Conformation around several equivalent bonds. Polymethoxy derivatives of benzene

Abstract

Dipole moments of benzene methoxy derivatives I-IX were measured in benzene solution and discussed in terms of the conformation around the Car-O bonds, exploiting the method of graphical comparison and systematic introduction of substituents. In the case of 1,2-dimethoxybenzene several explanations are in accord with the dipole moment data. However, considering all available evidence, most probable seems to be the presence of two conformers, one of which is non-planar with two non-equivalent methoxy groups (IC). The conformation of 1,2,3-trimethoxybenzene is similar to that found for many derivatives in the crystalline phase (VC), only the outer methoxy groups are probably slightly deviating from the coplanar position.