Concerted nucleophilic substitution (SN2)
An SN2 step forms a bond to a nucleophile as the leaving group departs through one transition state.
Key knowledge
An SN2 step forms a bond to a nucleophile as the leaving group departs through one transition state. Backside approach gives inversion of tetrahedral geometry at the reacting centre. In the simple bimolecular regime, rate=k[substrate][nucleophile]; steric accessibility, nucleophile, leaving group and solvent affect the rate.
Values and equations
r = k[RX][Nu]
- r
- reaction rate mol L⁻¹ s⁻¹
- k
- bimolecular coefficient L mol⁻¹ s⁻¹
- [RX]
- substrate concentration mol L⁻¹
- [Nu]
- nucleophile concentration mol L⁻¹
Conditions and scope
- The mechanism applies to appropriate substrates and conditions; competing elimination or ionization can change the observed pathway.
- Geometric inversion need not change an R label to S when substituent priorities change.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Inspected one-step/backside geometry and four kinetic variables; no universal solvent ranking is asserted.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-chem-sn2
- Revision
- core.1
- Structured reference record
- University core expansion