exams_exam_3_answers - wd ‘mq c." Chemistry 239...

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Unformatted text preview: wd ‘mq c." Chemistry 239 Autumn, 2005 Exam 3 Answer Key Your name: Student #: Sign here to indicate your approval of public return of your paper: 1 (24 pts.) Give structures or names for the compounds below. CHO OMe CHO OH H H H OMe H 0” OH H OH 1-naphthol CHZOMe CHZOH L-ribitol D—aliose 2-deOXy-D-ribose Fischer projection FiSChef fO'eCtion _ 2,3,4,6-tetra-O-methyi—D-glucose + , HO(CH2)2N(CH3)3 CH3(CH2)hC02H to § ~ stearic acid steroid ring system 2 (6 pts.) Complete a balanced equation for a proton transfer between the reactants below, label the stronger and weaker acids involved, and indicate whether the position of equilibrium is favorable (to the right) or unfavorable (to the left). N02 N02 N02 N02 OH + 0' ==== o“ + 0H stronger acid <— weaker acid w’ [more favorable stable] Chem 239 Autumn, 2005 Exam 3 Answer Key p. 2 3 (24 pts.) In the reactions below fill in the missing items (starting material[s], reagents and conditions over the arrow, or main organic product[s]). heat PhCOO—Q —————————-—> HO—Q'COPh or Ol‘on 0K AlCl3 CHO Ag+v NH3 [was __.__.. CHZOH OMe OMe + —-——-—> OMe 0M3 OMe OMe OMe OH 9 3HC02H + 2CH20 CHO CH==NH + CHO [H 0H] [H OH] H30 , [H OH] 3 4 4 CH20H CHZOH CHZOH 4 (8 pts.) Draw the structure of the aldaric acid that would be formed from D—altrose below. Indicate whether the aldaric acid would be optically active 'or not. Can you draw the structure of a different aldose that would give the same aldaric acid as that from D—altrose (explain)? CHO COZH the aldose to the right CHZOH CHO H0 H HO H (which is D-talose) HO H HO H‘ n. n would also give the same H : n H OH H OH aldanc acud 0H ' H OH CHZOH COZH ’ optically active H H ' Chem 239 Autumn, 2005 Exam 3 Answer Key p. 3 5 (12 pts.) A branched polysaccharide is hydrolyzed by a-glycosidase enzymes but not by B -glycosidase enzymes. Methylation followed by hydrolysis gives mainly 3,4,6— tri-O—methyl-D-mannose, along with a small amount of 4,6-di-O-methyl-D- mannose. Sketch the structure (showing all rings as chairs) of the branching \5 s... point of the polysaccharide, as well as the repeating chain structures leading away from the branch point. \ 6 (6 pts.) Classify the terpene cadinene (below) according to type of terpene (e.g., monoterpene, etc.) and outline how isoprene skeletons might form the structure. [ml 4N an}? WFRM mtwu Chem 239 Autumn, 2005 Exam 3 Answer Key p. 4 7 (10 pts.) Show curved arrows for all steps in the mechanism to form the alcohol below from the terpene terpene cation shown (below, right side) from + OH 8 (10 pts.) A naturally occuring monoterpene hydrocarbon reacts with 2 mol equiyalents of hydrogen upon catalytic hydrogenation to give 1—methyl—4— ‘ isopropylcyclohexane. Ozonolysis of the monoterpene gives the products shown below (1 mol equiv. each). Propose a structure for the monoterpene and show shorthand equations for both reactions. 8 f? CchCHZCHZCi‘HCCHg CHZCHO + CHZO ...
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This test prep was uploaded on 04/15/2008 for the course CHEM 239 taught by Professor Sasaki during the Spring '06 term at University of Washington.

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exams_exam_3_answers - wd ‘mq c.&amp;quot; Chemistry 239...

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