The Claisen condensation produces which of these?
a) An ∝-keto ester
b) A β-keto ester
c) A β-hydroxy ester
d) A β-hydroxyaldehyde
e) A
... [Show More] β-diketone
Answer: B
Topic: General Information
Section: 19.2
Difficulty Level: Easy
2) Cyclization reactions, such as the Dieckmann condensation, are best carried out using fairly
dilute solutions of the compound to be cyclized. Why is this so?
a) It then is possible to use less base.
b) The reagents generally are expensive.
c) A smaller amount of the compound to be cyclized can be used.
d) Intermolecular condensation is minimized at low concentration.
e) The concentration factor is unimportant.
Answer: D
Topic: General Information
Section: 19.2
Difficulty Level: Easy
3) Why is CH3ONa not used in the Claisen condensation of ethyl acetate?
a) CH3O- is a weaker base than the CH3CH2O- which is used.
b) CH3ONa+ is more difficult to prepare than CH3CH2ONa+
.
c) CH3O- would abstract a proton from the ethyl group of the ester.
d) Use of CH3ONa+ would result in transesterification.
e) CH3ONa+ can be used as well as CH3CH2ONa+
.
2
Answer: D
Topic: General Information
Section: 19.2
Difficulty Level: Easy
4) Which of these combinations is not one which would result in the formation of essentially one
Claisen condensation product when one compound is added slowly to the mixture of the other
and the base employed?
a) HCO2Et + CH3CH2CO2Et
b) PhCO2Et + CH3CO2Et
c) (CO2Et)2 + PhCH2CO2Et
d) (CH3)3CCO2Et + CH3CO2Et
e) PhCH2CO2Et + CH3CO2Et
Answer: E
Topic: General Information
Section: 19.2
Difficulty Level: Medium
5) What would be the major product of the following reaction?
IV
I II
V
III
OH
O
O
O
OH O
O
O
O
O O
O O
O
O
O
O
O
i. NaOC2H5
ii. H3O+ ?
a) I
b) II
c) III
d) IV
e) V
3
Answer: C
Topic: Reaction Products
Section: 19.2
Difficulty Level: Easy
6) What product is formed during the following reaction?
i. NaOC2H5, C2H5OH
ii. HOAc
IV
I II
V
Ph
O
OC2H5
O
OC2H5
Ph
O
OC2H5
O
Ph
O
OC2H5
O
O
O O
Ph Ph OC2H5
OH O
III
Ph
O
O
+
a) I
b) II
c) III
d) IV
e) V
Answer: B
Topic: Reaction Products
Section: 19.2
Difficulty Level: Easy [Show Less]