Reaction Mechanisms

Watch organic chemistry mechanisms unfold in 3D with electron flow animations.

SN2: Methyl Bromide + Hydroxide

CH₃Br + OH⁻ → CH₃OH + Br⁻

SN2
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Nucleophilic Attack

Step 1 of 2

About This Reaction

Bimolecular nucleophilic substitution. The hydroxide ion attacks methyl bromide from the backside, displacing bromide in a single concerted step with inversion of configuration.

Current Step

Nucleophilic Attack

The hydroxide ion (nucleophile) approaches the carbon atom from the backside - directly opposite to the bromine leaving group. This is called backside attack and is characteristic of SN2 reactions. The nucleophile begins to form a partial bond with carbon as it attacks.

Backside Attack

Mechanism Steps

Reaction

CH₃Br + OH⁻CH₃OH + Br⁻

26 e⁻ → 26 e⁻

Energy Diagram

EnergyReaction CoordinateReactantsTransition StateProductsEa = 75 kJ/molΔG = -15 kJ/mol

Key Concepts

  • Bimolecular (rate = k[substrate][nucleophile])
  • Backside attack (180° approach angle)
  • Concerted mechanism (single step, no intermediate)
  • Walden inversion (stereochemistry inverts)
  • Favored by: strong nucleophile, methyl/primary substrate, polar aprotic solvent

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