Group dipole moments

Functional group dipole moments

Introduction

The dipole moments listed below are derived from the table of → dipole moments. Since there is a significant difference between alkyl (methyl- , ethyl-) and aryl (phenyl-) derivatives they are listed separately. In the aryl derivatives it is possible to assign a direction to the dipoles based on the size of the dipole of p-derivatives. Negative values indicate that the substituent donates electrons, i. e. the direction of the dipole moment is from the substituent toward the ring.
The difference between the alkyl and aryl derivatives is due electron donation by resonance from substituents with free electron pairs to the aryl ring.


Dipole moments of functional groups
NameSymbolAlkylAryl
acetoxy‐‐OCOCH31.81-1.53
acetyl‐‐COCH32.762.90
amino‐‐NH21.20-1.48
bromo‐‐Br2.001.77
bromomethyl‐‐CH2Br1.801.85
chloro‐‐Cl2.051.69
chloroformyl‐‐COCl2.683.23
chloromethyl‐‐CH2Cl2.051.85
cyano‐‐CN3.404.00
cyanomethyl‐‐CH2CN3.503.50
dichloromethyl‐‐CHCl22.002.04
fluoro‐‐F1.001.57
formyl‐‐CHO2.402.75
hydrogen‐‐H0.000.00
hydroxy‐‐OH1.69-1.40
hydroxymethyl‐‐CH2OH1.661.68
iodo‐‐I1.871.70
isocyano‐‐NC3.473.51
isothiocyanato‐‐NCS3.313.00
mercapto‐‐SH1.39-1.33
methoxy‐‐OCH31.30-1.33
methoxycarbonyl‐‐COOCH31.741.85
methyl‐‐CH30.00-0.40
methylsulfanyl‐‐SCH31.57-1.27
nitro‐‐NO23.704.20
thiocyanato‐‐SCN3.643.59
trichloromethyl‐‐CCl31.572.11