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1

NEET 2016 Phase 2

MCQ (Single Correct Answer)
The compound that will react most readily with gaseous bromine has the formula
A
C3H6
B
C2H2
C
C4H10
D
C2H4

Explanation

Propene is most reactive towards Br2 (gaseous) than CH2 = CH2, HC $$ \equiv $$ CH and butane due to most electron density.
2

NEET 2016 Phase 2

MCQ (Single Correct Answer)
In the given reaction,


the product P is
A
B
C
D

Explanation

3

NEET 2016 Phase 2

MCQ (Single Correct Answer)
Which of the following compounds shall not produce propene by reaction with HBr followed by elimination or direct only elimination reaction ?
A
B
C
D

Explanation

4

NEET 2016 Phase 2

MCQ (Single Correct Answer)
In pyrrole the electron density is maximum on
A
2 and 3
B
3 and 4
C
2 and 4
D
2 and 5

Explanation

Pyrrole has maximum electron density on 2 and 5. It generally reacts with electrophiles at the C-2 or C-5 due to the highest degree of stability of the protonated intermediate.

Attack at position 3 or 4 yields a carbocation that is a hybrid of structures (I) and (II). Attack at position 2 or 5 yields a carbocation that is a hybrid not only of structures (III) and (IV) (analogous to I and II) but also of structure (V). The extra stabilization conferred by (V) makes this ion the more stable one.

Also, attack at position 2 or 5 is faster because the developing positive charge is accommodated by three atoms of the ring instead of by only two.

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