Here’s a simple version of the differences between E1 and E2 reactions:
E1 Reaction
- Steps: Two steps – first the leaving group leaves, then a base removes a proton.
- Intermediate: Forms a carbocation.
- Base: Weak base is enough.
- Substrate: Works best with tertiary carbons.
- Stereochemistry: No strict requirement.
- Solvent: Polar protic (like water or alcohol).
- Competition: Competes with SN1.
E2 Reaction
- Steps: One step – base removes a proton as the leaving group leaves.
- Intermediate: No carbocation.
- Base: Needs a strong base.
- Substrate: Works best with secondary or tertiary carbons; primary works with bulky base.
- Stereochemistry: Requires anti-periplanar arrangement (hydrogen opposite leaving group).
- Solvent: Polar aprotic (like acetone or DMSO).
- Competition: Competes with SN2.
Key idea:
- E1 = 2 steps, carbocation, weak base.
- E2 = 1 step, strong base, stereospecific.