HNMR Analysis of Reaction Mixtures

Author: Ella Baker | Majors: Biochemistry, Spanish | Semester: Spring 2024

My name is Ella Baker, and I recently completed my junior year at the University of Arkansas studying both Biochemistry and Spanish. I have had the privilege of researching this past academic year under the direction of my mentor Dr. Matthias McIntosh within the department of Chemistry and Biochemistry. I aspire to attend medical school after I graduate next spring and ultimately go on to earn my Doctor of Medicine. I gained the opportunity to work in the McIntosh lab simply by asking questions and reaching out. After first talking with him about what my post-grad plans were and what facet of research I wanted to engage in and learning more about what was expected of me, I felt that his lab was best suited for me and could help me to work in an area of furthering drug design/pharmaceutical research.

My research project is focused on the condensation of pyridinium ylides with aldehydes. The main area of my investigation is an offshoot of Dr. McIntosh’s research into the radical pathways of the rearrangements and dimerizations of N-alkyl pyridinium salts. Using this along with other previous work that has shown that it is possible to turn the N-alkyl pyridinium salts into carbon nucleophiles by treating the salts with a weak base, my focus is to expand the scope of our radical substrates by coupling them with aldehydes under basic conditions to design more interesting compounds with various functional groups. The findings of this project can be used for furthering pharmacological research and providing new ways for drug design and synthesis.

This past spring semester has been one of ups and downs. In the nature of chemical research, or any research for that matter, we ran into obstacles that proved what we initially thought would be a relatively facile condensation was not in fact facile. The reaction mixture, although it did often produce the desired signals in HNMR spectroscopy as well as intensive changes in color, returned starting materials. Also because N-alkyl pyridinium ylides have many side reactions at room temperature, the complexity of the reaction resulted in many failed attempts to isolate the desired products from the mixture. We believe that, based on these observations, the reverse reaction is more prominent than the forward in terms of equilibrium. Because of the many side reactions, our results do call for a look into the exchangeable positions of protons in our substrate to try and gain a better understanding of our reactions. This study is currently ongoing and could provide insight into the reasons behind the obstacles from early in the semester. This shift of study does not affect the overall goal of my project but did cause a different general procedure to examine the kinetics of proton exchange in these reactions.

Throughout the semester, my research mentor Dr. McIntosh as well as the PhD student Tristan Nolan alongside whom I work have been of great help in interpreting results and posing directions for what steps to take next. They remained encouraging even when I reached difficulties. In the coming months I plan to continue work in the lab and finish recording data to use in my final written report.