midterm 2

midterm 2 - Sample Questions Nicolas Moitessier CHEM 212...

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Sample Questions CHEM 212 Nicolas Moitessier 23 Stereochemistry 1. Chiral molecules are represented by: C 6 H 5 H 3 C Cl H 3 C C 6 H 5 Cl CH 3 H 3 C C 6 H 5 H 3 C Cl H H H 3 C Cl C 6 H 5 C 6 H 5 H H ClH 2 C AB C DE Ans.: C and D 2. Which compound does NOT possess a plane of symmetry? Ans.: V 3. Which structure represents (S)-1-chloro-1-fluoroethane? CH 3 Cl H F CH 3 H Cl F F H Cl H 3 C C Ans.: A and C 4. The Cahn-Ingold-Prelog stereochemical designations used for the following compound are:
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Sample Questions CHEM 212 Nicolas Moitessier 24 A) 2R,4S B) 2S,4R C) 2R,4R D) 2S,4S E) The R,S terminology doesn't apply in this case. Ans.: C 5. Which one of the following can exist in optically active forms? A) cis -1,3-Dichlorocyclohexane B) trans -1,3-Dichlorocyclohexane C) cis -1,4-Dichlorocyclohexane D) trans -1,4-Dichlorocyclohexane E) cis -1,2-Dichlorocyclohexane Ans.: B 6. What can be said with certainty if a compound has [ ± ] D 25 = -9.25º ? A) The compound has the (S) configuration. B) The compound has the (R) configuration. C) The compound is not a meso form. D) The compound possesses only one stereogenic center. E) The compound has an optical purity of less than 100%. Ans.: C 7. CH 3 CHBrCHBrCHBrCH 3 is the generalized representation of what number of stereoisomers? Ans.: 4 8. Which of the following compounds B, C D or E is the enantiomer of A? H H CH 3 F H H 3 C H F H H F H 3 C H H 3 C F F CH 3 H 3 C H F AB C DE Ans.: A does not have a non-superposable enantiomer 9. The following two molecules are:
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Sample Questions CHEM 212 Nicolas Moitessier 25 H CH 3 Cl Cl H H H Cl H 3 C Cl H H A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these. Ans.: B 10. The following two molecules are: H CH 3 Cl Cl H H H Cl H Cl H H 3 C A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these. Ans.: D 11. The following two molecules are: H CH 3 Br Cl H H H Cl H 3 C Br H H A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these. Ans.: A 12. The following two molecules are:
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Sample Questions CHEM 212 Nicolas Moitessier 26 H CH 3 Br Br Et H H Br Et Br H 3 C H A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these. Ans.: C 13. Which molecule is achiral? H CH 3 Br Br H 3 C H H Br H 3 C Br H 3 C H Br CH 3 Br H Et H H 3 C Br Et Br H H AB C D E H 3 C Br H 3 C Br Br H Ans.: A, C and E 14. Which of the following is a meso compounds? H CH 3 HO OH H 3 C H H OH H 3 C OH H 3 C H H 3 C CH 3 HO OH H 3 C H H 3 C Br Et Br H H ABC D E H 3 C Br H 3 C Br Br H H CH 3 HO OH H H F CH 2 OH H CH 3 HO G Ans.: A 15. Which compound does NOT possess a plane of symmetry?
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Sample Questions CHEM 212 Nicolas Moitessier 27 Ans.: V 16. Which of the following represent (R)-2-butanol? CH 2 CH 3 H 3 C OH H CH 2 CH 3 H OH H 3 C CH 2 CH 3 HO CH 3 H CH 2 CH 3 HO H H 3 C CH 3 H OH H 3 CH 2 C AB C DE Ans.: A, D and E 17. What is the percent composition of a mixture of (S)-(+)-2-butanol,[ ± ] D 25 = +13.52º, and (R)-(-)-2-butanol,[ ± ] D 25 = -13.52º, with a specific rotation [ ± ] D 25 = +6.76º?
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This note was uploaded on 11/15/2010 for the course CHEM 212 taught by Professor Harpp during the Spring '08 term at McGill.

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midterm 2 - Sample Questions Nicolas Moitessier CHEM 212...

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