Question 1

A reaction mixture is three parts of one enantiomer and one part of the other. What is the percent ee of this mixture?

Accepted Answer

A)  75 
B)  40 
C)  65 
D)  50 
A)  75 
B)  40 
C)  65 
D)  50 D

Question 2

How much of the R enantiomer is present in 10 g of a mixture which has an enantiomeric excess of 30% of the S isomer?

Accepted Answer

A)  3.0 g 
B)  3.5 g 
C)  6.5 g 
D)  7.0 g 
A)  3.0 g 
B)  3.5 g 
C)  6.5 g 
D)  7.0 g B

Question 3

How many stereogenic centers are present in the following compound?

Accepted Answer

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

Question 4

Which of the following structures has a different configuration from the other three?

Accepted Answer

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

Question 5

If a mixture has an ee of 90%, what is the percentage of each enantiomer?

Accepted Answer

A)  65% : 35% 
B)  55% : 45% 
C)  80% : 20% 
D)  95% : 5% 
A)  65% : 35% 
B)  55% : 45% 
C)  80% : 20% 
D)  95% : 5%

Question 6

What is the relationship between the following compounds?

Accepted Answer

A)  Constitutional isomers 
B)  Diastereomers 
C)  Enantiomers 
D)  Identical 
A)  Constitutional isomers 
B)  Diastereomers 
C)  Enantiomers 
D)  Identical

Question 7

Which of the following compounds is a meso compound?

Accepted Answer

A)  (2R, 3S)-dichlorobutane 
B)  (2R, 3R)-dichlorobutane 
C)  (2R, 3S)-3-chloro-2-butanol 
D)  (2R, 3R)-3-chloro-2-butanol 
A)  (2R, 3S)-dichlorobutane 
B)  (2R, 3R)-dichlorobutane 
C)  (2R, 3S)-3-chloro-2-butanol 
D)  (2R, 3R)-3-chloro-2-butanol

Question 8

Which of the following is the definition for a pair of diastereomers?

Accepted Answer

A)  A pair of stereoisomers with stereogenic centers which is not chiral. 
B)  A pair of stereoisomers that are superimposable mirror images of each other. 
C)  A pair of stereoisomers that are not superimposable mirror images of each other. 
D)  A pair of stereoisomers that are not mirror images of each other. 
A)  A pair of stereoisomers with stereogenic centers which is not chiral. 
B)  A pair of stereoisomers that are superimposable mirror images of each other. 
C)  A pair of stereoisomers that are not superimposable mirror images of each other. 
D)  A pair of stereoisomers that are not mirror images of each other.

Question 9

How many stereogenic centers are present in ephedrine, a bronchodilator and decongestant?

Accepted Answer

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

Question 10

How many stereoisomers are possible for a molecule with formula CH3CHBrCH(OH)CH3?

Accepted Answer

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

Question 11

What is the relationship between the following two compounds?

Accepted Answer

A)  Constitutional isomers 
B)  Stereoisomers 
C)  Identical 
D)  Not isomers, different compounds 
A)  Constitutional isomers 
B)  Stereoisomers 
C)  Identical 
D)  Not isomers, different compounds

Question 12

How many stereogenic centers are present in menthol?

Accepted Answer

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

Question 13

Which of the following statements is not true?

Accepted Answer

A)  A molecule that is superimposable on its mirror image is said to achiral. 
B)  A molecule that is not superimposable on its mirror image is said to be chiral. 
C)  A molecule that is superimposable on its mirror image is said to be chiral. 
D)  A carbon atom bonded to four different groups is a stereogenic center. 
A)  A molecule that is superimposable on its mirror image is said to achiral. 
B)  A molecule that is not superimposable on its mirror image is said to be chiral. 
C)  A molecule that is superimposable on its mirror image is said to be chiral. 
D)  A carbon atom bonded to four different groups is a stereogenic center.

Question 14

How many chiral stereoisomers can be drawn for dimethycyclopropane?

Accepted Answer

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

Question 15

Rank the following groups in order of decreasing priority according to the Cahn-Ingold-Prelog system. $$\begin{array} { c c c c } 
- \mathrm { NH } _ { 2 } & - \mathrm { NHCH } _ { 3 } & - \mathrm { CH } _ { 2 } \mathrm { NH } _ { 2 } & - \mathrm { CH } _ { 2 } \mathrm { NHCH } _ { 3 } \
\text { I } & \text { II } & \text { III } & \text { IV }
\end{array}$$

Accepted Answer

A)  I > II > III > IV 
B)  II > I > IV > III 
C)  II > I > III > IV 
D)  I > II > IV > III 
A)  I > II > III > IV 
B)  II > I > IV > III 
C)  II > I > III > IV 
D)  I > II > IV > III

Question 16

Which of the following structures has a different configuration from the other three?

Accepted Answer

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

Question 17

What is the percent ee of a mixture that has 70% of one enantiomer and 30% of the other?

Accepted Answer

A)  70 
B)  85 
C)  40 
D)  30 
A)  70 
B)  85 
C)  40 
D)  30

Question 18

Which of the following statements about meso compounds is not true?

Accepted Answer

A)  A meso compound generally has a plane of symmetry. 
B)  A meso compound and its mirror image are identical. 
C)  A meso compound is achiral. 
D)  A meso compound is chiral. 
A)  A meso compound generally has a plane of symmetry. 
B)  A meso compound and its mirror image are identical. 
C)  A meso compound is achiral. 
D)  A meso compound is chiral.

Question 19

What is the relationship between the following compounds?

Accepted Answer

A)  Constitutional isomers 
B)  Diastereomers 
C)  Enantiomers 
D)  Identical 
A)  Constitutional isomers 
B)  Diastereomers 
C)  Enantiomers 
D)  Identical

Question 20

Which of the following statements about starch and cellulose is true?

Accepted Answer

A)  Starch and cellulose are not stereoisomers. 
B)  In cellulose, the O atom joins two rings using one equatorial and one axial bond. 
C)  In starch, the O atom joins two rings using two equatorial bonds. 
D)  In cellulose, the O atom joins two rings using two equatorial bonds. 
A)  Starch and cellulose are not stereoisomers. 
B)  In cellulose, the O atom joins two rings using one equatorial and one axial bond. 
C)  In starch, the O atom joins two rings using two equatorial bonds. 
D)  In cellulose, the O atom joins two rings using two equatorial bonds.

Exam 5: Stereochemistry

A reaction mixture is three parts of one enantiomer and one part of the other. What is the percent ee of this mixture?

How much of the R enantiomer is present in 10 g of a mixture which has an enantiomeric excess of 30% of the S isomer?

How many stereogenic centers are present in the following compound?

Which of the following structures has a different configuration from the other three?

If a mixture has an ee of 90%, what is the percentage of each enantiomer?

What is the relationship between the following compounds?

Which of the following compounds is a meso compound?

Which of the following is the definition for a pair of diastereomers?

How many stereogenic centers are present in ephedrine, a bronchodilator and decongestant?

How many stereoisomers are possible for a molecule with formula CH3CHBrCH(OH)CH3?

What is the relationship between the following two compounds?

How many stereogenic centers are present in menthol?

Which of the following statements is not true?

How many chiral stereoisomers can be drawn for dimethycyclopropane?

Rank the following groups in order of decreasing priority according to the Cahn-Ingold-Prelog system. - - - - I II III IV

Which of the following structures has a different configuration from the other three?

What is the percent ee of a mixture that has 70% of one enantiomer and 30% of the other?

Which of the following statements about meso compounds is not true?

What is the relationship between the following compounds?

Which of the following statements about starch and cellulose is true?

Structure and Bonding

Acids and Bases

Introduction to Organic Molecules and Functional Groups

Alkanes

Understanding Organic Reactions

Alkyl Halides and Nucleophilic Substitution

Alkyl Halides and Elimination Reactions

Alcohols, Ethers and Epoxides

Alkenes

Alkynes

Oxidation and Reduction

Mass Spectrometry and Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Radical Reactions

Conjugation, Resonance, and Dienes

Benzene and Aromatic Compounds

Electrophilic Aromatic Substitution

Carboxylic Acids and the Acidity of the O-H Bond

Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction

Aldehydes and Ketones Nucleophilic Addition

Carboxylic Acids and Derivatives

Substitution Reactions of Carbonyl Compounds at the Alpha-Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Lipids

Synthetic Polymers

Filters

How many stereoisomers are possible for a molecule with formula CH₃CHBrCH(OH)CH₃?