Practice For Exam II

Practice For Exam II - Chemistry 261 Name(print) Some...

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Chemistry 261 Name(print) Some Practice Problems To Help Prepare for Exam II I. Give the stereochemical relationship between each pair of structures below. Use ONLY the terms: identical, geometric isomers, enantiomers, diastereomers, or structural isomers. READ CHOICES AGAIN. Cl CH 3 Cl OH H Cl Cl H OH Cl CH 3 Cl Cl H H Cl A. CH HO H H OH CH 3 H OH O CH 3 HO H H OH H HO CH O B. OH H CH 3 H 3 C H HO H HO CH 3 CH 3 OH H Cl HOOC COOH H 3 C CN CH 3 COOH NC HOOC CN Cl C. D. CN Cl Cl Cl Cl E.
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II. A. B. CH CHCH 3 O C. D. 3-methylcyclooctene E. CH CH Cl F Think carefullly! It's a bit different. O 2,5-dimethylcyclopentanol III. For the following structures, give the absolute configuration (R or S) for the designated carbon: CH 3 Cl H Br OH NC A. Front C: Back C: B. CH 2 OH HO H Cl OH CH 3 HO H 1 2 Carbon 1: Carbon 2: C. Cl H O CH 2 CH 3 H 3 C Carbon 1: Carbon 2: 1 2
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IV. Multiple Choice: Put the correct CAPITAL LETTER ANSWER 1. How many isomers of 1,3,5-heptatriene exist? (a) 1 (b) 2 (c) 4 (d) 8 (e) need more information 2. Which of the following is a definition of the rate-determining step of a reaction mechanism? (a) the first step (b) the last step (c) the step which crosses the highest energy barrier (d) the most exothermic step (e) the step just before the intermediate 3. Which of the following reactions of alkenes takes place with anti stereospecificity? (a) bishydroxylation (treatment with OsO 4 followed by NaHSO 3 ) (b) hydrogenation (treatment with H 2 /Pt) (c) addition of HBr (treatment with HBr) (d) bromohydrin formation (treatment with Br 2 , H 2 O) (e) none of the above 4. Which of the following alkenes undergoes the least exothermic hydrogenation upon treatment with H 2 /Pd? (a) 1 (b) 2 (c) 3 (d) 4 (e) need more information 5. What type of reactive intermediate is formed in the reaction of an alkene with Br 2 and water to give a bromohydrin? (a) carbocation (b) carbanion (c) radical (d) cyclic bromonium ion (e) a fleeting intermediate 6. What is (are) the major organic product(s) obtained from the following reaction? (a) only 1 (b) only 2 (c) only 3 (d) only 1 and 2 (e) none of the choices 7. Which of the following statements is not true regarding pairs of enantiomers? (a) They have identical melting points (b) They have identical boiling points (c) They rotate plane polarized light in opposite directions (d) They react at identical rates with chiral reagents (e) All of the above are true
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8. Which of the following structures does not have a plane of symmetry? (a) only 2 (b) only 1 and 2 (c) only 3 and 4 (d) only 1 , 2 and 4 9. How many stereoisomers of 4-chloro-2-methylpentane (CH 3 ) 2 CHCH 2 CHClCH 3 , exist? (a) 1
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Practice For Exam II - Chemistry 261 Name(print) Some...

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