - Green Chemistry Center

Process used to develop and teach greener
laboratory procedures
Assess existing
procedure
Identify hazards
or inefficiencies
Find/develop
alternative methods
Test efficacy
of new procedure
TRADITIONAL
H
GREENER
H
A safer bromination of an olefin
H
Br H
+
CCl
Br 4 or CH 2Cl 2
2
H
1. HBr
2. 30% H 2 O 2
ethanol, reflux
H
H Br H
ethanol
H
GREEN
ethanol
N H Br 3
N H Br + Br 2
H
Br
Br
We teach this simple process to
our students as we implement it.
Greener
alternative
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.
Reed, S.M.; Hutchison, J.E. J. Chem. Ed. 2000, 77, 1627-1629.
McKenzie, L. C.; Huffman, L. M.; Hutchison, J. E. J. Chem. Ed. 2005, 82, 306-310.
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.
O
Solventless Aldol Condensation
mp 40-42 oCmp 42-45 oCmp 178 - 181 ° C
Chemical Concepts:
Melting point determination
and depression
Aldol condensation reaction
Recrystallization skills
+
O
1. NaOH
2. H 3 O + workup
OCH 3
OCH 3
H 3 CO OCH 3
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.
O