Deck 5: Stereochemistry at Tetrahedral Centers

Question 1

Instructions: Place asterisks at all the chirality centers in each molecule below.
Place asterisks:

Answer 1

Question 2

Instructions: Identify the indicated hydrogens in the following molecules as pro-R or pro-S.
Identify:

Answer 2

Question 3

Instructions: Consider the structure of streptimidone below to answer the following question(s).


Refer to instructions.Assign R or S configuration to each chirality center indicated in streptimidone.

Answer 3

Question 4

Instructions: Identify the indicated hydrogens in the following molecules as pro-R or pro-S.
Identify:

Question 5

Instructions: Consider the structure of streptimidone below to answer the following question(s).


Refer to instructions.Does streptimidone have a meso stereoisomer? Explain.

Question 6

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 these

Question 7

(-)-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.

Question 8

Rank the following substituent groups from highest to lowest priority according to the sequencing rules.
CO₂CH₃ CO₂H OH Cl

Question 9

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.

Question 10

Which of the following has a plane of symmetry?

A)boot
B)laboratory beaker
C)hammer
D)both b and c
E)none of these

Question 11

Instructions: In the molecules below,assign R,S configurations to the chirality center indicated with an arrow.

Refer to instructions.The configuration of this carbon atom is _____.

Question 12

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

Question 13

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

Question 14

Instructions: Place asterisks at all the chirality centers in each molecule below.
Place asterisks:

Question 15

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

Question 16

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.

Question 17

Which of the following physical properties can be used to identify a compound?

A)R
B)S
C)a
D)[a]_D

Question 18

Instructions: Place asterisks at all the chirality centers in each molecule below.
Place asterisks:

Question 19

Instructions: In the molecules below,assign R,S configurations to the chirality center indicated with an arrow.

Refer to instructions.The configuration of this carbon atom is _____.

Question 20

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 -18.48 ^$\circ$ .What is the specific rotation of this unknown and specify if the compound is levorotatory or dextrorotatory?

Question 21

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

Question 22

Which of the following have the R configuration?

A)only 1
B)only 2
C)only 1 and 2
D)1,2 and 3

Question 23

Which of the following have the S configuration?

A)only 1
B)only 2
C)only 1 and 2
D)1,2 and 3

Question 24

How many stereoisomers of 3-bromo-2-butanol exist?

A)1
B)2
C)3
D)4

Question 25

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 these

Question 26

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

Question 27

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

Question 28

How many stereoisomers of 2,3-dimethylbutane exist?

A)1
B)2
C)3
D)4

Question 29

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

Question 30

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

Question 31

How many stereoisomers of 3-chloro-2-methylbutane exist?

A)1
B)2
C)3
D)4

Question 32

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

Question 33

Which of the following structures contain a plane of symmetry?

A)1
B)2
C)3
D)All three contain a plane of symmetry