Table 6.5 Dielectric Constants of Some Common Solvents
Name Structure Dielectric constant, ε
APROTIC (NONHYDROXYLIC) SOLVENTS
Hexane CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 1.9
Benzene C 6 H 6 2.3
Diethyl ether CH 3 CH 2 –O–CH 2 CH 3 4.3
Chloroform CHCl 3 4.8
Ethyl acetate CH 3 C(O)OC 2 H 5 6.0
Acetone (CH 3 ) 2 CO 20.7
Hexamethylphosphoramide
(HMPA) [(CH^3 )^2 N]^3 PO^30
Acetonitrile CH 3 CN 36
Dimethylformamide (DMF) (CH 3 ) 2 NCHO 38
Dimethyl sulfoxide (DMSO) (CH 3 ) 2 SO 48
PROTIC (HYDROXYLIC) SOLVENTS
Acetic acid CH 3 C(O)OH 6.2
tert-Butyl alcohol (CH 3 ) 3 COH 10.9
Ethanol CH 3 CH 2 OH 24.3
Methanol CH 3 OH 33.6
Formic acid HC(O)OH 58.0
Water H 2 O 80.4
1) Water is the most effective solvent for promoting ionization, but most organic
compounds do not dissolve appreciably in water.
2) Methanol-water and ethanol-water are commonmixed solvents for nucleophilic
substitution reactions.
