北京化工大学：《有机化学》课程教学资源（章节测验，含答案）Chapter 05 Stereoisomers

How many chiral centers are present in B-cadinene? CH3 CH(CHs)2 B)1 C)2 D)3 E)4 enantiomer only.) H,C、H Hc-ch？ D B)4 C)5 D)6 E)8 3.Optically pure (S-monosodium glutamate has a specific rotation of+24What +24° B)-24° C)-18 Ans:D 4.What would be the complete name of the following? H -CH2- Hsc CH3 (2R,4S)-2-bromopentane (S)-2-bromo-4-methylpentane Ans: Page 1

Page 1 1. How many chiral centers are present in β-cadinene? CH3 CH(CH3)2 H3C A) none B) 1 C) 2 D) 3 E) 4 Ans: D 2. Counting all stereoisomers, how many monochlorinated products of the free-radical chlorination of (R)-2-bromobutane are possible? (Note that the starting compound is one enantiomer only.) H3C H3C CH2 Br H Cl2 hν ? A) 3 B) 4 C) 5 D) 6 E) 8 Ans: D 3. Optically pure (S)-monosodium glutamate has a specific rotation of + 24°. What specific rotation would (R)-monosodium glutamate of 50% optical purity have? A) + 24° B) - 24° C) - 18° D) - 12° E) + 18° Ans: D 4. What would be the complete name of the following? H3C C CH2 C CH3 CH3 H Br H A) (2R,4S)-2-bromopentane D) (2R,4R)-2-bromo-4-methylpentane B) (R)-2-bromo-4-methylpentane E) (S)-2-bromo-4-methylpentane C) (S)-4-bromo-2-methylpentane Ans: B

5.How many total stereoisomers of the following are possible? I HO OH 0 OH HOH A)1B)2C)3D)4E)6 Ans:D 6.How many total stereoisomers of the following are possible OH CO,H B)2C)3 D)4E)6 7.How many total stereoisomers of the following are possible? H HO OH o OH HO A)1B)2C)3D)4E)6 Ans:C Page2

Page 2 5. How many total stereoisomers of the following are possible? O O OH HO OH H H HO H A) 1 B) 2 C) 3 D) 4 E) 6 Ans: D 6. How many total stereoisomers of the following are possible? HO2C CO2H OH CO2H A) 1 B) 2 C) 3 D) 4 E) 6 Ans: A 7. How many total stereoisomers of the following are possible? O O OH HO H HO OH H A) 1 B) 2 C) 3 D) 4 E) 6 Ans: C

hamines below might be appropriate for the resoion of acemi 人C Page3

Page 3 8. Which of the amines below might be appropriate for the resolution of racemic Ibuprofen? CO2H CH3 Ibuprofen A) H3C N H H B) H3C N H CH3 (racemic) C) H N H H3C CH3 D) N H H3C H H CH3 E) H3C N H H CH3 Ans: E

9.Which of the following Fischer projections represents(2R.3R)-tartaric acid? A) CO2H COZH B) CO2H -OH 0H CO2H CO2H CO2H CO2H -H H- OH 10.Which of the following statements is not true? A)Enantiomers have identical properties except in chiral environments or with B) 8 Enantiomers exhibit equal and opposite optical rotations. E)All of the above are true. Ans:C Page4

Page 4 9. Which of the following Fischer projections represents (2R,3R)-tartaric acid? A) CO2H CO2H H OH H OH B) CO2H CO2H HO H H OH C) CO2H CO2H HO H HO H D) CO2H CO2H H OH HO H E) none of the above Ans: B 10. Which of the following statements is not true? A) Enantiomers have identical properties except in chiral environments or with plane-polarized light. B) Reactions involving only achiral or racemic materials must produce achiral or racemic products. C) Diastereomers have identical properties in all environments. D) Enantiomers exhibit equal and opposite optical rotations. E) All of the above are true. Ans: C

11.How many stereogenic (chiral)centers are found in Rhizoxin? Rhizoxin HO.0:] 义人 H A)5B)7C)9D)11E)14 Ans:D Ans:E 13.The following two molecules may be described as: 8mdonos 14.The following molecule has how many possible stereoisomers? B)4C)8 16 E)32 Page5

Page 5 11. How many stereogenic (chiral) centers are found in Rhizoxin? O O O O O CH3 H H O H H CH3 H HO H H CH3 H OCH3 H N O Rhizoxin A) 5 B) 7 C) 9 D) 11 E) 14 Ans: D 12. The meso isomer of 3,4-dibromohexane has what stereochemical configuration? A) 3R, 4S B) 3R, 4R C) 3S, 4S D) 3S, 4R E) both A and D Ans: E 13. The following two molecules may be described as: A) constitutional isomers D) structural isomers B) diastereomers E) none of the above C) enantiomers Ans: B 14. The following molecule has how many possible stereoisomers? O A) 1 B) 4 C) 8 D) 16 E) 32 Ans: E

15.The correct structure for(R)-bromofluoroiodomethane is: A) I- Br 一H c) H- D B B Ans:A 16. The relationship between the following two compounds is: 0 H,. H Me Meo CO,Me CO2Me same molecule Ans:C Page6

Page 6 15. The correct structure for (R)-bromofluoroiodomethane is: A) I H Br F B) I Br H F C) H Br F I D) Br H I F E) F I H Br Ans: A 16. The relationship between the following two compounds is: O O Me CO2Me H Me O O Me CO2Me H Me A) same molecule D) mesos B) enantiomers E) conformers C) diastereomers Ans: C

17.A particular reaction produces the following two alcohols in a ratio of95:5 95:5 The enantiomer A)100 D)85 E)none of the above Ans:C 18.(S)-Naproxen,[alp=+66,is an analgesic (pain reliever),while its enantiomer is toxic Say that you were given a solution that contains 1 g of Naproxen in 20 mL of liquid,but the optical purity is not specified.You place it in a polarimeter tube(10 cm)and get a reading of+3.3 from the polarimeter.What is the percent optical purity of the sample B)100 C)0 D)10 E)75 19.Which of the following molecules have the S configuration? H H H.cBr H火 Et (CH3)C" iso-propyl Br B)L,ⅢC)Ⅲ，IV D)I,II,IV E)all of the above 20.What(R)or(S)stereochemistry is proper for the following molecule? HC、/ cH,CH, CiH A)(2R.3R) B)(2R,3S9 C)(2S,39 D)(25.3R)E)none of the above Ans:B Page7

Page 7 17. A particular reaction produces the following two alcohols in a ratio of 95:5. OH OH 95 : 5 The enantiomeric excess (% ee) is: A) 100 B) 95 C) 90 D) 85 E) none of the above Ans: C 18. (S)-Naproxen, [α]D = + 66°, is an analgesic (pain reliever), while its enantiomer is toxic. Say that you were given a solution that contains 1 g of Naproxen in 20 mL of liquid, but the optical purity is not specified. You place it in a polarimeter tube (10 cm) and get a reading of + 3.3° from the polarimeter. What is the percent optical purity of the sample? A) 50 B) 100 C) 0 D) 10 E) 75 Ans: B 19. Which of the following molecules have the S configuration? H Br H3C F (CH3)3C H H iso-propyl H3C Et D Br H I II III IV A) I, II B) I, III C) III, IV D) I, II, IV E) all of the above Ans: A 20. What (R) or (S) stereochemistry is proper for the following molecule? H3C C C CH2CH3 H Br Cl H 5 4 3 2 1 A) (2R,3R) B) (2R,3S) C) (2S,3S) D) (2S,3R) E) none of the above Ans: B

21.The best (most reliable)test for the presence of chirality inamolecue is carbon attached to four different groups. existanc of lity ble rror image F observation of optical rotation in a sample Ans:C 22.Which of the following molecules is not chiral? Ho是9HH HO2C CO,H HO2C OH CH2 CH Ans:D Page8

Page 8 21. The best (most reliable) test for the presence of chirality in a molecule is A) carbon attached to four different groups. B) existance of a mirror image. C) non-superimposability on mirror image. D) two or more isomers possible. E) observation of optical rotation in a sample. Ans: C 22. Which of the following molecules is not chiral? A) O B) O C) C C HO2C CO2H OH H H HO D) HO2C H2C C CH2 CO2H OH CO2H E) CH3 CH3 Ans: D

23.What would be the proper name of the following? OH (IR.2S 1 (15.2R)-trans-1.2-cyclohexanediol (1S.2R)-ci Ans:A Page9

Page 9 23. What would be the proper name of the following? OH OH A) (1R,2R)-trans-1,2-cyclohexanediol D) (1S,2S)-trans-1,2-cyclohexanediol B) (1R,2S)-trans-1,2-cyclohexanediol E) (1S,2R)-cis-1,2-cyclohexanediol C) (1S,2R)-trans-1,2-cyclohexanediol Ans: A

24.An unknown compound has been isolated in pure form and found to exhibit [a=+ 15(c=4,CH2Cl2).Which of the following might be the structure of the compound? A) Page 10

Page 10 24. An unknown compound has been isolated in pure form and found to exhibit [α]D = + 15° (c = 4, CH2Cl2). Which of the following might be the structure of the compound? A) H H B) H3C H3C H CH3 CH3 C) H3C CH3 H D) H3C H3C H H E) OH OH Ans: A