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

Citronellal is a naturally occurring aldehyde derived from essential oils like citronella. In this laboratory activity, citronellal undergoes a cyclization reaction to form isopulegol, a chiral terpene with various applications. The reaction utilizes montmorillonite (MK10) clay as a catalyst in a buffer medium at room temperature for 2 hours. NMR Spectroscopy is used to characterize the product. The experiment demonstrates several green chemistry principles (1,2,3,4,5,6, 7,9, 10 & 12), which aim to make chemical processes more sustainable and environmentally friendly. This experiment aligns with SDG 12 by employing green chemistry principles to minimize environmental impact and make the chemical process more sustainable. The use of a green catalyst and mild reaction conditions demonstrates a commitment to reducing the ecological footprint of chemical processes.
The experiment can be approached in a traditional lab setup, where students follow a predefined procedure to carry out the cyclization reaction, extract isopulegol, and analyze it using NMR spectroscopy. It can also be done in a guided-inquiry format where students design their own experiments or troubleshoot the reaction conditions under guidance. This approach fosters critical thinking and problem-solving skills as students explore the reaction conditions, catalyst effectiveness, and product analysis in a more open-ended format.
A Green and Efficient Cyclization of Citronellal into Isopulegol: Undergraduate Research and Guided Inquiry for Organic Chemistry Students. S. Ritter and L. Abraham. J. Chem. Educ. 2022, 99, 4134-4142