Chem 3BL - Lab Report E#16 - Kylie 15 September 2010 Chem...

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Kylie 15 September 2010 Chem 3B Lab Experiment #16 Discussion: NMR Spectra: on the following pages In order to determine the structure of the reaction's product, I first looked at a-pinine oxide's structure and found a reactive center where it could become protonated by sulfuric acid. Based on the TLC data, the product would be highly polar (more than the decomposed product – suggesting two -OH groups/hydrogen-bonding sites) and wouldn't have a conjugated structure. An option for such molecule was trans-sobrerol, and it matched the melting point data as well as the white crystalline-like appearance. It was necessary to analyze the mass spectrum to confirm the relative locations of the carbons and two oxygens, especially since there was no molecular weight data to confirm the presence of the two oxygens. The first step was to find out what substance had caused the decomposition of a-pinene oxide. Since a-pinene oxide undergoes carbocation rearrangement under acidic conditions, it was safe to assume that the slightly acidic silica gel on the TLC plate had protonated a-pinene oxide. The first TLC plate showed the relative polarities of pure a-pinene oxide (in hexane), the hexane filtrate that contained a-pinene oxide and sulfuric acid, the mother liquor (which contained the product and impurities), and the recrystallized product. Pure a-pinene oxide had the highest Rf value, which showed that it became a more polar molecule in acidic conditions; it reacted with the TLC plate's acidic silica gel, creating a product with an iodine spot below its
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This note was uploaded on 06/27/2011 for the course CHEM 3BL taught by Professor Chunmei during the Fall '08 term at University of California, Berkeley.

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Chem 3BL - Lab Report E#16 - Kylie 15 September 2010 Chem...

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