1

### NEET 2016 Phase 2

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

2

### NEET 2016 Phase 2

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.
3

### NEET 2016 Phase 2

Which of the following can be used as the halide component for Friedel-Crafts reaction?
A
Chlorobenzene
B
Bromobenzene
C
Chloroethane
D
Isopropyl chloride

## Explanation

Friedel–Crafts reaction :

Chlorobenzene, bromobenzene and chloroethene are not suitable halide components as lone pair of electrons of halogen are delocalized with $\pi$-bonds to attain double bond (C = X) character.
4

### NEET 2016 Phase 2

In which of the following molecules, all atoms are coplanar?
A
B
C
D

## Explanation

Biphenyl is coplanar as all carbon atoms are sp2 hybridised.