1999spring-final

1999spring-final - Name: _ ID# _ 6-11-99 Chemistry 140C...

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Name: ________________________ ID# _________________ 6-11-99 1 Chemistry 140C Spring 1999 – Final Exam This exam accounts for 50% of the final grade. Time 8:00 – 11:00 a.m. Mark your final answer clearly and completely erase irrelevant information! Remember: Exams written in pencil will not be regraded! Additional pages are at the end for your convenience. Please indicate if your final answer should be found at the end of the exam. Good Luck! Your Name (Please Print): _____________________________ Your ID # : Question # 1: . ..................................................................... /40 Question # 2: . /35 Question # 3: . /20 Question # 4: . Question # 5: . /30 Question # 6: . Question # 7: . /25 Question # 8: . Question # 9: . Question # 10: . ................................................................... /45 Total ..................................................................................... /300
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Name: ________________________ ID# _________________ 6-11-99 2 1. Digitoxin (structure 1 ) is a steroidal glycoside isolated from the herb foxglove. It has a dramatic stimulatory effect on heart action. (a) Is digitoxin a reducing or a non-reducing carbohydrate derivative? (b) Identify all glycosidic linkages in digitoxin, and classify them as α or β . Show your answer on the structure depicted above. (c) Show the structure of products obtained when digitoxin is hydrolyzed in aqueous acid. (d) What products are formed when digitoxin is treated with dimethyl sulfate in aqueous NaOH, and then hydrolyzed in aqueous acid? 1 1 (Digitoxin) O HO HO O H 3 C O HO O H 3 C O HO O H 3 C OH R O HO HO O H 3 C O HO O H 3 C O HO O H 3 C OH R O S O OCH 3 H 3 CO H 3 O + /H 2 O NaOH/H 2 O
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Name: ________________________ ID# _________________ 6-11-99 3 2. The following experiments were conducted in order to elucidate the sequence of an octapeptide : Complete hydrolysis (6N HCl) followed by amino acid analysis indicated a ratio of: Ala (1), Asp (2), Gly (2), Leu (1), Lys (1) and Tyr (1). Treatment of the octapeptide with 1-fluoro-2,4-dinitrobenzene followed by 6N HCl hydrolysis produced N -(2,4-dinitrophenyl)alanine together with free Asp, Gly, Leu, Lys and Tyr.
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1999spring-final - Name: _ ID# _ 6-11-99 Chemistry 140C...

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