Organic Chemistry With Biological Applications International Edition 2nd Edition by John E. McMurry - Test Bank

Organic Chemistry With Biological Applications International Edition 2nd Edition by John E. McMurry - Test Bank   Instant Download - Complete Test Bank With Answers     Sample Questions Are Posted Below   Chapter 5 – Stereochemistry at Tetrahedral Centers Match each definition to a term from the list below. Place the letter of the …

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Organic Chemistry With Biological Applications International Edition 2nd Edition by John E. McMurry – Test Bank

 

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Sample Questions Are Posted Below

 

Chapter 5 – Stereochemistry at Tetrahedral Centers
Match each definition to a term from the list below. Place the letter of the term in the blank to the left of the definition.
a. racemates f. meso compounds
b. chirality center g. optically active
c. chirality h. prochirality center
d. diastereomers i. optically inactive
e. enantiomers j. achiral
1.           describes organic molecules which rotate plane-polarized light.
ANS: g or e
2.           are designated either (±) or d,l.
ANS: a
3.           are stereoisomers that are not mirror images.
ANS: d
4.           is an atom in a molecule that is bonded to four different atoms or groups of atoms.
ANS: b
5.           are molecules which contain both chirality centers and a plane of symmetry.
ANS: f
6. _____ describes an sp3-hybridized atom that can become a chirality center by changing one of its attached groups.
ANS: h
7. Which of the following physical properties can be used to identify a compound?
a. R
b. S
c. *
d.
ANS: d
8. Which of the following has a plane of symmetry?
a. boot
b. laboratory beaker
c. hammer
d. both b and c
e. none of the above
ANS: d
9. If (+)-sucrose has a specific rotation of +66.47, what is the specific rotation of (-)-sucrose?
a. +66.47
b. -66.47
c. +33.43
d. -33.43
e. Must be determined with a polarimeter.
ANS: b
10. (-)-cholesterol
a. does not have a chiral center.
b. is dextrorotatory
c. rotates the plane of polarized light counterclockwise.
d. does not rotate polarized light.
ANS: c
11. The biological importance of enantiomers arises from?
a. Biological reactions involve receptor molecules.
b. Biological receptors are chiral.
c. Biological receptors require a specific enantiomer for reaction.
d. Each enantiomer has different biological properties.
e. all of the above
ANS: e
12. 2.10 g of an unknown compound was dissolved in 15.00 mL of ethanol.  The sample was placed in a 10.0 cm cell in a polarimeter and the angle of rotation was determined to be -18.48o.  What is the specific rotation of this unknown and specify if the compound is levorotatory or dextrorotatory?
ANS: -132 and levorotatory
Place asterisks at all the chirality centers in each molecule below.
13.
ANS:
14.
ANS:
15.
ANS:
16. Rank the following substituent groups from highest to lowest priority according to the sequencing rules.
CO2CH3CO2HOHCl
ANS:
Cl   >   OH   >   CO2CH3    >   CO2H
17. The numbers on the carbon center of the following molecule represent atomic numbers.
The molecule is in
a. the R configuration.
b. the S configuration.
c. The carbon is not a chiral center in this molecule.
d. The exact configuration cannot be determined without knowing additional atomic numbers.
ANS: b
18. The following atoms are commonly encountered in organic molecules.  For which is it not possible to isolate enantiomers due to rapid inversion?
a. trivalent phosphorus
b. trivalent nitrogen
c. divalent sulfur
d. trivalent sulfur
e. both b and c
ANS: b
In the molecules below, assign R, S configurations to the chirality center indicated with an arrow.
19. The configuration of this carbon atom is          .
ANS: R
20. The configuration of this carbon atom is          .
ANS: S
Consider the structure of streptimidone to answer the questions below:
21. Assign R or S configuration to each chirality center indicated in streptimidone.
ANS:
22. Does streptimidone have a meso stereoisomer? Explain.
ANS: No. Meso compounds are compounds that contain chirality centers but possess a plane of symmetry. Because the substituents on each chiral carbon are different in streptimidone, it is impossible for any stereoisomer to have a plane of symmetry.
Label each pair of molecules below as:
a. enantiomers
b. diastereomers
c. identical
23.
ANS: a
24.
ANS: c
25.
ANS: b
26.
ANS: b
27.
ANS: c
Identify the indicated hydrogens in the following molecules as pro-R or pro-S.
28.
ANS:
29.
ANS:
30. Which of the following is the definition of a pair of enantiomers?
a. A pair of structures that are superimposable mirror images of one another
b. A pair of stereoisomers that are non-superimposable mirror images of one another
c. A pair of stereoisomers that are not mirror images of one another
d. A pair of stereoisomers that have equal specific rotations
ANS: b
31. Which of the following is the definition of a pair of diastereomers?
a. A pair of structures that are superimposable mirror images of one another
b. A pair of stereoisomers that are non-superimposable mirror images of one another
c. A pair of stereoisomers that are not mirror images of one another
d. A pair of stereoisomers that have equal specific rotations
ANS: c
32. Which of the following correctly describes a molecule that is achiral?
a. Non-superimposability of the molecule on its mirror image
b. Superimposability of the molecule on its mirror image
c. Contains a carbon atom with four different substituents
d. Does not have a plane of symmetry
e. Both b and d.
ANS: b
33. Which of the following is the definition of a meso compound?
a. A molecule with chirality centers which is chiral
b. A molecule with chirality centers which is not chiral
c. A diastereomer with no chirality centers
d. A chiral compound with more than one chirality center
ANS: b
34. Which of the following statements is 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 produce different products in reactions with chiral reagents
e. all of the above
ANS: e
35. Which of the following compounds is/are achiral?
a. only 1
b. only 1 and 2
c. only 2 and 3
d. 1, 2 and 3
ANS: c
36. Which of the following have the S configuration?
a. only 1
b. only 2
c. only 1 and 2
d. 1, 2 and 3
ANS: c
37. Which of the following have the R configuration?
a. only 1
b. only 2
c. only 1 and 2
d. 1, 2 and 3
ANS: d
38. Which of the following structures represent the same stereoisomer?
a. only 1 and 2
b. only 1 and 3
c. only 2 and 3
d. 1, 2 and 3
ANS: c
39. How many stereoisomers of 2,3- dimethylbutane exist?
a. 1
b. 2
c. 3
d. 4
ANS: a
40. How many stereoisomers of 3-chloro-2-methylbutane exist?
a. 1
b. 2
c. 3
d. 4
ANS: b
41. How many stereoisomers of 3-bromo-2-butanol exist?
a. 1
b. 2
c. 3
d. 4
ANS: d
42.  Which of the following structures contain a plane of symmetry?
a. 1
b. 2
c. 3
d. All three contain a plane of symmetry
ANS: c
43. What is the relationship between the following pair of structures?
a. They are enantiomers
b. They are diastereomers
c. The are constitutional isomers
d. They are identical
ANS: b
44. What is the relationship between the following pair of structures?
a. They are enantiomers
b. They are diastereomers
c. The are constitutional isomers
d. They are identical
ANS: a
45. Which of the following structures is (are) chiral?
ANS: a and c

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