SN1Substitution Nucleophilic Unimolecular (1)
1. SN1 > SN2 (in alkaline/ethanolic solution)
• Formation of transition state requires more Ea
2. Leaving group: F < Cl < Br < I HalogenoalkanePolarity & ease to be nucleophilic attacked (n.a.)Bond strength & ease to break C-Xfluoro-↑ (most polar and
prone to n.a.)*
↓ (least polar and less prone to n.a.)↑ (strongest and hardest to break)
↓ (weakest and easiest to break)chloro-bromo-iodo-
*though C-F is the most polarized bond and susceptible to n.a, ultimately the C-X bond needs to be broken in the reaction, and due to C-F being a very strong bond it reacts very slowly.
3. Solvent
*Measured by colorimetry of silver halide precipitate formation upon rxn with AgNO3
SN2Substitution Nucleophilic Bimolecular (2)
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