Structure Determination of Unknown Organic Liquids Using NMR and IR Spectroscopy: A General Chemistry Laboratory

This experiment introduced general chemistry students to the basic concepts of organic structures and to the power of spectroscopic methods for structure determination. Students employed a combination of IR and NMR spectroscopy to perform de novo structure determination of unknown alcohols, without being provided with a list of possible structures. Students used IR spectra to identify functional groups present, then constructed trial structures and predicted the NMR spectrum, modifying the structure until agreement was obtained. The structure was confirmed by comparison of boiling point and density data, measured in triplicate, to literature values, and the precision and accuracy of student measurements was critically evaluated.