Synthesis and Analysis of a Versatile Imine for the Undergraduate Organic Chemistry Laboratory

Abstract

An important synthesis omitted from organic laboratory texts is that of imine preparation, a particularly relevant intermediate both synthetically and biologically. In this experiment students prepare and analyze N-p-methoxyphenyl (N-PMP) α-imino ethyl glyoxalate, an imine that has been used in the synthesis of biologically active molecules. In the first step, an ethyl acetate solution of p-anisidine and ethyl glyoxalate is reacted in the presence of molecular sieves at room temperature for 15 minutes or one week. The adapted literature technique used methylene chloride as the solvent, but ethyl acetate was an equally effective greener alternative. Students then vacuum distill the Celite-filtered reaction mixture to remove solvent. The imine product can then be analyzed by standard organic instrumental techniques, such as 1H NMR and GC–MS. The workup and analysis take 2–3 hours to complete, depending on instrument availability. Thus, the entire experiment can either be completed in one or two laboratory...