Resumen de 1H NMR Analysis of R/S Ibuprofen by the Formation of Diasteriomeric Pairs:: Microscale Stereochemistry Experiment for the Undergraduate Organic Laboratory
Stephanie E. Sen, Keith S. Anliker
A multicomponent experiment is described which elucidates the chirality of the commercially available analgesic, ibuprofen. This material, which is currently marketed in its racemic form, is converted into diastereomeric pairs by the formation of amide and ammonium salt derivatives with either (S)-(-)-alpha-methylbenzylamine or (1S,2S)-(-)-1,2-diphenylethylenediamine. Comparison of the 1H NMR spectrum obtained from recovered racemic ibuprofen with each of the derivatives shows differences which allow students to differentiate and quantify the (R) and (S) forms of the analgesic. Thus, in addition to demonstrating the differences in physical properties of enantiomeric and diastereomeric pairs, this experiment shows the utility of NMR spectroscopy in analyzing the enantiomeric purity of organic compounds by the formation of diastereomeric derivatives.
