Transcript 24_Test - Ventura College

Organic Chemistry, 6th edition
Paula Yurkanis Bruice
Chapter 24
Catalysis
Brian L. Groh
Minnesota State University, Mankato
Mankato, MN
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.1
Which of the following is/are common types of
catalysts used in organic reactions?
A.
B.
C.
D.
E.
Acid catalysts
Base catalysts
Nucleophilic catalysts
Metal ion catalysts
All of the above
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.1
Which of the following is/are common types of
catalysts used in organic reactions?
A.
B.
C.
D.
E.
Acid catalysts
Base catalysts
Nucleophilic catalysts
Metal ion catalysts
All of the above
Enzymes are also becoming more
commonly used in organic reactions.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.2
Which of the following is an intermediate in the
acid catalyzed hydrolysis of an ester?
O
A
OH
B
C
R
R
OCH3
H
D intermediates A, B, and C
OH
C
OCH3
C
OH2
R
C
OH
CH 3
O
H
E intermediates B and C
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.2
Which of the following is an intermediate in the
acid catalyzed hydrolysis of an ester?
O
A
OH
B
C
R
R
OCH3
H
D intermediates A, B, and C
OH
C
OCH3
C
OH2
R
C
OH
CH 3
O
H
E intermediates B and C
The ester oxygen in “A” is less basic than the carbonyl
oxygen.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.3
Which of the following are intermediates in base
catalyzed transesterification of a methyl ester?
O
R
O
CH3CH2OH
C
R
base
OCH3
R
C
OCH3
OH
O
OCH3
OCH2CH3
D
+ CH3OH
OCH2CH3
O
A
C
B
R
C
C
R
OH
E intermediates A and D
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
C
OCH3
OCH2CH3
24.3
Which of the following are intermediates in base
catalyzed transesterification of a methyl ester?
O
R
O
CH3CH2OH
C
R
base
OCH3
R
C
OCH3
OH
O
OCH3
OCH2CH3
D
+ CH3OH
OCH2CH3
O
A
C
B
R
C
C
R
OH
C
OCH3
OCH2CH3
E intermediates A and D
Initial attack by ethoxide gives A and formation of D
leads to generation of more ethoxide.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.5
Which of the following is not true of metal-ion catalysis?
A. It can make a reaction center more susceptible to
receiving electrons
B. It can make a leaving group a weaker base, and
therefore a better leaving group
C. It can increase the rate of a hydrolysis reaction by
increasing the nucleophilicity of water, as in C
D. It can increase the reaction rate by changing the
mechanism of the reaction.
E. It can increase the rate of a reaction by removing a
proton from the reactant.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.5
Which of the following is not true of metal-ion catalysis?
A. It can make a reaction center more susceptible to
receiving electrons
B. It can make a leaving group a weaker base, and
therefore a better leaving group
C. It can increase the rate of a hydrolysis reaction by
increasing the nucleophilicity of water, as in C
D. It can increase the reaction rate by changing the
mechanism of the reaction.
E. It can increase the rate of a reaction by removing a
proton from the reactant. – This is a base catalyst.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.7
What type of intramolecular catalysis is operating
in the following reaction?
S
Cl
S
Cl
Cl
mustard gas
A.
B.
C.
D.
E.
Acid
Base
Nucleophilic
Metal ion
None of the above
ClH 2O
S
Cl
OH
+ HCl
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.7
What type of intramolecular catalysis is operating
in the following reaction?
S
Cl
S
Cl
Cl
mustard gas
A.
B.
C.
D.
E.
Acid
Base
Nucleophilic
Metal ion
None of the above
ClH 2O
S
Cl
OH
+ HCl
Sulfur displaces the chloride ion by
intramolecular nucleophilic attack.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.8
Which factor(s) contribute to the catalytic activity of
enzymes?
A. Reacting groups are brought together at the
active site in the proper orientation.
B. Amino acid side chains serve as catalysts.
C. Metal ions in the active site act as catalysts.
D. Amino acid side chains stabilize transition states
and intermediates.
E. All of the above.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.
24.8
Which factor(s) contribute to the catalytic activity of
enzymes?
A. Reacting groups are brought together at the
active site in the proper orientation.
B. Amino acid side chains serve as catalysts.
C. Metal ions in the active site act as catalysts.
D. Amino acid side chains stabilize transition states
and intermediates.
E. All of the above.
Bruice: Organic Chemistry, © 2011 Pearson Education, Inc.