Deck 5: Stereochemistry

Question 1

What is the total number of compounds,stereoisomers included,designated by the general name "dichlorocyclopentane"?

A)4
B)5
C)7
D)8
E)9

Answer 1

7

Question 2

Chiral molecules are represented by:

A)I,II,III,IV and V
B)I,II,III and IV
C)I and II
D)III and IV
E)IV alone

Answer 2

III and IV

Question 3

Which of these is a comparatively insignificant factor affecting the magnitude of specific optical rotation?

A)concentration of the substance of interest
B)purity of the sample
C)temperature of the measurement
D)length of the sample tube
E)All of these choices are equally significant.

Answer 3

temperature of the measurement

Question 4

Which of the following compounds are chiral?

A)I,IV,and V
B)II only
C)II and III
D)III only
E)all compounds are achiral

Question 5

Which structure represents (S)-1-chloro-1-fluoroethane?

A)I
B)II
C)III
D)More than one of these choices.
E)None of these choices.

Question 6

How many stereogenic centers are in the following compound:

A)1
B)3
C)4
D)5
E)none of these choices

Question 7

Which of the following is NOT true of enantiomers? They have the same:

A)boiling point.
B)melting point.
C)specific rotation.
D)density.
E)chemical reactivity toward achiral reagents.

Question 8

Enantiomers are:

A)molecules that have a mirror image.
B)molecules that have at least one stereogenic center.
C)non-superposable molecules.
D)non-superposable constitutional isomers.
E)non-superposable molecules that are mirror images of each other.

Question 9

Cis-trans isomers are:

A)diastereomers.
B)enantiomers.
C)stereoisomers.
D)constitutional isomers.
E)More than one of these choices.

Question 10

Which of the following represent (R)-2-butanol?

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

Question 11

Which structure represents (R)-1-chloro-1-fluoroethane?

A)I
B)II
C)III
D)More than one of these choices.
E)None of these choices.

Question 12

Which structure represents (S)-2-bromobutane?

A)I
B)II
C)III
D)More than one of these choices.
E)None of these choices.

Question 13

Which molecule is achiral?

A)I
B)II
C)III
D)More than one of these choices.
E)None of these choices.

Question 14

What is IUPAC name of the following compound?

A)(R)-2-methyl-3-butyn-1-ol
B)(S)-2-methyl-3-butyn-1-ol
C)(R)-2-methyl-1-butyn-3-ol
D)(S)-2-methyl-1-butyn-3-ol
E)None of these choices

Question 15

Which of the following is true about any (R)-enantiomer?

A)It is dextrorotatory.
B)It is levorotatory.
C)It is an equal mixture of + and -.
D)It is the mirror image of the (S)-enantiomer.
E)(R)indicates a racemic mixture.

Question 16

What is the molecular formula for the alkane of smallest molecular weight which possesses a stereogenic center?

A)C₄H₁₀
B)C₅H₁₂
C)C₆H₁₄
D)C₇H₁₆
E)C₈H₁₈

Question 17

Which of the following is the enantiomer of the following substance?

A)I
B)II
C)III
D)It does not have a non-superposable enantiomer.
E)Both II and III.

Question 18

Pairs of enantiomers are:

A)I,II and III,IV
B)I,II
C)III,IV
D)IV,V
E)None of the structures.

Question 19

(R)-2-Chlorobutane is represented by:

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

Question 20

Which molecule is achiral?

A)I
B)II
C)III
D)More than one of these choices.
E)None of these choices.

Question 21

What is the enantiomeric excess of a compound that shows a specific rotation [ $\alpha$ ] = +18.6,where the pure enantiomer has a reference value of [ $\alpha$ ]
= +24.8?

A)6.6%
B)21.5%
C)50%
D)75%
E)0%,racemic mixture

Question 22

An alkane which can exhibit optical activity is:

A)Neopentane
B)Isopentane
C)3-Methylpentane
D)3-Methylhexane
E)2,3-Dimethylbutane

Question 23

The name of the compound formed when 1,2-dimethylcyclohexene is treated with H₂ in Pd/C is:

A)cis-1,2-dimethylcyclohexane
B)trans-1,2-dimethylcyclohexane
C)mixture of cis- and trans-1,2-dimethylcyclohexane
D)meso-1,2-dimethylcyclohexane
E)none of these choices

Question 24

Of the compounds which correspond to the general name "dichlorocyclobutane," how many are optically active?

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

Question 25

The compounds whose molecules are shown below would have:

A)the same melting point.
B)different melting points.
C)equal but opposite optical rotations.
D)More than one of these choices.
E)None of these choices.

Question 26

CH₃CHBrCH₂CHClCH₃ is the generalized representation of what number of stereoisomers?

A)3
B)4
C)5
D)6
E)7

Question 27

Which of the following is a meso compound?

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

Question 28

Which molecule is a meso compound?

A)I
B)II
C)III
D)More than one of these choices.
E)None of these choices.

Question 29

If a solution of a compound (30.0 g/100 mL of solution)has a measured rotation of +15º in a 2.0 dm tube,the specific rotation is:

A)+50
B)+25
C)+15
D)+7.5
E)+4.0

Question 30

How many stereogenic centers are there in Lovastatin (Mevacor®,a cholesterol-lowering drug)?

A)4
B)5
C)6
D)7
E)8

Question 31

Which of the following is true of any (S)-enantiomer?

A)It rotates plane-polarized light to the right.
B)It rotates plane-polarized light to the left.
C)It is a racemic form.
D)It is the mirror image of the corresponding (R)-enantiomer.
E)It has the highest priority group on the left.

Question 32

The reaction of with H₂/Ni forms:

A)2-methylheptane
B)(R)-2-methyl-5-heptanol
C)(S)-6-methyl-3-heptanol
D)(R)- and (S)-6-methyl-3-heptanol
E)Achiral 6,6-dimethyl-3-hexanol

Question 33

What can be said with certainty if a compound has [ $\alpha$ ] = -9.25 ?

A)The compound has the (S)configuration.
B)The compound has the (R)configuration.
C)The compound is not a meso form.
D)The compound possesses only one stereogenic center.
E)The compound has an optical purity of less than 100%.

Question 34

For the generalized structure BrCH₂CHClCH₂CHClCH₂Br there exists what number of stereoisomers?

A)2
B)3
C)4
D)6
E)8

Question 35

In the absence of specific data,it can only be said that (R)-2-bromopentane is:

A)dextrorotatory (+).
B)levorotatory (-).
C)optically inactive.
D)achiral.
E)analogous in absolute configuration to (R)-2-chloropentane.

Question 36

Which of the following is (are)meso?

A)I
B)II
C)III
D)IV
E)Two of these choices.

Question 37

The name of the product produced when cis-2-methyl-2-buten-1-ol is treated with H₂ in Pd/C is:

A)(R)-2-methyl-1-butanol
B)(S)-2-methyl-1-butanol
C)racemic mixture of 2-methyl-1-butanol
D)2-methyl-1-butanol
E)None of these choices.

Question 38

Which compound would show optical activity?

A)cis-1,4-Dimethylcyclohexane
B)trans-1,4-Dimethylcyclohexane
C)cis-1,4-Dimethylcycloheptane
D)trans-1,4-Dimethylcycloheptane
E)More than one of these choices.

Question 39

Which of the following is (are)meso compound(s)?

A)I
B)II
C)III
D)Both II and III
E)Both I and III

Question 40

What is the percent composition of a mixture of (S)-(+)-2-butanol,[ $\alpha$ ] = +13.52,and (R)-(-)-2-butanol,[ $\alpha$ ]
= -13.52,with a specific rotation [ $\alpha$ ]
= +6.76?

A)75% (R),25% (S)
B)25% (R),75% (S)
C)50% (R),50% (S)
D)67% (R),33% (S)
E)33% (R),67% (S)

Question 41

Hexane and 3-methylpentane are examples of:

A)enantiomers.
B)stereoisomers.
C)diastereomers.
D)constitutional isomers.
E)None of these choices.

Question 42

The molecules shown are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 43

The two compounds shown below are:

A)identical.
B)enantiomers.
C)diastereomers.
D)conformational isomers.
E)meso forms.

Question 44

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 45

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 46

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 47

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 48

How many distinct dimethylcyclopropanes are there?

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

Question 49

How many chiral stereoisomers can be drawn for CH₃CHFCHFCH(CH₃)₂?

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

Question 50

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 51

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)stereoisomers.

Question 52

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 53

The molecules below are:

A)structural isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 54

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 55

Which statement is not true for a meso compound?

A)The specific rotation is 0.
B)There are one or more planes of symmetry.
C)A single molecule is identical to its mirror image.
D)More than one stereogenic center must be present.
E)The stereochemical labels,(R)and (S),must be identical for each stereogenic center.

Question 56

The structures represent:

A)a single compound.
B)enantiomers.
C)meso forms.
D)diastereomers.
E)conformational isomers.

Question 57

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 58

Which statement is true of 1,3-dimethylcyclobutane?

A)Only one form of the compound is possible.
B)Two diastereomeric forms are possible.
C)Two sets of enantiomers are possible.
D)Two enantiomeric forms and one meso compound are possible.
E)None of the previous statements is true.

Question 59

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 60

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 61

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 62

The molecules shown are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 63

Which of the following substances is/are achiral?

A)I
B)II
C)III
D)IV
E)More than one of these choices.

Question 64

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 65

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 66

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 67

Which of the following are enantiomers of the compound (+)-camphor:

A)I only
B)I and II only
C)II only
D)I and III only
E)I,II and III

Question 68

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 69

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 70

The molecules shown are:

A)enantiomers.
B)diastereomers.
C)constitutional isomers.
D)two conformations of the same molecule.
E)not isomeric.

Question 71

Which of the following compounds (I-IV)represent enantiomers?

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

Question 72

Which compounds (I-IV)form a set of stereoisomers?

A)I,II and III
B)II,III and IV
C)II and III
D)I,III and IV
E)I,II,III and IV

Question 73

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 74

Which compound (I-IV)is a meso compound?

A)I
B)II
C)III
D)IV
E)None of these choices.

Question 75

The molecules below are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.

Question 76

The molecules below are:

A)enantiomers.
B)diastereomers.
C)constitutional isomers.
D)two different conformations of the same molecule.
E)not isomeric.

Question 77

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 78

Which compound (I-IV)is (2R,3R)-2,3-butanediol?

A)I
B)II
C)III
D)IV
E)None of these choices.

Question 79

I and II are:

A)constitutional isomers.
B)enantiomers.
C)identical.
D)diastereomers.
E)not isomeric.

Question 80

The molecules shown are:

A)constitutional isomers.
B)enantiomers.
C)diastereomers.
D)identical.
E)None of these choices.