Archive
14th of September 2015
Chemistry
Q:

can you explain me substitution nucleophilic bimolecular(SN2) and substituion nucleophilic unimolecular(SN1).

Jaskamal Kaur - CBSE - Class XII Science

Monday, September 14, 2015 at 18:18:PM

A:

SN2 reactions are known as bimolecular nucleophilic substitution reactions. The mechanism for these types of reaction is as follows.

In these reactions, inversion of configuration takes place. The increasing order of reactivity is

3 o halide < 2 o halide < 1 o halide

The reason behind the above trend is as follows.

Due to the presence of bulky substituents in 3 o and 2 o halides, nucleophile cannot approach.

For both SN1 and SN2 reaction, the order of reactivity of halides is

R−F << R−Cl < R−Br < R−I

The stereochemical aspects of nucleophilic substitution recation can be summarized as

In SN2 reaction, complete stereochemical inversion of configuration takes place.

Monday, September 14, 2015 at 18:48:PM