Class 12 Chemistry Haloalkanes and Haloarenes SN2 reaction and conditions required for it

SN2 reaction and conditions required for it

Alkyl halide: SN2 reaction will be slowed down if there exists steric congestion around the carbon atom undergoing the inversion process.

CH3X > RCH2X  >> R2CHX >>> R3CX

i.e. we conclude that if there is less congestion then the reaction will be faster.

Leaving group: the leaving group with a full negative charge is always expelled out. As a result the best leaving groups are those that can best stabilize an anion.

Solvent: Surroundings which the solvent surrounds can cause a reaction to go faster or slower. Solvent are of two types:

  1. Protic solvent: Nucleophile suffers salvation in which Protic solvent hydrogen bonds with anion that tries to attack the alkyl halide thus creating a shield around the nucleophiles. As a result reaction is slowed down. E.g. Alcohol, water
  2. Aprotic (polar) solvent: Aprotic solvents are those not capable of donating H's. Due to which it's favorable in SN2 reaction because it's a 1step reaction and it doesn't require forming or having H's to stabilize the Carbocation step. E.g. Acetone, DMSO.

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