Question 1

Name the condensation reaction that forms this molecule and identify the starting material that would be needed.

Accepted Answer

The compound is a beta-hydroxyketone, so it was formed by the aldol addition reaction. The alpha-beta bond is formed in the addition, and the hydroxy group had come from a carbonyl. The precursor must be cyclodecane-1,5-dione.

Question 2

The deuterium exchange of the compound replaces all the protons. The hydrogen labeled with an asterisk is not normally acidic, as it cannot be resonance stabilized. Explain how this hydrogen is able to undergo a deuterium exchange.

Accepted Answer

The proton labeled with an asterisk is not acidic as drawn, but the adjacent hydroxy group is part of an enol, which can undergo keto-enol tautomerization to a dicarbonyl, making the indicated hydrogen acidic. The proton on carbon 2 can be exchanged for a deuterium, as can the remaining protons, as they are all on alpha carbons too. The last step is another keto-enol tautomerization to give the product.

Question 3

Deduce the structure of the starting material given the product and conditions.

Accepted Answer

The conditions suggest the Hell-Volhard-Zelinsky (HVZ) reaction, where the alpha carbon of a carboxylic acid is brominated. Thus, the starting material is simply the starting material without the bromine.

Question 4

Write an arrow-pushing mechanism for the isomerization of enol to cyclohexanone under (a) aqueous acidic conditions and (b) aqueous basic conditions. Show all proton transfer steps in each mechanism and two resonance structures for each intermediate.

Accepted Answer

(a) The acidic mechanism starts with pro

Question 5

Can this compound be prepared in good yield by an aldol reaction? If so, give the starting materials. If not, explain why.

Accepted Answer

The compound below is an alpha-beta unsa

Question 6

One equivalent of ethanethiol reacts with a naphthalene-1,4-dione derivative to yield primarily A or B, but not both.
​a. Show a reaction mechanism for the formation of the favored product, and state in 10 words or less why your choice is favored over the other.
   ​
b. The actual observed product of this reaction is different than either A or B. The observed product shows no C=O stretch in IR. Show this product below, and in 10 words or less, state why this actual product forms.

Accepted Answer

a. Thiols will undergo conjugate additio

Question 7

The reaction of lithium aluminum hydride with the F1F1F1S1F1F1F10,F1F1F1S1F1F1F10-unsaturated ketone forms either compound A or

Accepted Answer

Compound A is the major product. Lithium

Question 8

Outline a malonic ester synthesis of the carboxylic acid.

Accepted Answer

Working backward, start by analyzing the

Question 9

Predict the major organic product for the reaction. If you believe no reaction would occur, write NR.

Accepted Answer

An acid-catalyzed halogenation

Question 10

Outline a one-step synthesis for the transformation. Hint: Use an organometallic reagent.

Accepted Answer

The overall reaction is a conjugate addi

Question 11

Deduce the structure of the starting material given the product and conditions.

Accepted Answer

The conditions suggest the Hell-Volhard-

Question 12

Choose the best reagent(s) for carrying out the conversion.

Accepted Answer

A)  PhMgBr, ether; then aqueous acid 
B)  PhCH2MgBr, ether; then aqueous acid 
C)  Ph3P=CHPh 
D)  LiCuPh2, ether 
A)  PhMgBr, ether; then aqueous acid 
B)  PhCH2MgBr, ether; then aqueous acid 
C)  Ph3P=CHPh 
D)  LiCuPh2, ether

Question 13

Predict the major organic product for the reaction. If you believe no reaction would occur, write NR.

Accepted Answer

The alpha protons are acidic a

Question 14

Only one of these three carboxylic acids can be synthesized from the malonic ester synthesis. Circle the compound that can be synthesized and explain why the other two carboxylic acids cannot be synthesized using the malonic ester synthesis.

Accepted Answer

The malonic ester synthesis prepares car

Question 15

Which ester cannot be used in a Claisen condensation?

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D

Question 16

Which of these compounds could not have been prepared by an aldol addition/condensation reaction?

Accepted Answer

A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  compounds B and C 
A)  compound A 
B)  compound B 
C)  compound C 
D)  compound D 
E)  compounds B and C

Question 17

Indicate the missing starting material and product, given the conditions provided. When filling in the product, indicate only the major organic product(s). If you believe no reaction would occur, write NR.

Accepted Answer

The intermediate shown is a beta-hydroxy

Question 18

Give both enolates formed from deprotonation of the given ketone with base and draw a curved-arrow mechanism to show how they are formed.

Accepted Answer

The enolate is formed by deprotonation o

Question 19

When allowed to react with D2O in the presence of a trace amount of NaOD, which hydrogens in the molecule will be exchanged by deuterium (D)?

Accepted Answer

A)  Ha 
B)  Hb 
C)  Hc 
D)  Ha and Hb 
E)  Ha and Hc 
A)  Ha 
B)  Hb 
C)  Hc 
D)  Ha and Hb 
E)  Ha and Hc

Question 20

Choose the reaction conditions that would convert acetophenone to methyl benzoate in the best yield.

Accepted Answer

A)  step 1: NaBH4 in methanol; step 2: heat the product of step 1 in aqueous H2SO4 
B)  step 1: Br2 in acetic acid; step 2: heat the product of step 1 in methanol 
C)  step 1: excess Br2 in aqueous NaOH; step 2: heat the product of step 1 with methanol in aqueous NaOH 
D)  step 1: excess Br2 in aqueous NaOH; step 2: treat the product of step 1 with methanol in catalytic H2SO4 
A)  step 1: NaBH4 in methanol; step 2: heat the product of step 1 in aqueous H2SO4 
B)  step 1: Br2 in acetic acid; step 2: heat the product of step 1 in methanol 
C)  step 1: excess Br2 in aqueous NaOH; step 2: heat the product of step 1 with methanol in aqueous NaOH 
D)  step 1: excess Br2 in aqueous NaOH; step 2: treat the product of step 1 with methanol in catalytic H2SO4

Exam 22: The Chemistry of Enolate Ions, Enols, and Α,β-Unsaturated Carbonyl Compounds

Name the condensation reaction that forms this molecule and identify the starting material that would be needed.

The deuterium exchange of the compound replaces all the protons. The hydrogen labeled with an asterisk is not normally acidic, as it cannot be resonance stabilized. Explain how this hydrogen is able to undergo a deuterium exchange.

Deduce the structure of the starting material given the product and conditions.

Write an arrow-pushing mechanism for the isomerization of enol to cyclohexanone under (a) aqueous acidic conditions and (b) aqueous basic conditions. Show all proton transfer steps in each mechanism and two resonance structures for each intermediate.

Can this compound be prepared in good yield by an aldol reaction? If so, give the starting materials. If not, explain why.

The reaction of lithium aluminum hydride with the ,-unsaturated ketone forms either compound A or

Outline a malonic ester synthesis of the carboxylic acid.

Predict the major organic product for the reaction. If you believe no reaction would occur, write NR.

Outline a one-step synthesis for the transformation. Hint: Use an organometallic reagent.

Deduce the structure of the starting material given the product and conditions.

Choose the best reagent(s) for carrying out the conversion.

Predict the major organic product for the reaction. If you believe no reaction would occur, write NR.

Only one of these three carboxylic acids can be synthesized from the malonic ester synthesis. Circle the compound that can be synthesized and explain why the other two carboxylic acids cannot be synthesized using the malonic ester synthesis.

Which ester cannot be used in a Claisen condensation?

Which of these compounds could not have been prepared by an aldol addition/condensation reaction?

Indicate the missing starting material and product, given the conditions provided. When filling in the product, indicate only the major organic product(s). If you believe no reaction would occur, write NR.

Give both enolates formed from deprotonation of the given ketone with base and draw a curved-arrow mechanism to show how they are formed.

When allowed to react with D2O in the presence of a trace amount of NaOD, which hydrogens in the molecule will be exchanged by deuterium (D)?

Choose the reaction conditions that would convert acetophenone to methyl benzoate in the best yield.

Chemical Bonding and Chemical Structure

Alkanes and Organic Nomenclature

The Curved-Arrow Notation, Resonance, Acids and Bases, and Chemical Equilibrium

Introduction to Alkenes and Alkynes

Addition Reactions of Alkenes and Alkynes

Principles of Stereochemistry

Cyclic Compounds and Reaction Stereochemistry

Nomenclature and Noncovalent Intermolecular Interactions

The Chemistry of Alkyl Halides

Free-Radical Reactions, Main-Group Organometallic Compounds, and Carbenes

The Chemistry of Alcohols and Thiols

The Chemistry of Ethers, Epoxides, Glycols, and Sulfides

Introduction to Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Dienes and Aromaticity

The Chemistry of Benzene and Its Derivatives

Allylic and Benzylic Reactivity

The Chemistry of Aryl Halides, Vinylic Halides, and Phenols

The Chemistry of Aldehydes and Ketones

The Chemistry of Carboxylic Acids

The Chemistry of Carboxylic Acid Derivatives

The Chemistry of Amines

Carbohydrates

The Chemistry of Thioesters, Phosphate Esters, and Phosphate Anhydrides

The Chemistry of the Aromatic Heterocycles and Nucleic Acids

Amino Acids, Peptides, and Proteins

Pericyclic Reactions

Filters

When allowed to react with D₂O in the presence of a trace amount of NaOD, which hydrogens in the molecule will be exchanged by deuterium (D)?