Enhancing the Chemistry Curriculum with FT-NMR

Enhancing the Chemistry Curriculum with FT-NMR Spectroscopy
Andrew Koch, St. Mary’s College
St. Mary’s College submitted a proposal to the National Science Foundation to fund the purchase of a
high-field Fourier-transform nuclear magnetic resonance spectroscopy (FT-NMR). The successful
proposal incorporated a project that includes both enhancing student learning by adapting and
implementing lab experiences based on inquiry methods and introducing students to contemporary
technology by integrating the use of the FT-NMR throughout the chemistry curriculum. This project
builds upon current department initiatives, which include establishing inquiry-based laboratory work in
the first-year chemistry courses. The FT-NMR will support inquiry-based labs in upper division
chemistry courses as well as support student research in chemistry.
By incorporating the use of the FT-NMR into a wide range of courses, the department will be able to
introduce a broad spectrum of students to a powerful analytic tool. Both the importance of the
incorporation of modern technology in science courses that reach a wide audience and the value of
inquiry-based activities have been recognized as supportive of student learning. Inquiry-based instruction
provides for a learner-centered environment where students can develop concepts using laboratory data.
A principal objective of this project is to provide for student development through the introduction of
concepts that are expanded on throughout the curriculum. A 300 MHz NMR will help us meet this goal
because the fundamental theories of NMR and simple spectral analysis can be introduced very early. As
the student's knowledge of chemistry increases, more sophisticated theories and techniques can be
explored. Below we outline adaptations of published experiments that will enable us to make connections
throughout our curriculum, move toward a more decision-based method of instruction and place greater
emphasis on critical thinking, analysis, problem solving and self-education.
We will introduce the basic concepts and theory of NMR spectroscopy in the first year. During the
second year we will continue our introduction of the theory and allow students to discover the power of
the NMR for structure elucidation and as a tool for predicting structure-based reactivity. After solving
simple one-dimensional spectra, students can expand their understanding of the instrument by learning
advanced techniques. Finally, students will be expected to generate ways to use the FT-NMR to advance
their St. Mary's Projects.
General Chemistry Applications
The department members have developed an in-house laboratory manual that employs inquiry-based
experiments. The manual was modeled after the work of Ditzler and Ricci at the College of the Holy
Cross. In our exploration of inquiry-based exercises in general chemistry lectures, we have found
investigation of atomic structure to be one of the most successful exercises in providing a solid
foundation for future material. Nuclear spin will be added to our discussion of the different elements,
chemical bonding, formal charge and isotopes. When electronegativity is covered, a relationship between
chemical shift and electron density will be explored.
Organic Chemistry Applications
We have already adopted a laboratory program that fosters students' use of all of the tools at their
disposal to gather evidence supporting their hypotheses. A critical component of this method of
instruction is the ability of students to decide what they need to do and when they need to do it. They
must discover the power and limitations of the instruments they use, learn what questions to ask, solve
problems and draw connections from previous courses.
By including some of the basic theories behind NMR spectroscopy in general chemistry, we can review
and build upon them during the first part of organic chemistry. Students will be introduced to the concept
of spin-spin splitting, given the sample of aspirin they prepared in general chemistry and asked for a full
interpretation of the spectrum. The aromatic region of aspirin is easily resolved at higher field with firstorder splitting which is easily distinguishable from second-order splitting. The discussion of secondorder splitting will come after the laboratory to give students the opportunity to observe it themselves.
One of our goals is to illustrate how science acts as a tool for society. Walters et al. have reported an
experiment examining different cinnamic esters related to protection against skin damage by UV
radiation. Students use molecular modeling to investigate the change in the electronic spectrum of
cinnamic esters by varying functional groups on the ring. They then come up with a list of compounds to
explore. Groups of students prepare different cinnamates, decide how best to characterize them and
evaluate their potential as sunscreens. Through evaluation of electronic spectra students will find that
both the nature and location of ring substituents lead to changes in those spectra. They then need to
explore the question: why does position of the substituent affect the electronic properties? Ideally this
would come before orientation in electrophilic aromatic substitution has been covered so that students
have the opportunity to discover the special effect of the ortho and para substituents. They will be asked
to acquire data to support their hypothesis that meta substituents do not transfer electronic effects to the
ester, which is apparent from 13C chemical shifts.
One of the hardest concepts for students to grasp is that of competing reactions. This concept becomes
important during the second semester of organic when students are introduced to condensation chemistry.
Students will explore the competitive reactions between hydrazines and _-dicarbonyls to give 5membered rings containing two nitrogens. Half the class will run reactions between hydrazines and _ketoesters to yield pyrazolones, the others between hydrazines and _-diketones to give pyrazoles.
Students from each group will use FTIR and NMR to assign structures for their products on a
comparative basis. In the next lab period students will react a ___-diketoester, ethyl diacetoacetate, with
either hydrazine or phenylhydrazine to determine if ethyl diacetoacetate reacts like a diketone or a
ketoester.
Inorganic Chemistry Applications
Continuing the theme of a discovery-based approach to chemistry, a series of experiments will be
implemented in the inorganic course that will be enriched by the use of high-field NMR. The
experiments incorporate organometallic compounds that are examined extensively in the course. Students
will explore the preparation and characterization of a series of (_6-arene)Cr(CO)3 compounds to identify
structure-reactivity relationships. By incorporating a range of arenes, the experiment will allow each
student to synthesize and characterize a unique compound. Characterization of the compounds
incorporates 1H and 13C NMR as well as FT-IR. Students will pool the collected data to identify
structure correlations.
Advanced Spectroscopy Applications
The goal of this course is to introduce students to the power of NMR spectroscopy as an analytical tool
while providing them with a level of theory appropriate for upper-level undergraduates. The course will
start with a review of the basic principals and theory behind a high field spectrometer, with a lab
component to reinforce these concepts. Students will first learn operations like tuning and determining a
standard 90o pulse-widths. They will then carry out standard experiments such as DEPT, HETCOR,
APT, COSY, etc. These experiments will be performed during the early part of the course and should
offer an excellent way to visualize the theory.
After the experiments to demonstrate techniques, students will first use dynamic 1H NMR to determine
the activation enthalpy and entropy for rotation about the carbonyl carbon-nitrogen bond in
dimethylformamide. Structures will be determined for a variety of different compounds such as camphor,
menthol or verbenone. Students can use not only chemical shifts and coupling constants, but can choose
from the 1-D and 2-D experiments DEPT, HH and HC-COSY and NOE as necessary. The continuation
of structure elucidation will then be brought up in the context of previous organic labs. Students will be
asked to pick a compound that they had worked with in organic, e.g., the D-A product15 or a previous
unknown, and devise a scheme for rigorous analysis.
St. Mary’s Goals
Among the many goals for the St. Mary's Projects is the expectation that students will gain "a sense of
what it is like to be a practitioner within a field and relate theory to practice." To foster this, the college
seeks to provide students access to state-of-the-art instrumentation. For the chemistry program, the 300
MHz NMR is a cornerstone element of an enriched research environment where students gain firsthand
experience participating in the research process. The St. Mary's Project provides a culminating
experience where students apply the knowledge acquired in their studies in probing chemical systems in
collaboration with faculty mentors.
Evaluating Success
As the improvement in student learning is a major goal of the project, the PI's will use appropriate
assessment tools as an element of the evaluation plan. Heady (JCST) has recently provided a good
introduction to the elements of an appropriate assessment process. The Field-tested Learning Assessment
Guide developed in conjunction with the New Traditions Project (DUE-9455928) at the University of
Wisconsin also has assessment information.
Students participating in undergraduate research will be monitored for appropriate use of the FT-NMR in
their projects. When the FT-NMR is used by students for research projects, they will be interviewed at
the end of the project to determine their understanding of the mechanics of using the instrument and their
ability to evaluate the spectra provided by the instrument. The college has recently initiated an active
effort to keep in touch with alumni. To gain insight into the impact access to the FT-NMR has had on our
students, we will arrange to have questions included in the chemistry and biology alumni surveys that
solicit input on alumni experience with the instrument and the influence it has had in their current
positions.
The College will secure the services of a consultant with experience in using FT-NMR in an
undergraduate setting. Further, the consultant will advise the department on curricular issues regarding
the FT-NMR to ensure successful implementation into the curriculum.

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