Introducing GC/MS into the
Undergraduate Organic Lab
Dan Blanchard, Ph.D.
Kutztown University
http://faculty.kutztown.edu/blanchar/
GC/MS as an Organic Tool
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Goals of Organic Lab
Characterization
Logistics
Challenges
Experiments
Conclusions
Goals of Organic Laboratory at KU
1.
2.
3.
4.
Learn Laboratory Techniques
Carry Out Organic Syntheses
Explore Chemistry of Everyday Life
Demonstrate Concepts from Lecture
Most Involve Synthesis or Isolation
Importance of Characterization
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Synthesis Routine
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React
Isolate
Purify
CHARACTERIZE
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Isolation Routine
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Isolate
Purify
CHARACTERIZE
Characterization
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Traditionally Melting Range
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Not related to structure
Sample purity dependence
Not modern techniqe
GC/MS
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Can be introduced early at basic level
Can be developed across the course
Modern technique
GC/MS – Logistics
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Should students operate the
instrument in the Organic lab?
One Solution: The Autosampler
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Allows for more samples and longer
run times
Students can enter their own
information.
Students should get to operate the
instrument once.
Challenges of Introducing GC/MS
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Introducing two
techniques at once
Two graphs for one run!
Heaviest ion versus
most abundant ion
Fragmentation: multiple
simultaneous reactions
Identification of Volatile Flavor
Components by Headspace Analysis
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Simple sample preparation
Short run times
Identification is made by molar mass alone
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limonene, ethyl butyrate, benzaldehyde, isoamyl acetate
Drawback: Not all candies have adequate volatile
components
Kjonaas, R.A.; Soller, J.L.; McCoy L.A., J. Chem. Educ. 1997, 74, 1104-1105.
Isolation of the Active Ingredients
from Cough Syrup
CH3O
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Includes acid-base
extraction
Example of combining
traditional concept with
GC/MS
OH
H
N
H
CH3
N
CH3
OH
OH
O
O
CH3
Sherren, A. T. Presented at The American Chemical Society National Meeting, Boston,
MA, 1999.
CH3
Fatty Acids Present in Snack Foods
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Isolation of oils from potato chips
Detection of prepared FAMES
No MS interpretation
Food for discussion
Rubinson, J.F.; Neyer-Hilvert, J., J. Chem. Educ. 1997, 74, 1106-1107.
Grignard Synthesis of an Unknown
C6-C9 Alcohol
O
1) R'
Mg0
ether
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R"
R
R MgBr
R Br
OH
R"
2) H3O+
Unknown alkyl halide plus unknown ketone
Product is characterized by IR, 13C NMR, GC/MS
NO molecular ion
Fragmentation analysis is required
Everett, T.S., J. Chem. Educ. 1998, 75, 86-87.
R'
Also Adopted
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Isolation of Essential Oils from various spices
Pavia, D.L.; Lampman, G.M.; Kriz, G.S.; Engel, R.G. Introduction to Organic
Laboratory Techniques, A Microscale Approach, Third Edition; Saunders:
Philadelphia, 1999; pp 487-492.
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Chlorination Reactivity Ratios for
Methylcyclohexane
Bishop, R.D., Jr., J. Chem. Educ. 1995, 72, 743-745.
CH3
Also Modified
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Acetylation of Ferrocene
O
Fe
CH3
O
O
Cl
Fe
O
AlCl3
Amenta, D.S.; DeVore, T.C.; Gallaher, T.N.; Zook, C.M.; Mosbo, J.A.,
J. Chem. Educ. 1996, 73, 572-575.
Fe
Also Tried
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Preparation of a C-4 or
C-5 Acetate Ester
O
O
Pavia, D.L.; Lampman, G.M.; Kriz,
G.S.; Engel, R.G. Introduction to
Organic
Laboratory Techniques, A
Microscale Approach, Third
Edition; Saunders:
Philadelphia, 1999; pp 472-475.
McGoran E.C.; Melton, C.; Taitch,
D., J. Chem. Educ. 1996, 73, 88-92
O
O
Conclusions
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There exist a wide range of experiments which
already incorporate GC/MS.
There are a wide range of experiments which
can be modified to incorporate GC/MS.
GC/MS is a modern structurally-based
characterization technique that can be
introduced early in the organic course and
developed across both semesters.
Acknowledgements
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National Science Foundation, Division of
Undergraduate Education
Organic lab students at KU 1999-2004
Colleagues and lab instructors at KU 19992004
References
Kjonaas, R.A.; Soller, J.L.; McCoy L.A., J. Chem. Educ. 1997, 74, 1104-1105.
Sherren, A. T. Presented at The American Chemical Society National Meeting,
Boston, MA, 1999.
Rubinson, J.F.; Neyer-Hilvert, J., J. Chem. Educ. 1997, 74, 1106-1107.
Everett, T.S., J. Chem. Educ. 1998, 75, 86-87.
Pavia, D.L.; Lampman, G.M.; Kriz, G.S.; Engel, R.G. Introduction to Organic
Laboratory Techniques, A Microscale Approach, Third Edition; Saunders:
Philadelphia, 1999; pp 487-492.
Amenta, D.S.; DeVore, T.C.; Gallaher, T.N.; Zook, C.M.; Mosbo, J.A., J.
Chem. Educ. 1996, 73, 572-575.
Bishop, R.D., Jr., J. Chem. Educ. 1995, 72, 743-745.
Pavia, D.L.; Lampman, G.M.; Kriz, G.S.; Engel, R.G. Introduction to Organic
Laboratory Techniques, A Microscale Approach, Third Edition; Saunders:
Philadelphia, 1999; pp 472-475.
McGoran E.C.; Melton, C.; Taitch, D., J. Chem. Educ. 1996, 73, 88-92