Deck 5: Stereoisomerism

Question 1

Chiral molecules that have nonsuperimposable mirror images are called:

A) enantiomers
B) diastereomers
C) meso compounds
D) stereogenic
E) symmetrical

Answer 1

enantiomers

Question 2

How many stereoisomers with the formula CH₃CHICHICH₃ are possible?

A) 1
B) 2
C) 3
D) 4
E) 5

Answer 2

3

Question 3

What is the process that separates enantiomers?

A) separation
B) decoupling
C) resetting
D) resolution
E) selective binding

Answer 3

resolution

Question 4

How many stereogenic centers are present in the following molecule?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 5

How many stereoisomers can be obtained from the monobromination of pentane?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 6

Which of the following molecules has a mirror plane of symmetry?

A) 1
B) 2
C) 3
D) 4
E) all of them

Question 7

Which of the molecules below has a stereogenic carbon atom?

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

Question 8

Which of the following objects is chiral?

A) egg
B) pencil
C) cross country skis
D) paperclip
E) shoes

Question 9

Which of the following statements about enantiomers is INCORRECT?

A) they cannot be differentiated by spectra
B) they have the same melting and boiling points
C) the mirror image of the R enantiomer is the S enantiomer
D) the specific rotation of enantiomers has the same magnitude
E) without exception, S enantiomers will rotate plane-polarized light to the left (counterclockwise)

Question 10

How many stereogenic carbons are in the following molecule?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 11

The total number of possible stereoisomers of 1-bromo-2-chlorocyclopentane is:

A) 2
B) 4
C) 6
D) 8
E) 0

Question 12

An unknown sample is tested with a polarimeter for optical activity.The results of the test require movement of the analyzer.What samples would give this result?

A) pure enantiomer
B) meso compound
C) racemic mixture
D) both B and C
E) none of these

Question 13

How many chiral stereoisomers can be drawn for CH₃CHClCHBrCH₃?

A) 1
B) 2
C) 3
D) 4
E) 8

Question 14

The total number of possible stereoisomers of is:

A) 2
B) 4
C) 6
D) 8
E) 0

Question 15

How many stereogenic centers are present in the following molecule?

A) 1
B) 2
C) 4
D) 6
E) 8

Question 16

The number of stereogenic centers in progesterone is: progesterone (no stereochemistry shown)

A) 2
B) 3
C) 4
D) 5
E) 6

Question 17

An unknown sample is tested with a polarimeter for optical activity.The results of the test required no movement of the analyzer.What samples would give this result?

A) pure enantiomer
B) meso compound
C) racemic mixture
D) both B and C
E) none of these

Question 18

A 50:50 mixture of enantiomers

A) is a meso form.
B) is a pair of diastereomers.
C) is a racemic mixture.
D) rotates plane polarized light.
E) is a pair of conformers.

Question 19

The observed rotation for 100 mL of an aqueous solution containing 1 g of sucrose, placed in a 2-decimeter sample tube, is +1.33° at 25°C.What is the specific rotation of sucrose?

A) +66.5°
B) +266°
C) +41.5
D) +133°
E) 108°

Question 20

The terms that best describe the isomeric relationship between staggered and eclipsed ethane are

A) configurational, achiral, diastereomers.
B) conformational, chiral, enantiomers.
C) conformational, achiral, diastereomers.
D) configurational, chiral, enantiomers.
E) conformational, achiral, enantiomers.

Question 21

Which of the following statements about the pair of molecules shown below is not true?

A) They have the same boiling point.
B) One rotates plane polarized light in the opposite direction from the other.
C) They have the same density.
D) One rotates plane polarized light a different number of degrees than the other.
E) They are mirror images of each other.

Question 22

Which of the three molecules below is a diastereomer of the following molecule?

A) I
B) II
C) III
D) there are no diastereomers
E) both I and II

Question 23

According to the R-S convention, which priority is correct for the following sets of groups?

A) NH₂ > Cl > CH₃ > H
B) Cl > NH₂ > CH₃ > H
C) Cl > CH₃ > NH₂ > H
D) H > Cl > CH₃ > NH₂
E) CH₃ > NH₂ > Cl > H

Question 24

Which of the three molecules below is the enantiomer of the following molecule?

A) I
B) II
C) III
D) there are no enantiomers
E) both II and III

Question 25

The terms that best describe the relationship between (2R,3S)-2-bromo-3-chlorobutane and (2S,3R)-2-bromo-3-chlorobutane are

A) configurational, achiral, diastereomers.
B) conformational, chiral, diastereomers.
C) configurational, chiral, enantiomers.
D) conformational, chiral, enantiomers.
E) configurational, chiral, diastereomers.

Question 26

The correct IUPAC name for the following molecule is:

A) (E)-2-bromo-3-chloro-5-methyl-2-hexene
B) (E)-2-bromo-3-chloro-5-methyl-3-hexene
C) (Z)-2-bromo-3-chloro-5-methyl-3-hexene
D) (Z)-2-bromo-3-chloro-5-methyl-2-hexene
E) (E)-5-bromo-4-chloro-2-methyl-4-hexene

Question 27

Which name describes the following structure?

A) (R)-3-methyl-1-penten-3-ol
B) (S)-3-methyl-1-penten-3-ol
C) (R)-3-ethyl-1-buten-3-ol
D) (R)-3-methyl-1-pentyn-3-ol
E) (S)-3-ethyl-1-buten-3-ol

Question 28

Which of the following would constitute a pair of enantiomers?

A) staggered and eclipsed forms of ethane
B) cis and trans-2-butene
C) meso- and (2R,3R)-2,3-dibromobutane
D) (2R,3R) and (2S,3S)-tartaric acid
E) none of these

Question 29

(R)-2-chlorobutane is correctly represented by which of the following:

A) I
B) II
C) III
D) IV
E) V

Question 30

The priority order for R/S nomenclature is

A) -CH=CH₂ > -OH > -CH₃ > -CH₂CH₃
B) -OH > -CH₂CH₃ > -CH=CH₂ > -CH₃
C) -OH > -CH=CH₂ > -CH₂CH₃ > -CH₃
D) -CH₃ > -CH₂CH₃ > -CH=CH₂ > -OH
E) -CH₂CH₃ > -CH₃ > -CH=CH₂ > -OH

Question 31

Which of the following groups has the highest priority for assigning R-S absolute configuration?

A) CH₂=CH-
B) (CH₃)₂CH-
C) (CH₃)₃C-
D) CH₃CH₂-
E) CH₃-

Question 32

What is correct name for the following structure?

A) (R,S)-2,3-dichlorobutane
B) (2R,3S)-2,3-dichlorobutane
C) (2S,3S)-2,3-dichlorobutane
D) (2R,3R)-2,3-dichlorobutane
E) none of these

Question 33

Of the following structures, how many are classified "E"?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 34

Of the following structures, how many are classified "Z"?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 35

Which of the following structures depicts (R)-3-ethyl-2,3-dimethylhexane?

A)
B)
C)
D)
E)

Question 36

Which of the following molecules are the same?

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

Question 37

Which of the following are achiral conformers?

A) staggered and eclipsed forms of ethane
B) cis and trans-2-butene
C) meso and (2R,3R)-2,3-dibromobutane
D) (R) and (S)-lactic acid

Question 38

Which name describes the following structure?

A) (R)-4-methyl-1-hexen-4-ol
B) (S)-4-ethyl-1-penten-4-ol
C) (R)-4-ethyl-1-penten-3-ol
D) (S)-4-methyl-1-hexen-4-ol
E) (S)-4-methyl-1-hexyn-4-ol

Question 39

The terms that best describe the relationship between (2R,3S)-2,3-butanediol and (2S,3S)-2,3-butanediol are

A) configurational, diastereomers.
B) conformational, enantiomers.
C) conformational, diastereomers
D) configurational, enantiomers.
E) configurational, cis/trans.

Question 40

Which of the following structures is (E)-2,3-dichloro-2-pentene?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 41

When (R)-3-bromo-2-methyl-1-butene is reacted with HBr, two stereoisomers are formed.What is the relationship of these stereoisomers?

A) enantiomers
B) meso compounds
C) diastereomers
D) E
E) Z

Question 42

When (S)-3-bromo-1-butene is treated with HBr, two stereoisomeric products form.What is the relationship of these two products?

A) enantiomers
B) diastereomers
C) meso compounds
D) racemic mixture
E) cis/trans

Question 43

Which one of the following structures represents a meso compound?

A)
B)
C)
D)
E)

Question 44

The Fischer projection that represents the same molecule as is:

A)
B)
C)
D)
E)

Question 45

Treating 1-butene with HBr produces a product with one stereogenic carbon.What is the name of the product?

A) 2-bromo-1-butene
B) 1-bromobutane
C) (R)-2-bromobutane
D) (S)-2-bromobutane
E) both C and D in equal amounts

Question 46

How many stereogenic carbons are produced from the following sequence of reactions?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 47

The absolute configuration around the stereogenic center of the molecule below is:

A) R
B) S
C) E
D) Z
E) trans

Question 48

Enantiomers may differ in the following property:

A) the rate at which they react with a chiral reagent
B) boiling point
C) melting point
D) number of degrees they rotate plane polarized light
E) solubility in water

Question 49

The product of addition of bromine to (R)-3-buten-2-ol will be

A) a 50:50 mixture of enantiomers.
B) a mixture of enantiomers formed in unequal amounts.
C) a 50:50 mixture of diastereomers.
D) a mixture of diastereomers formed in unequal amounts.
E) optically inactive.

Question 50

What is the absolute configuration around C-2 and C-3?

A) R, R
B) S, S
C) R, S
D) S, R
E) E, Z

Question 51

The Fischer projection formula for (S)-lactic acid (2-hydroxypropanoic acid) is

A)
B)
C)
D)
E)