STUDYING INTERMEDIATES OF OLEFIN METATHESIS USING PARAHYDROGENS TO INDUCE HYPERPOLARIZATION
Roberto Naranjo Jr, Louis Bouchard, Stefan Gloeggler.
University of California, Los Angeles, Los Angeles, CA.
Olefin metathesis is an important reaction in the petrochemical industry, which provides high energy hydrocarbons that are used in everyday life. The reaction takes two smaller carbon chains and connects them through their double bond creating a longer hydrocarbon chain with high energy. In order to develop an efficient, synthetic alternative to our diminishing natural supply, understanding the mechanism and the intermediate molecules of the olefin metathesis reaction are needed. This knowledge will allow us to prepare a continuous-flow alkane metathesis reaction that would be beneficial to the industry. Dimethyl acetylenedicarboxylate was hydrogenated with parahydrogens and then pushed in the reactor in an NMR magnet. Inside the reactor, the dimethyl maleate (after hydrogenation) will undergo olefin metathesis catalyzed by Grubb’s catalyst. Using NMR spectroscopy and gas chromatography mass spectrometry, we will determine the optimal conditions and mechanism of the metathesis reaction. By using parahydrogens during the metathesis reaction, we observed a heightened signal approximately 102 - 104 times stronger and sharper in contrast to orthohydrogens. The double bond in the catalyst attached to our reactant creates a unique, intermediate molecule that is visible in the NMR machine with a hyperpolarized signal. The experiments gave us a good understanding of the mechanism and conditions under which the metathesis is more efficient. These results can help in developing these longer hydrocarbon chains and biofuels through alkane metathesis and other catalyzed reactions that produce efficient, clean energy.