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TOPIC-1
ALDOL REACTION
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1) Which one of the following is not likely to be formed during aldol reaction?
a) -hydroxy carbonyl compound
b) ,-unsaturated carbonyl compound
c) -hydroxy carbonyl compound
d) All of the above are possible

2) Enolate formed during aldol reaction acts as a/an:

a) electrophile
b) nucleophile
c) Lewis base
d) proton donor
ACi hem stry

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3) The number of separable aldol condensation products possible when a mixture of benzaldehyde and
acetaldehyde is treated with a strong base?
a) 2

ACi
b) 1
c) 3
d) 4 hem stry

Explanation: Two geometrical isomers from self condensation of acetaldehyde and two more geometrical
isomers of crossed aldol condensation between acetaldehyde and benzaldehyde.

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4) Which of the following does not show aldol reaction?
a) Methanal
b) Ethanal
c) Propanone
d) Propanal

Explanation: No alpha hydrogens.

reaction is NOT possible?

ACi hem stry
5) In which of the following case(s), the dehydration of -hydroxy carbonyl compound formed in the aldol

a) Extended conjugation in the final product i.e. ,-unsaturated carbonyl compound.

b) Heating the reaction mixture.
c) Non-aqueous reaction conditions.
d) Absence of -hydrogen between carbonyl and hydroxyl groups in the aldol.

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6) The correct statement(s) regarding aldol reaction is/are:

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a) The carbonyl group of molecule acting as electrophilic center is converted to hydroxyl
group in the aldol.
b) Benzaldyhyde hem stry
does not undergo self aldol reaction when treated with an alkali.
c) Only one product is formed when a mixture of acetone and acetaldehyde is treated with an alkali.
d) A sigma C-C bond is formed during elimination step.

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7) Which of the following is the likely initial step in the mechanism of the aldol reaction?
a) The carbonyl carbon of one aldehyde attacks the carbonyl oxygen of another.
b) The carbonyl oxygen is protonated by the base ion.
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c) A nucleophilic base attacks the carbonyl carbon atom.
d) An -hydrogen is abstracted by the base to form an enolate anion.

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hem stry

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8) The product in the following reaction is:

ACi
10% NaOH, H2O

o
CHO hem 5stry
C

a) b)

H
HO H
O
O OH

c)

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OH
d)

O
O HO

Answer: a

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ACi hem stry

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9) Major product of the following reaction is:

O H3O+

a)
ACi hem stry

OH
b) OH

c) d) OH
OH

O O

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10) Which of the following is/are not the aldol product(s)?

a) O b) O

OH

c) OH O

Answer: a & d
d)

ACi
O

hem stry

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ACi
11) The correct statement about the following reaction is:
-
OH stry
hem
O
Reactants


a) The product is resulted from crossed aldol condensation of acetaldyhyde and acetone.
b) The reactants are acetone and butyraldehyde.
c) The product is the result of self aldol condensation of propionaldehyde.
d) The reactants are acetone and butanone.

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12) The major product of the following retro aldol reaction is:

O
HO OH-

a) b)
H H

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O O O O

c) d)
H H
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O O O O

Answer: b

Explanation: Aldol reaction is reversible. It is possible for aldol to undergo retro-aldol reaction by breaking
bond between C-C and thereby restoring the carbonyl group that acted as electrophilic center during
aldol formation.
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H2O -

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O O
- O
OH H O H
-
O O

ACi hem stry

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13) Which combination of reagents would give a successful mixed aldol reaction?

A) CH3COC2H5 & PhCHO

B) CH3COCH3 and PhCOCH3
C) CH3COCH3 and PhCHO
E) CH3COC2H5 and C2H5COOC2H5

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14) The product formed in the following reaction is:

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O

aq. Na2CO3

O ACi 
hem stry

HO O HO O
a) b)

O O
c) d)

Answer: c
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OH OH

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ACi hem stry

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