Koofer - am U IC University of Illinois at Chicago CHEM 233...

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UIC University of Illinois at Chicago CHEM 233: Organic Laboratory I Midterm Exam: Spring 2009 Exam Time: 90 minutes Instructor: Dr. Chad Landrie Instructions and Policies: 1. Do not open or begin exam until instructed. 2. Place your UIC ID on your desk. No ID = No exam . 3. Verify that the information on the label below is correct. 4. Sign your full name below the label in ink . 5. Write answers legibly with a pen or pencil in th spaces provided. Answers and work outside the spaces provided will not be graded. 6. For full credit, show all work and equations wher appropriate. 7. Only handheld calculators may be used for mathematical work. 8. No cell phones , wireless earpieces PDAs iPODs, laptops or similar devices may be used at anytime during the exam. Use o these tems, however briefly, will result in immediate exam confiscation and failure. 9. A periodic table has been pro ided for you on the last page of the exam. 10. When finished, turn your ex m into YOUR TA only. Exams that are not personally returned to YOUR TA or that leave the classroom at anytime, will not be graded. ___________________________ Signature _____________ / 100 points Place Seating Label Here Sample Exam
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1. (10 pts) Consider the experimental description below for the steam distillation of carvone from caraway seeds. The experimental methods and analyses contain a number of mistakes and oversights. Based on your own investigation, find 10 of these errors and briefly explain the nature of the error as well as a suitable correction. No explanation & correction = no credit. List corrections below; do not make corrections within the paragraph itself. Two diastereomers of carvone, which are diterpene natural products derived from 10-carbon isopropyl fragments, were isolated from spearmint seeds by steam distillation. The seeds were dissolved in water and steam was generated in situ by boiling water directly in the stillpot. The cloudy distillate was poured into a separatory funnel and extracted with ethanol. The organic layers were combined and then Na 2 CO 3 was added to remove trace impurities. After filtering, the majority of the solvent was removed by boiling/evaporation leaving a fragrant oil. Infrared spectroscopy of the oil indicated the resenc of an alkene (~2200 cm -1 ) and an ester (~1675 cm -1 ), which supported the conclusion that carvone was isolated. Finally, thin layer chromatography showed that the isolated oil had a smaller R f -value compared to an authentic sample of car one.
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This note was uploaded on 08/23/2011 for the course BIOCHEM 352 taught by Professor Nicholas during the Spring '11 term at Ill. Chicago.

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Koofer - am U IC University of Illinois at Chicago CHEM 233...

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