At Cal Poly, San Luis Obispo we offer an upper division spectroscopy laboratory course that introduces our majors to the characterization of organic molecules using advanced techniques. The traditional format includes analysis of Mass Spectral Data, 1H and 13C Nuclear Magnetic Resonance (NMR) data, and a variety of two-dimensional NMR such as 1H-1H COSY, 1H-13C HMQC, 1H-13C HMBC and NOESY experiments. Our recent efforts have been to expand this curriculum into the characterization of nitrogen containing molecules. Unfortunately, the low relative abundance and gyromagnetic ratio of nitrogen makes one-dimensional nitrogen NMR difficult to obtain in the timeframe of an undergraduate laboratory. The advantage of the 1H-15N HMBC and HSQC indirect detect method is that students have been able to obtain data in a three hour lab setting. The alkaloids we examined for this study were caffeine, xanthine and adenine. Our results indicate that these alkaloids give correlations within an acceptable timeframe, which allows for both a classroom discussion of nitrogen chemical shifts and the determination of molecular structure of unknowns.

Exploiting 1H-15N two-dimensional nuclear magnetic resonance correlations in the characterization of alkaloids in an advanced organic spectroscopy course

251st National Meeting (2016)

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