Question 1

Explain why an intramolecular reaction resulting in the formation of five- or six-membered rings occurs more readily than the corresponding intermolecular reaction.

Accepted Answer

An intramolecular reaction has

Question 2

Give the first step of the mechanism for aldolase.

Accepted Answer

A) Fructose-1,6,-diphosphate forms an imine with a lysine residue at the active site of the enzyme. 
B) A tyrosine residue functions as a base catalyst to cleave the bond between C-3 and C-4. 
C) The enamine intermediate rearranges to an imine. 
D) Hydrolysis of the imine releases dihydroxyacetone phosphate. 
E) A molecule of glyceraldehyde-3-phosphate is expelled. 
A) Fructose-1,6,-diphosphate forms an imine with a lysine residue at the active site of the enzyme. 
B) A tyrosine residue functions as a base catalyst to cleave the bond between C-3 and C-4. 
C) The enamine intermediate rearranges to an imine. 
D) Hydrolysis of the imine releases dihydroxyacetone phosphate. 
E) A molecule of glyceraldehyde-3-phosphate is expelled.

Question 3

Show why typical metal-bound water has a considerably lower pKa than that of water.

Accepted Answer

The metal ion binds to water making it e

Question 4

Which of the following statements concerning general-acid catalysis is (are)correct?

Accepted Answer

A) The proton is transferred to the reactant during the slow step of the reaction. 
B) The transition state of the slow step of the reaction has a partially transferred proton instead of a fully transferred proton. 
C) Typically, a general-acid catalyst is stronger than a specific-acid catalyst. 
D) both A and B 
E) all of the above 
A) The proton is transferred to the reactant during the slow step of the reaction. 
B) The transition state of the slow step of the reaction has a partially transferred proton instead of a fully transferred proton. 
C) Typically, a general-acid catalyst is stronger than a specific-acid catalyst. 
D) both A and B 
E) all of the above

Question 5

What is the main purpose for using metal-ions as catalysts in the following hydrolysis reaction?

Accepted Answer

A) increases the rate by making water a stronger base, thereby increasing its electrophilicity 
B) increases the rate by making water a stronger base, thereby increasing its nucleophilicity 
C) increases the rate by making water a stronger acid, thereby increasing its nucleophilicity 
D) increases the rate by making water a stronger acid, thereby increasing its electrophilicity 
E) increases the rate by making water a stronger acid, thereby decreasing its nucleophilicity 
A) increases the rate by making water a stronger base, thereby increasing its electrophilicity 
B) increases the rate by making water a stronger base, thereby increasing its nucleophilicity 
C) increases the rate by making water a stronger acid, thereby increasing its nucleophilicity 
D) increases the rate by making water a stronger acid, thereby increasing its electrophilicity 
E) increases the rate by making water a stronger acid, thereby decreasing its nucleophilicity

Question 6

The specificity of an enzyme for its substrate is an example of ________.

Accepted Answer

A) molecular recognition 
B) the anomeric effect 
C) specific-acid catalysis 
D) general-acid catalysis 
E) a pericyclic reaction 
A) molecular recognition 
B) the anomeric effect 
C) specific-acid catalysis 
D) general-acid catalysis 
E) a pericyclic reaction

Question 7

Provide the two general ways that metal ions catalyze organic reactions.

Accepted Answer

They can increase electrophili

Question 8

Which of the following is not true about metal-ion catalysts?

Accepted Answer

A) They coordinate with atoms with nonbonded electrons. 
B) They can make a reaction center more susceptible to receiving electrons and stabilize a developing charge on the transition state. 
C) They can make a leaving group a weaker base and therefore a better leaving group. 
D) They act as Lewis bases. 
E) They can increase the electrophilicity of a reaction center. 
A) They coordinate with atoms with nonbonded electrons. 
B) They can make a reaction center more susceptible to receiving electrons and stabilize a developing charge on the transition state. 
C) They can make a leaving group a weaker base and therefore a better leaving group. 
D) They act as Lewis bases. 
E) They can increase the electrophilicity of a reaction center.

Question 9

Which of the following sets of parameters are all altered when a reaction is carried out in the presence of a catalyst?

Accepted Answer

A) ΔG°, ΔH°, Keq 
B) Ea, free energy of activation, krate 
C) ΔG°, krate, Keq 
D) ΔH°, DS°, Ea 
E) ΔH°, ΔS°, krate 
A) ΔG°, ΔH°, Keq 
B) Ea, free energy of activation, krate 
C) ΔG°, krate, Keq 
D) ΔH°, DS°, Ea 
E) ΔH°, ΔS°, krate

Question 10

A pure sample of the trans-2-bromocyclopentanol enantiomer shown below reacts with HCl. The reaction proceeds by way of a bromonium ion. What is/are the product(s)of the reaction?

Accepted Answer

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

Question 11

What factor(s)would affect the rate of an intramolecular reaction?

Accepted Answer

There are three main factors:

Question 12

The compound CH3OCH2CH2CH2CH2Br undergoes a solvolysis reaction in aqueous ethanol solution. Which of the following is evidence that a neighboring group effect is occurring?

Accepted Answer

A) CH3CH2CH2CH2Br reacts more slowly than CH3OCH2CH2CH2CH2Br does. 
B) The reaction is faster when the concentration of water is higher. 
C) The reaction is first order. 
D) HBr is a product of the reaction. 
A) CH3CH2CH2CH2Br reacts more slowly than CH3OCH2CH2CH2CH2Br does. 
B) The reaction is faster when the concentration of water is higher. 
C) The reaction is first order. 
D) HBr is a product of the reaction.

Question 13

Describe the first step of a specific-base-catalyzed dehydration of a hydrate.

Accepted Answer

A) base abstracts a proton, electron pair from O-H bond goes to oxygen 
B) negative charge from oxygen forms double bond, hydroxide departs as leaving group 
C) base abstracts a proton, electron pair from O-H bond forms a double bond, hydroxide departs as leaving group 
D) hydroxide departs as leaving group, then negative charge from oxygen forms a double bond 
E) electron pair from O-H bond forms a double bond, base abstracts a proton 
A) base abstracts a proton, electron pair from O-H bond goes to oxygen 
B) negative charge from oxygen forms double bond, hydroxide departs as leaving group 
C) base abstracts a proton, electron pair from O-H bond forms a double bond, hydroxide departs as leaving group 
D) hydroxide departs as leaving group, then negative charge from oxygen forms a double bond 
E) electron pair from O-H bond forms a double bond, base abstracts a proton

Question 14

Give the product(s)for the following reaction.   
A)   
B)   
C)   
D)   
E)

Accepted Answer

The answer of Give the product(s)for the following reaction. ...

Question 15

Which of the following represents the first step(s)in the mechanism involving general-base catalysis for the reaction shown below?

Accepted Answer

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

Question 16

What technique is used to gain information about protein structure and function by replacing single amino acids along a peptide chain?

Accepted Answer

site-speci

Question 17

Which of the labeled bonds in the following peptide chain will break when carboxypeptidase A is used to hydrolyze the chain?

Accepted Answer

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

Question 18

Why is histidine a versatile catalytic group?

Accepted Answer

Because the imidazole ring in

Question 19

Which of the following is not true about the enzyme carboxypeptidase A?

Accepted Answer

A) Arg 145 and Tyr 248 are involved in the catalytic process of the enzyme. 
B) The metal ion in carboxypeptidase A is partially liganded to the oxygen of the carbonyl group that will be hydrolyzed. 
C) Carboxypeptidase A catalyzes the hydrolysis of the C-terminal peptide bond in proteins. 
D) Carboxypeptidase A is a metalloenzyme. 
E) The metal ion in carboxypeptidase is a Cu+2. 
A) Arg 145 and Tyr 248 are involved in the catalytic process of the enzyme. 
B) The metal ion in carboxypeptidase A is partially liganded to the oxygen of the carbonyl group that will be hydrolyzed. 
C) Carboxypeptidase A catalyzes the hydrolysis of the C-terminal peptide bond in proteins. 
D) Carboxypeptidase A is a metalloenzyme. 
E) The metal ion in carboxypeptidase is a Cu+2.

Question 20

Rank the following compounds in increasing order of reactivity in the intramolecular displacement of p-bromophenolate to form a cyclic anhydride. Explain your ranking.

Accepted Answer

B < C < A. B is slower than C since it h

Exam 23: Catalysis

Explain why an intramolecular reaction resulting in the formation of five- or six-membered rings occurs more readily than the corresponding intermolecular reaction.

Give the first step of the mechanism for aldolase.

Show why typical metal-bound water has a considerably lower pKa than that of water.

Which of the following statements concerning general-acid catalysis is (are)correct?

What is the main purpose for using metal-ions as catalysts in the following hydrolysis reaction?

The specificity of an enzyme for its substrate is an example of ________.

Provide the two general ways that metal ions catalyze organic reactions.

Which of the following is not true about metal-ion catalysts?

Which of the following sets of parameters are all altered when a reaction is carried out in the presence of a catalyst?

A pure sample of the trans-2-bromocyclopentanol enantiomer shown below reacts with HCl. The reaction proceeds by way of a bromonium ion. What is/are the product(s)of the reaction?

What factor(s)would affect the rate of an intramolecular reaction?

The compound CH3OCH2CH2CH2CH2Br undergoes a solvolysis reaction in aqueous ethanol solution. Which of the following is evidence that a neighboring group effect is occurring?

Describe the first step of a specific-base-catalyzed dehydration of a hydrate.

Give the product(s)for the following reaction. A) B) C) D) E)

Which of the following represents the first step(s)in the mechanism involving general-base catalysis for the reaction shown below?

What technique is used to gain information about protein structure and function by replacing single amino acids along a peptide chain?

Which of the labeled bonds in the following peptide chain will break when carboxypeptidase A is used to hydrolyze the chain?

Why is histidine a versatile catalytic group?

Which of the following is not true about the enzyme carboxypeptidase A?

Rank the following compounds in increasing order of reactivity in the intramolecular displacement of p-bromophenolate to form a cyclic anhydride. Explain your ranking.

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds

Isomers: the Arrangement of Atoms in Space

Alkenes Thermodynamics and Kinetics

Reactions of Alkenes

Reactions of Alkynes Introduction to Multistep Synthesis

Electron Delocalization, Resonance, and Aromaticity More About Molecular Orbital Theory

Substitution Reactions of Alkyl Halides

Elimination Reactions of Alkyl Halides Competition Between Substitution and Elimination

Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds

Organometallic Compounds

Reactions of Alkanes, Radicals

Mass Spectrometry, Infrared Spectroscopy, and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Alpha Carbon of Carbonyl Compounds

Reactions of Benzene and Substituted Benzenes

More About Amines Heterocylic Compounds

Carbohydrates

Amino Acids, Peptides, and Proteins

The Organic Mechanisms of the Coenzymes

The Chemistry of Metabolism

Nucleosides, Nucleotides, and Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

Filters

The compound CH₃OCH₂CH₂CH₂CH₂Br undergoes a solvolysis reaction in aqueous ethanol solution. Which of the following is evidence that a neighboring group effect is occurring?