Chapter 23 - Carbonyl Condensation Reactions
Exhibit 23-1
Draw the structure of the aldol self-condensation product for each of the following compounds. If a compound does not
undergo aldol self-condensation, explain why it does not.
1.
ANSWER:
POINTS: 1
2.
ANSWER:
POINTS: 1
3.
ANSWER:
POINTS: 1
4.
ANSWER:
POINTS: 1
Exhibit 23-2
Consider the reaction below to answer the following question(s):
5. Refer to Exhibit 23-2. Write the complete stepwise mechanism for the reaction above. Show all intermediate structures
and all electron flow with arrows.
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Chapter 23 - Carbonyl Condensation Reactions
ANSWER:
POINTS: 1
6. Refer to Exhibit 23-2. This reaction is an example of:
a. an intramolecular Claisen condensation
b. an intramolecular aldol condensation
c. a Robinson annulation
d. a Michael reaction
ANSWER:
POINTS: 1
7. Refer to Exhibit 23-2. The product of this reaction is:
a. a β, γ-unsaturated aldehyde
b. an α, β-unsaturated ketone
c. an α, β-unsaturated aldehyde
d. an enol
ANSWER:
POINTS: 1
10. In the alkylation of cyclohexanone, better yields are obtained by first reacting cyclohexanone with an equivalent of
lithium diisopropylamide in THF and then adding the alkyl halide, rather than mixing cyclohexanone, alkyl halide, and a
catalytic amount of sodium ethoxide in ethanol. Explain this observation by pointing out what the problems with the
second reaction conditions might be and how the first set of reaction conditions help alleviate the problems.
ANSWER: When cyclohexanone is placed in a solution of sodium ethoxide in ethanol, the enolate is generated in small
amounts in the presence of large amounts of ketone-ideal conditions for an aldol self-condensation.
Consequently, aldol self-condensation competes with alkylation of the enolate, and product mixtures result.
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Chapter 23 - Carbonyl Condensation Reactions
Conversely, when cyclohexanone is treated first with an equivalent of LDA, the enolate is rapidly generated
and no ketone remains. Addition of alkyl halide then yields the desired alkylated product.
POINTS: 1
Exhibit 23-4
Each of the following compounds can be prepared by a mixed aldol condensation reaction. Give the structures of the
aldehyde and/or ketone precursors for each aldol product and formulate the reaction.
11.
ANSWER:
POINTS: 1
12.
ANSWER:
POINTS: 1
13.
ANSWER:
POINTS: 1
Exhibit 23-5
Consider the reaction below to answer the following question(s).
14. Refer to Exhibit 23-5. Which carbonyl compound functions as the electrophile in this reaction?
ANSWER:
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Chapter 23 - Carbonyl Condensation Reactions
POINTS: 1
15. Refer to Exhibit 23-5. Draw the structure of the enolate ion that is generated during the course of this reaction.
ANSWER:
POINTS: 1
16. Refer to Exhibit 23-5. This reaction is an example of:
a. a mixed Claisen condensation.
b. a Dieckman condensation.
c. a Michael reaction.
d. a mixed aldol reaction.
ANSWER:
POINTS: 1
Exhibit 23-6
Draw the structure of the product you would expect to obtain by Claisen condensation of each of the following esters. If
an ester does not undergo Claisen condensation, explain why it does not.
17.
ANSWER:
POINTS: 1
18.
ANSWER:
POINTS: 1
19.
ANSWER:
POINTS: 1
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Chapter 23 - Carbonyl Condensation Reactions
Exhibit 23-7
Consider the reaction below to answer the following question(s):
Acetoacetic ester can be prepared by the Claisen self-condensation reaction of ethyl acetate.
20. Refer to Exhibit 23-7. Write the complete stepwise mechanism for this reaction. Show all electron flow with arrows
and draw all intermediate structures.
ANSWER:
POINTS: 1
21. Ethyl acetate can be prepared from ethanol as the only organic starting material. Show all reagents and structures for
all intermediates in this preparation.
ANSWER:
POINTS: 1
22. Give the structures of the ester precursors for the following Claisen condensation product and formulate the reaction.
ANSWER:
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Chapter 23 - Carbonyl Condensation Reactions
POINTS: 1
Exhibit 23-8
Consider the compound 2-methyl-2-carboethoxycyclopentanone, whose structure is shown below, to answer the following
question(s).
23. Refer to Exhibit 23-8. Formulate a synthesis of 2-methyl-2-carboethoxycyclopentanone starting with acyclic
precursors using a Dieckmann cyclization as a key carbon-carbon bond forming step. Show all reagents and all
intermediate structures.
ANSWER:
POINTS: 1
24. Refer to Exhibit 23-8. When 2-methyl-2-carboethoxycyclopentanone is treated with sodium ethoxide in ethanol
solution followed by a mild aqueous acid work-up, 5-methyl-2-carboethoxycyclopentanone is isolated as the major
product. This reaction proceeds by a reverse Claisen condensation mechanism followed by a recyclization. On the
structures provided below, show electron flow with arrows in this interesting reaction.
ANSWER:
POINTS: 1
25. Oxaloacetic acid is an important intermediate in the biosynthesis of citric acid. Synthesize oxaloacetic acid using a
mixed Claisen condensation as a key carbon-carbon bond forming reaction.
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Chapter 23 - Carbonyl Condensation Reactions
ANSWER:
POINTS: 1
Exhibit 23-9
Draw the structures of the precursors to each of the following Michael reaction products. Label the Michael donor and the
Michael acceptor in each case and formulate the reaction.
26.
ANSWER:
POINTS: 1
27.
ANSWER:
POINTS: 1
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Chapter 23 - Carbonyl Condensation Reactions
28.
ANSWER:
POINTS: 1
29.
ANSWER:
POINTS: 1
30.
ANSWER:
POINTS: 1
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