Concerted elimination (E2)
In an E2 step, removal of a β hydrogen, formation of an alkene bond and leaving-group departure occur together.
Key knowledge
In an E2 step, removal of a β hydrogen, formation of an alkene bond and leaving-group departure occur together. The simple rate law depends on substrate and base. Orbital alignment makes antiperiplanar geometry commonly favourable, giving conformational and stereochemical constraints.
Values and equations
r = k[RX][Base]
- r
- E2 reaction rate mol L⁻¹ s⁻¹
- k
- bimolecular coefficient L mol⁻¹ s⁻¹
- [RX]
- substrate concentration mol L⁻¹
- [Base]
- base concentration mol L⁻¹
Conditions and scope
- Syn elimination can occur in constrained cases; antiperiplanar preference is not an absolute rule for every substrate.
- Product selectivity depends on substrate geometry, base and conditions; substitution can compete.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Inspected concerted mechanism, bimolecular kinetics, isotope evidence and anti/syn geometry.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-chem-e2
- Revision
- core.1
- Structured reference record
- University core expansion