Illustrated Glossary of Organic Chemistry

Trifluoroethanol: CF3CH2OH. A nonpolar (ε = 8.6) protic solvent, notable for its poor nucleophilicity due to the electron-withdrawing inductive effect of the trifluoromethyl group.


Lewis structure for trifluoroethanol.

CF3CH2OH
Slow

CF3CH2OH
Molecule A
Carbocation intermediate (reddish-orange)
Solvolysis product
The powerful electron-withdrawing inductive effect of the trifluoromethyl group makes trifluoroethanol a poor nucleophile. For example, dissolving molecule A (colorless) in trifluoroethanol (colorless) immediately gives a reddish-orange color due to a highly conjugated carbocation formed by ionization of the carbon-chlorine bond. This color persists for about a minute before fading away, indicating that the carbocation is capturing trifluoroethanol slowly.



CH3CH2OH 		Fast

CH3CH2OH
Molecule A
Carbocation intermediate (reddish-orange)
Solvolysis product
When the solvolysis solvent is ethanol, no transient color is observed, indicating the carbocation captures ethanol very quickly.