Definition of Dielectric Constant:
- Dielectric Constant Measure of a solvent’s polarity.
- High dielectric constant = high polarity (e.g., water = 80).
Effect:
- High ε (e.g., water) stabilizes ionic species and may increase or decrease the rate depending on the mechanism.
- Solvents with low dielectric constants may:
- Promote neutral or non-ionic pathways
- Inhibit ionization-dependent reactions
- For ionic reactions, lower dielectric constants reduce rate