A Citrus Serenade: An Improved Procedure for the Imine Condensation Reaction in Undergraduate Laboratories

The imine condensation reaction is commonly addressed in second semester organic chemistry classrooms. With recent pushes toward green chemistry and developing safer reactions, there is a growing interest in attempting organic reactions in the presence of water or aqueous solvents. The work discussed here provides an important update to a previously reported laboratory experiment that utilizes freshly squeezed fruit juices and water as the reaction solvents to compare the reactivity of the imine condensation with respect to steric, electronic, and pH effects. Five different aromatic benzaldehyde derivatives are reacted with n-butylamine, sec-butylamine, and tert-butylamine in the presence of an aqueous solvent. Students from multiple sections were able to successfully perform the updated reaction and analyze the products with 1H NMR spectroscopy, calculate the percent conversion for each reaction, and analyze reaction trends. The conversion rates for this imine condensation laboratory experiment greatly exceed those from our previously reported study which utilized organic solvents ( J. Chem. Educ. 2023, 100 (1111), 4456). Strategies for implementation of this updated imine condensation project are presented.