NMR Spectroscopy in the Undergraduate Curriculum - American

Chapter 2

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NMR Spectroscopy in First-Year Chemistry at the University of Technology Sydney Janice Alexander,*,1 Jason Ashmore,2 Anthony Baker,2,3 and Scott Chadwick2 1Chemistry

and Forensic Science, Flathead Valley Community College, 777 Grandview Drive, Kalispell, Montana 59901, United States 2School of Mathematical and Physical Sciences, University of Technology Sydney, P.O. Box 123, Broadway, NSW 2007, Australia 3College of Science, Health, and Engineering, LaTrobe University, Victoria 3086, Australia *E-mail: [email protected]

First-year general chemistry classes at large universities typically enroll students with diverse backgrounds. The vast majority of these students are not chemistry majors. NMR instrumentation was introduced to this class to engage these students in their learning and to represent modern chemistry to students for whom this course might be their only chemistry experience. We have incorporated NMR spectroscopy into the general chemistry laboratory experiments at the University of Technology Sydney in Sydney, Australia. Benchtop NMR spectrometers now mean that students can have close and frequent access to instrumentation. This chapter describes the use of the picoSpin-45 NMR spectrometer in the introductory laboratory, the types of experiments performed, quiz and survey results, and implementation challenges and successes.

© 2016 American Chemical Society Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


University of Technology Sydney First-Year Chemistry The University of Technology Sydney (UTS) hosts approximately 1200 students a year in first-year chemistry. The incoming student background has shifted to an increasing number of students without a prior background in chemistry. Approximately 13% of first-year chemistry students have a non-English speaking background and 14% are of low socio-economic status. As an avenue to increase student engagement, retention and success, the desire was to incorporate modern instrumentation into first-year Chemistry 1 and 2 courses with hands-on experience. It was surmised that having students complete instrument based practical exercises would engage them more strongly with their learning. In the course of this project, that assumption has been explored. A laboratory practical (experiment) introducing Fourier Transform Infrared (FTIR) spectroscopy was introduced into Chemistry 1, followed by introduction of nuclear magnetic resonance (NMR) spectroscopy and expansion of FTIR in two laboratory practicals into Chemistry 2. This project, begun by the UTS School of Chemistry and Forensic Science (now UTS School of Mathematical and Physical Sciences), dovetailed nicely with an institutional shift towards implementation of significant teaching and learning methodology changes including focus on active learning and incorporation of ‘Graduate Attributes.’ UTS Faculty of Science Graduate Attributes include: disciplinary knowledge and its appropriate application, an inquiry-oriented approach, professional skills and their appropriate application, ability and motivation for continued intellectual development, engagement with the needs of society, communication skills, and initiative and innovative ability (1). Graduate attributes at UTS are equivalent to course, program and degree outcomes in the United States. The project paired the desire of UTS faculty to incorporate instrumentation into first-year chemistry with the experience of Flathead Valley Community College (FVCC). A faculty member from FVCC spent six months with UTS faculty on the project. FTIR and NMR experiments were first incorporated into first-year chemistry at FVCC in the mid 1990’s. Exposure to instrumental methods has not usually been part of the Australian first-year chemistry student experience. Typical lecture sections of first-year chemistry hold 450 students with 32 students in a lab section facilitated by two demonstrators (teaching assistants). Lab practicals are held once a week for three hours. Practicals are spread across the week, both day and evening, such that only one section of lab meets at any given time. During the implementation of this project significant expansion of the School of Chemistry and Forensic Science was in process including construction of a SuperLab designed to hold 200 students at one time. Design of this project needed to include both the current parameters of lab space during the implementation semester, as well as the future parameters for following semesters working in the SuperLab. The SuperLab, shown in Figure 1, opened January 2015 hosting physics, chemistry, and biology students simultaneously in sections of up to 80 students per discipline.

14 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Figure 1. UTS Superlab. Photo by Jason Ashmore. Chemistry 1 is offered both fall and spring semesters, whereas Chemistry 2 is offered spring and summer semesters. Chemistry 2 includes sections of both regular Chemistry 2 and Advanced Chemistry 2. Advanced Chemistry 2 students attend the same lecture as regular Chemistry 2 students; however the advanced students attend an additional hour of lecture each week and are placed into separate lab practical sections. Typically the additional hour of lecture each week is seminar style with research presentations by faculty in the School of Chemistry and Forensic Science, followed by a quiz covering the material from the previous week’s research presentation. Students scoring above a cutoff in Chemistry 1 are invited to register for Advanced Chemistry 2. A maximum of sixty-four students are admitted to Advanced Chemistry 2, restricted by allowed enrollment in two lab sections. The project implementation plan incorporated FTIR instrumentation into Chemistry 1 and Advanced Chemistry 2, and NMR instrumentation into Advanced Chemistry 2, with the intent of a rollout to all of Chemistry 2 sections in future years.

UTS Instrumentation In order to implement NMR spectroscopy into first-year chemistry, and across the curriculum, the School of Chemistry and Forensic Science chose to purchase a benchtop NMR spectrometer. Purchased in 2014, the ThermoScientific picoSpin-45 NMR spectrometer provides 1H NMR. This instrument is ideal for incorporation into large first-year chemistry laboratories as it is portable and has high throughput. The picoSpin-45 NMR weighs about 10 pounds, only requires about an hour to stabilize when moved from room to room, does not use cryogens, and is about the size of a stack of two chemistry textbooks. This makes it extremely easy to move the NMR spectrometer from one laboratory to another between laboratory periods. In addition the instrument is highly durable, thus accidental student bumps or pushes do not require shimming. 15 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


The picoSpin-45 NMR, shown in Figure 2, uses syringe injection into a sample loop negating the need to purchase and care for NMR tubes. In addition, water is stored in the sample loop allowing easy storage and cleaning and avoiding the use of solvents such as methylene chloride in first-year classes. To shim the instrument, water is used as the standard.

Figure 2. The UTS picoSpin-45 NMR. Photo by Jason Ashmore.

Since first-year chemistry experiments were aimed at understanding of proton NMR through analysis of standard knowns and unknowns, or simple synthesis of an easily resolved product, one scan was sufficient for spectra of high enough resolution for basic interpretation. A five minute time allotment per sample to inject, run the sample, and receive an autoanalysis printout of the spectrum is reasonable allowing high throughput in large labs. If more time is available, the practical can be designed for manual student manipulation of the spectra. The current cost of $30,000-$40,000 makes this an affordable investment for institutions adding NMR across the curriculum. Students name their file and run the experiment with the picoSpin software in Mozilla Firefox. All parameters have been pre-set for them. Once the sample run is finished “ScriptOnePulse Completed Successfully” appears on the screen as seen in Figure 3 and the student saves the fid-avg.jdx file shown in Figure 4. The student then opens the jdx file in the MNova software and uses a preset automatic processing template to obtain the processed spectrum for printing. In the follow up experiment, students use an automatic processing template set for initial processing that allows the student to manually integrate the spectrum. FTIR spectra were collected with a Cary 630 FTIR-ATR spectrophotometer. Four FTIR spectrometers were located in a lab across the hall from the student lab.



Figure 3. Picospin-45 NMR software showing a completed run.



Figure 4. PicoSpin-45 NMR software showing the FID.

Design A project of this nature requires significant collaboration and coordination. Development and testing of laboratory experiments occurred over a four month time frame including synthesis parameters, resolution of products and unknowns, ease of spectral interpretation, and timing of the entire process to fit within a laboratory period. UTS prints its own lab manuals for students, thus changing the master comes with its own timeline requirements and department faculty work hours. At a large institution like UTS it is important to consider the entire chain affected by shifting one experiment, including the lab manual, chemical supply and safety information documentation, and bulk chemical supply purchasing, preparation, and disposal. Inevitably this increases the workload of technicians and faculty. Demonstrators were trained on the use of the picoSpin-45 NMR several weeks prior to pilot implementation of the first experiment. The demonstrators also performed a test run of an experiment from start to finish. Demonstrators followed the directions in the laboratory manual provided to them one hour before their test run, working slowly as students likely would, to complete the experiment. This provided insight into typical student procedural misunderstandings as well as approximate timing for student completion of the experiment. The test run 18

Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


led to revision of the experimental procedure for greater clarity. In addition, demonstrators expressed a higher level of comfort both before and during facilitation of the experiment based upon their experience from the test run. Awareness of likely areas of student difficulty, as well as learning how to use and troubleshoot the new picoSpin-45 NMR, were products of the demonstrators test run. Students were introduced to basic theory and simple analysis of 1H NMR spectra in an Advanced Chemistry 2 seminar session. A research faculty member utilizing proton NMR in his polymer research collaborated with the implementation team to give a jointly created presentation to the students. The presentation included a short basic introduction to NMR, spectral interpretation and utility, and progressed into examples from the faculty members’ research. In addition, the laboratory manual contained an Appendix devoted to theory of NMR, spectral interpretation, and step-by-step instructions for both NMR data acquisition and spectral processing. Students were expected to run samples on an FTIR and perform spectral analysis by relying on their memory of an FTIR lab from the prior semester and reading of a lab manual Appendix devoted to theory, spectral interpretation, and instrument procedure for the FTIR. Several weeks later students performed their first experiment (Experiment 2) of the semester utilizing the NMR and FTIR instrumentation. The second experiment (Experiment 4) was held the following week. The labs were sequenced as building blocks with spectral processing and interpretation. A faculty member and technician were present during the first experiment to provide backup and troubleshooting for the demonstrators as needed. During the second experiment they were ‘on call if needed’ elsewhere in the building. The second experiment ran smoothly and demonstrators did not need any assistance. Students completed a quiz and a survey the week following the last NMR/ FTIR experiment. In addition, demonstrators gathered anecdotal student feedback and provided their own feedback of what worked well and areas for improvement including suggestions on how to implement improvements. Faculty and staff buy in was critical for success of the project.

Experiment 2 – Organic Reactions During the first instrumentation experiment students worked in groups of two or three to identify an unknown aldehyde, ketone, primary alcohol, or tertiary alcohol through color tests, FTIR and 1H NMR. Rather than design a brand new experiment, this first instrumental experiment was created by retooling an existing experiment. The traditional practical utilized color tests based on oxidation and condensation reactions to classify an unknown sample as an aldehyde, ketone, primary alcohol, or tertiary alcohol. NMR and IR spectroscopy were added to the practical to support classification and identification of the unknown. NMR analysis included peak splitting (n + 1) and chemical shift. Students react primary, secondary, and tertiary alcohols with acidic dichromate noting a change to a colorless solution to verify oxidation of a primary or secondary alcohol to an aldehyde or ketone. Students then react aldehydes and 19

Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


ketones with acidic dichromate verifying conversion of an aldehyde to a carboxylic acid through rapid oxidation via color change from orange to green/blue. Alcohols are differentiated from aldehydes and ketones through the condensation reaction of aldehydes and ketones with DNP (2,4-dinitrophenylhydrazine) to the resultant crystalline imine products. Students are then provided an unknown liquid narrowed down to a list of the four options shown in Figure 5.

Figure 5. Experiment 2 chemical formulas of unknown samples. Students are instructed to acquire FTIR and 1H NMR spectra and run the color tests in order to identify their unknown. Rotation of student groups through the four FTIR spectrophotometers and the picoSpin-45 NMR are incorporated for efficiency. The four unknowns are quite easy to distinguish from each other as shown in the FTIR spectra in Figures 6-9 and 1H NMR spectra in Figures 10-13.

Figure 6. FTIR spectrum of butanal.

Figure 7. FTIR spectrum of 2-methyl-2-butanol. 20 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Figure 8. FTIR spectrum of butanone.

Figure 9. FTIR spectrum of 1-propanol.

Figure 10. 1H NMR spectrum of butanal. 21 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Figure 11. 1H NMR spectrum of 2-methyl-2-butanol.

Figure 12. 1H NMR spectrum of butanone. 22 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Figure 13. 1H NMR spectrum of 1-propanol. FTIR interpretation is limited to simple functional group analysis. NMR analysis included chemical shift and peak splitting. For this first NMR experiment, integration of peaks was not incorporated. The idea was to build scaffolding over time, allowing students to more deeply integrate the material by providing smaller chunks. Student results from color tests did not always match up with the FTIR and NMR spectra. This led to a wonderful teaching moment as these students realized for themselves the inconsistency of results and began to wonder whether their color test results or spectral results were correct. The idea of human error, as well as attention to procedural detail, took on new meaning. In addition, understanding the reasoning for repeat trials emerged. Demonstrators struggled to manage timing, efficient rotation, and student challenges with syringe operation and instrumentation during the first lab section. This experience led them to revise their facilitation methods and the second lab section ran smoothly.

Experiment 4 − Preparation and Characterization of Isoamyl Acetate Experiment 4 was run the week after Experiment 2. This provided continuity, retention of information, and body memory from the first instrumentation experiment. Students worked in groups of three to synthesize an ester with analysis of product by FTIR and NMR. Group size was critical for timely completion of FTIR and NMR analysis, including spectral interpretation, after synthesis. 23 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Isoamyl acetate is prepared from acetic anhydride and isoamyl alcohol in an acidified solution as shown in Figure 14. Excess acetic anhydride is converted to acetic acid with the addition of water prior to isolation of the product via extraction. The synthetic design was pre-tested to ensure it yielded good results even with common student missteps.

Figure 14. Isoamyl acetate synthesis scheme. Several steps were added in processing and interpreting NMR spectra to this second experiment. Students are required to manually integrate spectra and analyze integration as seen in Figure 15 in addition to assignment of chemical shift and analysis of peak splitting. Students then answer questions such as: 1. 2. 3. 4. 5.

Briefly explain why the signal for group B appears as a singlet whereas that of group A appears as a triplet. The two CH2 groups have the same intensity (integration) but different splitting patterns. Why? What is the purpose of adding the TMS to the sample? Why can two of the three CH3 groups both be labelled as group C? Based on your IR spectrum, were you successful in converting reactant to product; and is your product reasonably pure? How do you know?

Figure 15. 1H NMR spectrum of synthesis product isoamyl acetate. 24 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Demonstrator Feedback Demonstrators stated hands-on training prior to lab practical facilitation, similar to their experience, is important to institutionalize for future demonstrators. This training is critical to prepare them to solve unforeseen instrumental issues and to be better prepared to respond to unusual student spectra. In addition, a standard operating procedure requiring a test run of the unknowns shortly before the lab practical will ensure fewer instrumental issues. To complete the lab in a timely fashion, efficiency is critical. For timely lab practical completion, minimum group sizes of three students, rotation of groups through all available instrumentation, and starting a group on sample injection as soon as the prior group begins processing data are all necessary. A demonstration of syringe loading and air bubble removal is also important. Students tend to be slow and unsure during the first of the two experiments, thus auto-processing of NMR spectra and no integration until the second experiment is optimal. In addition, rotation of groups through instrumentation is best begun as soon as students start the lab period. Demonstrators proposed replacing 2-methyl-2-butanol with t-butanol due to the complexity of the spectrum. Demonstrators also felt the flow chart in Figure 16 would be a useful addition to Experiment 2. This flow chart was developed by the implementation team for an in-house teaching and learning presentation. A suggestion to diminish the lag time between seminar presentation of NMR and student laboratory practicals was put forth.



Figure 16. NMR flow chart to identify unknown samples in Experiment 2.

Project Assessment of Student Experience Assessment of student engagement and accessibility of material was evaluated through a post-laboratory quiz, administration of a survey, and anecdotal evidence through students’ comments. Eighty one percent of sixty three students scored an 80% or higher (≥ 4) on the quiz as shown in Figure 17. This was the first time NMR had been incorporated into the course, thus the quiz provided an assessment of students understanding of NMR and interpretation of NMR spectra.



Figure 17. Advanced Chemistry 2 NMR quiz results.

A survey focused on engagement and accessibility of material, ASCIv2 modified by Xu (2), was administered to determine students’ attitudes to the experience. The short survey assesses eight factors on a Likert scale as shown in Figure 18. Validation studies by Xu (2) determined the factors comfortable, satisfying, pleasant, and organized load on emotional satisfaction whereas easy, simple, clear, and unchallenging load on intellectual accessibility. Emotional satisfaction data from the survey thus is an indicator of student engagement. Attitude in regards to using the NMR, using the FTIR, interpreting NMR spectra, and interpreting FTIR spectra were assessed.

Figure 18. A section of the Advanced Chemistry 2 student survey. 27 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Surveys with missing results were removed from the data set prior to analysis. The remaining fifty eight surveys were used for the analysis. As seen in Figure 19, survey results show consistency across factors. Students rated using an instrument more favorably than spectral interpretation. Across all categories FTIR was consistently scored at a more positive value than NMR. It is interesting to note that despite this difference, students find NMR essentially equally satisfying, organized, and pleasant as FTIR. Student attitudes of satisfaction and pleasantness are not necessarily based upon what they perceive as the easier method. With the exception of unchallenging, all factors scored in the top half of the scale supporting a positive response for both emotional satisfaction and intellectual accessibility. Overall survey results support continuation of the instrumentation labs in first-year chemistry. Anecdotal student comments such as “It’s satisfying when and if you get it right,” and “It’s cool to do a prac using an instrument I would use in industry”also support giving students an opportunity to experience hands-on modern instrumentation in the laboratory.

Figure 19. Advanced Chemistry 2 Likert ASCIv2 student survey results.

Conclusion Determining the structures of molecules from spectral information is a challenge for inexperienced scientists. However it builds skills in synthesising various pieces of evidence to propose a potential structure and then check that proposal in more detail against all the data available. The exercise thus goes beyond a base-level knowledge and understanding exercise and certainly engages the students in higher-order thinking. It is an excellent exercise in “thinking like a chemist.” The pilot semester went well as evidenced by student survey results, quiz results, and student comments both verbally and on end-of-semester evaluation forms. Survey results support student engagement with these types of laboratory practicals. Student comments indicate appreciation of experiences in the first 28 Soulsby et al.; NMR Spectroscopy in the Undergraduate Curriculum: First Year and Organic Chemistry Courses Volume 2 ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


year more similar to what they envision employment to require. The next steps for sustainability of instrumentation in the laboratory are reasonable to implement. Demonstrator training appears to be the limiting factor in expansion of instrumentation to all sections of Chemistry 2, and eventually to Chemistry 1. Addition of NMR spectroscopy into Chemistry 1 will allow for expansion of inquiry based instrumentation experiments in Chemistry 2 due to increased student experiences with this type of lab practical. Incorporating instrumentation into large enrollment courses with first-year students has been shown to be entirely feasible. Many of the students in large-enrollment, first-year chemistry courses are not intending to major in chemistry, so it is important to give them an up-to-date view of chemistry in the relatively limited exposure that they will have to chemistry in a higher education context. It is important that, as professional scientists postgraduation, they understand the sorts of questions that chemists ask, why they ask them, and how they answer them.

Acknowledgments Ali Hunt, Nadine Krayem, Simon Ting.

References 1.

2.

Developing and Embedding Graduate Attributes: A University-wide Perspective. University of Technology, Sydney. https://www.itl.usyd.edu.au/projects/nationalgap/resources/gapposters/ developing%20and%20embedding%20graduate%20attributes-%20a%20uniwide%20perspective%20uts%20-%20n.%20parker.pdf (accessed November 16, 2015). Xu, X.; Southam, D.; Lewis, J. E. Attitude toward the subject of chemistry in Australia: An ALIUS and POGIL collaboration to promote cross-national comparisons. Aust. J. Ed. Chem. 2012, 72, 32–36.


NMR Spectroscopy in the Undergraduate Curriculum - American

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