Transcript Discovery Based Learning Using NMR Spectroscopy

Transition to an Investigative
Laboratory Program in Chemistry
at Birmingham-Southern College
David J. A. Schedler and
Laura K. Stultz
Introduction
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National Science Foundation Grant
Investigative Laboratories
Development of Laboratory Projects
Examples
Project Goals
Student Goals
Improve
- Problem solving and
collaborative skills
- Ability to apply
experimental techniques
to solve a chemical
problem.
- Ability to communicate
results (written and oral)
Curricular Goals
- Improved laboratory
experience
- Better synergy between
lecture and laboratory
- Connections between
chemistry courses
Investigative Laboratories
• Students discover results instead of
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verifying them
Experimental protocols are largely student
designed
Work is done in collaborative groups
Interpretation of results through data
analysis
Group discussion
Project Plan
Gradualism Model – stepwise presentation of
new material with specific goals
Instrumental techniques as common thread
- Molecular Modeling
- FTNMR (1H and 13C)
Project based Laboratories – Reinforces
concepts and skills
Student involvement in laboratory design
• First Semester Focuses
on Techniques and
Instrumentation
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Distillation
Crystallization
Melting point
TLC
GC
NMR
• Second Semester
Focuses on
Application
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NMR
FT-IR
Molecular modeling
Stereochemistry and
Coupling Constants
• Projects should have
clearly stated:
• Objective
• Outcome
• Introduction
• Theory for the
instrumentation to
be used
• background into the
chemistry involved
• Experimental
Procedure
OH
O
H3C
NaBH4
NaOH, H2O
OH
H3C
trans-3-methylcyclohexan-1-ol
2.39 kcal/mol
H3C
cis-3-methylcyclohexan-1-ol
1.34 kcal/mol
Heq
OH
Heq
Hax
Heq
Heq OH
Heq
H3C
Hax
Hax
Hax
Hax
H 3C
Entry
Dihedral
Expected
Dihedral
Angle(°)
Expected
value
(Hz)
Entry
Dihedral
Expected
Dihedral
Angle (°)
Expected
value
(Hz)
1
HeqCCHeq
60
2.5
1
HaxCCHe
60
2.5
60
2.5
180
12
180
12
q
2
HeqCCHeq
60
2.5
3
HeqCCHax
60
2.5
4
HeqCCHax
60
2.5
2
q
3
Hax
HaxCCHa
x
4
OH
HaxCCHe
HaxCCHa
Hax
x
Heq
Heq
Heq
OH
Hax
Heq
Hax
Jax-eq
Jax-ax
Jax-eq
H
OH
H3C
Heq
Hax
Jax-eq
Jax-ax
Jax-eq
Ψ Quintet
Ψ Triplet of Ψ triplets
OH
OH
O
+
O
O
O
toluene
CH3
O
CH3
O
Adapted from: McDaniel, Keith F.; Weekley, R. Matthew “The Diels-Alder Reaction of 2,4-Hexadien-1-ol
with Maleic Anhydride: A Novel Preparation for the Undergraduate Organic Chemistry Laboratory Course” J. Chem. Educ. 1997, 74, 1465.
Diels-Alder Reaction
• prediction of reaction
product
• carry out reaction using
previously learned lab
techniques
OH
O
O
O
OH
O
CH3
O
Structure Determination
•NMR
•IR
•Mechanistic explanation
CH3
O
O
H1
H2
H4
CH3
H3
O
A
B
H1
O
OH
H2
H4
O
Dihedral Measured
Angle A
(°)
CH3
Calculated Measured Calculated
J Value A Angle B J Value B
(Hz)
(°)
(Hz)
H1CCH2 18.93
8.42
179.31
11.19
H2CCH3 40.36
5.61
53.33
3.64
H3CCH4 45.28
4.85
99.05
1.18
www.casper.organ.su.se/ke3690/jhh.html
program calculates 3JHH values according to:
C.A.G. Haasnoot, F.A.A.M. DeLeeuw and C. Altona Tetrahedron 36 (1980) 2783-2792
H3
O
O
OH
O
H1
H2
H4
CH3
H3
O
O
OH
O
A
H1
CH3
H3
Measured
Angle
(°)
Calculated
J Value A
(Hz)
Measure
J Value A
(Hz)
H1CCH2
18.93
8.42
8.9
H2CCH3
40.36
5.61
5.5
H3CCH4
45.28
4.85
4.6
O
OH
H2
H4
Dihedral
O
H2
H1
H3
• Electron Transfer Self
Exchange Rates
• Kinetic NMR
experiment
• Factors that affect the
electron transfer rates
Jameson, D.L.; Anand, R. J. Chem. Ed., 2000, 77, 88
Acknowledgements
• National Science Foundation
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(Award DUE-0126478)
Dr. Regina Stanton
Mr. Patrick McTamney
Ms. Karen Johnson
Mr. Nathan Boyd
Birmingham-Southern College
www.bsc.edu/chemistrylabs.htm