Isolation and Reactions of Cholesterol

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Carleton University | Isolation and Reactions of Cholesterol | S10-CHEM 2203 Formal Lab Report | Emily Giroux: 100-688-773 | Lab partner: Sarah Heinzle | TA: Jamie Davey | 5/26/2010 | 4-cholesten-3-one (C27H45O) was synthesized from its cholesterol (C27H45OH) precursor by sequentially brominating, oxidizing, debrominating, and isomerizing the compound to produce cholesterol dibromide, dibromocholestanone, 5-cholesten-3-one and 4-cholesten-3-one. Recrystallization and FT-IR spectroscopy were the main techniques used to purify and confirm identity and purity of the compounds, respectively. Functional group characterization by FT-IR spectra analysis of the 5-cholesten-3-one and 4-cholesten-3-one samples resembled the literature spectra of the pure compounds. The 5 cholesten-3-one and 4-cholesten-3-one sample spectra produced absorbance peaks from 3000-2800cm-1 characteristic of their carbon skeleton and hydrocarbon tail. The 5-cholesten-3-one sample spectra also possessed mainpeaks at 1718cm-1 and 1468cm-1, indicative of the compound’s unconjugated ketone and alkene bond, respectively. The 4-cholesten-3-one sample spectra produced absorbance peaks at 1677cm-1 and 1466cm-1, characteristic of the compound’s conjugated ketone and alkene bond, respectively. The minor presence of the hydroxyl functional group was noted in the 5-cholesten-3-one sample spectra, and of conjugated and unconjugated ketone groups in the 5-cholesten-3-one and 4-cholesten-3-one sample spectra, respectively. The recovery of 5-cholesten-3-one from cholesterol was 18.9%. This yield was significantly affected by the loss of product due to a spill during the debromination process. The recovery of 4-cholesten-3-one from 5-cholesten-3-one was 82.7%. The FT-IR spectra obtained for the sample compounds confirmed that the reactions employed throughout the synthesis of 4-cholesten-3-one were
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