Solvent- and Catalyst-Free Transesterification of Phosphites with 1-Dodecanol: An Undergraduate Experiment Based on 31P NMR Kinetic Monitoring

Abstract This laboratory session describes the transesterification reaction involving diphenyl phosphite (DiPhPH) and 1-dodecanol. Based on previous optimization work carried out in our laboratory, the synthesis methodology involves heating the reaction mixture (DiPhPH and 1-dodecanol) in the complete absence of a catalyst or solvent, using a Kugelrohr-type distillation apparatus. Furthermore, the reaction product can be isolated without a time-consuming purification step (chromatography) or recrystallization, which is compatible with the duration of a standard laboratory session (4 h). This experiment has two educational benefits. The first is the study of the reactivity of two other phosphites; diethyl phosphite (DiEtPH) and dimethyl phosphite (DiMePH) compared with DiPhPH, achieved by monitoring the reaction kinetics using 31P nuclear magnetic resonance (NMR) spectroscopy. The second is demonstrating the importance of implementing experimental procedures that involve more environmentally friendly reaction conditions, such as solvent-free, catalyst-free, and purification-free reactions. The experiment was also seen as an opportunity to introduce students to 31P NMR spectroscopy as an alternative to thin-layer chromatography (TLC) for monitoring reaction progress. To achieve the objectives of this series of experiments, four laboratory sessions of 4 h each were scheduled. Students were evaluated at the end of these sessions based on a literature review they were required to complete prior to the laboratory sessions, as well as a written report they were required to submit in the form of an article published in a scientific journal.