A Green and Efficient Cyclization of Citronellal into Isopulegol: A Guided-Inquiry Organic Chemistry Laboratory Experiment

Abstract

This project introduces green chemistry to the undergraduate laboratory through two pedagogical techniques: undergraduate research and guided-inquiry. Through these two learning activities, an efficient synthetic procedure for the PRINS cyclization of citronellal into isopulegol, focused on minimizing negative environmental impact, was developed. This project involved two stages. First, a senior undergraduate student applied the principles of green chemistry to the cyclization of citronellal, a naturally occurring aldehyde, into isopulegol, a commercially important compound. The cyclization reaction was achieved in high yield with montmorillonite (MK10) catalyst in buffer medium at room temperature stirring for 2 h. Second, the student researcher, with faculty supervision, transformed this study into a laboratory experiment for Organic Chemistry II students, using inquiry-based pedagogy. Through this project, the student researcher gained experience applying green chemistry principles in the field and in the classroom. The organic chemistry students likewise benefitted, as they gained autonomy, interest in green chemistry, and confidence in the research process, according to the results of a student survey. Thus, this study allowed both the student researcher and the organic chemistry students to expand their experience, autonomy, and appreciation for and application of green chemistry.

Analysis of complex mixtures with benchtop nuclear magnetic resonance: Solvent suppression with T2 and diffusion filters

“…Benchtop NMR spectrometers are being used in many different fields ranging from academic teaching, natural product research, food industry to process, and reaction monitoring in industrial settings. [2][3][4][5] However, due to the lower magnetic field strength, NMR signatures that are well resolved from one another at higher magnetic fields might overlap in low-field NMR. 6 In addition, the use of fully protonated-process-solvents, along with the presence of macromolecules in complex mixtures, might impact proper quantitation of the analytes of interest.…”

“…The small size, robustness, and low cost of ownership of these compact instruments enables incorporation of NMR as an analytical technique into a number of practical applications, where NMR spectroscopy was not a viable option before. Benchtop NMR spectrometers are being used in many different fields ranging from academic teaching, natural product research, food industry to process, and reaction monitoring in industrial settings 2–5 . However, due to the lower magnetic field strength, NMR signatures that are well resolved from one another at higher magnetic fields might overlap in low‐field NMR 6 .…”