10 Halogen Derivaties
4. Distinguish between
SN1 and SN2 mechanism of substitution reaction ?
Answer:-
| Factor | SN1 | SN2 |
|---|---|---|
| Kinetics | 1st order | 2nd order |
| Molecularity | Unimolecular | Bimolecular |
| Number of steps | Two steps | One step |
| Bond making and bond breaking | First the bond in the reactant breaks and then a new bond in the product is formed. | Simultaneous |
| Transition state | Two steps, two transition states | One step, one transition state |
| Direction of attack of nucleophile | Back side attack and front side attack | Only back side attack |
| Stereochemistry | Racemisation (If the substrate is optically active) | Inversion of configuration (If the substrate is optically active) |
| Type of substrate | Mainly 3° substrates | Mainly 1° substrate |
| Polarity of solvent | Polar protic solvent favorable | Aprotic (non-polar) or solvent with low polarity favorable |
| Intermediate | Intermediate involved | No intermediate |