Collect. Czech. Chem. Commun. 1980, 45, 2410-2416

Dipole moment and electron distribution of the amide group

Otto Exnera and Zlata Papouškováb

a Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6
b Institute of Chemical Process Fundamentals, Czechoslovak Academy of Sciences, 165 02 Prague 6-Suchdol


Dipole moments of five substituted N,N-dimethylbenzamides Ia-Ie were measured in benzene and dioxan solutions. The group moment of 12.7 . 10-30 C m (at an angle of 80° to the C(1)-C bond) was resolved into components and a mesomeric moment of 4.7 . 10-30 C m (in the direction from N to C) was derived, accounting for the conjugation within the dimethylamide group. A smaller mesomeric moment in the same direction was found for the unsubstituted amide group. The results are but roughly consistent with an interpretation in terms of the mesomeric formulae A ##e B.