Question

The alkyl halides most reactive in Sy2 reaction is
(a) C H CH CH CH Br
(b) CH3-CH CH Br
CH3
CH3
(d) CH5-C-Br
(c) CH,CH-CH CH3
CH
Br
otion is
2​

Answer 1

Answer:

Since S

N

2 reaction, has transition state as intermediate, no carbocation formations are there and nucleophile attack on less hindered carbon from the back side.

The minimum hindrance is provided by the primary carbon and maximum hindrance provided by the tertiary carbocation.

Thus Primary alkyl halide will give S

N

2 mechanism faster and tertiary alkyl halide will give slowest S

N

2 mechanism.