Nucleophilic Substitution Reaction
Nucleophilic Substitution Reaction
Nucleophilic substitution reaction is an organic reactions where one nucleophile replaces another nucleophile. The group which takes electron pair and displaced from the carbon is known as leaving group and the molecule on which substitution takes place is known as substrate. The leaving group leaves as a neutral molecule or anion. Nucleophilic substitution reaction is of three types-
1. Unimolecular Substitution (SN1) Reaction
2. Bimolecular Substitution (SN2) Reaction
3. Intermolecular Substitution (SNi) Reaction
| SN1 Reactions | SN2 Reactions |
|---|---|
| Unimolecular reaction | Bimolecular reaction |
| Follows a 1st order kinetic | Follows a 2nd order kinetic |
| Involves in at least two steps | Involves in single step |
| Rate of reaction depends on the concentration of the substrate | Rate of reaction depends on the concentration of both the substrate and the nucleophile |
| The rate-determining step involves a single molecule | The rate-determining steps involve two molecules. |
| It involves rearrangements of carbocations | No rearrangements of the carbocation. |
| Compared to the reactant, product have both inverted and retained configuration. | Compared to the reactant, products will have an inverted configuration. |
| Reactivity order: 3o > 2o > 1o > methyl |
Reactivity order: 3o < 2o < 1o < methyl |