1
MCQ (Single Correct Answer)

AIPMT 2010 Mains

Which one of the following compounds will be most readily dehydrated?
A
B
C
D

Explanation

The intermediate is carbocation which is destabilised by C = O group (present on - carbon to the –OH group) in the first three cases. In (c), –hydrogen is more acidic which can be removed as water. Moreover, the positive charge on the intermediate carbocation is relatively away from the C = O group.
2
MCQ (Single Correct Answer)

AIPMT 2010 Prelims

Among the given compounds, the most susceptible to nucleophilic attack at the carbonyl group is
A
CH3COOCH3
B
CH3CONH2
C
CH3COOCOCH3
D
CH3COCl

Explanation

CH3COCl is most susceptible to nucleophilic attack. The susceptibility of a substrate towards nucleophilic attack depends on how good a leaving group is attached to it. Cl is a weak base and therefore a good leaving group.
3
MCQ (Single Correct Answer)

AIPMT 2010 Prelims

Which of the following reactions will not result in the formation of carbon-carbon bonds?
A
Reimer-Tiemann reaction
B
Cannizzaro reaction
C
Wurtz reaction
D
Friedel-Crafts acylation

Explanation


Here you can see no new C–C bond is formed in Cannizzaro reaction.
4
MCQ (Single Correct Answer)

AIPMT 2010 Prelims

Acetamide is treated with the following reagents separately. Which one of these would yield methyl amine?
A
NaOH/Br2
B
Sodalime
C
Hot conc.H2SO4
D
PCl5

Explanation

Among the given reagents only NaOH/ Br2 converts -CONH2 group to -NH2 group. This is known as Hofmann bromamide reaction.

CH3-CONH2 + NaOH +Br2

   $$ \to $$ CH3NH2 + NaBr + Na2CO3 + H2O

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