Deck 5: Stereochemistry at Tetrahedral Centers

Question 1

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

Answer 1

Cl > OH > CO₂CH₃ > CO₂H

Question 2

(−)-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.

Answer 2

rotates the plane of polarized light counterclockwise.

Question 3

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

Answer 3

phenylpyruvate

Question 4

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

Question 5

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 6

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

Question 7

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 8

In the molecules below, assign R, S configurations to the chirality center indicated with an arrow. norepinephrine
alanine
Refer to instructions. The configuration of this carbon atom is _____.

Question 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.

Question 10

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°. What is the specific rotation of this unknown and specify if the compound is levorotatory or dextrorotatory?

Question 11

In the molecules below, assign R, S configurations to the chirality center indicated with an arrow. norepinephrine
alanine
Refer to instructions. The configuration of this carbon atom is _____.

Question 12

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

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

Question 14

Place asterisks at all the chirality centers in each molecule below.
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 15

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

A) R
B) S
C) α
D) [α]_D

Question 16

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 17

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 18

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

Question 19

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 20

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

Question 21

Which of the following compounds is (are) achiral? A B C ​

A) only A
B) only A and B
C) only B and C
D) A, B, and C

Question 22

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 23

Which of the following have the R configuration? A B C ​

A) only A
B) only B
C) only A and B
D) A, B, and C

Question 24

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 25

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

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

Question 26

Which of the following structures represent the same stereoisomer? A B C ​

A) only A and B
B) only A and C
C) only B and C
D) A, B, and C

Question 27

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

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

Question 28

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

Question 29

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 30

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 31

Which of the following structures contain a plane of symmetry? A B C ​

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

Question 32

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 33

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 34

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 35

Which of the following structures is (are) chiral?

A)

B)

C)

D)

Question 36

Which of the following have the S configuration? A B C ​
​

A) only A
B) only B
C) only A and B
D) A, B, and C

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

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

Question 39

How many stereoisomers of 2,3-dimethylbutane exist?

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

Question 40

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