Deck 6: Sterechemistry at Tetrahedral Centers

Question 1

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

Answer 1

both b and c

Question 2

Match each definition to a term from the list below.
Is an atom in a molecule that is bonded to four different atoms or groups of atoms.

A)racemates
B)chirality center
C)chirality
D)diastereomers
E)enantiomers
F)meso compounds
G)optically active
H)prochirality center
I)optically inactive
J)achiral
K)chirality center or meso compounds
L)enantiomers or optically active
M)optically active or optically inactive

Answer 2

chirality center

Question 3

Match each definition to a term from the list below.
Are designated either (±) or d,l.

A)racemates
B)chirality center
C)chirality
D)diastereomers
E)enantiomers
F)meso compounds
G)optically active
H)prochirality center
I)optically inactive
J)achiral
K)chirality center or meso compounds
L)enantiomers or optically active
M)optically active or optically inactive

Answer 3

racemates

Question 4

Match each definition to a term from the list below.
Describes an sp³-hybridized atom that can become a chirality center by changing one of its attached groups.

A)racemates
B)chirality center
C)chirality
D)diastereomers
E)enantiomers
F)meso compounds
G)optically active
H)prochirality center
I)optically inactive
J)achiral
K)chirality center or meso compounds
L)enantiomers or optically active
M)optically active or optically inactive

Question 5

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

Question 6

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 7

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

A) R
B) S
C) ( $\alpha$ )
D) ([ $\alpha$ ]_D)

Question 8

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

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

Match each definition to a term from the list below.
Are stereoisomers that are not mirror images.

A)racemates
B)chirality center
C)chirality
D)diastereomers
E)enantiomers
F)meso compounds
G)optically active
H)prochirality center
I)optically inactive
J)achiral
K)chirality center or meso compounds
L)enantiomers or optically active
M)optically active or optically inactive

Question 11

Instructions: Consider the structure of streptimidone below to answer the following question(s). streptimidone
Refer to instructions. Does streptimidone have a meso stereoisomer? Explain.

Question 12

Instructions: In the molecules below, assign R, S configurations to the chirality center indicated with an arrow.
Refer to instructions. The configuration of the carbon atom labeled 19 is _____.

Question 13

Instructions: Consider the structure of streptimidone below to answer the following question(s). streptimidone
Refer to instructions. Assign R or S configuration to each chirality center indicated in streptimidone.

Question 14

Match each definition to a term from the list below.
Are molecules which contain both chirality centers and a plane of symmetry.

A)racemates
B)chirality center
C)chirality
D)diastereomers
E)enantiomers
F)meso compounds
G)optically active
H)prochirality center
I)optically inactive
J)achiral
K)chirality center or meso compounds
L)enantiomers or optically active
M)optically active or optically inactive

Question 15

(-)-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 16

Match each definition to a term from the list below.

Describes organic molecules which rotate plane-polarized light.

A)racemates
B)chirality center
C)chirality
D)diastereomers
E)enantiomers
F)meso compounds
G)optically active
H)prochirality center
I)optically inactive
J)achiral
K)chirality center or meso compounds
L)enantiomers or optically active
M)optically active or optically inactive

Question 17

Instructions: In the molecules below, assign R, S configurations to the chirality center indicated with an arrow.
Refer to instructions. The configuration of the carbon atom labeled 20 is _____.

Question 18

Instructions: Place asterisks at all the chirality centers in each molecule below.
Rank the following substituent groups from highest to lowest priority according to the sequencing rules.
CO₂CH₃,CO₂H,OH,Cl

Question 19

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

Question 20

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 21

Which of the following structures contain a plane of symmetry?

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

Question 22

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 23

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 24

Instructions:
Refer to the structure below to answer the following questions.

-Refer to instructions. (S)-(-)-Serine:

A) is dextrorotatory
B) rotates plane-polarized light in a counterclockwise direction
C) rotates plane-polarized light in a clockwise direction
D) is racemic

Question 25

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

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

Question 26

How many stereoisomers of 2,3-dimethylbutane exist?

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

Question 27

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 28

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 29

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 30

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 31

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 32

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

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

Question 33

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 34

A natural product having [ $\alpha$ ]_D = +40.3° has been isolated and purified. This information indicates that the natural product:

A) is racemic.
B) does not rotate plane-polarized light.
C) is levorotatory.
D) is dextrorotatory.

Question 35

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 36

Instructions:
Refer to the structure below to answer the following questions.

-Refer to instructions. Draw the enantiomer of (S)-(-)-serine in a wedge-dash projection.

Question 37

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 38

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 39

Instructions:
Refer to the structure below to answer the following questions.

-Refer to instructions. Give the complete name of the enantiomer of (S)-(-)-serine.